Microperimetry and reading saccades in solar retinopathy. Follow-up study with the scanning laser ophthalmoscope

Patients with solar retinopathy often complain of minute central scotomas and are handicapped when reading. The purpose of this study was to verify scotomas that are too small to be detected by standard perimeters and to analyze patients' reading patterns. Methods: Nineteen patients (12 female, 7 male, aged 5-46 years) with acute solar retinopathy after watching a solar eclipse on 12 October 1996 underwent scanning laser ophthalmoscope (SIO) microperimetry within 10 days after exposure using stimulus size Goldmann 1 (0.11 degrees) with the 20 degrees field. Size and depth of scotomas were measured. Eye movements during reading were recorded on videotape. Follow-up was at 1 and 6 months. Results: Thirty-one eyes (7 patients unilateral, 12 bilateral) showed scotomas. Four eyes showed anatomic changes in the retinal pigment epithelium but no functional loss. VA was 0.16 to 0.5 in 5 eyes, 26 had VA of 0.8-1.2. Scotomas could be detected in all eyes with subjective impairment. Scotoma size varied from 0.3 to 1.7 degrees(1 patient 6 degrees). Fortyfour percent were deep scotomas (0 dB). All defects improved at 1 and at 6 months; 25 % were no longer detectable. Reading speed was reduced in 75 % of eyes (42 % at 6 months): 200-860 signs/min, median: 510, normal greater than or equal to 660 (at 6 months: 350-920 signs/min, median 670). This was especially due to increased number of regressions (in 81 % of eyes, 21 % at 6 months). The frequency and width of saccades were no different from normal subjects. Conclusion: Minute scotomas (diameter = 0,3 degrees) can be detected with the SLO. All patients showed objective improvement of their field defect up to 6 months, even when this was not noted by the patient or thought to be due to habituation. Small scotomas can dramatically reduce reading performance.