Screening and Diagnosis

To determine if you or a loved one has AMD, you’ll have to see your eye care provider for a complete eye exam. The eye exam usually begins with your doctor asking about your medical history and any vision problems you might be experiencing. Next, your eye doctor makes a quick check of your eyes using a light to ensure the exterior parts of your eyes are functioning correctly. Finally, your doctor measures your visual acuity, assesses your need for glasses and examines your eyes for signs of disease. Part of the examination, such as taking your medical history and the initial eye test, may be performed by a technician who assists your doctor.

Visual Acuity

Visual Acuity is measure on an eye chart giving a number such as 20/20, 20/60, or 20/200. Visual acuity of 20/20 is considered normal for a healthy person. Visual acuity of 20/60 indicates that a letter on an eye chart that should be easily seen at 60 feet needs to be moved to 20 feet to been seen by the same person.

Pinhole Vision

Having a person look through a single pinhole gives the doctor an estimate of the best vision that could be achieved with new eyeglasses. It is an easy and useful method to determine whether a change in glasses would help and what the best vision could be.

Refraction

This is the test that the eye doctor uses to determine your exact prescription. During a refraction, the doctor puts the instrument called a phoropter in front of your eyes and shows you a series of lens choices. He or she will then ask you which of the two lenses in each choice looks clearer.

Based on your answers, the doctor will continue to fine-tune your power until reaching a final prescription that is then used in your eyeglasses and contacts. Refraction determines your level of farsightedness, nearsightedness, astigmatism and presbyopia.

Amsler Grid

The Amsler grid is a simple screening test used to assess central vision, at the macula. The Amsler grid looks like graph paper - a series of small squares - with a dot in the center of the grid. The patient is instructed to stare at the dot and notice if any lines appear wavy or missing.

Eye Pressure

The doctor will test the pressure inside the eye. This is an important screen for glaucoma, a condition causing damage to the optic nerve by higher than normal pressure in the eye.

Dilation

The dilation process is fairly simple: a doctor or technician instills eye drops that make your pupils expand. The pupil is the ‘window’ that the doctor uses to examine the back (posterior) segment of your eye – the retina and the vitreous fluid. In order to examine the posterior segment, your doctor will generally use an instrument (ophthalmoscope) that incorporates a light and a magnified viewing system. Without dilating drops, the instrument’s light causes the pupil to shrink, virtually closing the viewing ‘window.’

A dilated exam will better reveal ocular conditions such as macular degeneration, retinal detachments, retinal tears, swelling, hemorrhages, vitreous infections, tumors, glaucoma and cataracts. A dilated exam can also reveal problems associated with ‘whole-body’ diseases like diabetes, vascular disease and hypertension.

Slit Lamp

The slit lamp is an instrument that the eye doctor uses to examine the health of your eyes. The slit lamp, also called a biomicroscope, allows the doctor to get a highly magnified image of the structures of the eye in order to thoroughly evaluate them for signs of infection or disease.

During this test the doctor will have you place your chin on the chin rest of the slit lamp and will then shine the lamp's light at your eye. The doctor looks through a set of oculars (much like a microscope in a science lab) and examines each part of the eye in turn. Your doctor will first examine the structures of the front of the eye (lids, cornea, conjunctiva, iris, etc.). Then, with the help of a special high-powered lens, he or she will view the inside of the eye (retina, optic nerve, macula and more). A whole range of eye conditions and diseases can be detected with slit-lamp examination, including cataracts, macular degeneration, corneal ulcers, and much more.

Fluorescein Angiography

Fluorescein angiography is a photographic procedure. A teaspoonful of fluorescein dye is injected into a vein in the arm, and pictures are taken every few seconds as the dye travels through the blood vessels in the back of the eye. Photographs using fluorescein dye highlight abnormal blood vessels and identify fluid leaks in the retina, as well as overall vigor of the retinal circulation.

Optical Coherence Tomography

Optical Coherence Tomography, “OCT” for short. OCT is a new, non-invasive technology used for imaging the retina, the multi-layered sensory tissue lining the back of the eye. Similar to CT scans of internal organs, OCT uses the optical backscattering of light to rapidly scan the eye and describe a pixel representation of the anatomic layers within the retina. Each of these ten important layers can be differentiated and their thickness can be measured.