天津职业大学文本 Nearpoint of Convergence Test Procedure, Target Selection, and Normative Data_眼屈光学

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m中00=w。学号方 ORIGINAL ARTICLE Nearpoint of Convergence:Test Procedure, Target Selection,and Normative Data MITCHELL SCHEIMAN,OD,FAAO,MICHAEL GALLAWAY,OD.FAAO. KELLY A.FRANTZ,OD,FAAO,ROBERT J.PETERS,OD,FAAO,STANLEY HATCH,OD,FAAO, MADALYN CUFF,OD,and G.LYNN MITCHELL,MAS,FAAO mi Co可Cpwy.Pria,Pw则南wi5G以.f指isCege时ptowery Chi,带ws代A以片rk PriY,Gned是ide,Mdichigan(%w Fngland Cailegr of Optomet可%Roon,Menechett (SH以Privte Prctin%C以Cwx ofOp.The Ohie Sr Lininrruty,Cala,Ohie (GLM) ABSTRACT:Background.The purpose of this study was to help determine the must appropriate target to be used for the assessment of the nearpoint of convergence,normative data for the hreak and recovery in adults,and the diagnostic value of the red-glass modification and repetition of the nearpoint of convergence.Methods.A total of 175 subjects with normal binocular vision and 38 subjects with convergence insufficiency were evaluated.The nearpoint of cunvergence was measured three ways,with an accummodative target,a penlight,and a penlight with red and green glasses.The nearpoint of convergence was also measured using a penlight for 10 repetitions.Results.Results suggest a clinical cutoff value of 5 cm for the nearpoint of convergence break and 7 cm for the nearpoint of comergence recovery with either an accommodative target or a penlight with red and green glasses.Conclusion.This study establishes normative data for the nearpoint of convergence break and recovery in the adult population and supports the value of various test modifications when other testing is equivocal.(Optom Vis Sci 2003:80:214-225) Key Words:nearpoint of convergence,cumvergence irsufficierxy,binacular visin testing he assessment of the nearpoint of convergence (NPC)is review of the literature found only one reoent study that was de- widely wed by eye care practiriones in the routine peimary signed to detemine the normative data for this test.In this study. anniandioften indhdoasa test pmecdume Hayrs et al.d espected vahes for the NPC fur sceol- for vision seenings.The NPCisaso considered an important aged children.We were unabk to retreve any study that system diagnostic finding in the assessment of convergence invaffiien- atically investgated the expected values for the NPC in adults. cy Foe cxample,Daum reviewad 58 studics of convengna l'able I is a cumpilarion of rooommendations in current texctboolks insufficiency and found that 36%of the studies specified a receded and articles.As the table illustrates there areavarety of nearpoint of comvergence as an important criterion for diagnosis of recommendations for target seection,and the recommended ex convergence insufficiency.A survey conducted by Rouse et pected findings foe the hreak range fram to 17.5 cm.More than derermined that the NPC was ud in making the diagnoeis of half of the authon did not indude an cxpccred finding for the convergence insufficiency by 9.3.8%6 of optometrists surveyed recovery measurement.The expected findings for those who did Thirty-five percent af the doctors indicatd that one criterion was mport a reoowery finding ranged from 8 to 11 em.Other than the suficient to diagnos convergence insufficiency,and the most fre- study by Hayes et al.,not one of the other authors prowided quently used singl diagnostic characteristic w the NPC.Given supportive daaor refeefoc their supaesions for either the its widrspread anddiagtic imporanee.is surpring that rrcommended tarpet o epocted finding. the NPC test procedure,target selection.and ommaive data have We were able to find one aride that reported the NPCin adults received limited investigtion since its introduction as an impor- with normal binocularity and adults with convergence insufficien tant routinc tet prooodure in the late 19th and cary 20th cy.This study was not designed spccifically to ineigie nor- cenmrinx线6 mrive data foe NPC.Howrver,in the cnurse of stadlying the Although most authocs describe the NPC as part of the mini reationship between the NPC and verpence amplitudes in comver mum database for routine vision exmination,7-our gerce insufficiency patients,the authoes reported an average hreak

ORIGINAL ARTICLE Nearpoint of Convergence: Test Procedure, Target Selection, and Normative Data MITCHELL SCHEIMAN, OD, FAAO, MICHAEL GALLAWAY, OD, FAAO, KELLY A. FRANTZ, OD, FAAO, ROBERT J. PETERS, OD, FAAO, STANLEY HATCH, OD, FAAO, MADALYN CUFF, OD, and G. LYNN MITCHELL, MAS, FAAO Pennsylvania College of Optometry, Philadelphia, Pennsylvania (MS, MG), Illinois College of Optometry, Chicago, Illinois (KAF), Private Practice, Grand Rapids, Michigan (RJP), New England College of Optometry, Boston, Massachusetts (SH), Private Practice, (MC), College of Optometry, The Ohio State University, Columbus, Ohio (GLM) ABSTRACT: Background. The purpose of this study was to help determine the most appropriate target to be used for the assessment of the nearpoint of convergence, normative data for the break and recovery in adults, and the diagnostic value of the red-glass modification and repetition of the nearpoint of convergence. Methods. A total of 175 subjects with normal binocular vision and 38 subjects with convergence insufficiency were evaluated. The nearpoint of convergence was measured three ways, with an accommodative target, a penlight, and a penlight with red and green glasses. The nearpoint of convergence was also measured using a penlight for 10 repetitions. Results. Results suggest a clinical cutoff value of 5 cm for the nearpoint of convergence break and 7 cm for the nearpoint of convergence recovery with either an accommodative target or a penlight with red and green glasses. Conclusion. This study establishes normative data for the nearpoint of convergence break and recovery in the adult population and supports the value of various test modifications when other testing is equivocal. (Optom Vis Sci 2003;80:214–225) Key Words: nearpoint of convergence, convergence insufficiency, binocular vision testing The assessment of the nearpoint of convergence (NPC) is widely used by eye care practitioners in the routine primary care examination1, 2 and is often included as a test procedure for vision screenings.3–7 The NPC is also considered an important diagnostic finding in the assessment of convergence insufficiency.8–13 For example, Daum10 reviewed 58 studies of convergence insufficiency and found that 36% of the studies specified a receded nearpoint of convergence as an important criterion for diagnosis of convergence insufficiency. A survey conducted by Rouse et al.14 determined that the NPC was used in making the diagnosis of convergence insufficiency by 93.8% of optometrists surveyed. Thirty-five percent of the doctors indicated that one criterion was sufficient to diagnose convergence insufficiency, and the most frequently used single diagnostic characteristic was the NPC. Given its widespread use and diagnostic importance, it is surprising that the NPC test procedure, target selection, and normative data have received limited investigation since its introduction as an important routine test procedure in the late 19th and early 20th centuries.15, 16 Although most authors describe the NPC as part of the minimum database for a routine vision examination,1, 2, 7, 17–33 our review of the literature found only one recent study that was designed to determine the normative data for this test. In this study, Hayes et al.33 suggested expected values for the NPC for schoolaged children. We were unable to retrieve any study that systematically investigated the expected values for the NPC in adults. Table 1 is a compilation of recommendations in current textbooks and articles.1, 2, 7, 17–33 As the table illustrates, there are a variety of recommendations for target selection, and the recommended expected findings for the break range from 5 to 17.5 cm. More than half of the authors did not include an expected finding for the recovery measurement. The expected findings for those who did report a recovery finding ranged from 8 to 11 cm. Other than the study by Hayes et al.,33 not one of the other authors provided supportive data or a reference for their suggestions for either the recommended target or expected findings. We were able to find one article that reported the NPC in adults with normal binocularity and adults with convergence insufficiency.25 This study was not designed specifically to investigate normative data for NPC. However, in the course of studying the relationship between the NPC and vergence amplitudes in convergence insufficiency patients, the authors reported an average break 1040-5488/03/8003-0214/0 VOL. 80, NO. 3, PP. 214–225 OPTOMETRY AND VISION SCIENCE Copyright © 2003 American Academy of Optometry Optometry and Vision Science, Vol. 80, No. 3, March 2003

