304054s17元41500L77.401f.10-15号 CPTOETRY ANDVEKIN SCIENC红 C车色0m■可4y ORIGINAL ARTICLE Accommodation Causes With-the-Rule Astigmatism in Emmetropes MITSUO TSUKAMOTO,MD,TAKAYUKI NAKAJIMA,MD,JUNKO NISHINO,MD, YOSHIAKI HARA,MD,HIROSHI UOZATO,PhD,and MOTOTSUGU SAISHIN,MD, Depariment fOphtaimolo Nan Medical Universiy.Nars.apan ABSTRACT:Purpase:To measure the changes in astigmatism when bilateral emmetropes accommodate.Methodks: Bilateral emmetropes accommodative responses were measured with an improved photorefractometer PR-1100,which measured hinocular refraction in all meridians simultancously as a fixation target was shown in natural space.Resuts: The accommodative responses in the vertical meridian are greater than those in the horizontal meridian.In the horizontal meridian,the accommodative responses are less than the accommodative stimulus.Conclusions:When accommodating the majority of hilateral emmetropes show with-the-rule astigmatism and lag of accommodation in the horizontal meridian.(Optom Vis Sci 2000;77:150-155) Key Words:accommodation,bilateral emmetropia,astigmatism,meridian,photorefractometer commodation has conventionally becn measurod by atb- In our preliminary cspcriments,we usod a Canon R-1 (which jective methods since Dooders in 1864The min rea- can measure refraction in all miridians and permits a preontation so for this approach has been the lack ofobjective means of a fixation target in real spuce but cannot measure simultaneous for evaluating accommodatica,with the exception of retinoscopy. binocular refraction).Therefore,we were not able to detect In the illumination and obscrvation systems of retinascopy,how- simultancous interaction betwren both cyes Then,as Cornsweet ever.the parient's pupdl must be aperrure-stop.the examiner's docribed.we had the impron that there might be a ei cojugae point must be at the patient's pupil,and the differenoe in accummodative behavior in well-trained subiects esaminer and the puatient must shaire the sime ocular apric axis,a compared with untrained subjects. retinoscopic axis.Therefore.it isdifficuoplace a visul arger We planned to measure accommodative behavior under ordi with a relativdhy lrge visual angle on a patient's line of sight.and nary visual ciramstances in this cxperiment.To maintain such even if the visual target is placed in asmall deviated direction from ciroumstancs,dolls were shown in real spaoc to stimulate accom- the line of sight.it is difficult for the parient to fixcate the target modation.and no trained subjects were employed.In our fint because of darzle from the retinoscope beam.Recently,because of study of binocular ccommodation,we chose only sbjects with the devdopment of infrared optometers,"rescarchers have been bilateral emmetropia,as the most fundamencal state of refraction. able to objecrively measre accommodtian.However,they have for this study.We found that bilateral emmesropes caused with. not been able to measure binocular accommodation simulta the-rule astigmatism.and kss rospons than stimulation in the horizontal meridian. noudy and in all meridians.With this measuring system,the fellow eye's accommodative behaior is difficult to assess simulta- nem小y. In 1990,we developed the PR 1000 phocorefractive refractom MATERIALS AND METHODS eter (Topoon,Tokyo,Japan),which cnabls us to masare bin- Instrument ocular eve refraction simultaneously in vertical and horizoetal me- The PR-1000 refractometer was developed for measuring in ridians (Fig.1).This instrument was originally developed to fantsrefrction.employing Howland's phoefaction theory. measure infant refraction.The PR-1000 was improwod todeectall We uriginally introduod a diffu light source in the illminating meridians'refraction (the PR-1100)by changing the sofrware in- system,and a knife dge in the detecing system,as shown in Fig. cluded.WWe then modified the PR-1100 to meisure accommoda- 2.The PR-1000 has these functions:n infrared light souroe is tion. mounted as the iluminating source topreventdaing the patient
ORIGINAL ARTICLE Accommodation Causes With-the-Rule Astigmatism in Emmetropes MITSUO TSUKAMOTO, MD, TAKAYUKI NAKAJIMA, MD, JUNKO NISHINO, MD, YOSHIAKI HARA, MD, HIROSHI UOZATO, PhD, and MOTOTSUGU SAISHIN, MD, Department of Ophthalmology, Nara Medical University, Nara, Japan ABSTRACT: Purpose: To measure the changes in astigmatism when bilateral emmetropes accommodate. Methods: Bilateral emmetropes accommodative responses were measured with an improved photorefractometer PR-1100, which measured binocular refraction in all meridians simultaneously as a fixation target was shown in natural space. Results: The accommodative responses in the vertical meridian are greater than those in the horizontal meridian. In the horizontal meridian, the accommodative responses