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In Vivo Imaging of Cone Photoreceptors in Mucopolysaccharidosis Type II and Retinal Degeneration: A Case Report

Year: 2026

Type: article

Abstract: Introduction: Mucopolysaccharidosis type II (MPS II, Hunter syndrome) is a rare X-linked lysosomal storage disorder frequently associated with progressive pigmentary retinopathy and retinal degeneration. High-resolution, noninvasive imaging techniques have expanded our ability to assess photoreceptor integrity and retinal microvasculature in vivo. This study evaluates multimodal retinal imaging, including the High Magnification Module (HMM®) without adaptive optics (AO), in adults with MPS II. Case Presentation: Three adult patients aged 22–45 years with genetically confirmed MPS II and pigmentary retinopathy underwent multimodal retinal imaging using spectral-domain optical coherence tomography (SD-OCT; Spectralis® OCT), OCT angiography (OCT-A), and the HMM® add-on lens. SD-OCT demonstrated perifoveal outer retinal atrophy, characterized by attenuation of the ellipsoid zone and thinning of the outer nuclear layer. In 1 patient with successful OCT-A image acquisition, OCT-A revealed reduced capillary density within regions corresponding to outer retinal atrophy, indicating associated microvascular compromise. In 1 patient with successful HMM image acquisition, high-magnification imaging with the HMM, performed without AO, showed clear rarefaction of cone photoreceptors in areas of structural loss, providing direct cellular-level insight into photoreceptor degeneration. The imaging quality in this patient allowed visualization of the cone mosaic despite the absence of AO. Conclusion: Multimodal retinal imaging combining SD-OCT, OCT-A, and HMM without AO may provide complementary information on photoreceptor structure and retinal microvasculature in patients with MPS II. This case series provides a proof-of-concept for the feasibility of HMM imaging in 1 patient for in vivo visualization of the cone mosaic in MPS II and highlights limitations in image acquisition in patients with more advanced retinal degeneration.

Source: Case Reports in Ophthalmology

DOI: 10.1159/cop/acaag022