TABLE 1. Previous suggestions for NPC target selection and expected findings.a Source Expected Break Expected Recovery Target/Method Based on Davies17 7 cm NR Target not specified, suggests repeating test 8–12 times Not stated Capobianco18 6–10 cm NR Penlight, stresses importance of red glass test Not stated Carter19 5 cm 9 cm Pencil, pen point, or other small object Not stated Duke-Elder20 10 cm NR Target and method not specified Not stated Burian and von Noorden21 8–10 cm NR Target not specified, stresses importance of red glass modification Not stated Hoffman and Rouse22 5 cm 8 cm Target and method not indicated Not stated Mohindra and Molinari23 6 in Within 2 in of break Red glass, repetition suggested Not stated Pickwell and Hampshire24 10 cm NR Black vertical line on a white card Not stated Cohen et al.7 10 cm NR A bell Not stated Shippman et al.25 5 cm NR Target and method not indicated Clinical study London26 5 cm 8 cm Penlight, important to repeat to check for fatigue effects, talks of diagnostic potential of NPC with red glass (suggests that a difference of 3 cm has diagnostic value) Not stated Helveston et al.27 11 cm NR Accommodative target Not stated Wick28 NR NR Target not indicated, repeat test five or more times Not stated Pickwell29 10–15 cm NR Any suitable target Not stated Carlson et al.2 17.5 cm Within 7.5 cm of break Penlight for screening, use accommodative target and red glass/penlight if NPC is greater than 4 in/7 in. Not stated London30 6–10 cm NR Accommodative target or penlight, repeat five times Not stated Eggers31 10 cm NR Target not indicated Not stated Griffin and Grisham32 8 cm 11 cm Small detailed target, perform five times Class notes Grosvenor1 8 cm NR Penlight, suggests repeated testing; if NPC is greater than 12–15 cm with repeated testing, it is evidence of a convergence insufficiency. Not stated Hayes et al.33 6 cm 10 cm Astron International Accommodative Rule and a 20/30 single column of letters. Examiner moved target at a rate of approximately 1–2 cm/s. Well-designed study a NPC, nearpoint of convergence; NR, not reported. Nearpoint of Convergence—Scheiman et al. 215 Optometry and Vision Science, Vol. 80, No. 3, March 2003

216 Nearpoint of Convergence-Scheiman et aL finding of s em(range,1 to 15 cm)for a group of 46 adult clinical METHODS patients with noemal binoculr vision.The average hreak for adults diagnod with convergence insufficiency was 7.9 cm (rangr,I to Two groups of subjects were evaluated.The first group con- 20 cm).The authurs did not rport the target uad for the teing sisted of optometry students (N 175;ag range,22 to 37 years; The rocent study by Hayes ct al was designed to establish averige age,24.9).These subjects received a full eye examination pormative values for the NPC using a standardized and reliable We orally reviewed the study with each subject and ourlined the protecal.They sudid 297 schookhildren in kindenganen,thind riks and benefits.After receiving consent.we enroDed subjects in grack,and sixth gradke who had pasd a schonl-based Modificd the sudy.All subjects had 20/20 visual acuity in both eyes (dis Cinical Tochnigue vision scrcening.Baod on their resules,they tance and near)with best refraction.We excluded all subjects with suggested a clinical cutoff value of 6 cm for the NIC break for a strabismic or nonstrabismic binoolar vision problem ornc schoolchildren usingn accommodative target. cummodative disorder.We uod traditional normative valuo to There has also heen speculation about modification af the stan- determine whether a subject had an accommodative or ponstrabis- dard pruoxdure to make the tost more ansitive and of greater mic binooular vision disorder. diagnosic and prognustic valuc.In an entirely ancodotal report in Gmp two consisted of clinic paticnts at The Fye Institte of 1952,Capobianco recommended that the NPC be performed The Pennsylvania Collge of Optometry and the lllinois Eye In- twice,onxce with a penlight and igain with a penlight and a red glass stitute of the Illinois College of Optometry (N-38:age rangr,9 in front ofonc cyc.Capobianco refers to this scoond methed as the to52 years:average age,20.2).We orally reviewed the study with subjcctive NPC.She suggests that this modification might poen- each subjer and nutlined the ricks and henefits.After reeriving tially yield useful diagnostic and prognoetic information.Acoord- conent,we cnrollad subicers in the study.We cxduded subicers ing to Capobianco,in cases in which a comvergence insufficiency is with <2020 visual acuicy in each eye with best comection or suspected but the NPC with a penlight alone is normal the sub conseant strabismus.All subjects in this group were diagnased with jective NPC may be more rensote and demonstrate a better corre. comergenee insulfieiency tang eriteru of exophoris greater at lation with fusional amplituds.Thus,the red-ghss NPC may be a near than at far,receded NPC (we selected a value of 5 cm for the more sniive diagnostictes.She chaims that the test ao provides NPC based on the previous worlr of Shippman et al.,and re- information about progress in treatment because the NPC tested duced positive fisional vergence amplitdes SD from Moe- with the red glass modification improves moce rapidy than the gan's expected findings).The NPC was considered abnormal if the NPC tested with the penlight alone.Although several autbors rec mesurement was receded wich any of the three targers described ommend that this procodure be incorporatod as par of the stan- below. dard ssessment of conve amplitude o reearch We administered an cight-item symptom qucsionnaire (Table daa have been produced t support its use or any of Capobianco's 2)to al subjects.This questionnaire was adapted from question- asertions about the value of the test. naire developed and used by Cooper et al Each item wis scod Another modification that has been suggested is repetition of on a scale ofone to five.The lower the scoee,the los the sympoms the NIC with the asumption that symptomatic patients will The highest pussible sympcom soon was 40,indicating a wery show a greater recession in the NPC with repeated testing com symptomaric sbjct,and the lowes posibk orwas eight,in- pared with normals.Davies.7in 1946,appears to be the orginal dicating no symptoms.This survey has not been tested for reliabil- source for this recommendation.He advocaced repeating the NPC ity and rpeatability.A symptom survey (Comvergence Insffi- eight to 12 times and sueed that a hreakdown would occur at cicncy and Reading Study sympeom surve)is now aailbl that about five to six repetitioes and the beeak would recede to 25 to0 has been shown to be a valid instrument foe differentiating conver- cm.This would indicate poor comvergence reserve.Subsequent gence insufficiency (CI)chillren from those with normal binocu- authors have suggested chat this might be a wocthwhile part of the lr vision.However,at the time we performrd this study.this NPC evaluation.Although this may mae intu symptom survey wis not available. itive sense,again no supporing dataexist Even ifa dlinician adopes For all subjects,the NPC was assessed hy one of the authors this approch,the literature is undlear abou how much ofa change using a standard push-up technique with a Bernell Accommo- in the NPC with repeticion should be considered significant. dative Rule.We used an instructional set similar to the one first Thus,we have dinical test that is comidered part of the min described by Hayes et al.The Accommodative Rule was imum database for a primary eye cre exminio is ofren used as placed just above the nose at the brow berween the rwo eyes. a screening peocedure for binoculr vision peoblems and is a key The target was moved toward the subjccts at a rate of about 1 to criteron for the dagnosis of convergence insuffxiency.yet there is 2 cm/s.Subjects were encouraged to try to keep the target alack of supportive,clinical research.There isa lack of agreement single.The subjective break and recovery values were meisured about the most appropeiate tanget and the expecred finding for a and recordod in centimeters.If there was no subjective report of pormal or abnormal break in adults.In addition,although clini- diplopia,the points at which the patient objectively loet and cians have developed several potentially valuahle modifications of regained ocular alignment were recorded as the break and re- the NPC test.there are ne data to validlate the use of these eowery.The NPC was measured ance with each of the follow- mndificarion& ing an accommodative target (AT)(single 20/30 letter),a pen- The purpose of this study is to investigate these issues and belp light (PL),and with penlight while the subject wore red/grn determine the moot appropeiate target to be used for the NPC. glasses (PLRG).Red and green glases were used instead ofa red normative data for the hreak and recowery in adults and the clinical glass to free both hands of the examiner so that he could hold value of modifications of the test using filrers and rrperitions. the Accommodative Rule with both hinds.The order of testing

