Abstract: Objective To assess the characteristics of intraretinal cysts (IRC) in patients with inherited retinal degenerations (IRD) using spectral domain optical coherence tomography (SD-OCT) images. Design Retrospective case series. Participants 92 eyes of 56 patients diagnosed with IRD at Beijing Tongren Hospital between 2020 and 2024, including 34 patients (54 eyes) with retinitis pigmentosa (RP), 15 patients (24 eyes) with Bietti crystalline dystrophy (BCD) and 7 patients (14 eyes) with autosomal recessive bestrophinopathy (ARB). Methods 92 eyes of 56 cases in the IRD database, all displaying IRC, were further examined to analyze the macular structures on SD-OCT and vascular changes on fundus fluorescein angiography (FFA). On SD-OCT iamges, the characteristics and locations of IRC, as well as structural alterations in the outer layers of the retina such as the outer limiting membrane (OLM), ellipsoid zone (EZ), outer segments of photoreceptors layer (PRL-OS), interdigitation zone (IZ), and retinal pigment epithelium (RPE) were assessed. Main Outcome Measures The morphology and locations of IRC, structural alterations in the outer layers of the retina on SD-OCT images. Results IRC appeared in different forms including "the central type", "the microcystic macular edema (MME) type", and "the mixed type" on SD-OCT images. In RP patients, IRC demonstrated as the central type or the mixed type in 24 eyes (44.5%), and as MME type in 30 eyes (55.5%). IRC were observed in the inner nuclear layer (INL) (54 eyes, 100%), outer nuclear layer (ONL) (25 eyes, 46.3%), and Ganglion cell layer (GCL) (5 eyes, 9.3%). Structural changes such as partial or complete loss of OLM, EZ, IZ, and RPE layers at parafovea were noted, and fovea affected in 23 eyes (42.6%). IRC located in preserved sections of these layers in 46 eyes(77.8%). Conversely, BCD patients all displayed IRC as the MME type (24 eyes, 100%) with MME of dispersed distribution located in the INL (24 eyes, 100%) and GCL (10 eyes, 41.7%). Severe loss of the OLM, EZ, IZ, and RPE layers was noted throughout the macula, and usually presented as multifocal and typically presented as interval distributed with preserved and lost sections, while IRC located at the lost sections. The IRC in ARB patients presented as the mixed type (10 eyes, 71.4%) or the MME type (4 eyes, 28.6%), with multiple continuous distributed MME located in the INL (14 eyes, 100%) and enlarged or coalesced cavities in ONL (10 eyes, 71.4%), and accompanied by neurosensory retinal detachment, thickening of PRL-OS and hyperreflective dots (HRD). Additionally, findings from FFA showed retinal vascular leakages(14 eyes, 87.5%), fishing net shaped telangiectasia and aneurysmal dilation(2 eyes, 12.5%) and petaloid hyperfluorescence at the macula(12 eyes, 75%)   in RP patients(n=10, 16 eyes), while BCD (n=7, 14 eyes) and ARB (n=3, 6 eyes) exhibited none of these alterations. Conclusions IRC secondary to different types of IRD has distinct features on SD-OCT. RP can manifest as either of three types, while BCD as MME type and ARB mainly as the mixed type, with diversed degenerative structural alterations in the outer layers of the retina. (Ophthalmol CHN, 2024, 33: 435-440)

Key words: intraretinal cysts, inherited retinal degenerations, retinitis pigmentosa, Bietti crystalline dystrophy, autosomal recessive bestrophinopathy