Stargardt Disease Diagnosis

Stargardt Disease Diagnosis

Genetic testing may help distinguish the type of Stargardt disease a person has and provide information about the mode of inheritance and risks to other family members, although examination of the retina by a professional is the usual way a diagnosis of Stargardt is made.

A substance called lipofuscin starts to accumulate under the retina and deposits of lipofuscin can be seen as yellowish flecks in the macula or central retina of people affected by Stargardt disease. These flecks of yellow vary widely between people, with different numbers, appearance, colours of yellow and size seen in different people. The shapes of the flecks can be very irregular. The flecks form a ring pattern spreading out from the center of the retina.

Diagnostic Tests for Stargardt Disease:

A standard eye chart and other tests may be used to assess symptoms of vision loss in Stargardt disease, including:

Visual field testing. Visual fields testing attempts to measure distribution and sensitivity of field of vision. Multiple methods are available for testing; none is painful and most share a requirement for the patient to indicate ability to see a stimulus / target. This process results in a map of the person’s visual field, and can point to a loss of central vision or peripheral vision.

Color Testing: There are several tests that can be used to detect loss of color vision, which can occur late in Stargardt disease. Three tests are often used to get additional information: fundus photography combined with autofluorescence, electroretinography, and optical coherence tomography.

Fundus Photography: A fundus photo is a picture of the retina. These photos may reveal the presence of lipofuscin deposits. In fundus autofluorescence (FAF), a special filter is used to detect lipofuscin. Lipofuscin is naturally fluorescent (it glows in the dark) when a specific wavelength of light is shined into the eye. This test can detect lipofuscin that might not be visible with standard fundus photography, making it possible to diagnose Stargardt disease earlier.

Electroretinography (ERG) measures the electrical response of rods and cones to light. During the test, an electrode is placed on the cornea and light is flashed into the eye. The electrical responses are viewed and recorded on a monitor. Abnormal patterns of light response suggest the presence of Stargardt disease or other diseases that involve retinal degeneration.

Optical coherence tomography (OCT) is a scanning device that works a little like ultrasound. While ultrasound captures images by bouncing sound waves off of living tissues, OCT does it with light waves. The patient places his or her head on a chin rest while invisible, near-infrared light is focused on the retina. Because the eye is designed to allow light in, it’s possible to get detailed pictures deep within the retina. These pictures are then analyzed for any abnormalities in the thickness of the retinal layers, which could indicate retinal degeneration. OCT is sometimes combined with infrared scanning laser ophthalmoscope (ISLO) to provide additional surface images of the retina.