Abstract
Purpose: :
To describe distinct phenotypic patterns of foveal degeneration in occult macular dystrophy (OMD).
Methods: :
A retrospective study of OCT findings was conducted of 18 patients with OMD, who met all of the following diagnostic criteria: 1) presented with central vision deficits; 2) exhibited a normal full-field ERG (ffERG); and 3) displayed focal central dysfunction on multifocal ERG testing (mfERG). Clinical data examined included optical coherence tomography (OCT), correlative best-corrected visual acuity (VA), ffERG, and mfERG.
Results: :
Patients ranged in age at first visit from 9 to 51 years (8 females, 10 males). Average follow-up time for patients with multiple visits was 28.5 months (N = 11; range = 4 to 61 months;). VA at time of OCT ranged from 20/15 to 20/500 (average 20/56.5). Average photopic b-wave and rod-isolated b-wave amplitudes from 36 eyes were 147.5 μV (range = 82-278 μV) and 259.4 μV, respectively. On OCT imaging, 9 patients exhibited foveal atrophy (N = 7 for mild atrophy; N = 2 for severe atrophy), with 6 displaying definitive loss of the foveal inner segment/outer segment (IS/OS) line. Five patients displayed outer retinal cavitation (empty space) at the fovea, all of whom displayed early cavitation changes. Four patients displayed both foveal atrophy as well as cavitation, one of whom displayed late, advanced foveal cavitation. Two (50%) of these patients displayed definitive loss of the IS/OS line at the fovea. All 11 patients with multiple follow-up OCTs individually displayed a consistent phenotype throughout their follow-up period. There was no relationship between VA and the pattern of atrophy. A majority of patients displayed a broadened foveal pit (14 of 18). One patient developed a lamellar hole at the fovea in one eye.
Conclusions: :
OMD patients seem to exhibit three distinct phenotypic patterns of foveal degeneration, including atrophy, cavitation, as well as cavitation superimposed on atrophy. Interestingly, patients with multiple visits did not seem to transition or progress from one phenotype to another. These patterns may represent distinct pathophysiologic processes.
Keywords: macula/fovea • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • electroretinography: clinical