are less than the accommodative stimulus. Conclusions: When accommodating the majority of bilateral emmetropes show with-the-rule astigmatism and lag of accommodation in the horizontal meridian. (Optom Vis Sci 2000;77:150–155) Key Words: accommodation, bilateral emmetropia, astigmatism, meridian, photorefractometer Accommodation has conventionally been measured by subjective methods since Donders in 1864.1–4 The main reason for this approach has been the lack of objective means for evaluating accommodation, with the exception of retinoscopy. In the illumination and observation systems of retinoscopy, however, the patient’s pupil must be aperture-stop, the examiner’s retinal conjugate point must be at the patient’s pupil, and the examiner and the patient must share the same ocular optic axis, a retinoscopic axis.5, 6 Therefore, it is difficult to place a visual target with a relatively large visual angle on a patient’s line of sight, and even if the visual target is placed in a small deviated direction from the line of sight, it is difficult for the patient to fixate the target because of dazzle from the retinoscope beam. Recently, because of the development of infrared optometers,7 researchers have been able to objectively measure accommodation. However, they have not been able to measure binocular accommodation simultaneously and in all meridians. With this measuring system, the fellow eye’s accommodative behavior is difficult to assess simultaneously. In 1990, we developed the PR-1000 photorefractive refractometer (Topcon, Tokyo, Japan),8, 9 which enables us to measure binocular eye refraction simultaneously in vertical and horizontal meridians (Fig. 1). This instrument was originally developed to measure infant refraction. The PR-1000 was improved to detect all meridians’ refraction (the PR-1100) by changing the software included. We then modified the PR-1100 to measure accommodation. In our preliminary experiments, we used a Canon R-1 (which can measure refraction in all meridians and permits a presentation of a fixation target in real space but cannot measure simultaneous binocular refraction).10–12 Therefore, we were not able to detect simultaneous interaction between both eyes. Then, as Cornsweet described,13 we also had the impression that there might be a difference in accommodative behavior in well-trained subjects compared with untrained subjects. We planned to measure accommodative behavior under ordinary visual circumstances in this experiment. To maintain such circumstances, dolls were shown in real space to stimulate accommodation, and no trained subjects were employed. In our first study of binocular accommodation, we chose only subjects with bilateral emmetropia, as the most fundamental state of refraction, for this study. We found that bilateral emmetropes caused withthe-rule astigmatism, and less response than stimulation in the horizontal meridian. MATERIALS AND METHODS Instrument The PR-1000 refractometer was developed for measuring infants’ refraction, employing Howland’s photorefraction theory.14 We originally introduced a diffuse light source in the illuminating system, and a knife edge in the detecting system, as shown in Fig. 2.8, 9 The PR-1000 has these functions: an infrared light source is mounted as the illuminating source to prevent dazzling the patient; 1040-5488/100/7703-0150/0 VOL. 77, NO. 3, PP. 150–155 OPTOMETRY AND VISION SCIENCE Copyright © 2000 American Academy of Optometry Optometry and Vision Science, Vol. 77, No. 3, March 2000
Aocomodatin and Astigmatisn-Tsukamoto e al.151 HGURE 1. The extemal fomm of the PR-1100.The left panel shows the view from the operator's side.The operator posieions the suhject's eyus in the licad frames on the monilur dfiplay Glluvraled at baitom)with the two control handes,ocuses both eyes'images,and pushes the measuremene button to sore a rerord.The rtght panel shows he view from the subject's side.In oed nary use as a pediatnc refractometer,inside the msering:windnw a viual fisation tanyet is hlcking andl makes a sound fnt altintiun.In his experimn, the subject looked at a visual fixation target theough a mirror.The lower ponel shows the view of the monior diplay.The shjuct's my ant ponitiond n ftam and then focuud. simultaneous binocular measurement is made during binocular viewing:the measurement does not need a dark room:the wave length of the light source is 830 to 950 nm:the ingrument is ploed 1.2 m away from a parient the amount of energy at the patient's cye is 3.98 X 10-Wicm';the measuring range is -5 to +diopeers in each meridian,the measuring time is 0.15 s for one 一 record:four measurement records can be stored,and after the fifth measurcment,the first (oldest)rccoed disippcan;and the mini- mum pupil diameter rquird is 3.0 mm.The