finding of 5 cm (range, 1 to 15 cm) for a group of 46 adult clinical patients with normal binocular vision. The average break for adults diagnosed with convergence insufficiency was 7.9 cm (range, 1 to 20 cm). The authors did not report the target used for the testing. The recent study by Hayes et al.33 was designed to establish normative values for the NPC using a standardized and reliable protocol. They studied 297 schoolchildren in kindergarten, third grade, and sixth grade who had passed a school-based Modified Clinical Technique vision screening. Based on their results, they suggested a clinical cutoff value of 6 cm for the NPC break for schoolchildren using an accommodative target. There has also been speculation about modification of the standard procedure to make the test more sensitive and of greater diagnostic and prognostic value. In an entirely anecdotal report in 1952, Capobianco18 recommended that the NPC be performed twice, once with a penlight and again with a penlight and a red glass in front of one eye. Capobianco refers to this second method as the subjective NPC. She suggests that this modification might potentially yield useful diagnostic and prognostic information. According to Capobianco, in cases in which a convergence insufficiency is suspected but the NPC with a penlight alone is normal, the subjective NPC may be more remote and demonstrate a better correlation with fusional amplitudes. Thus, the red-glass NPC may be a more sensitive diagnostic test. She claims that the test also provides information about progress in treatment because the NPC tested with the red-glass modification improves more rapidly than the NPC tested with the penlight alone. Although several authors recommend that this procedure be incorporated as part of the standard assessment of convergence amplitude,2, 21, 23, 26 no research data have been produced to support its use or any of Capobianco’s assertions about the value of the test. Another modification that has been suggested is repetition of the NPC, with the assumption that symptomatic patients will show a greater recession in the NPC with repeated testing compared with normals. Davies,17 in 1946, appears to be the original source for this recommendation. He advocated repeating the NPC eight to 12 times and suggested that a breakdown would occur at about five to six repetitions and the break would recede to 25 to 30 cm. This would indicate poor convergence reserve. Subsequent authors have suggested that this might be a worthwhile part of the NPC evaluation.1, 2, 23, 26, 28, 30, 32 Although this may make intuitive sense, again no supporting data exist. Even if a clinician adopts this approach, the literature is unclear about how much of a change in the NPC with repetition should be considered significant. Thus, we have a clinical test that is considered part of the minimum database for a primary eye care examination, is often used as a screening procedure for binocular vision problems, and is a key criterion for the diagnosis of convergence insufficiency, yet there is a lack of supportive, clinical research. There is a lack of agreement about the most appropriate target and the expected finding for a normal or abnormal break in adults. In addition, although clinicians have developed several potentially valuable modifications of the NPC test, there are no data to validate the use of these modifications. The purpose of this study is to investigate these issues and help determine the most appropriate target to be used for the NPC, normative data for the break and recovery in adults, and the clinical value of modifications of the test using filters and repetitions. METHODS Two groups of subjects were evaluated. The first group consisted of optometry students (N 175; age range, 22 to 37 years; average age, 24.9). These subjects received a full eye examination. We orally reviewed the study with each subject and outlined the risks and benefits. After receiving consent, we enrolled subjects in the study. All subjects had 20/20 visual acuity in both eyes (distance and near) with best refraction. We excluded all subjects with a strabismic or nonstrabismic binocular vision problem or an accommodative disorder. We used traditional normative values to determine whether a subject had an accommodative or nonstrabismic binocular vision disorder.34, 35 Group two consisted of clinic patients at The Eye Institute of The Pennsylvania College of Optometry and the Illinois Eye Institute of the Illinois College of Optometry (N 38; age range, 9 to 52 years; average age, 20.2). We orally reviewed the study with each subject and outlined the risks and benefits. After receiving consent, we enrolled subjects in the study. We excluded subjects with 20/20 visual acuity in each eye with best correction or constant strabismus. All subjects in this group were diagnosed with convergence insufficiency using criteria of exophoria greater at near than at far, receded NPC (we selected a value of 5 cm for the NPC based on the previous work of Shippman et al.25), and reduced positive fusional vergence amplitudes (1 SD from Morgan’s expected findings). The NPC was considered abnormal if the measurement was receded with any of the three targets described below. We administered an eight-item symptom questionnaire (Table 2) to all subjects. This questionnaire was adapted from a questionnaire developed and used by Cooper et al.36 Each item was scored on a scale of one to five. The lower the score, the less the symptoms. The highest possible symptom score was 40, indicating a very symptomatic subject, and the lowest possible score was eight, indicating no symptoms. This survey has not been tested for reliability and repeatability. A symptom survey (Convergence Insufficiency and Reading Study symptom survey37) is now available that has been shown to be a valid instrument for differentiating convergence insufficiency (CI) children from those with normal binocular vision. However, at the time we performed this study, this symptom survey was not available. For all subjects, the NPC was assessed by one of the authors using a standard push-up technique with a Bernell Accommodative Rule. We used an instructional set similar to the one first described by Hayes et al.33 The Accommodative Rule was placed just above the nose at the brow between the two eyes. The target was moved toward the subjects at a rate of about 1 to 2 cm/s. Subjects were encouraged to try to keep the target single. The subjective break and recovery values were measured and recorded in centimeters. If there was no subjective report of diplopia, the points at which the patient objectively lost and regained ocular alignment were recorded as the break and recovery. The NPC was measured once with each of the following: an accommodative target (AT) (single 20/30 letter), a penlight (PL), and with penlight while the subject wore red/green glasses (PLRG). Red and green glasses were used instead of a red glass to free both hands of the examiner so that he could hold the Accommodative Rule with both hands. The order of testing 216 Nearpoint of Convergence—Scheiman et al. Optometry and Vision Science, Vol. 80, No. 3, March 2003

