Fundus Auto fluorescence and Enhanced Depth Imaging Spectral-Domain Optical Coherence Tomography in Hunter Syndrome-New Insights

Hunter syndrome or mucopolysaccharidosis type II is a rare progressive multi-systemic disorder, caused by an abnormal storage of glycosaminoglycans (GAGs) in almost every cell type, including most ocular tissues. Patients have a short life expectancy and ocular manifestations can be present early in the course of disease. To report the fund us auto fluorescence and tomographic ocular findings in Hunter syndrome. A 18-year-old male patient with Hunter syndrome with progressive nyctalopia was submitted to color fundus photography, blue fundus auto fluorescence (FAF), fluorescein angiography (FA) and spectral domain optical coherence tomography with enhanced-depth imaging (EDI-SD OCT). 

Results and discussion: Fundus examination and wide-field fluorescein angiogram revealed normal optic discs and bilateral pigmentary atrophic changes at the mid periphery with macular sparing. SD OCT revealed a retinal thinning due to external retinal atrophy affecting the photoreceptor layer beyond the parafoveal area. Although a prominent central external limiting membrane (ELM) was present, both the ellipsoid zone band and ELM could not be tracked beyond the central 2-mm and 2.5 mm diameter ring, respectively. EDI-SD OCT revealed a highly irregular choroid, especially in its outer boundary, probably due to GAG scleral deposition. Blue FAF presented a symmetric hyper auto fluorescent parafoveal ring that corresponded to the area where the ELM was present in the absence of the ellipsoid band.