Bilateral Concordance of the Fundus Hyperautofluorescent Ring in Typical Retinitis Pigmentosa Patients

Abstract

Background It has long been assumed that in retinitis pigmentosa, disease presentation and progression are symmetrical. This study investigated whether hyperautofluorescent ring size, one known marker of disease progression, is symmetrical in typical RP patients. Materials and Methods A total of 88 patients with typical retinitis pigmentosa were enrolled in the study. Each presented with a hyperautofluorescent ring when imaged at baseline with fundus autofluorescence (AF). Vertical and horizontal diameters were analyzed according to mode of inheritance and age group. Seven of 88 patients had data missing in one eye and were excluded from further analysis. Results There was no significant relationship between hyperautofluorescent ring diameter and inheritance mode. There was a tendency toward smaller ring size with age and 3.7% of subjects displayed marked asymmetry in ring size between right and left eyes, although their electroretinogram results did not differ. Overall, when patients were considered as a group, there was a high correlation between right and left eyes’ horizontal and vertical diameters (r = 0.99, p<0.0001; r = 0.98, p<0.0001). Comparing individual patients’ eyes, and accounting for measurement error, a smaller majority of patients displayed symmetry of the hyperautofluorescent ring in both dimensions (85.7% in the vertical dimension, 87.3% in the horizontal dimension). Conclusion This study confirmed the highly symmetrical nature of the hyperautofluorescent ring in RP patients, except in a small subgroup. AF results, which provide less variability per image, and are consistently interpreted between different observers, may be a more sensitive and reliable method for testing symmetry than many functional tests.

Multimodal Imaging of Central Retinal Disease Progression in a 2-Year Mean Follow-up of Retinitis Pigmentosa

“…Asymmetry between left and right eye disease severity is sometimes seen at baseline, 36 and we have observed asymmetry in progression during clinical followup using structural assessments (Figure 4). Hence, to assess the proportion of asymmetry between progression rate in the left and right eye, the difference between left and right eye progression rates was compared against the variation of progression rates calculated using test-retest measurements of the right eye.…”

“…20,24,28,29,31,36 The ellipsoid zone line was able to follow up patients until the end stage of the disease, but a major limitation of the ellipsoid zone line is that because the field is limited to 30° by the SD-OCT device, the disease can only be monitored when it has already reached the posterior pole, and hence we were unable to monitor 2 (2.8%) of the patients in our study. 31 An advantage of AF is the capacity to image a wider field that allows assessment of patients with earlier stage disease, though future OCT devices such as swept-source OCT will also provide a wider view.…”

“…56 Our previous study using hyperautofluorescent ring measurements showed 12.7–14.3% of patients with RP present with asymmetrical ring size, which was similar to the 10% of patients reported from an Usher Syndrome natural progression study. 23,36 Another study using AF and SD-OCT to monitor RP progression also found asymmetry between eyes with no significant correlation between the left and right eye. 40 In the present study, we observed approximately 20% of our patients had a significant difference in structural progression rate at the posterior pole between left and right eyes.…”

“…6,20,31,35,36 Furthermore, these two imaging modalities are widely available, and they can be more child friendly than ERG, which is important for monitoring family members of patients with RP. Given these qualities, these imaging modalities may be useful for visualizing the natural course of disease in a slow progressing disease like RP, and they may need consideration as outcome measurements to supplement functional measurements in assessing the efficacy of upcoming gene therapy and other treatment trials in RP, in which patients are often enrolled at advanced stage disease.…”

“…37–39 In recent studies from our group and others, a small proportion of the patients were observed to have baseline asymmetry using structural imaging techniques. 23,36,40 However, asymmetric disease progression has yet to be described in typical retinitis pigmentosa patients.…”