The EyeThe Eye

Eye test

Sclera

Cornea

Aqueoushumour

Pupil

Iris

Cilarybody

Suspensoryligament

Lens Vitreoushumour

Retina

Fovea

Blindspot

Choroid

OpticNerve

ChoroidRodIntermediate

neuroneOptic

neurone

Cone

Vesicle(Rhodopsin)

ToCentralNervousSystem

Convergence

Generatorpotential

Rhodopsin

Light

Opsin + trans-retinalATP

ADP + PiHyperpolarisation

Choroid

Rods and Cones

Relay neurones

Optic neurones

Rods Cones120 million per eye 6 million per eye

Not present in fovea Concentrated mainly in the fovea

Contain only one type of photosensitive pigment, Rhodopsin

Convergence: About 100 rods are connected to each optic neurone. This amplifies the weak signal generated by low light intensities but reduces acuity (resolution)

Contain one of three types of a photosensitive pigment called iodopsin. (Blue, Red or Green cones)Convergence: In the fovea one Cone is connected to each optic neurone. This gives good visual acuity (resolution) but reduces sensitivity

Slow response to light, stimuli added over time

Fast response to light, can perceive more rapid changes in stimuli

Have more pigment than cones, so can detect less light

Have less pigment than rods, require more light to detect images

Stacks of membrane-enclosed disks are unattached to cell membrane

Disks are attached to outer membrane

Very light sensitive; sensitive to scattered light

Not very light sensitive; sensitive only to direct light

Confer achromatic vision Confer color vision

Rods

Cones

Fovea Blind Spot

Vitreous Humour

Blind Spot

Choroid

Choroid

Cones

FoveaBipolar

neurones

Opticneurones

14.

2.

5.

4.

3.

1.

6.

7. 8.

9.

12.

10.

13.

11.