Eye Tests and Exams

Here's a brief guide to the special eye tests your eye doctor may perform during an eye exam. In addition to a complete examination of your eye, your doctor may want to order one of the following eye tests.

Applanation Method

This eye test helps doctors diagnose glaucoma by measuring the amount of pressure needed to flatten a portion of the cornea. This is often done by placing a dye in the eye from a thin strip of paper coated with the dye. This dye stains the front of the eye and enables a better eye exam by the doctor. The patient is given local anesthesia drops and the pressure is measured using a tonometer held in the hand or attached to a slit lamp.

Corneal and Retinal Topography

These are computerized tests used to create a "map" of the curvature of the cornea or surface of the retina. This test is not necessary during a routine eye exam. The analysis will show distortions of the surface 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, corneal transplants, as well as for fitting contact lenses. The retinal test may be used to follow patients with serious conditions of the retina.

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 and retinal detachment. 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.

Pupillary Dilation Test

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

Refraction Test

This eye test determines your eyeglasses prescription. Tthe patient looks at a chart, usually 20 feet away, or in a mirror simulating 20 feet distance and tries to read it while looking through a special instrument known as a phoropter. The eye 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 needed for glasses or contacts. This eye test will also identify  presbyopia, hyperopia, myopia, and astigmatism.