opcrator viws both eyesofa patient on the monicor.chooses the appropriate mot 苦罚甲 (no blinking no moving of the patient,etc),and pushes the but ton.One record is then stored The scoond version of the PR-1000,the PR-1100,can detect refraction in all meridians.This improwement was achieved by changing the original software.The accuracy of the PR-1100 is FIGURE 2. shown in Fig.3.We modified the PR-1100 for this experiment as Optical principle ofa PR-1100.The left panel showws a schematic dinpzam shown in Fig,4.Two 30 X 50 cm dichroic mirrocs were placed 20 which uses a surface iluminant and a knile edge.The middle panel shows cm from the subject and dedined ar 15".The subpect's head paui. the distriheion c the surface illuinant ard the knife edae A port of the tion was controlked using a chin rest holder set behind the mirrors light which eierges loo the subjett's retina is bkcked by the lik edge and the re对the light flux reaches a CCD网sensor which is set on中e Visual fixation targets to stimulate accommodation were peeented optical cunjugale plane of the subject's pupil.The rigle panel shons the chrough the dichroic mirror at 5 m and 0.5 m,with the axis of the lighe intensey dstnhution which appears in the sibject's pupil The slpe refractomecer aligned with the subject's eyes (except for the error of the inturpily cistrilngion tpnds on e sLjoct's sofraction. Opisureiry and Vinien Scieuce.Vel.77.Na玉Marh25O间
simultaneous binocular measurement is made during binocular viewing; the measurement does not need a dark room; the wavelength of the light source is 830 to 950 nm; the instrument is placed 1.2 m away from a patient; the amount of energy at the patient’s eye is 3.98 3 1025 W/cm2 ; the measuring range is 25 to 15 diopters in each meridian, the measuring time is 0.15 s for one record; four measurement records can be stored, and after the fifth measurement, the first (oldest) record disappears; and the minimum pupil diameter required is 3.0 mm. The operator views both eyes of a patient on the monitor, chooses the appropriate moment (no blinking, no moving of the patient, etc), and pushes the button. One record is then stored. The second version of the PR-1000, the PR-1100, can detect refraction in all meridians. This improvement was achieved by changing the original software. The accuracy of the PR-1100 is shown in Fig. 3. We modified the PR-1100 for this experiment as shown in Fig. 4. Two 30 3 50 cm dichroic mirrors were placed 20 cm from the subject and declined at 45°. The subject’s head position was controlled using a chin rest holder set behind the mirrors. Visual fixation targets to stimulate accommodation were presented through the dichroic mirror at 5 m and 0.5 m, with the axis of the refractometer aligned with the subject’s eyes (except for the error FIGURE 1. The external form of the PR-1100. The left panel shows the view from the operator’s side. The operator positions the subject’s eyes in the lined frames on the monitor display (illustrated at bottom) with the two control handles, focuses both eyes’ images, and pushes the measurement button to store a record. The right panel shows the view from the subject’s side. In ordinary use as a pediatric refractometer, inside the measuring window a visual fixation target is blinking and makes a sound for attention. In this experiment, the subject looked at a visual fixation target through a mirror. The lower panel shows the view of the monitor display. The subject’s eyes are positioned in the frames and then focused. FIGURE 2. Optical principle of a PR-1100. The left panel shows a schematic diagram, which uses a surface illuminant and a knife edge. The middle panel shows the distribution of the surface illuminant and the knife edge. A part of the light which emerges from the subject’s retina is blocked by the knife edge, and the rest of the light flux reaches a CCD area sensor which is set on the optical conjugate plane of the subject’s pupil. The right panel shows the light intensity distribution which appears in the subject’s pupil. The slope of the intensity distribution depends on the subject’s refraction. Accomodation and Astigmatism—Tsukamoto et al. 151 Optometry and Vision Science, Vol. 77, No. 3, March 2000
