Abstract
Purpose:
To study longitudinal changes in preferred retinal location (PRL) and visual function in Stargardt disease (STGD) and assess their relationship to changes in short wavelength fundus autofluorescence (SW-FAF) and retinal structure measured with spectral domain optical coherence tomography (SD-OCT).
Methods:
Seventeen patients (20 eyes) aged 21-70 yrs with STGD and at least one ABCA4 mutant allele were studied for 12 to 36 months. All tested eyes had best corrected visual acuity >=20/200. At each visit, the location and stability of the PRL were evaluated with the Nidek microperimeter (MP-1; Nidek Tech., Padua, Italy). Stability was quantified using the bivariate contour ellipse area (BCEA) technique. Visual fields were measured with the MP-1 (10-2 program 4-2 protocol). SW-FAF images were obtained with the HRA2-SLO and with the Spectralis HRA+OCT (Heidelberg Eng., Heidelberg, Germany). Corresponding horizontal SD-OCT line scans through the foveal and PRL regions were also obtained. To evaluate change in the pattern of fundus autofluorescence, serial SW-FAF images were registered to each other. To evaluate their relationship to functional changes, the SW-FAF images were registered to the visual field results in the MP-1 using NAVIS software.
Results:
At the initial visit the PRL was superior to the fovea (range 1°-12°) for 13 patients (15 eyes), temporal (1°) for 2 patients (2 eyes), supero-temporal (ST 5°- 3°) for 1 and foveal for 2 patients. BCEA values, containing 95% of the fixation points, ranged from 2 to 26 deg2. At the most recent visit, the PRL was superior to the fovea (range 1° to 14°) for 16 patients (19 eyes). Only one patient retained a foveal PRL. BCEA values ranged from 2 to 42 deg2. The eccentric PRLs were associated with increased visual sensitivity compared to the foveal area and with a more intact inner segment ellipsoid band. They were also associated with a central scotoma on the MP-1 corresponding to an atrophic hypofluorescent area on SW-FAF and SD-OCT. At the most recent visit this area had increased for 16 patients (19 eyes) both vertically (mean 1245 to 1664μm) and horizontally (mean 1562 to 2014μm).
Conclusions:
Over a period of only 12 to 36 months there were changes in the location and stability of the PRL. These were associated with changes observed on SW-FAF and SD-OCT.
Keywords: 696 retinal degenerations: hereditary •
550 imaging/image analysis: clinical •
758 visual fields