Primary care optomety

DR. Ann Benedicto O.D. at ISOPTIK

Primary Care Optometry

Optometry is a health care profession concerned with eyes and related structures, as well as vision, visual systems and vision information processing in humans like most professions, optometry education, certification, and practice is regulated in most countries. Optometrists and optometry-related organizations interact with governmental agencies, other health care professionals, and the community to deliver eye and vision care. Optometry is one of four eye care professions, the others being Ophthalmology (which is a branch of surgery) Opticians and Orthoptics (a sub-specialty of ophthalmology primarily dealing with strabismus).

What is an Optometrist - A person who is professionally trained and licensed to examine the eyes for visual defects, diagnose problems or impairments, and prescribe corrective lenses or provide other types of treatment.

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Anatomy of Eye

Credit: Pub Med Central

Cornea- As light enters the eye, it first passes through a lubricating tear film that coats the cornea. The clear cornea covers the front of the eye and helps to focus incoming light.

After light passes through the cornea it travels through a clear, watery fluid called the aqueous humor. The aqueous humor circulates throughout the front part of the eye, maintaining a constant pressure inside the eye.

IRIS
The iris is the colored part of the eye. As light conditions change, the iris may dilate to make the pupil bigger or constrict to make the pupil smaller. This allows more or less light into the eye

Crystalline lens
After light travels through the pupil, it must pass through the lens. The human lens, much like the lens of a camera, is responsible for focusing light. The lens can change its shape to focus on nearby and distant objects.

Vitreous
After being focused by the lens, light passes through the center of the eye on its way to the retina. The eye is filled with a clear, jelly-like substance called the vitreous.

Retinal vessels
The retinal blood vessels nourish the inner layers of the retina.

Retina
The retina is a thin, light-sensitive tissue lining the back of the eye that acts much like film in a camera. Light must be properly focused onto the retina, and the surface of the retina must be flat, smooth, and in good working order to produce a clear image.

Macula
The center or bullÕs eye of the retina is called the macula. The macula contains a high concentration of photoreceptor cells which convert light into nerve signals. Because of the high concentration of photoreceptors, we are able to see fine details such as newsprint with the macula. At the very center of the macula is the fovea, the site of our sharpest vision.

Choroid
Behind the retina, a layer of blood vessels called the choroid supplies oxygen and nutrients to the outer layers of the retina.

Sclera
The white part of the eye is called the sclera. The sclera is composed of tough, fibrous tissue that protects the inner workings of the eye.

Optic nerve
The optic nerve is a bundle of nerve fibers which carries visual information from the eye to the brain.

How does the Human Eye Works?

The individual components of the eye work in a manner similar to a camera. Each part plays a vital role in providing clear vision. So think of the eye as a camera with the cornea, behavingmuch like a lens cover. As the eye's main focusing element, the cornea takes widely diverging rays of light and bends them through the pupil, the dark, round opening in the center of the colored iris. The iris and pupil act like the aperture of a camera.

Next in line is the lens which acts like the lens in a camera, helping to focus light to the back of the eye. Note that the lens is the part which becomes cloudy and is removed during cataract surgery to be replaced by an artificial implant nowadays.

The very back of the eye is lined with a layer called the retina which acts very much like the film of the camera. The retina is a membrane containing photoreceptor nerve cells that lines the inside back wall of the eye. The photoreceptor nerve cells of the retina change the light rays into electrical impulses and send them through the optic nerve to the brain where an image is perceived. The center 10% of the retina is called the macula. This is responsible for your sharp vision, your reading vision. The peripheral retina is responsible for the peripheral vision.

As with the camera, if the "film" is bad in the eye (i.e. the retina), no matter how good the rest of the eye is, you will not get a good picture.
The human eye is remarkable. It accommodates to changing lighting conditions and focuses light rays originating from various distances from the eye. When all of the components of the eye function properly, light is converted to impulses and conveyed to the brain where an image is perceived.