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Assessing Foveal Cone Mosaic in White Dot Syndromes
Gunay Uludag, MD
Gunay Uludag, Muhammad Sohail Halim, Maria Soledad Ormaechea, Nripun Sredar, Moataz M Razeen, Anh Tran, Sarakshi Mahajan, Muhammad Hassan, Rubbia Afridi, Khalid Yusuf, Jeonghun Bae, Diana V. Do, Yasir Sepah, Alfredo Dubra, Quan Dong Nguyen
Byers Eye Institute, Stanford University, Palo Alto, California
Department of Ophthalmology, Hospital Universitario Austral, Buenos Aires, Argentina
Purpose: To examine the cone-photoreceptor mosaic in patients with white dot syndromes using confocal adaptive optics scanning light ophthalmoscopy (AOSLO).
Methods: Five patients (8 eyes) with white dot syndromes (Table) were imaged using AOSLO. The cases consisted of one eye with punctate inner choroidopathy (PIC), two eyes with birdshot chorioretinopathy (BSCR), two eyes with multifocal choroiditis and panuveitis (MCP), one eye with acute posterior multifocal placoid pigment epitheliopathy (APMPPE), and two eyes with multiple evanescent white dot syndrome (MEWDS). One healthy female subject (2 eyes) was also included in the study for comparison. Image sequences (150 frames), of 1.0° and 1.5° field of view spanning the depth of the retina, were captured using 790 nm light (54 μW at the pupil). Fifty (50) frames of each sequence were registered and averaged to improve the signal-to-noise ratio. A semi-automated MATLAB algorithm was used to identify cone-centers in the region of interest (ROI; 1o away from the foveal center). The number of cones per deg2 in the ROI was calculated for each eye. Subsequently, the number of neighboring photoreceptors for each cone was measured using Voronoi tiling. Percentage of cones with abnormal number of neighboring cones (<5 or >7) was calculated.
Results: The mean age of patients was 41 years (range: 18 to 84 years). The age of the control subject was 31 years. Four (80%) of the patients were females. Number of cone photoreceptors per squared-degree and the percentage of cones with abnormal number of neighboring cone photoreceptors were tabulated and shown in Table. Subjects with white dot syndromes had lower cone density (13-70%) and higher percentages of abnormal neighboring cones (40-190%) compared to those of normal eyes (Figure).
Conclusion: Adaptive optics enables detailed visualization of structural integrity of cone photoreceptors in the retina. Among patients with white dot syndromes in our study, BSCR and MCP demonstrated the least number of cones per squared-degree.