152 Apcornudation and Astigmatism-Tsukamolo e al. RM-Acco -4 42 4 4=k500 FIGURE 3. developed by lopcon by using schematic eyes.The horiznnal axis shows the values measured with a RMA600o.The vertical axs shows the values muwrd wh the PR-1100.The slardard dviin isDndcconis ppiusimady 1.0.The cemer panl shews a comparion of he sphencal powers measured with PR-1100 and RM-A6000 for volunteer adult subjects (54 eyest.The standard devanan s 035 D and the corelaton cofcient is 0.98.The right pand shems a commparisun c cylintrical powers memund wih PR-1100 and RM-A60CO fur volumer adult subjects (54 eyes The standand deviation is U.25 D and the comelation coeffident s 0.93. TABLE 1. Selection of subjects.Bilateral emmetropia occurred in only 5.8%(15 subjects)of the primary selection (259 subjects)and in only 0.6%of the general population (2486. Primary Male Female Bilateral Age Sclection Make Female emmctropia 12 11 5 0 0 0 13 11 7 2 14 0 15 21 15 1 1 16 15 9 2 2 20 0 0 18 32 o 22 0 19 100 100 0 20 32 0 M 21 0 D 22 2 0 0 23 0 1 D R Total 259 59 200 15 o FIGURE 4. en's universiry.These 2486 people,aged 12 to 26 years,indicate A diagrammatic averhead view of te impiuved PR-1100,D.PR-1100:M dichreic mrmr:sibject's nipht eye;L sbject's left eye T.viuial the genxeral population of an urban ar.Primarily,259 members. fixation target.Subjerts are posiioned so their eyes are algned with the as shown in Table 1,were sekected who had corrected decimal nptical axis nf the PR-1100,using the chin net holder set hehind a mimor visual acuiry of 1.0 (correspoods to 5/5)oc better,octhophoria. The vi Fation target is preened caully on the vial axs,which normal binocular function,intact ocular media,and intact ocular is ind cated wih marks fundus Visual acuiry tes was measured for each eye using,Landolt rings at 5 m,while the fellow eye was occluded Orthophoria was caused by patient's convergence).The error caued hy convergence examined using the cover test.Keratometric records were taken is referred to below as"simulation."Two different-sized small dolls with a Capon RK 2.A binocular function test was administered with approximate visul angles of 10 were employed as visal using a synoptophore (major amblyoscope),with a visual angle of fication targets. target size.Binocular function was judged as"normal"when subjects had simultaneous foveal perception and fiion (a fuonal Subjects amplitude of divergence of or more,with convergence of 12or more on each target under two conditions with and without-2 D The subjeces were selected from a group of studencs from an lnses).Ooulr media was examined by sit lamp microscopy.and elementary school,a junior high school,a high school,and a wom- ocular fundus was ohserved using funduscope. Opiauetry aud Vinien Scicuce.Vel.77,Na天Marh20同
caused by patient’s convergence). The error caused by convergence is referred to below as “simulation.” Two different-sized small dolls with approximate visual angles of 10° were employed as visual fixation targets. Subjects The subjects were selected from a group of students from an elementary school, a junior high school, a high school, and a women’s university. These 2486 people, aged 12 to 26 years, indicate the general population of an urban area. Primarily, 259 members, as shown in Table 1, were selected who had corrected decimal visual acuity of 1.0 (corresponds to 5/5) or better, orthophoria, normal binocular function, intact ocular media, and intact ocular fundus. Visual acuity test was measured for each eye using Landolt rings at 5 m, while the fellow eye was occluded. Orthophoria was examined using the cover test. Keratometric records were taken with a Canon RK-2. A binocular function test was administered using a synoptophore (major amblyoscope), with a visual angle of 3° target size. Binocular function was judged as “normal” when subjects had simultaneous foveal perception and fusion (a fusional amplitude of divergence of 4° or more, with convergence of 12° or more on each target under two conditions with and without 22 D lenses). Ocular media was examined by slit lamp microscopy, and ocular fundus was observed using a funduscope. TABLE 1. Selection of subjects. Bilateral emmetropia occurred in only 5.8% (15 subjects) of the primary selection (259 subjects) and in only 0.6% of the general population (2486). Age Primary Selection Male Female Bilateral emmetropia Male Female 12 11 5 6 0 0 0 13 11 7 4 2 2 0 14 6 3 3 1 0 1 15 21 15 6 2 1 1 16 15 6 9 2 2 0 17 20 13 7 0 0 0 18 32 10 22 1 0 1 19 100 0 100 2 0 2 20 32 0 32 4 0 4 21 4 0 4 0 0 0 22 6 0 6 0 0 0 23 1 0 1 1 0 1 Total 259 59 200 15 5 10 FIGURE 3. The accuracy of a PR-1100. The left panel shows a comparison of PR-1100 and RM-A6000 (a commercially used conventional autorefractometer developed by Topcon) by using schematic eyes. The horizontal axis shows the values measured with a RM-A6000. The vertical axis shows the values measured with the PR-1100. The standard deviation is 0.1D and the correlation coefficient is approximately 1.0. The center panel shows a comparison of the spherical powers measured with PR-1100 and RM-A6000 for volunteer adult subjects (54 eyes). The standard deviation is 0.35 D and the correlation coefficient is 0.98. The right panel shows a comparison of cylindrical powers measured with PR-1100 and RM-A6000 for volunteer adult subjects (54 eyes). The standard deviation is 0.25 D and the correlation coefficient is 0.93. FIGURE 4. A diagrammatic overhead view of the improved PR-1100; D, PR-1100; M, dichroic mirror; R, subject’s right eye; L, subject’s left eye; T, visual fixation target. Subjects are positioned so their eyes are aligned with the optical axis of the PR-1100, using the chin rest holder set behind a mirror. The visual fixation target is presented carefully on the visual axis, which is indicated with marks. 152 Accomodation and Astigmatism—Tsukamoto et al. Optometry and Vision Science, Vol. 77, No. 3, March 2000