Ncarpoint of CorwergenceScheiman ct al.217 TABLE 2. Symptom Questonnaire 1.How long can you do reanwork fi.e..reating writing compuer work,sewing etc)without discumlrt headches,eye ache, burning stingng watering bluminess,double vision.kss al vision.or liredness? 1.at least 3 hours 2.up to 2 hours 3.up t 1 hour 4.up to 301 minures 5.up to 15 minutes 2.How often do you get headaches when you do neanwork? 1.never (0%of the timch 2.ocasionally (approximalehy 25%of the timel 3.often (approximately 50%of the time) 4.very omen (approomately 75'%of the timel 5.every time I do nearwork (100%of the time) 3.lf you experience headaches during nearwork how bothersome are these headaches fi.e to what degree do they interiere with your nomal functioningl? 1.minimally bothersome 2.mildly bothersome 3.moderateh bothersomne 4.中bothersorne 5.cxtromely bothersome 4.Do your cyes pull,ache,or water whon you do nearwork 1.never (0%of the time) 2.occasionally lapproodimately 25%.of the timel 3.often (pproximately 501%of the time) 4.very oiten lapprooumately 73%%of the timel 5.cvery time I do nearwork 1100%%of the time 5.Does the reading malerial ever become blury.run together,or jump when you do neanork? 1.never (0%of the time) 2.occasionally lapprooumately 25'%of the timel 3.olten (approximalely 50%of the time) 4.very often (approximatehy 75%of the timel 5.every time I do nearwork (100%of the time) 6.Does reading material ever become double when you do nearwork? 1.never (0%of the time) 2.occasionally (approximalehy 25%of the time) 3.ollen (pproximalely 50%ol the time) 4.very ofton (approodmately 75'%of the timel 5.cvery time I do nearwork 110%of the time) 7.Immediately following prolonged nearwork do abjects a distance appear blurry for a short period of time? 1.nover (r%,of the timel 2.occasionally tapprooimatel5%of the timel 3.often (approximately0%of the time) 4.very cften lapprooimaehy 7%of the timel 5.every time I dlo nearwork (1005 of the time) 8.Do your cyes fccl tircd or do you lose your concontration whon doing ncarwork? 1.never (of the timel 2.occasionally (approximalely 25%of the timel 3.oflen (approximalely 50%of the lime) 4.very omen (approoimately 75%%of the timel 5.every time I do nearwork (100%oi the time) with these three targets was randomized.After a 30-s hreak,the were grncratrd for boch hreak and reoomery measurements oh- NPC with a penlight was then performed an additional 10 tained using cach of the thrce targat types Thea calculations were times.Finally,each subject filled out the cight-item symptom performed sparaty for nummal and comergenoe insufficicry questionnaire to assess the presence and severity of asthenopic subjects Within each group,a repeated-measures analysis of vari- complaints during nearpoint activiries.All testing was per- ance was used to compare the mean hreak and recwery values formrd with full rnom illumination. ohtained with cach of the targetsfae testing was performod Descriptive statisticx (mcans,sandard deviation,mcdians ctc.)using Schcff's mcthud of multipk comparison.Gien the non- O小wwr句d Virion Srieuer,Vl8 No 3 March2U

with these three targets was randomized. After a 30-s break, the NPC with a penlight was then performed an additional 10 times. Finally, each subject filled out the eight-item symptom questionnaire to assess the presence and severity of asthenopic complaints during nearpoint activities. All testing was performed with full room illumination. Descriptive statistics (means, standard deviation, medians, etc.) were generated for both break and recovery measurements obtained using each of the three target types. These calculations were performed separately for normal and convergence insufficiency subjects. Within each group, a repeated-measures analysis of variance was used to compare the mean break and recovery values obtained with each of the targets. Post hoc testing was performed using Scheffe’s method of multiple comparison. Given the nonTABLE 2. Symptom Questionnaire 1. How long can you do nearwork (i.e., reading, writing, computer work, sewing, etc.) without discomfort, headaches, eye ache, burning, stinging, watering, blurriness, double vision, loss of vision, or tiredness? 1. at least 3 hours 2. up to 2 hours 3. up to 1 hour 4. up to 30 minutes 5. up to 15 minutes 2. How often do you get headaches when you do nearwork? 1. never (0% of the time) 2. occasionally (approximately 25% of the time) 3. often (approximately 50% of the time) 4. very often (approximately 75% of the time) 5. every time I do nearwork (100% of the time) 3. If you experience headaches during nearwork how bothersome are these headaches (i.e., to what degree do they interfere with your normal functioning)? 1. minimally bothersome 2. mildly bothersome 3. moderately bothersome 4. very bothersome 5. extremely bothersome 4. Do your eyes pull, ache, or water when you do nearwork? 1. never (0% of the time) 2. occasionally (approximately 25% of the time) 3. often (approximately 50% of the time) 4. very often (approximately 75% of the time) 5. every time I do nearwork (100% of the time) 5. Does the reading material ever become blurry, run together, or jump when you do nearwork? 1. never (0% of the time) 2. occasionally (approximately 25% of the time) 3. often (approximately 50% of the time) 4. very often (approximately 75% of the time) 5. every time I do nearwork (100% of the time) 6. Does reading material ever become double when you do nearwork? 1. never (0% of the time) 2. occasionally (approximately 25% of the time) 3. often (approximately 50% of the time) 4. very often (approximately 75% of the time) 5. every time I do nearwork (100% of the time) 7. Immediately following prolonged nearwork do objects at distance appear blurry for a short period of time? 1. never (0% of the time) 2. occasionally (approximately 25% of the time) 3. often (approximately 50% of the time) 4. very often (approximately 75% of the time) 5. every time I do nearwork (100% of the time) 8. Do your eyes feel tired or do you lose your concentration when doing nearwork? 1. never (0% of the time) 2. occasionally (approximately 25% of the time) 3. often (approximately 50% of the time) 4. very often (approximately 75% of the time) 5. every time I do nearwork (100% of the time) Nearpoint of Convergence—Scheiman et al. 217 Optometry and Vision Science, Vol. 80, No. 3, March 2003

