Purpose: To investigate the clinical findings, natural course, and pigment development of patients with retinitis pigmentosa (RP) sine pigmento using multimodal imaging.
Methods: We reviewed the medical records of 810 consecutive patients with RP and assessed serial ultra-widefield fundus photography, fundus autofluorescence, and optical coherence tomography images. Electrophysiological and visual field analysis findings were also reviewed.
Results: Of the 774 patients with RP who met the inclusion criteria, 88 were diagnosed with RP sine pigmento, with a prevalence of 11.4%. The mean age of the patients was 35.57 years compared with 49.83 years for patients with typical RP. Fifty-nine patients (67%) demonstrated minimal color change, whereas 29 (33%) presented with grayish flecks in the retinal pigment epithelium on fundus photography. All patients with RP sine pigmento had abnormalities on fundus autofluorescence, and the commonest fundus autofluorescence findings were punctate or reticular hypoautofluorescence. Of the 62 patients without pigmentation at the first visit and at the follow-up visits, 14 (22.6%) had developed pigmentation at their follow-up visit, with an average time of 3.92 years. Most patients retained a visual acuity of ≥20/50 within the age of 50 years.
Conclusion: Diagnosing RP sine pigmento based solely on ophthalmoscopic findings is more difficult than in more typical cases. Multimodal imaging can provide insights into the clinical characteristics to facilitate the diagnosis, classification, and follow-up of patients.