Aocomodation and Astigmatism-Tsukamoto et al.153 2 a L当酒口) 自e(D HIGURE 5. subjectsl.The left pane shows results for the horizontal meridian.The mean values are -1.19 D.and -1.10 D.the staedard devutioes an 0.36 D and 0 36 D;the mirimum niartons ate =a 50 D and -0.42 D.the maximum reiractons are -1.83 D and -1.57 D in the right eyes and in the kft eyes, espectively.A diohle rircle shows twn overlappedd dita poiints.The ript punel shmys resus foe the verical meridian,he mean values are -1.96 D and -1.91 D:the standard deviations are 0.39 D and Q37 D:the micimu refractioes ans -1.25 D and =1.25 D:the maxium refrartinns are =50D and -2.67 D in the righc eyes and the left eyes,respectivdly.The comelation coefficient values of boch eyes 1.5 2 14 Horizontal merkfion (D) RIGURE 6. Cnmpovisn of arrommodave resporsrs hetwern horizental and vertiral meridians (15 vhject The left panel shows res.lts for the left eve.The right panel shows results for he right eve.The comelation coefficients are nl.)0 and d 12,in the rphe eyes and the leit eye,respectivel.In the data for earh r 14se5 how wrh-小euke通gm,ind one su山oc1 sagainstthe-de2 stigmatism of0.17 n.The cases of the apai-h-mle antipmnatism belon耶的neh加the whjert with with--nule asigmotim,the mean values are 0.84 D lin the right eyel and 0.88 D (in the let eyel:the mirimu vakaes am d8 D (rghe eyel and nldD (eft eyet:and the maximum walues are 1.25 D iright eyei and 1.42 D def eyel.The cases of the minimum value belong to the same subjedt,and the cases of the maximum value bekeg:in difecent subperts. The definitiun of emmctropia in this paper is as follos:spher- with-the-rule aigmatism,and two subjeots showed a mixture of ical refractive error of0.50 Dor less,and a cylindrical error of against-and wich-the-rule astigmatism. 0.50 D or less(mean of three measurements).Secondarily,only 15 subjects were selected as having bilateral emmetropia from the primarily slctod group of 259 members undr the abowe defini- Measurement tion.Tbesc fifteen pople were used as subjects in this study.Even The subjects wure instructed by an operator to fixate the targct though the astigmatism of the 15 subjects was <0.50 D.eight (having a visual angk of approximady 10)placed at 5 m.and an subjects sbowed against the rule astigmatism,five subjects showed instnament operator used the improved PR-1100 to take three plswvefry and Vinen Scieucr.Ved.77,Nn玉Mah20间
The definition of emmetropia in this paper is as follows: spherical refractive error of 6 0.50 D or less, and a cylindrical error of 6 0.50 D or less (mean of three measurements). Secondarily, only 15 subjects were selected as having bilateral emmetropia from the primarily selected group of 259 members under the above definition. These fifteen people were used as subjects in this study. Even though the astigmatism of the 15 subjects was , 0.50 D, eight subjects showed against-the-rule astigmatism, five subjects showed with-the-rule astigmatism, and two subjects showed a mixture of against- and with-the-rule astigmatism. Measurement The subjects were instructed by an operator to fixate the target (having a visual angle of approximately 10°) placed at 5 m, and an instrument operator used the improved PR-1100 to take three FIGURE 5. Accommodative responses (refraction stimulated by visual fixation target at 0.5 m) in each meridian (15 subjects). The left panel shows results for the horizontal meridian. The mean values are 21.19 D, and 21.10 D; the standard deviations are 0.36 D and 0.36 D; the minimum refractions are 20.50 D and 20.42 D; the maximum refractions are 21.83 D and 21.67 D in the right eyes and in the left eyes, respectively. A double circle shows two overlapped data points. The right panel shows results for the vertical meridian, the mean values are 21.96 D and 21.91 D; the standard deviations are 0.39 D and 0.37 D; the minimum refractions are 21.25 D and 21.25 D; the maximum refractions are 22.50 D and 22.67 D in the right eyes and the left eyes, respectively. The correlation coefficient values of both eyes are 0.83 and 0.91 in the horizontal and the vertical meridians, respectively. FIGURE 6. Comparison of accommodative responses between