218 Nearpoint of Comvergence-Scheiman et al. normal distribution of NPC values for both groupe,natural log- tically significant,were 0.7cm and thenefore not clinically mcan- transormed values were used when performing these analyses. ingful.For clinical testing purposes,the break and recovery data for Miced model analysis was used to model the repeated measure nermal subjecs are essentially identical for each of the three target ments cbtained for both NPC break and recovery as a function of typex measurenent number.In addition,indicator variables were in. The distribution of brcak and nocovery values for cach of the cluded in the model to determine whether the slope of the line three targets is shown in Fig.1 and 2.Cumulative distributions relating break ot recovery to measrement number was consistent are shown in Fig支.Break values for cac小of the three targets are across the entire range of repears.Akiake's Infocmation Criterion unimocal and right skewed with a cnncrntration of mranrements values were used to judge model fit.Due to the non normal dis. in the0.5-to 3.0-cm range (Fig.1).In fict,slighdly moce than 70% tribution of break and recovery values.nanaral log,transformed of the subjects had break values of3 cm with AT (Fig 3).The data was used in all anlyses.These analyses were performed sepa- percentage of subpects with valuts of5$cm increases to 75%using ratehy for CI and pormal subjects. PL and exceeds 80%using PLRG.More than 90%of subjects had break values in the range of 0.5 to 5.0 cm regard ess of the target. RESULTS As with break,the distributions of NPC ncuviry valucs an Normative Data and Target Selection unimodal and skewed to the right (Fig.2).As indicated by the median values in Table 3,more than 50%6 of the recovery measure- Descripcive staristics for both break and recovery values ob ments were 24.0 cm for sach of the three tangets.Recovery mea- tained from the pormal subjects are summarized in Table 3.The srcments of 10 cm were obeervod in over 90%of the subjicurs mean hreak for both the AT ard PLRG targets is about 25 cm. using each target. The mean break vale for the PI target is slighely lower at 2.0 em Also included in Tahle 3 are descriptive staristics for the NPC The mean recowery for the AT and PLRG targets was also similar at hreak and recoery measumments obeained from suhjeets with 435 cm and larger than the mean for PL ar 3.7 cm.Repeated. convergence insufficiency.The mean brek for AT is lowest at just measures anysis of variance (ANOVA)indicated a significant over 9 cm,increasing to almost 12 cm wich PI and almost 15 cm difference in the mean break meauurements obtained via the three with PLRG.AT also produced the lowest mean recovery at 12.5 targrts(p D.0001).Po Awe texting indicated a significant differ- cm,followed hy PL with a mean of just over 17.5 cm.As with ence in AT and PL (p 0.0001).AT and PLRG (p -0.0033). break.the mean recovery for PLRG was largest at slightly more and PL and PLRG (p=0.0018).The acrual differences,however. than 20.5 cm.The rpeated-measurs ANOVA indicatd a signif. were <0.cm and are not comsidered clinically meaningful.A icant difference in the mean break measurements obtained via the significant differencen ean NPC revery foe the three tgets three tagets (p0001).Por testing indicated a significant was also found (p 0.0001)using the repeared-measures difference in AT and Pl.(p 0.0104)and AT and PI.RG (p ANOVA.The mean recowvery for AT and PL were significant dif. 0.0001).Unlike normal subjcets,the statistically significant differ ferent(p-D000)ang with the mens foe PLand PLRG(pences in break values obtained with the three tarets were also 0.0001).As with the break valuss,the differences although staris- clinically meaningful.A significant difference in mean NPC recow- TABLE 3. Descriptive statistics for NPC hreak and recovery by method obtained and study group." Method Oltained Mean SD Minimum Median Maximum ▣sub3sN=3l Break Accommodlative langet 932 6.74 05 7,75 310 Penlight 11.06 且.40 2.D 10.0 410 Penlight with KG glasses 14.75 10.0 2.D 11.0 410 Recovery Accommodative target 12.47 7.83 1.D 10.5 360 Penlight 1768 11.24 4.D 14.25 510 Penlight with R/G glasses 20.59 12.32 5.0 15.5 56.0 Noemal binocular vision subjects IN 175) Break Accommodative targct 2.49 1.74 a.5 2.0 70 Penlight 2.06 1.85 0.5 1.5 100 Penlight with R/G glasses 2.38 2.11 0.5 2.0 110 Recovory Accommodative target 4.35 2.74 1.D 4.0 110 Penlight 3.74 2.87 0.5 3.0 14.0 Penlight with R glasses 435 3.26 1.D 4.0 170 NPC,nearpoint of convergence:Cl comvergence inuficiency:RiG,red and green. 小wwr时wud Viion &iewer,Vd8nNn3Manh2nU

