To develop a grading system for retinitis pigmentosa (RP), providing clinicians with a simple, objective measure of disease severity. An observational case series of 14 patients with RP. Disease severity was assessed using four criteria; clinical appearance, visual acuity (best corrected LogMAR, BCVA), perimetry (mean deviation, MD) and Fourier-domain optical coherence tomography (outer retinal thickness, ORT at the fovea). Each criterion was scored on a severity scale from 0 (mild disease) to 4 (severe disease), giving an overall score out of 16. The mean BCVA was 0.37 LogMAR (range 0.02 to PL), mean MD was −25.35 dB (range −7.48 to −34.38 dB), mean retinal thickness at the fovea was 189.4 μm (range 96.5−264.5 μm) and mean ORT at the fovea was 140.6 μm (range 63.4−193.4 μm). The clinical appearance correlated well with each of the quantitative measures of disease severity; BCVA (0.62, p = 0.022), MD (−0.903, p < 0.0001) and ORT (−0.698, p = 0.005). Applying the grading system to our patients, the severity scores were evenly spread between grades 1 and 14. We present a simple, objective grading system for RP offering a potential tool for grading disease severity with applications such as assessing progression, comparing patient populations and measuring outcomes in clinical trials.
This investigation was supported in part by an unconditional training grant of £300 from Takeda UK Limited. The authors are grateful to Dr. Alan Hackshaw, University College London, for his assistance with the statistical analysis, and to Mr. Gucharan Rai, Optometrist, and Mr. Julian East, Medical Photographer, both of Whipps Cross University Hospital, for their assistance with data collection.
Conflict of interest
None of the authors have a conflict of interest with the submission.
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