Epidemiology of Inherited Retinal Diseases in the United States: IRIS® Registry (Intelligent Research in Sight) Analysis

Background and objective: Evaluate disease characteristics and secondary comorbidities following retinitis pigmentosa (RP), choroideremia (CHM), and achromatopsia (ACHM) diagnosis in the United States.

Patients and methods: A retrospective cohort study of patients with new RP, CHM, or ACHM diagnoses between January 1, 2013, and December 31, 2019, in the IRIS® Registry. Main outcome measures were frequency of new RP, CHM, and ACHM, and frequency and hazard ratios for subsequent comorbidities.

Results: Overall, 40,302 IRIS Registry patients (58% female) received a new diagnosis of RP, CHM, or ACHM. RP was most common (95%, n = 38,179), followed by ACHM (4%, n = 1583), and CHM (1%, n = 540). RP and CHM presented in younger patients (plurality 45 to 64 years old) compared to ACHM (plurality 75 to 84 years old). In multivariable regression, patients with ACHM were significantly less likely to receive a cataract diagnosis (hazard ratio [HR] = 0.43, 95% CI = 0.39 to 0.47), cataract surgery (HR = 0.64, 95% CI = 0.56 to 0.74), or CME diagnosis (HR = 0.28, 95% CI = 0.23 to 0.33) compared to patients with RP. There was no significant difference between CHM and RP. Rhegmatogenous retinal detachment (RRD) diagnosis and repair were most likely among patients with CHM, compared to patients with RP, and patients with ACHM were less likely to receive an RRD diagnosis but more likely to undergo surgical repair compared to patients with RP (HR = 0.62, 95% CI = 0.49 to 0.79, and HR = 2.57, 95% CI = 1.59 to 4.14, respectively).

Conclusion: Patients with inherited retinal diseases can develop treatable ocular conditions that may affect their vision. Cataract and cystoid macular edema (CME) appear to be most associated with RP. Although RRD is rare, it may be disproportionately diagnosed in RP relative to repair rates and was most likely among CHM patients, perhaps reflecting coding practices and/or misdiagnosis.