normal distribution of NPC values for both groups, natural logtransformed values were used when performing these analyses. Mixed model analysis was used to model the repeated measurements obtained for both NPC break and recovery as a function of measurement number. In addition, indicator variables were included in the model to determine whether the slope of the line relating break or recovery to measurement number was consistent across the entire range of repeats. Akiake’s Information Criterion values were used to judge model fit. Due to the non-normal distribution of break and recovery values, natural log transformed data was used in all analyses. These analyses were performed separately for CI and normal subjects. RESULTS Normative Data and Target Selection Descriptive statistics for both break and recovery values obtained from the normal subjects are summarized in Table 3. The mean break for both the AT and PLRG targets is about 2.5 cm. The mean break value for the PL target is slightly lower at 2.0 cm. The mean recovery for the AT and PLRG targets was also similar at 4.35 cm and larger than the mean for PL at 3.74 cm. Repeatedmeasures analysis of variance (ANOVA) indicated a significant difference in the mean break measurements obtained via the three targets (p 0.0001). Post hoc testing indicated a significant difference in AT and PL (p 0.0001), AT and PLRG (p 0.0033), and PL and PLRG (p 0.0018). The actual differences, however, were 0.5 cm and are not considered clinically meaningful. A significant difference in mean NPC recovery for the three targets was also found (p 0.0001) using the repeated-measures ANOVA. The mean recovery for AT and PL were significant different (p 0.0001) along with the means for PL and PLRG (p 0.0001). As with the break values, the differences, although statistically significant, were 0.7 cm and therefore not clinically meaningful. For clinical testing purposes, the break and recovery data for normal subjects are essentially identical for each of the three target types. The distribution of break and recovery values for each of the three targets is shown in Figs. 1 and 2. Cumulative distributions are shown in Fig. 3. Break values for each of the three targets are unimodal and right skewed with a concentration of measurements in the 0.5- to 3.0-cm range (Fig. 1). In fact, slightly more than 70% of the subjects had break values of 3 cm with AT (Fig. 3). The percentage of subjects with values of 3 cm increases to 75% using PL and exceeds 80% using PLRG. More than 90% of subjects had break values in the range of 0.5 to 5.0 cm regardless of the target. As with break, the distributions of NPC recovery values are unimodal and skewed to the right (Fig. 2). As indicated by the median values in Table 3, more than 50% of the recovery measurements were 4.0 cm for each of the three targets. Recovery measurements of 10 cm were observed in over 90% of the subjects using each target. Also included in Table 3 are descriptive statistics for the NPC break and recovery measurements obtained from subjects with convergence insufficiency. The mean break for AT is lowest at just over 9 cm, increasing to almost 12 cm with PL and almost 15 cm with PLRG. AT also produced the lowest mean recovery at 12.5 cm, followed by PL with a mean of just over 17.5 cm. As with break, the mean recovery for PLRG was largest at slightly more than 20.5 cm. The repeated-measures ANOVA indicated a significant difference in the mean break measurements obtained via the three targets (p 0.0001). Post hoc testing indicated a significant difference in AT and PL (p 0.0104) and AT and PLRG (p 0.0001). Unlike normal subjects, the statistically significant differences in break values obtained with the three targets were also clinically meaningful. A significant difference in mean NPC recovTABLE 3. Descriptive statistics for NPC break and recovery by method obtained and study group.a Method Obtained Mean SD Minimum Median Maximum CI subjects (N 38) Break Accommodative target 9.32 6.74 0.5 7.75 31.0 Penlight 11.86 8.40 2.0 10.0 41.0 Penlight with R/G glasses 14.75 10.0 2.0 11.0 41.0 Recovery Accommodative target 12.47 7.89 1.0 10.5 36.0 Penlight 17.68 11.24 4.0 14.25 51.0 Penlight with R/G glasses 20.59 12.32 5.0 15.5 56.0 Normal binocular vision subjects (N 175) Break Accommodative target 2.49 1.74 0.5 2.0 7.0 Penlight 2.06 1.85 0.5 1.5 10.0 Penlight with R/G glasses 2.38 2.11 0.5 2.0 11.0 Recovery Accommodative target 4.35 2.74 1.0 4.0 11.0 Penlight 3.74 2.87 0.5 3.0 14.0 Penlight with R/G glasses 4.35 3.26 1.0 4.0 17.0 a NPC, nearpoint of convergence; CI, convergence insufficiency; R/G, red and green. 218 Nearpoint of Convergence—Scheiman et al. Optometry and Vision Science, Vol. 80, No. 3, March 2003

220 Nearpoint of Comvergence-Schciman ct al NPC bmak 。Agcor moc小程用时 +和钢树 42 NPC Ereak (cml 0 29 N2C rEEoMTy 的 Fenijti +PN生 43 HPC Recoee方eo FIGURE 3. Cumulative distr bution of rearpoint of comergence INPCI beak and reenwry fer nermul subjects by methed cf musirements Figs.4 and 5.Cumulative distributions are plocted in Fig.6.Both AT and PLRG have unimodal NPC break distributions that are skewed to the right.A high peoporion (of the hreak mea- surements with AT are in the range of0.5 to 10 cm.PIRG values although skewed,are not quite as concentrated with in the rangs of 0.5 to 10 cm.The distribution of hreak values far Pl.has chree modal values at 8.10.and 12 cm and appears less skewed than the disuibution for the other two targets.In fact,the distri- burion appears almost unifoem in the range of0.to 15 cm. NPC recovery measurements abeained using the AT target abo follow a unimodal distrihution with a lrge comcentration in the 23 range of 0.5 to 15 cm.In fact,nearly 80%of the subjects have merein this rnge.The distibution ofves for the PL FIGURE 4. target is also unimodal but appears less skewed than the AT distri- batian.Only slightly moee than one halfofthe suhjcets have values ginee imufficivecy suljetts hy mus.rement method of15 cm.As with NPC hecak,the distribution of reoovery values for the PLRG targer is more evenly spread across the range ofvalues 7a shoms the change in mean NPC break ower the 10 repeated compuared with the other rwo target rypes.Slightly 5 of the measurements.According to the mixod modd analysis,the mean subjeets have recoery￥isod≤1 em using the PLRG targ性. NPC hreak increases from measurement onc to mcasrement fv (p value for slope <00001)but then changes littie from measure- Modification of Test Procedure:Ten Repetitions ments six to 10 (p value for slope =0.0865).The mean NPC recovery inereased from 17.7 cm at measurement one to 21.9 at The average NPC beak for Cl subjcers was 12.1 cm at the first measurement 10 (Fig,7h.The change,although nee remarkable, measurement,but it inencascd to 15.9 cm at mcasurcment 10.Fig was mure dramatic frum measuremant onc to three (p valuc for O小wwr可d Vurion Sriruer,Vcl3 No 3 March2nU

