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Eye Tests and Exams

Here's a brief guide to the special eye tests your eye doctor may perform during an eye exam. 

Applanation Tonometry

This eye test helps doctors diagnose glaucoma by measuring the amount of pressure needed to flatten a portion of the cornea. This is done by placing local anesthetic drops and a dye in the eye from a thin strip of paper coated with the dye. The dye colors the tears on the surface of the eye. The pressure is measured as the tip of the tonometer lightly touches the eye. This instrument can be hand-held or attached to a slit lamp.

 

Corneal and Retinal Topography

These are specialized computerized tests used to create a "map" of the curvature of the cornea or surface of the retina. The corneal test can show distortions of the surface of the eye, such as swelling or scarring, as well as conditions such as astigmatism. This corneal test may be used to evaluate patients before they undergo any refractive surgery or corneal transplants, as well as for fitting contact lenses. The retinal test may be used to follow patients with serious conditions of the retina, such as age-related macular degeneration and retinal detachment. 

 

Fluorescein Angiogram

The fluorescein angiogram is an eye test used to evaluate the blood circulation in the retina. It is useful in helping diagnose diabetic retinopathy,  retinal detachment, and macular degeneration. During this eye test, a special dye, called fluorescein, is injected into a vein in the arm. The dye quickly travels to the blood vessels inside the eye. Once it reaches the eye, a specialized camera equipped with special filters that highlight the dye is used to photograph the fluorescein as it circulates though the blood vessels in the back of the eye. This will enable the doctor to diagnose any circulation problems, swelling, leaking, or abnormal blood vessels.

 

Dilated Pupillary Exam

During this eye test, the eye doctor places special drops in the eye that cause the pupil to dilate (expand). By dilating the pupils, the doctor can examine your retina for any signs of disease.

Refraction

This eye test determines your eyeglasses prescription. During the test, you look at a chart, usually 20 feet away, or in a mirror that simulates 20 feet of distance, and try to read it while looking through a special instrument known as a phoropter. The doctor moves lenses of different strengths into place for the patient to look through. The doctor will ask you which of the choices looks clearer or more blurry, and based on these answers will determine the appropriate prescription for glasses or contacts. This eye test will also identify presbyopia, hyperopia, myopia, and astigmatism.

Slit-Lamp Exam

This test looks at the eye with a microscope shining an adjustable beam of light shaped like a small slit on the eye. The doctor may also dilate your pupils while you are undergoing this exam. The eye test can be used to help diagnose cataracts, glaucoma, retinal detachment, macular degeneration, injuries to the cornea, and dry eye disease. 

 

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