RETINA -

• It is inverted. Innermost, sensitive layer. The part of ratina which is attached to choroid is pars optica.
• The part of retina attached to cilliary body is ora-serreta.
• In retina 2 parts are clear -   (A) Pigmented layer          (B) Neuro-sensory layer.
• Pigmented layer is of hexagonal or rectangular cells.
• Fusein pigment present adopted to absorb light rays.
• From these cells microvilli are given out to engulf extra pigment granules.
• Inside it, a layer of rods and cones is present.
• Rods are 1150 lakh and cones are 65 lakh.
• Rods are mone long, meant to judge abject in dim light in it rodopsin (retinine + opsine or skotoprine) present for it vitamin A (ratinol) is necessary i.e. in defficiency of vit A. night blindness (nyctalopia) is caused.
• Rhodopsin is known as visual purple.