The Eyes and Vision

I. Anatomy of the Eye The eye consists of 3 layers or tunics Fibrous tunic- The eye consists of 3 layers or tunics Fibrous tunic- Cornea – (the outside front of the eye) important in focusing light onto the retina; can become damaged by foreign objects, chemicals, or trauma (cornea + lens focus the light) Cornea – (the outside front of the eye) important in focusing light onto the retina; can become damaged by foreign objects, chemicals, or trauma (cornea + lens focus the light) Sclera- maintains shape of eye and protects; makes up the white of the eye. Goes around the entire eye

I. Anatomy of the Eye Vascular tunic - Vascular tunic - Iris- controls the amount of light passing through the pupil – COLORED part of eye Iris- controls the amount of light passing through the pupil – COLORED part of eye Pupil – the dark center of the eye which lets light into eye. Pupil – the dark center of the eye which lets light into eye. Lens – very hard clear part of eye in middle which focuses the light. (cornea + lens focus the light) Lens – very hard clear part of eye in middle which focuses the light. (cornea + lens focus the light) Ciliary bodies – muscles which control the size of the Iris and therefore also the pupil. Ciliary bodies – muscles which control the size of the Iris and therefore also the pupil.

I. Anatomy of the Eye Neural Tunic - Neural Tunic - Retina – detects light and forms image for transmission to the brain. The back of the eye. Site of Rods and cones. Retina – detects light and forms image for transmission to the brain. The back of the eye. Site of Rods and cones. –Black parts are rods. Colored parts are cones.

I. Anatomy of the Eye (cont) The eye consists of 2 Fluid Filled Cavities - The eye consists of 2 Fluid Filled Cavities - Aqueous humor- fills the anterior cavity, helps keep shape, refracts light, maintains pressure. Between cornea & lens Aqueous humor- fills the anterior cavity, helps keep shape, refracts light, maintains pressure. Between cornea & lens Vitreous humor- fills the posterior cavity, has same functions as aqueous humor and keeps retina firmly pressed against choroid. Between lens and retina Vitreous humor- fills the posterior cavity, has same functions as aqueous humor and keeps retina firmly pressed against choroid. Between lens and retina

Vitreous humor

II. Physiology of Vision The sense of sight relies most upon the 2 different types of cells in the retina The sense of sight relies most upon the 2 different types of cells in the retina Rods - permit vision when there is dim light. They form outlines or silhouettes of objects and are concerned with twilight vision. Rods - permit vision when there is dim light. They form outlines or silhouettes of objects and are concerned with twilight vision. Cones - allow vision where there is sufficient light to permit close detailed vision. The cones enable one to see detail and are responsible for color vision. Cones - allow vision where there is sufficient light to permit close detailed vision. The cones enable one to see detail and are responsible for color vision. Cones and Rods change the light waves into neuronal signals. Cones and Rods change the light waves into neuronal signals.

RodCone

II. Physiology of Vision (cont) Visual Pathway- Light enters the eye through the pupil and is refracted or bent, so that it is focused on the retina. Visual Pathway- Light enters the eye through the pupil and is refracted or bent, so that it is focused on the retina. Refraction occurs as light passes through the cornea, the aqueous humor, the lens and the vitreous humor on its way to the retina. Refraction occurs as light passes through the cornea, the aqueous humor, the lens and the vitreous humor on its way to the retina. Cornea – aqueous humor – pupil – lens – vitreous humor – retina (rods & cones) – optic nerve – brain (occipital lobe) Cornea – aqueous humor – pupil – lens – vitreous humor – retina (rods & cones) – optic nerve – brain (occipital lobe)

III. Disorders Myopia- nearsightedness Myopia- nearsightedness Hyperopia- farsightedness Hyperopia- farsightedness Astigmatism – irregularity in the curve of the cornea or lens Astigmatism – irregularity in the curve of the cornea or lens Cataracts- lens becomes cloudy Cataracts- lens becomes cloudy Glaucoma – damage to the optic nerve usually caused by high intraocular pressure. Glaucoma – damage to the optic nerve usually caused by high intraocular pressure.

Cataract

Glaucoma

Take care of your eyes!