Figs. 4 and 5. Cumulative distributions are plotted in Fig. 6. Both AT and PLRG have unimodal NPC break distributions that are skewed to the right. A high proportion (70%) of the break measurements with AT are in the range of 0.5 to 10 cm. PLRG values, although skewed, are not quite as concentrated with 50% in the range of 0.5 to 10 cm. The distribution of break values for PL has three modal values at 8, 10, and 12 cm and appears less skewed than the distribution for the other two targets. In fact, the distribution appears almost uniform in the range of 0.5 to 15 cm. NPC recovery measurements obtained using the AT target also follow a unimodal distribution with a large concentration in the range of 0.5 to 15 cm. In fact, nearly 80% of the subjects have measurements in this range. The distribution of values for the PL target is also unimodal but appears less skewed than the AT distribution. Only slightly more than one half of the subjects have values of 15 cm. As with NPC break, the distribution of recovery values for the PLRG target is more evenly spread across the range of values compared with the other two target types. Slightly 50% of the subjects have recovery values of 15 cm using the PLRG target. Modification of Test Procedure: Ten Repetitions The average NPC break for CI subjects was 12.1 cm at the first measurement, but it increased to 15.9 cm at measurement 10. Fig. 7a shows the change in mean NPC break over the 10 repeated measurements. According to the mixed model analysis, the mean NPC break increases from measurement one to measurement five (p value for slope 0.0001) but then changes little from measurements six to 10 (p value for slope 0.0865). The mean NPC recovery increased from 17.7 cm at measurement one to 21.9 at measurement 10 (Fig. 7b. The change, although not remarkable, was more dramatic from measurement one to three (p value for FIGURE 3. Cumulative distribution of nearpoint of convergence (NPC) break and recovery for normal subjects by method of measurements. FIGURE 4. Distribution of nearpoint of convergence (NPC) break values for convergence insufficiency subjects by measurement method. 220 Nearpoint of Convergence—Scheiman et al. Optometry and Vision Science, Vol. 80, No. 3, March 2003

Nearpoint of Conwvergence-Scheiman ct al.221 break value for CI subicors,the break values do not change more Aocommocarive Ta图 dramatically at early repeated measurements and then remain rel- atively constant.In conrast.there does appear tobe an initialjump in the NPC recovery values for normal subject from measurement one to measurement two (p value for slope -0.001),after which the values remain relatively consrant (p value for slope 0.17357). At measurement one the mean NPC recovery is 3.99 cm.but it increases to49 cm at repeat two and is 53 cm at the last mea surensent (Fa.Sh). Symptoms On the eightitem symptom quesionnaire,the lowest possible 5 score was eight with a maimum of 0.The mean value for normal subjects was 13.0G (range.8 to 32).and the mean for convergence insufficiency subjecis wis 22.05 (range,9 to 32)This difference was statistically significant (t-11.80,p0.0001).Correlations Pe时 berween sympcoms and the NPC findings did vary with target selection.The highest correlation berween symptom score and NPC finding (=0.37)was observed for NPC recovery performed with the PLRG (Table 4). DISCUSSION This study ws designed to determine normative data for the NPC hreak and recowvery in adult subiecrs the most appropeiate target(s)to he used for the asesment of the NPC,and the dig- nostic value of commonly used modifications of the NPC.The distriburion of NPC break values showed a concentration for all targets in the 0.5-to S-cm range.The maximum beeak value ob- served with the AT was 7 em.compured with 10 cm for PI.and 11 em for PI.RG.Fighty-five percent of subjeets hid a break of 4.5 cm with all targets.In a previous study designed to determine normarive values for children.Hayes e alsugeted a clinical cutofT value of 6 cm.In their sudy,8946 of their suhjeets had a hreak af 56 cm.In onr stidly,9896 of the ghjrets bad a break of 56 cm with the AT,and 96%had a bncak of c6 cm with the PLRG targct.Using a similar criterion of 85%,we rccommend a value of 4.5 cm.Becuse clinicians generally do measure the NPC hreak to the halfcentimeter,we sugg rounding the climical c off value foe the NPC beeak to 5 em. For the NPC reooery,abour 85%of subjcets had a rcooery of 7cm with all tangts.Thus,we rcummend a clinical outff value of 7 em for the NPC recovery.Others studies have ued values ranging from 5 to 11 cm for the hreak and 8 to 11 cm for che NPC Resevery (om ecwery Hawever,out finding of cm the FIGLRE 5. poctod break valuc for normal subjccts compins fanorably with the Distrihuten nf nerpoint of convenyenre INPC trewery values for con- expected break valuc of6 cm for children found by Hayes et al. vergence insulliciency subjects by measurement method. One of the questions we wanted to address was target selection The res of this study that elinical dgnes can be mde with any of the thre targas.ahough the acoommodtive target slope -0.0298)than from measurement four to 10 (p value for appcan to prowide the bot procision.When evaluating the NPC. scp-025431. we are trying todeermine the patient's ability tocoverge using all There was little change in the NPC break values for normal aspects of convergence including fusonal convergenoe,proximal subjccts across the 10 measurement.The mean break was 2.2 at comergnce,and accommodative convergence.Becase the use of mcasurcment one and 2.9 at mcasurement 10(Fig.8a).The mixed an A'T masimixes the acoommodative dcmand and accommoda- mudel analysis indicatcd that the smalincrease in mcan break was tive comergenoc,the NPC should,theurctically,be mximized consistent acrss the 10 repeated measurements.That is,unlike the with this type of target.Ciuffred recommended the use ofan 小serey aud Viion &iewer.Vd.aNn玉Munh2nU

slope 0.0298) than from measurement four to 10 (p value for slope 0.2543). There was little change in the NPC break values for normal subjects across the 10 measurements. The mean break was 2.2 at measurement one and 2.9 at measurement 10 (Fig. 8a). The mixed model analysis indicated that the small increase in mean break was consistent across the 10 repeated measurements. That is, unlike the break value for CI subjects, the break values do not change more dramatically at early repeated measurements and then remain relatively constant. In contrast, there does appear to be an initial jump in the NPC recovery values for normal subject from measurement one to measurement two (p value for slope 0.004), after which the values remain relatively constant (p value for slope 0.4737). At measurement one the mean NPC recovery is 3.99 cm, but it increases to 4.49 cm at repeat two and is 5.3 cm at the last measurement (Fig. 8b). Symptoms On the eight-item symptom questionnaire, the lowest possible score was eight with a maximum of 40. The mean value for normal subjects was 13.06 (range, 8 to 32), and the mean for convergence insufficiency subjects was 22.03 (range, 9 to 32). This difference was statistically significant (t 11.80, p 0.0001). Correlations between symptoms and the NPC findings did vary with target selection. The highest correlation between symptom score and NPC finding (r 0.37) was observed for NPC recovery performed with the PLRG (Table 4). DISCUSSION This study was designed to determine normative data for the NPC break and recovery in adult subjects, the most appropriate target(s) to be used for the assessment of the NPC, and the diagnostic value of commonly used modifications of the NPC. The distribution of NPC break values showed a concentration for all targets in the 0.5- to 5-cm range. The maximum break value observed with the AT was 7 cm, compared with 10 cm for PL and 11 cm for PLRG. Eighty-five percent of subjects had a break of 4.5 cm with all targets. In a previous study designed to determine normative values for children, Hayes et al.33 suggested a clinical cutoff value of 6 cm. In their study, 85% of their subjects had a break of 6 cm. In our study, 98% of the subjects had a break of 6 cm with the AT, and 96% had a break of 6 cm with the PLRG target. Using a similar criterion of 85%, we recommend a value of 4.5 cm. Because clinicians generally do measure the NPC break to the half-centimeter, we suggest rounding the clinical cutoff value for the NPC break to 5 cm. For the NPC recovery, about 85% of subjects had a recovery of 7 cm with all targets. Thus, we recommend a clinical cutoff value of 7 cm for the NPC recovery. Others studies have used values ranging from 5 to 11 cm for the break and 8 to 11 cm for the recovery.1, 2, 7, 17–33 However, our finding of 5 cm as the expected break value for normal subjects compares favorably with the expected break value of 6 cm for children found by Hayes et al.33 One of the questions we wanted to address was target selection. The results of this study suggest that clinical diagnosis can be made with any of the three targets, although the accommodative target appears to provide the best precision. When evaluating the NPC, we are trying to determine the patient’s ability to converge using all aspects of convergence including fusional convergence, proximal convergence, and accommodative convergence. Because the use of an AT maximizes the accommodative demand and accommodative convergence, the NPC should, theoretically, be maximized with this type of target. Ciuffreda38 recommended the use of an FIGURE 5. Distribution of nearpoint of convergence (NPC) recovery values for convergence insufficiency subjects by measurement method. Nearpoint of Convergence—Scheiman et al. 221 Optometry and Vision Science, Vol. 80, No. 3, March 2003

