PSYCH 2E03 Lecture Notes - Bifocals, Cycloplegia, Ciliary Muscle
12 Jun 2013
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Document Summary
Distance between far and near point far point: 6 meters, no accommodation required. Ciliary muscles contract, suspensory ligaments become loose and anterior curvature of lens increases. When ciliary muscles are relaxed suspensory ligaments is pulled, lens is flatter. Accommodated state: when ciliary muscles are contracted, suspensory ligament become loose and the lens becomes curved due to the elastic properties of the lens. Oculomotor, stimulates all three processes which contribute to accommodation. Presbyopia = old eye accommodation is compromised with ageing lens gets fixated at a particular curvature lens is no longer flexible lens becomes more and more flat. Damage to iii cranial nerve (ocullomotor nerve) causes cycloplegia cyclopegics are drugs that cause paralysis of accommodation in cycloplegia, pupils are dilated and lens remains fixed in a relatively flat position. Atropine a cetylcholine receptor blocker causes cycloplegia lasting for a few hours, especially in the smooth muscles. Administering atropine drops on the cornea dilates pupils.
