Eye Health: 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 done by taking a thin strip of paper stained with the dye fluorescein. This dye stains the front of the eye and enables a better eye exam by the doctor. The patient is then given a local anesthesia in the form of drops and the pressure is measured using a tonometer.

Corneal Topography

During this eye test, a computer is used create a "map" of the curvature of the cornea. The computer analysis will show any distortions of the cornea such as scarring, as well as conditions such as astigmatism. This eye test is used to screen patients before they undergo any refractive surgery, as well as for fitting contact lenses and corneal transplants.

Fluorescein Angiogram

This 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 measures your ability to see objects at specific distances. Often doctors will ask the patient to look at a chart, usually 20 feet away, and try to read it while looking through a special instrument known as a phoropter. The phoropter moves lenses of different strengths into place for the patient to look through. The doctor will ask you which of the choices looks clearer and based on these answers will determine the appropriate prescription needed for glasses or contacts. This eye test is useful in helping to diagnose presbyopia, hyperopia, myopia, and astigmatism.

Slit-lamp Exam

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