Longitudinal Microstructure Changes of the Retina and Choroid in Retinitis Pigmentosa

Hyperreflective ganglion cell layer band in a large cohort of non-syndromic retinitis pigmentosa: Frequency and clinical correlations

PURPOSE

Recently, an 'hyperreflective ganglion cell layer band' (HGB) has been described on spectral-domain optical coherence tomography (SD-OCT) in a subset of patients with retinitis pigmentosa (RP). This study aims to validate and describe the frequency of HGB in a large cohort of Portuguese patients with RP.

METHODS

This single-centre, cross-sectional cohort study included consecutive patients with a genetic diagnosis of RP. SD-OCT images were reviewed to identify the presence of the HGB and other retinal comorbidities. The HGB was defined as a continuous hyperreflective band within the thickness of the ganglion cell layer (GCL). We built mixed-effects regression models, accounting for inter-eye correlations, to investigate features predictive of visual acuity. Subsequently, a reduced model was fitted.

RESULTS

A total of 398 eyes from 201 patients were included. HGB was identified in 69 (17.3%) eyes from 39 (19.4%) patients. Patients presenting with the HGB were significantly younger at diagnosis and at symptom onset. Median BCVA [ETDRS (IQR)] was 65 (29) letters in eyes with the HGB and 70 (21) letters in eyes without HGB (p < 0.001). In both the full and reduced mixed-effects models, the presence of HGB and macular hole (MH) was significantly associated with worse BCVA.

CONCLUSIONS

This study validates the recent description of HGB within the GCL in a subset of patients with RP. Eyes with HGB demonstrated significantly worse BCVA compared to those without HGB, suggesting that the presence of HGB may serve as an SD-OCT biomarker of worse visual prognosis in these patients.

Quantitative microvascular analysis in different stages of retinitis pigmentosa using optical coherence tomography angiography

As retinitis pigmentosa (RP) is chronic and progressive, the chronological sequence of microvascular changes is important for understanding its pathophysiology. We aimed to investigate retinal and choroidal microvascular changes according to the RP stages. The stages of RP were classified into three stages according to the integrity and width of the inner segment ellipsoid zone: early, ≥ 2500 μm; moderate, < 2500 μm; advanced, absence. Using optical coherence tomography angiography, quantitative microvascular parameters were analyzed. In total, 91 eyes from 49 patients were included. For the superficial capillary plexus (SCP) and deep capillary plexus (DCP), perfusion densities (PDs) in the early stage (SCP: 37.32 ± 8.11%; DCP: 21.19 ± 9.15%) were greater than those in moderate (SCP: 34.16 ± 6.65%, P = 0.011; DCP: 15.67 ± 8.85%, P = 0.031) and advanced stages (SCP: 33.71 ± 9.02%, P = 0.030; DCP: 12.83 ± 6.29%, P < 0.001). The choroidal vascularity index in the early stage (0.58 ± 0.03) was greater than those in the moderate (0.57 ± 0.02, P = 0.017) and advanced stage (0.56 ± 0.02, P = 0.033). The area and perimeter of foveal avascular zone (FAZ) in advanced stage (0.44 ± 0.26 mm2, 2.96 ± 0.86 mm, respectively) were larger than those in early (0.26 ± 0.11 mm2, P = 0.020; 2.19 ± 0.53 mm, P = 0.006, respectively) and moderate stage (0.28 ± 0.13 mm2, P = 0.043; 2.24 ± 0.67 mm, P = 0.013, respectively). During RP disease progression, retinal and choroidal microvascular vessel density decreases in the early stage, followed by FAZ enlargement in the advanced stage.

HYPERREFLECTIVE BAND IN THE GANGLION CELL LAYER IN RETINITIS PIGMENTOSA

PURPOSE

To describe a sign that takes the form of a continuous hyperreflective band within the thickness of the ganglion cell layer (GCL), thus dubbed the "hyperreflective ganglion cell layer band" (HGB), which the authors detected in a fraction of patients affected by retinitis pigmentosa (RP).

METHODS

Retrospective, cross-sectional, observational study. Optical coherence tomography (OCT) images of patients with RP examined between May 2015 and June 2021 were retrospectively reviewed for the presence of HGB, epiretinal membrane (ERM), macular hole, and cystoid macular edema (CME). The ellipsoid zone (EZ) width was also measured. A subgroup of patients underwent microperimetry in the central 2°, 4°, and 10°.

