Contents 。Basic optics. Refractive power of the eye. Refractive status of the eye. ·Refractive errors. ·Eyeglasses. ·Contact lenses. ·Refractive surgery. 。Visual aids
Contents • Basic optics. • Refractive power of the eye. • Refractive status of the eye. • Refractive errors. • Eyeglasses. • Contact lenses. • Refractive surgery. • Visual aids
Basic optics
Basic optics
Light In physics,the term light refers to electromagnetic radiation of any wavelength, whether visible or not. --Increasing Frequency (v) 1024102 1020 108 1016 102 10o 10 105 1031010°vHz Y rays X ray Microwave FM AM Long radio waves Radio wa ave 1016 104 102 10n 108 106 10 10-2 10° 102 102 1010 入(m Increasing Wavelength(入)→ Visible spectrum 400 500 600 Increasing Wavelength ()in nm-
Light • In physics, the term light refers to electromagnetic radiation of any wavelength, whether visible or not
Light 。Visible light (commonly referred to simply as Visible Spectrumm light)is electromagnetic radiation Radio 700600500400 that is visible to the human eye, 1GHz 100GHz Infrared and is responsible for the sense AM m of sight.Visible light has a 540-1650lk2 88-108MH Ultraviolet wavelength in the range of about SotX-rays ha同 380 nanometres(nm),or Frequency (Hz) G-rays 380X 10-9m,to about 740 3x102,3x104,3x10,3x100,3x10103X10123X104,3x1063X1003x103X1023x10 nanometres-between the Wavelength (m) invisible infrared,with longer wavelengths and the invisible Mountains Factory People Button Point Dust Bacteria Virus Atom Atomic nucleus Size ultraviolet,with shorter wavelengths
Light • Visible light (commonly referred to simply as light) is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has a wavelength in the range of about 380 nanometres (nm), or 380×10−9 m, to about 740 nanometres – between the invisible infrared, with longer wavelengths and the invisible ultraviolet, with shorter wavelengths
Lenses Prism Ap●xN Light Base Refracied Light Minus Lens Plus Lens Base Apex Light Light Apex 日a50 Focal Point Point Light Light Base Apex
Lenses
SUSPENSORY LIGAMENT FOVEA IRIS PUPIL LENS CORNEA OPTIC NERVE RETINA REEL lunexposed lilm) FILM PLANE LENS REEL [expase时lnl
Refractive power of the eye D=+60D H n=1.33 n=1 F N F 17mm 5.6mm 17mm 22.6mm Figure 1-13.Schematic eye
Refractive power of the eye
Refractive status of the eye. Emmetropla 。Emmetropia Oblect at Refractive state of the eye Infinity when parallel rays of Shortslghted light from a distant Myopla(long eye) object are brought to Object at Infinity focus on the retina with the eye at rest (i.e.not Longsighted accommodating) Hypermetropla(short eye) Object at Infinlty When out of focus on the retina Ametropia
Refractive status of the eye. • Emmetropia Refractive state of the eye when parallel rays of light from a distant object are brought to focus on the retina with the eye at rest (i.e. not accommodating) When out of focus on the retina : Ametropia
Refractive errors (Ametropia) ·Myopia Emmetropla Object (nearsightedness or shortsightedness) Shortslghted Myopta (long eye) Object t Infinity 。Hyperopia Longslghted (hypermetropia,farsightedness or; Hypermetropla (short eye) Object longsightedness) at Infinity
Refractive errors (Ametropia) • Myopia (nearsightedness or shortsightedness) • Hyperopia (hypermetropia ,farsightedness or; longsightedness)
Astigmatism CROSS SECTION OF NORMAL EYE CROSS SECTION OF ASTIGMATIC EYE Retina Retina Lens Lens Cornea Cornea (soccer ball shape) (rugby ball shape】 1st fodal point 2nd focal point Vertical Vertical Focal point light rays light rays Horizontal Blur zone (horizontal and (horizontal and Horizontal light rays light rays vertical light rays share vertical light rays have common focal point) different local points)
Astigmatism
