Eye Exams - Retina

Without a healthy retina, the human eye is like a camera without film. The retina receives light rays from the front of the eye and sends them through the optic nerve to the brain where they are turned into clear, bright, colorful images. Ophthalmologists who specialize in the retina are usually called vitreo-retina specialists because they also deal with disorders of the vitreous, a clear, jelly-like substance that lies between the eye’s natural lens and the retina. When disease or injury causes clouding of the vitreous or damage to the retina, the result is a partial or complete loss of vision.

If your primary eye doctor finds signs of a retina disorder during a general eye exam, you will probably be referred to a retina specialist for additional tests and possible treatment. Early detection and treatment holds the best promise for treating retinal disorders because once the retina is damaged, repair is extremely difficult.

Preparation for the Examination

A visit to the retina specialist starts with the creation of a patient record. This will include your address and telephone numbers, insurance information, names of other doctors, list of medications being taken, and past medical records if available. Some doctors will even ask that the patient bring to the exam all medications currently being used. Because a retina exam includes dilating the eyes, it’s a good idea to bring sunglasses to wear for the trip home.

The Examination

A retina exam is focused on the back of the eye. For this reason, the doctor will spend a lot of time looking through your pupil at the vitreous, retina and other structures located inside the back portion of the eye. Every patient can expect to have their eyes dilated so the doctor can get a clear view of these structures.

The following methods are normally used in diagnosing retina problems:

• Indirect ophthalmoscopy uses a specialized microscope that allows the doctor to observe the vitreous, retina and other internal structures in the eye. The ophthalmoscope is probably the first instrument you will see used by the doctor during your exam because it provides an overview of the situation.
• A visual field or perimetry test measures the ability of your eye to see straight ahead and to the side (peripheral vision). During a visual field test, one eye is temporarily covered and the patient is asked to look straight ahead at a fixed space. There are two kinds of tests: a moving target test and a fixed target test.

In the moving target test, the targets are moved from the side, where they are not visible, toward the center of vision until the patient sees them. This test can be performed with either a black screen on the wall or with a large bowl-shaped instrument.

A fixed target test, called computerized static perimetry, uses small points of light that appear bright or dim but do not move. During this test, a patient sits in a chair facing either a bowl-shaped instrument or a computer screen.

The visual field examination detects “blind spots” that may be caused by diseases of the retina.

Fluorescein angiography
Fluorescein angiography is a test used to examine blood vessels in the retina. This procedure involves the injection of a vegetable-based fluorescein dye into the blood stream. As the blood circulates through the retina, a series of rapid, sequential photographs are taken of the eye. This commonly performed test provides useful anatomic and functional information about the retina and is one of the most important tools in the diagnosis and treatment of retinal disorders.

B-scan ultrasound
B-scan ultrasound is a method for viewing the structures at the back of the eye through the use of high frequency sound waves, while A-Scan ultrasound uses similar technology to evaluate the internal characteristics of tumors and other lesions in the eye. This technology provides a topographical view of the eye with information that is not otherwise possible.

Fundus photography
Fundus photography uses specialized film and digital cameras to document abnormalities in the retina. It is important in following the progress of certain retinal diseases and to monitor treatment.

Upon completion of the tests required for an accurate diagnosis, the doctor will discuss the various treatment options. Although retinal disorders are often complicated to treat, modern medical science has made significant treatment advances in recent years.

Common Retina Disorders

Diabetic retinopathy
Diabetic retinopathy is a potentially serious complication of diabetes that results in the weakening of tiny blood vessels that nourish the retina. These vessels may leak causing a variety of complications including the formation of scar tissue on the retina and a decrease in nourishment to the retina or blood in the vitreous humor (fluid that fills the inner cavity of the eye) causing cloudy vision. If the condition is not caught and treated during the early stages, it can lead to in blindness.

Macular Degeneration
Macular degeneration is a common retinal disease that is often associated with aging. It is caused by a degeneration of the photoreceptors in the macula or central region of the retina, the area responsible for central, straight-ahead vision such as that used for reading and seeing faces.

Retinal detachments
Retinal detachments can be caused by disease or injury. Here, a segment of the retina becomes separated or peels away from the back wall of the eye. Unless treated promptly, this condition can result in immediate loss of vision.

Vitreous disorders are usually characterized by “floaters” or cloudy vision. Floaters are particles that float in the vitreous and cast shadows on the retina. They appear to be strung together with a web-like thread. Some floaters are formed before birth, while others occur normally with aging. The sudden appearance of many floaters can be an indication of a serious eye disorder and should be checked by an eye doctor.

See Retina, Age-related Macular Degeneration, and Diabetes in Eye Care Encyclopedia.