The document discusses the anatomy of the eye, including the outer layers like the sclera and cornea, middle layers such as the iris and choroid, and inner retinal layer. It also explains how light enters the eye and is processed, normal vision versus problems like astigmatism and blindness, and the causes and treatments of common vision issues such as cataracts and glaucoma. Color vision is enabled by the three types of cone pigments that are sensitive to different wavelengths of light.

1. Looking Into the Eye Understanding Anatomy, Normal Vision, and Vision Problems By: Deniz Harland

3. Anatomy of the Eye

4. Outermost Layer The Sclera maintains the shape of the eye The Cornea is the front sixth of the sclera and is clear . All light must first pass through the cornea when it enters the eye. Extraocular Muscles Sclera Cornea The Extraocular Muscles are attached to the sclera and move the eye

5. Second Layer The Choroid (or Uveal Tract) is the second layer of the eye . It contains the blood vessels that supply blood to structures of the eye. The Iris is the colored part of the eye . The color is determined by the color of the connective tissue and pigment cells. The iris is an adjustable diaphragm around an opening called the pupil . The Ciliary Body is a muscular area that is attached to the lens. It contracts and relaxes to control the size of the lens for focusing. The Dilator Muscle makes the iris smaller and therefore the pupil larger, allowing more light into the eye. The Sphincter Muscle makes the iris larger and the pupil smaller , allowing less light into the eye. Choroid Ciliary Body Sphincter Muscle Dilator Muscle Iris

6. Innermost Layer Retina Rod Cells Fovea Centralis Macula Cone Cells The Rod Cells are responsible for vision in low light The Cone Cells are responsible for color vision and detail The Retina is the light-sensing portion of the eye The Macula is in the back of the eye and in the center of the retina The Fovea Centralis is in the center of the macula, contains only cones, and is responsible for seeing fine detail clearly.

7. Muscles Six muscles attached to the sclera that control the movements of the eye Rotates eye Rotates eye Lowers eye Raises eye Moves eye away from nose Moves eye towards nose Primary Function Inferior oblique Superior oblique Inferior rectus Superior rectus Lateral rectus Medial rectus Muscle

12. Blind Spot Activity Test the presence of the blind spot by 1- Covering your right eye with your hand 2- Staring at the yellow circle as you move closer to the screen Or cover your left eye and stare at the red square as you move. Result: the square (or circle depending on which eye in covered) will disappear