The Visual System Part 1 Refraction Glaucoma Glaucoma

The Visual System Part 1

Refraction Glaucoma & Glaucoma test

Degree of cell packing in retina

Intrinsic Muscles of the Eye: The Iris • Iris – circular. . . constricts – radial. . . …dilates • Dilating pupil for eye exam: how to do it? Pharmacology of pupillary dilation: Atropine

Intrinsic Muscles of the Eye: Ciliary Muscle • Ciliary muscle relaxed = tension on zonular fibers = tension on lens = flattened lens = distant focus • Ciliary muscle contracted = tension on zonular fibers reduced = less tension on lens = lens becomes more spherical =near focus • Eye strain Using a Microscope or Binoculars

Accommodation animation 1) Demonstrate Convergence 2) Measure NPA With Convergence

NPA Left eye ________mm NPA Right eye _______ mm Sex of subject ___ Age in months___ Normally use corrective lenses/contacts? yes/no Wearing corrective lenses/contacts for test: yes/no

0. 06 0. 07 0. 08 0. 09 0. 12 0. 14 0. 16 0. 18 0. 3 0. 4 Presbyopia

Disorders of Focus • Myopia = nearsighted – eyeball too long, cornea/lens to “strong” – image focused in front of retina – correct with concave lens • Hyperopia = farsighted – eyeball too short, cornea/lens to “weak” – image focused behind retina – correct with convex lens • Astigmatism – irregular surface of lens or cornea

Cataract •

Extraocular muscles • Motor innervation by CN III, IV, VI Strabismus= misalignment of eyes Storytime

Suprachiasmatic Nucleus for diurnal cycling Visual reflexes: Aka. Area 17 and V 1 Accomodation, Saccades, Tracking, Pupillary reflex

Goliath?

Evolution of Binocular Vision Mapping the boundary of each visual field

Retinotopy

Point Localization Experiment • • • Work in pairs 3 consecutive stimuli to same site Trial 1 = Red pen Trial 2 = Black pen Trial 3 = Blue pen Last digit SSN even = pen in dominant hand Last digit SSN odd = pen in non-dom hand 1 st subject tests hand first 2 nd subject tests calf first Test calf on same side as holding the marking pen.