Eye Anatomy Lab 3 PDF

## The Eye ### Parts of the Eye * **Sclera**: outermost layer of the eye; opaque; supports the eye & site of attachment for oculomotor muscles * **Cornea**: responsible for allowing light to enter the eye and helps to focus it; avascular & transparent * **Choroid**: deep to sclera and conta...

## The Eye ### Parts of the Eye * **Sclera**: outermost layer of the eye; opaque; supports the eye & site of attachment for oculomotor muscles * **Cornea**: responsible for allowing light to enter the eye and helps to focus it; avascular & transparent * **Choroid**: deep to sclera and contains richly pigmented melanocytes and highly vascularized * to absorb light that reaches the choroid layer * **Retina**: deep to choroid layer; capture image forming rays & convert them to action potentials * **Rods**: photoreceptor cells that detect black & white * **Cones**: photoreceptor cells that detect color & responsible for high acuity vision * **Fovea centralis**: centre of retina; high concentration of cones; extremely detailed vision * **Optic disc**: joins to the optic nerve; no photoreceptor cells so cannot form image; "blind spot" * **Anterior cavity**: Space between cornea and iris is filled with aqueous humour secreted by ciliary body * **Posterior cavity**: gelatinous substance known as vitreous humour; maintains shape of eye * **Lens**: anterior to P.C. and ciliary body; transparent flexible disc focuses light on retina * **Suspensory ligaments**: lens connected to C.B. to pull lens into flat shape to focus light from far away * **Ciliary body**: continuation of choroid layer & contains ring of smooth muscles that surround lens; contraction of smooth muscles causes lens change shape * **Iris**: anterior to ciliary body; highly pigmented & gives color of the eye * **Pupil**: centre of iris which light will pass through to reach retina * **Pupillary sphincter**: contracts to decrease diameter of pupil allowing less light into eye * **Pupillary dilator**: contracts to increase diameter of pupil allowing more light into eye * **Circular lens**: close vision = closer focus point = loose ligaments = contracted ciliary muscles (round) * **Stretched lens**: far vision = further focus point = tight ligaments = relaxed ciliary muscles (flat) ### Diagram of the Eye  ### Vision Problems * **Emmetropia:** normal vision associated with properly functioning eye * **Myopia:** eyeball too long so image focused in front of retina (nearsightedness) * **Hyperopia:** eyeball too short so image focused behind retina (farsightedness) * **Presbyopia:** normal individuals become farsightedness as they get older