Fundus autofluorescence technology encouraging in evaluating age-related macular degeneration, study finds

November 1, 2010

Results of a recent clinical sutdy provide promising evidence of the value of ultra-widefield fundus autofluorescence imaging in the evaluation of age-related macular degeneration.

Vancouver, British Columbia-Results of a recent clinical study provide promising evidence of the value of ultra-widefield fundus autofluorescence (FAF) imaging in the evaluation of age-related macular degeneration (AMD), according to lead investigator SriniVas Sadda, MD, who presented the findings of the study at the annual meeting of the American Society of Retina Specialists.

In a study using FAF imaging technology (200Tx [formerly the P200MAAF multi-wavelength scanning laser ophthalmoscope], Optos), peripheral FAF abnormalities were found in 77% of eyes in the series, especially in those with retinal degenerations, inflammation, and AMD.

Using the images, 174 eyes showed peripheral changes outside the central pole area of the retina, the area viewed using standard narrow-field, 30° field of view imaging technology. The findings demonstrated that peripheral FAF abnormalities often correlate with areas of retinal pigment epithelium disturbance, and that when correlation occurs, the abnormalities often appear more striking on FAF imaging than on the pseudocolor images due to better contrast, according to Dr. Sadda, associate professor of ophthalmology and director, Medical Retina Unit, Ophthalmic Imaging Unit, and Doheny Image Reading Center at the Doheny Eye Institute, University of Southern California, Los Angeles.

"The significance of these findings still needs to be defined and requires further study," Dr. Sadda said. "However, the evaluation of peripheral FAF abnormalities may aid in diagnosis and provide new insights into disease pathogenesis. This study follows the recently published results from the Reykjavik/Moorfields study and adds to the growing body of evidence of the importance of studying the periphery of the retina in the diagnosis and management of AMD."

The retrospective analysis reviewed the records of all patients referred to the Doheny Eye Institute imaging unit for FAF imaging who had widefield images (200CAF or 200Tx, Optos) obtained over a 6-month period. The research team collected widefield and non-widefield FAF images obtained at the same visit as well as demographic data, including disease diagnosis.

All widefield images were evaluated for the presence of FAF abnormalities, defined as increased or decreased, beyond the central 30°. The frequency of abnormalities was computed, and FAF abnormalities within disease categories were scrutinized for characteristic patterns.

The analysis included 225 eyes of 122 patients with ultra-widefield imaging. In all, 174 eyes (77%) had abnormal peripheral FAF studies. This included 100% of the eyes with a diagnosis of ocular tumors (n = 6) or retinal degenerations (n = 31) and 90% of those with inflammatory or infectious retinal diseases diagnosed (n = 54). The analysis also revealed that 76% of eyes with AMD (n = 34) and 63% of those with miscellaneous eye diseases (n = 45) had abnormal peripheral FAF imaging, as did 36% (n = 4) of the eyes with central serous chorioretinopathy.

Patterns of pathology

"Age-related maculopathy and AMD, similar to several other retinal disorders, show distinct topographical patterns of pathology," Dr. Sadda said. "Although diagnosis of AMD relies on changes in the macula, there appear to be alterations in the retinal periphery as well in these patients. The importance of these findings and their clinical significance still needs to be defined, but they are an area of great current interest to our research group."

The 200Tx has red (633 nm), green (532 nm), and blue (488 nm) scanning lasers; the green is used for excitation, while the red is used for detection. The device also utilizes technology [Virtual Point SLO] in which the optical path allows images to be captured from a point that is "virtually" in the eye, Dr. Sadda said. The device scans up to 200° of the retina and has an image capture time of 0.25 seconds. Color, fluorescein angiography, and FAF imaging are available from the same platform.

The company's widefield autofluorescence devices also will be used in a substudy of the Age-Related Eye Disease Study 2. The new imaging technology will be used to determine the frequency and significance of peripheral retinal abnormalities in this population.