eye anatomy

 

 

 

 

Your tear film is the first optical surface on your eye. That's why a dry eye can sometimes yield unreliable refractions and lead to intermittent blur.

The cornea is the clear dome that is arches over your colored iris. Along with the lens, the cornea's curvature determines how much astigmatism you have.

Your iris is the colorful muscle that contracts to adjust the size of your pupil. Iris color depends on the amount of melanin overlying it. If the eye were a camera, the pupil would be the aperture. 

The lens is the clear pillow that sits immediately behind the iris and pupil. UV exposure, smoking, diabetes, trauma and other factors can lead to the opacification of this lens. The result is called a cataract. The lens is held in a sac which in turn is held and manipulated by zonules or ropes connected to the iris. When you switch from distance to near, those zonules change their pull, altering the shape of your lens to focus. Your ability to change that focus diminishes gradually over time, typically leading to a need for readers around the age of 40. 

Behind the lens and filling the largest cavity in the eye is a sac of fluid called the vitreous. This gel is filled with protein clumps called floaters that tend to increase over time. If you notice a dramatic change in your floaters, it's important to get your eyes checked promptly, as new floaters can be associated with retinal detachment.

Your retina is the thin cellophane lining the wall of the eye. This is where your rods and cones live. Since the retina is made up of nerves, anything that damages the retina (like macular degeneration, diabetic retinopathy, etc) is irreparable.

The choroid is the bed of blood vessels underlying the retina. It nourishes the retina. If the two are separated (as in a retinal detachment) the retina could die.

The optic nerve is where the nerves of the retina gather into a bundle and exit the eye to the brain. This is the reason you have a blind spot! Also, we optometrists and ophthalmologists watch this optic nerve vigilantly for signs of glaucoma, as the disease is usually painless but blinding.

While the peripheral retina has more rods, specializing in motion and night vision the macula boasts the densest gathering of cones, giving you your central vision, with all its color and detail.