Abstract
Purpose:
Some forms of Retintis pigmentosa are characterized by a ring of increased fundus autofluorescence (FAF). This ring was previously correlated by optical coherence tomography (OCT) with the loss of the inner segment ellipsoid (ISe) and outer segment (OS) layers. Here we report the correlation of the FAFpattern with retinal layer thickness mapping at different stages during progression of the disease.
Methods:
Patients underwent a standard ophthalmological examination including FAF and Spectral Domain (SD)-OCT (Spectralis, Heidelberg Engineering, Germany). The underlying mutations were identified by either next generation panel-based sequencing (NGS) or Sanger sequencing which was also applied to confirm the results of NGS.<br /> Retinal Layers in SD-OCT recordings were segmented using DiOCTA, an automated OCT-segmentation software(1). The photoreceptor layers and the RPE layer were displayed as thickness distribution profiles and were correlated with FAF intensities in the macula and the vessel arcades
Results:
Twenty-six patients between 3y and 71y from 23 families with molecular genetically defined Retinitis pigmentosa (mutations in RPGR, RP2, PDE6B, EYS, PRPF31, RHO, and USH2A) were followed for up to 6 years.<br /> FAF showed a unique qualitative pattern dominated by a ring of increased FAF and a dark foveal area. Outside the ring of increased FAF the peripheral retina presented with increased FAF within the vascular arcades. The rims of this area focussed with increasing development of bone spicules and atrophy of the peripheral retina. OCT revealed photoreceptor layers within the ring of increased FAF and a severe loss of the photoreceptor layers including the outer nuclear layer (ONL) outside the ring of increased FAF. RPE was slightly thicker below the ring of increased FAF. The ONL and outer plexiform layers (OPL) were severely reduced outside the ring but not completely lost in areas of remaining peripheral FAF.<br /> No obvious reduction of the ring diameter during the observation period was observed in individual patients but from cross-sectional observations contraction of the ring with progression of the disease can be inferred.
Conclusions:
A ring of increased FAF in some forms of RP correlated with increased RPE thickness in patients with Retinitis pigmentosa. We describe the development of this FAF pattern in RP patients with different genotypes and at different disease states