horizontal and vertical meridians (15 subjects). The left panel shows results for the left eye. The right panel shows results for the right eye. The correlation coefficients are 0.20 and 0.12, in the right eyes and the left eyes, respectively. In the data for each eye, 14 subjects show with-the-rule astigmatism, and one subject shows against-the-rule astigmatism of 0.17 D. The cases of the against-the-rule astigmatism belong to one subject. In the subject with with-the-rule astigmatism, the mean values are 0.84 D (in the right eye) and 0.88 D (in the left eye); the minimum values are 0.08 D (right eye) and 0.08 D (left eye); and the maximum values are 1.25 D (right eye) and 1.42 D (left eye). The cases of the minimum value belong to the same subject, and the cases of the maximum value belong to different subjects. Accomodation and Astigmatism—Tsukamoto et al. 153 Optometry and Vision Science, Vol. 77, No. 3, March 2000
154 Aocomnodation and Astigmatism-Tsukamoto al. TABLE 2. Two-way ANOVA on accommodative respanse between eyes (right:left)and meridars (horizontal:vertical) The interaction between eyes and meridians is negligible,but the meridians show a highly significant dilference between horizontal and vertical.There is no significant difference in the factor hetween the right eye and the leit eye. Factors Degree of Sum of P f0.051 freedom Square Fo EysR:□ 00723 1 0.0723 0.5293 0.4699 4.0130 Meriddians (HVI 9.411D 1 9.4D10 6H.7931 2.542E.11 4.D130 Ineraction 00057 1 0.0057 0.04150 0.8393 4.0130 Eror 76528 6 0.1367 Total 17.1318 59 一 Horizontal Meridan respcotivdy.All of the accommodtive responses in the horizontal Retina meridian are lower than the 2.0D accommodative stimulus.In the vertical meridian the mean accommodative response is -1.96 D (SD 0.39)in right cyes and -191 D (SD)0.37)in lefir cyes. In the verical meridian,accommodtive responses are different frum the 2.0 D accommodative stimulus.The mean deviation of Ertmetropia Vertical Me:dan the accommodative reponse from the accommodative stimulation is cakulated by the equation (accommodative response-accommodative stimulacion)] numher of abject The caloulated vahue are 0.38 D in right eyes and 0.37 D in left eyes.These values doady correspond to the sandard deviations described above.In terms of anisometropic accommodarion.there Acccmmrod由ted Erm行tpio sms to be a groater amount in the horcontal meridian than in the FIGURE 7. enical meridian. Shemalit of iccummodaliun bchavir of a majurity of bilaktal um- Fig 6 and Table 2 democstrae the cange ofcyfindricpower cusd metropes. by aocommodation.Of 15 subjecs,14 showed with the rule astigma tian.10 of whomn showed astigmarism over 0.5 D:ther mean values records.Then the operator presented the new target (having the arc -108 D and -1.11 D,thcir minimum vales are -092 D and same visual angle)at 0.5m.and again the instrument operacor toolc -0.67 D.and the maximum values are-1.25 D and -1.42 D.in the three records. righ:andkfteyes repectively.Theother four suhjects whohdwith the rule stigmatism shoed05 D or ker.and coesubject showed agnst Simulation the ruk astigmatism of0.17D.Ther:was no subjeor showing aniome tropiaover (lD in both meridins,except for coe subject who sbowed Generally.accommodacicn iccompanies comergence.There a derence of 0.58 D in the hurizontal meridians. fore,when the subjects look at the targer set at 0.5 m,the subjecs On relaxation of accommodation,as a matter of course,there visual aes are no longer aligned with the refracometer's optical axis.We simulated the elfect of this alignment error using ray wis no marked astigmatism or anisometropia.On accommoda tion,mot subjects showed some igmatism as described above traces in the pon Gaussian area (not limited to the range where and no nisometropi Concerning comeal istigmatism.all the sino "0)by compurer.The program was composed in Math- subjects showed with-the-rule astigmarism.and the mean values emarica (version 5.0:Wolfiam Research.Inc.,Champaign,IL). were 0.84 D (SD 0.43)and 0.91 D (SD 0_34)in the right and left The effect resulted in agains-the-rule astigmatism of 0.18 D at eyes,respectively.In this study we could noc find any meaningful 3mm pupil sixe on the Gullstrand's schematic eye (accommoda relation to accommodarion. tion model).assuming 60 mm berween the cencers of rocation of the eyes.The effect depends on pupil size.The more pupil size increse线，he more against-he-ule astigmarism inca线. DISCUSSION RESULTS Information on the interaction in both eyes on accommodation islimited.bc ofac of anappeopriate mesurinm The accommodative responses,in the hoionral meridian and The development of an infrared opeometer has made recording in the vertical meridian.are shown in Fg 5.In the horicontal data possible,but detection is only on one cye and in one meridi- meridian,these mean values are -1.19 D (SD 0.36)and -1.10 D an Using the Canon R-1,all the meridians could be desected o (SD 0.36):the maximum values are -1.83 D and -1.67 D:and accommodation.Furthermore.this instrument wis able to present the ranges are 133 D and 125 D for the righs and lef eyes.a visual fication t in narural spaceWe performed Opisuretry and Vinien Scie.Vel.77.Na王Marh2O间