Ncarpoint of CorwergenceSchciman ct al.223 A ) B 1 FIGURE 8. FIGURE 7. Mean.nearpoint of convergence NPC break and recovery lor nomal Mean nearpoint of convergence (P break ard recovery for conver- 甲in布nYhc木cmss mpetedd masunmen书，Farh hi repsesents 1 5D. insufficiency hid a hreak that was5 cm more receded with the PIRG and a rerowery >8 cm more receded with the PL.RG com- and PI.as well as berween AT and PIRG were dinically significant. pared with the AT.Differences approaching thee as should There was also aistically signifiant difference berween the PL aler a clinikian to the possibility of a subtk conveinsu and PLRG.although the mean difference of 29 cm berween the ciency.Our data tnd to support Capubiancu's suggestion. break with a PIRG and PL.may be too small to he clinically Of our 38 subjeces with coavergence insufficiency,13 had an ueful.The greatest differences herwern any rwo tests were 5.45 em NPC that was within the expeeted range for hoch berak and reow- berwren the AT hreak and the PLRG break and 8.17 cm berwcen cry using the ATalonc.When the NPC was npcatod witha PLRG, the AT recovery and che PLRG recowery in the convergence insuf. all 13 of these subjccts were found to have a nocoded NPC.In 11 of icc守eup. the 13,the NPC was reoeded with the PL target,and all 13 of these Theoeetically,the PIRG target not only minimins the accom- subjects were found to have a reoeded NPC with the 10-repetition modative-convergrnee component,but so makes hinoclriry more difficult hecaue of the dissocarive factor cnated by the red TABLE 4. and greelsseCapobinco suggested that the use of wo Correlations between symptoms and NPC variables for the targees (AT followed by a PLRG)might allow clinicians to detect convergence insufficiency group." more subele convergence insafficiency penblems Mast dinicians have encomnterd sittutions in which diagnostic testing is civ AT Bek AT Rie PL-Bck PL-Rec PLRG-Rrk PLRG-Ri cal,althuugh the history dinical hypothesis of a binuc- 5mmr-Q19r-021f-27r-035学r-03'r-0370 ular problem.The use of the PLRG tanget may be particularly MUIL useful in this siruarion.Our resules suggest that in a ptient with NPC,pearpoint of converpence;AT,accommodadive tarpet normal binoculariry,there should he virtally no difference be- Brk.break:Rec,recovery.PL,penlight:PLRG.penlight while twcen the bneak and ncwery findings when the NPC is performed wearing red and green glasses. with an AT or a PLRG.In this sudy,patients with convergmnce p 005. O小wwr句d Virion Sriruer,Vl8 No 3 March2U

and PL as well as between AT and PLRG were clinically significant. There was also a statistically significant difference between the PL and PLRG, although the mean difference of 2.9 cm between the break with a PLRG and a PL may be too small to be clinically useful. The greatest differences between any two tests were 5.43 cm between the AT break and the PLRG break and 8.17 cm between the AT recovery and the PLRG recovery in the convergence insufficiency group. Theoretically, the PLRG target not only minimizes the accommodative-convergence component, but also makes binocularity more difficult because of the dissociative factor created by the red and green glasses. Capobianco18 suggested that the use of two targets (AT followed by a PLRG) might allow clinicians to detect more subtle convergence insufficiency problems. Most clinicians have encountered situations in which diagnostic testing is equivocal, although the history suggests a clinical hypothesis of a binocular problem. The use of the PLRG target may be particularly useful in this situation. Our results suggest that in a patient with normal binocularity, there should be virtually no difference between the break and recovery findings when the NPC is performed with an AT or a PLRG. In this study, patients with convergence insufficiency had a break that was 5 cm more receded with the PLRG and a recovery 8 cm more receded with the PLRG compared with the AT. Differences approaching these values should alert a clinician to the possibility of a subtle convergence insufficiency. Our data tend to support Capobianco’s suggestion. Of our 38 subjects with convergence insufficiency, 13 had an NPC that was within the expected range for both break and recovery using the AT alone. When the NPC was repeated with a PLRG, all 13 of these subjects were found to have a receded NPC. In 11 of the 13, the NPC was receded with the PL target, and all 13 of these subjects were found to have a receded NPC with the 10-repetition TABLE 4. Correlations between symptoms and NPC variables for the convergence insufficiency group.a AT Brk AT Rec PL-Brk PL-Rec PLRG-Brk PLRG-Rec Symptom score r 0.19 r 0.21 r 0.27 r 0.35b r 0.33b r 0.37b a NPC, nearpoint of convergence; AT, accommodative target; Brk, break; Rec, recovery; PL, penlight; PLRG, penlight while wearing red and green glasses. b p 0.05. FIGURE 7. Mean nearpoint of convergence (NPC) break and recovery for convergence insufficiency subjects across repeated measurements. Each bar represents 1 SD. FIGURE 8. Mean nearpoint of convergence (NPC) break and recovery for normal subjects across repeated measurements. Each bar represents 1 SD. Nearpoint of Convergence—Scheiman et al. 223 Optometry and Vision Science, Vol. 80, No. 3, March 2003

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天津职业大学文本 Nearpoint of Convergence Test Procedure, Target Selection, and Normative Data_眼屈光学

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天津职业大学文本 Nearpoint of Convergence Test Procedure, Target Selection, and Normative Data_眼屈光学