MAPPING THE DENSE SCOTOMA AND ITS ENLARGEMENT IN STARGARDT DISEASE.

PURPOSE

To describe the enlargement of the dense scotoma over time in Stargardt disease and to highlight methodologic issues in tracking enlargement.

METHODS

Retrospective study of patients with full mapping of the border of the dense scotoma using the MP-1 for at least two visits.

RESULTS

14 eyes of 7 patients met this criterion. Patients had median of 3 visits (range 2-5), with median total follow-up of 4.5 years (range 1.5-8). Mean baseline visual acuity was 20/56 (range 20/25-20/200), mean baseline dense scotoma area was 2.23 mm (range 0.41-5.48), and mean dense scotoma enlargement rate was 1.36 mm/year (range 0.22-2.91). The younger patients tended to have more rapid loss of visual acuity, which tended to plateau when the visual acuity was 20/100 or worse. The patients who developed Stargardt before age 20 years, and the single patient who developed Stargardt disease after age 40 years, had more rapid enlargement rates, with preservation of central vision in the oldest patient. The ability to precisely define the dense scotoma area was dependent on the density location of the points tested; this led to significant variability in the assessment of the scotoma enlargement rate in three of the seven patients. The dense scotoma was not described adequately by the extent of the homogeneous dark area on fundus autofluorescence imaging.

CONCLUSION

Microperimetry is necessary for mapping the scotoma in patients with Stargardt disease, because current imaging is not adequate. Standardized grid testing, plus a standardized procedure for refining the border of the dense scotoma, should allow more precise testing and longitudinal assessment of enlargement rates.