records. Then the operator presented the new target (having the same visual angle) at 0.5m, and again the instrument operator took three records. Simulation Generally, accommodation accompanies convergence. Therefore, when the subjects look at the target set at 0.5 m, the subjects’ visual axes are no longer aligned with the refractometer’s optical axis. We simulated the effect of this alignment error using ray traces in the non-Gaussian area (not limited to the range where sinu'u) by computer. The program was composed in Mathematica (version 3.0; Wolfram Research, Inc., Champaign, IL). The effect resulted in against-the-rule astigmatism of 0.18 D at 3-mm pupil size on the Gullstrand’s schematic eye (accommodation model), assuming 60 mm between the centers of rotation of the eyes. The effect depends on pupil size. The more pupil size increases, the more against-the-rule astigmatism increases. RESULTS The accommodative responses, in the horizontal meridian and in the vertical meridian, are shown in Fig. 5. In the horizontal meridian, these mean values are 21.19 D (SD 0.36) and 21.10 D (SD 0.36); the maximum values are 21.83 D and 21.67 D; and the ranges are 1.33 D and 1.25 D for the right and left eyes, respectively. All of the accommodative responses in the horizontal meridian are lower than the 2.0 D accommodative stimulus. In the vertical meridian the mean accommodative response is 21.96 D (SD 0.39) in right eyes and 21.91 D (SD 0.37) in left eyes. In the vertical meridian, accommodative responses are different from the 2.0 D accommodative stimulus. The mean deviation of the accommodative response from the accommodative stimulation is calculated by the equation: {[S(accommodative response 2 accommodative stimulation)2 ] / number of subjects}1/2 The calculated values are 0.38 D in right eyes and 0.37 D in left eyes. These values closely correspond to the standard deviations described above. In terms of anisometropic accommodation, there seems to be a greater amount in the horizontal meridian than in the vertical meridian. Fig. 6 and Table 2 demonstrate the change of cylindrical power caused by accommodation. Of 15 subjects, 14 showed with-the-rule astigmatism, 10 of whom showed astigmatism over 0.5 D; their mean values are 21.08 D and 21.11 D, their minimum values are 20.92 D and 20.67 D, and the maximum values are 21.25 D and 21.42 D, in the rightandlefteyes,respectively.Theotherfoursubjectswhohadwith-therule astigmatism showed 0.5 D or lower, and one subject showed againstthe-rule astigmatism of 0.17 D. There was no subject showing anisometropia over 0.35 D in both meridians, except for one subject who showed a difference of 0.58 D in the horizontal meridians. On relaxation of accommodation, as a matter of course, there was no marked astigmatism or anisometropia. On accommodation, most subjects showed some astigmatism as described above and no anisometropia. Concerning corneal astigmatism, all the subjects showed with-the-rule astigmatism, and the mean values were 0.84 D (SD 0.43) and 0.91 D (SD 0.34) in the right and left eyes, respectively. In this study we could not find any meaningful relation to accommodation. DISCUSSION Information on the interaction in both eyes on accommodation is limited, because of lack of an appropriate measuring system.15–17 The development of an infrared optometer has made recording data possible, but detection is only on one eye and in one meridian.7 Using the Canon R-1, all the meridians could be detected on accommodation. Furthermore, this instrument was able to present a visual fixation target in natural space.10–12, 18, 19 We performed FIGURE 7. Schematic of accommodation behavior of a majority of bilateral emmetropes. TABLE 2. Two-way ANOVA on accommodative response between eyes (right: left) and meridians (horizontal: vertical) The interaction between eyes and meridians is negligible, but the meridians show a highly significant difference between horizontal and vertical. There is no significant difference in the factor between the right eye and the left eye. Factors Degree of freedom Sum of Square F0 P F(0.05) Eyes (R:L) 0.0723 1 0.0723 0.5293 0.4699 4.0130 Meridians (H:V) 9.4010 1 9.4010 68.7931 2.542 E-11 4.0130 Interaction 0.0057 1 0.0057 0.04150 0.8393 4.0130 Error 7.6528 56 0.1367 — — — Total 17.1318 59 — — — — 154 Accomodation and Astigmatism—Tsukamoto et al. Optometry and Vision Science, Vol. 77, No. 3, March 2000