RESULTS

One hundred and fifty-four eyes from 77 subjects were included in the study. The HGB was present in 39 (25.3%) eyes with RP. Mean best-corrected visual acuity (BCVA) was 0.39 ± 0.05 logMAR (approximately 20/50 Snellen equivalent) and 0.18 ± 0.03 logMAR (approximately 20/32 Snellen equivalent) in eyes with and without HGB, respectively ( P < 0.001). The two groups did not differ regarding EZ width; mean 2°, 4°, and 10° retinal sensitivity; and prevalence of CME, ERM, and macular hole. The multivariable analysis showed the presence of HGB to be a predictor of poorer BCVA ( P < 0.001).

CONCLUSION

HGB is an OCT finding detectable in approximately a quarter of eyes with RP and is associated with a poorer visual function. In the discussion, the authors speculate about possible morphogenetic scenarios to explain this observation.

Choroidal vascular index in cystoid macular edema associated with retinitis pigmentosa

BACKGROUND

Retinitis pigmentosa (RP) is an inherited degenerative disease characterized by night blindness (nyctalopia), visual field defects, and varying degrees of vision loss. Choroid tissue has an essential role in the pathophysiology of many chorioretinal diseases. The choroidal vascularity index (CVI) is a choroidal parameter obtained as the ratio of the luminal choroidal area to the total choroidal area. The study aimed to compare the CVI of RP patients with and without CME with each other and with healthy individualsAU: Please confirm that the provided email ''ademoztel@hotmail.com" is the correct address for official communication, else provide an alternate e-mail address to replace the existing one..

METHODS

A retrospective, comparative study of 76 eyes of 76 RP patients and 60 right eyes of 60 healthy subjects was conducted. The patients were divided into two groups: those with and those without cystoid macular edema (CME). The images were obtained using enhanced depth imaging optical coherence tomography (EDI-OCT). CVI was calculated by using the binarization method with ImageJ software.

RESULTS

The mean CVI was significantly lower in RP patients compared to the control group (0.61±0.05 and 0.65±0.02, respectively, p<0.01). The mean CVI in RP patients with CME was significantly lower than in those without CME (0.60±0.54 and 0.63±0.35, respectively, p=0.01) The CVI was positively correlated with subfoveal choroidal thickness (r=0.74, p=0.001), central macular thickness (r=0.27, p<0.001) and visual acuity (logMAR) (r=-0.23 p=0.03) in RP patients.

CONCLUSIONS

The CVI is lower in RP patients with CME than in patients without CME and in RP patients compared to healthy subjects, indicating an ocular vascular involvement in the pathophysiology of the disease and the pathogenesis of RP-associated cystoid macular edema.

Structure-Function Relationship in Patients with Retinitis Pigmentosa and Hyperautofluorescent Rings

This study aimed to investigate the association between retinal sensitivity and retinal microstructures in fundus autofluorescence (FAF) and optical coherence tomography (OCT) in patients with retinitis pigmentosa (RP) and hyperautofluorescent (hyperAF) rings. This cross-sectional study included 44 eyes from 26 consecutive patients with RP. The morphological geometry of the hyperAF ring, such as three distinct FAF regions, hyperAF ring area, and longest diameter of the hyperAF ring on FAF, and the retinal microstructure, such as total retinal thickness (TRT) and outer retinal thickness (ORT), on OCT, were evaluated. A strong correlation of mean retinal sensitivity with hyperAF ring area (R = 0.8013, p < 0.001) and longest diameter of the hyperAF ring (R = 0.9072, p < 0.001) was observed. Segmented linear regression (SLR) analysis revealed breakpoints of 12.83 mm² and 5.21 mm, respectively. ORT (R = 0.6551, p < 0.001) was more strongly correlated with retinal sensitivity than TRT (R = 0.2732, p < 0.001). SLR analysis revealed a breakpoint between the ORT and retinal sensitivity of 145.12 μm. In patients with RP and hyperAF rings, retinal sensitivity was strongly associated with the morphological geometry of the hyperAF ring. ORT, rather than TRT, strongly correlated with retinal sensitivity.