Optics

External Eye

Eye Globe

Eye Structures Cornea – clear window, refracts light Anterior Chamber – contains aqueous humor that nourishes cornea Iris – controls amount of light

Eye Structures Posterior Chamber – contains aqueous humor that nourishes cornea Lens – refracts light Vitreous Humor – maintains eyeball shape

Eye Layers Sclera – protection (clear front is cornea) Choroid – vascular layer Retina – nerve layer - Macula Lutea - Fovea - Optic disk

Eye Structures Retina – changes light energy into chemical energy and then electrical energy Rods – black/white vision Cones – color vision: red, blue, green

Flow of Light Cornea Anterior Chamber Pupil Lens Vitreous Humor Retina

Bending Light Terms Refraction – bending light Concave – surface with negative curve Convex – surface with positive curve

Ophthalmic to Optometric Sphere – add sphere and cylinder Cylinder – change sign Axis – Add 90 if 90 or less, subtract 90 if greater than 90

Lensometer Determine lens prescription Line up vertical and horizontal lines

Major Disorders Glaucoma – increased internal pressure due to obstruction in aqueous humor flow Cataract – cloudy lens Detached Retina – separation of retina from choroid layer

Major Disorders Conjunctivitis – inflammation of lining of eyelids Macular Degeneration – loss of central vision Strabismus – eyes do not track together

Surgical Interventions Radial Keratotomy – incisions in cornea to correct myopia Lasix – reshaping inside of cornea Scleral Buckle – band to hold retina in place