Accomudation and Astigmalism-Tsukamolo e al.155 experiments on accommodarion by using the Canon-RI and were refrative sr uf infs.I Cunet Aopeuts in Opadldmd. able to get useful impressions conceming interaction in both eyes ogy.Proccedingsof the 13th Congress of the Asia-Pacfi Academy of and in meridians.However,we were not able to reach a condusion. Ophthalmulgy:1991 May 12-17:Kyut,Japan.Tukyu:Excerpa As far as we know,there is no instriment that simultancomshy Medica.1为l:701-. mcasurcs binocular accommodation in all merilians and in natural 10.Saichin M,Looato H,Yamimeeo K,Makinn H.Nalo S Refractinn visual circumstances such as presnting a visual fisation target in behnior in oedinary visiou.Par 1.Concerning accummodation lag. utural space.16- Folin Ophehalmol Ipn 1982:33:1052-7. The PR-1100.origirlly developed for infant refraction,and 11.Sihin M.Ueoo H.Makino H.Nida S.Yamsenow K.Lg of empkyinga phoenrefraction system,can measure both eyesand all accommodaion.In:Breinin GM,Siegel IM,eds Advances in Diag- mrridians simultancously.However,the dctcuod rcoords using nntic Visual Optio:Proceefinges of the Secoed Intertational Sym- ponium,1982 Out 23-25,Tooun,AZ.Berlin:Springer-Verlag. the improved PR-1100 ane only static rcurds;to get dynamic or 1悲6974. chronological record.fiarther improvement will be necessary. 12.Saishin M.Optical charactrriic of the human eye.Nippon Gank The resules from this experiment would indicate that the major- Caklui Zaxhi 1994:98:1201-12. ity ofbilteral cmmctrope cxhihit with-the-rule asigmtism when 13.Commeureer TN,Crane HD.Trining the vismal acoommodarion syo accommodating (Fig.7).The previouly dexribod simulation, .Vinice Ro197万：1k713-5. demonstrating that comvergence causcs against-the-rul astigma- 14.Howland HC.Howland B.Photorefracrion:a technigse for study of tism,supports this finding.becase the astigmatism is in the op- refractive veate at a datance.Opt Soc Am 1974:64:240-9. posite dirnction. von Helmbol H,Southall JPC.Helmhol's Treatise on Physiclog. The phenumcron of bg of accommodation was reported in i:al Optics.Vol 1,New Yark:Dewer Pablicarions,1962:139-40. 1922.Th subjccts markedly shuwed the hg of accommocation 16.Adler FH.Han M.Ir.Adler's Physiology of the Eye Clinkcal only in the borizontal meridian The cause of with-the-rule astig- Applicarion rh ed.St Louis Modby-Yeae Book.1992:391-411. matism and Lag of acoommodation in the horicontal meridian, 17.Benpunin WI.Boroh IM.Burih's Clinical Refraccioe Philadelphi when hilateral emmetmopes accommodate,is unknown.The one WB Sranders 1999.p.105-58. i8.民comnlidd M,《ilmartin且A:cummodasivr acptation to mceccu- factor may be the roncoxial optical sysom af a human living cyc. lar and binocular stimuli.Am J Opcom Physiol Opt 1988:655562-G. which is widely rooognized by the existence of plural optical aes 19.rrne.PA.Gieri GiA,Pirrce H].An imnegrated spoem fnr measring optic xis,viual axis,fixation axis,line of sight,and pupillary ais satic and dynamic accommodarioe with a Canan AuporefR.l refrac. One subject showed a littk anisometropia on accommodation. momerer.Ophthalmic Physiol Ope 1996;16520-7 More inetigation on anisomctropia in conncction with accom- 20.Capbdll FW.Coerdaioe uf sccomodation between the two cys. mudation will be ncocsary. J0ocAm155738-9 Brerivrd Sepiembrr d.1998:final reviise necial Noeeraber 8.1999. 21.Harmukawa Y.A study on accommodarion and comvergenceby simul. taecous meaaurmeet of the relractiun of both eyes aed the rye poui- rion.Folia Opachalmol Jpn 198:3%1247-16. 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experiments on accommodation by using the Canon-R1 and were able to get useful impressions concerning interaction in both eyes and in meridians. However, we were not able to reach a conclusion. As far as we know, there is no instrument that simultaneously measures binocular accommodation in all meridians and in natural visual circumstances such as presenting a visual fixation target in natural space.18–25 The PR-1100, originally developed for infant refraction, and employing a photorefraction system, can measure both eyes and all meridians simultaneously. However, the detected records using the improved PR-1100 are only static records; to get dynamic or chronological records, further improvement will be necessary. The results from this experiment would indicate that the majority of bilateral emmetropes exhibit with-the-rule astigmatism when accommodating (Fig. 7). 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Mitsuo Tsukamoto Department of Ophthalmology Nara Medical University 840 Shijyo-cho, Kashihara Nara 634-8522 Japan Accomodation and Astigmatism—Tsukamoto et al. 155 Optometry and Vision Science, Vol. 77, No. 3, March 2000