Visual field and Visual Acuity changes in the Natural History of Choroideremia

Abstract

Purpose : To evaluate the natural history of visual acuity (VA) and visual field (VF) sensitivity in choroideremia (CHM). Choroideremia (CHM) is an X-linked degenerative retinal disease caused by deletions or mutations in the CHM gene which impacts the Rab escort protein-1 (REP-1). Study of the natural history of CHM may inform future therapeutic approaches.

Methods : A global retrospective chart review of anonymized patient records from 8 institutions. Eligibility criteria included male and born between 01Jan1930 to 31Dec2005, genetically confirmed CHM, and ≥2 clinic visits spanning ≥5 years. Data including VA and kinetic VF sensitivity (measured by sum total meridian degrees) were collected.

Results : Deidentified medical charts from 125 males (age at clinic visit ranged 2-82 years) were collected. All had recorded VAs that were converted to a LogMAR score. Age and VA demonstrated a non-linear relationship: VA remained fairly stable through the fourth decade of life then worsened by a rate of 0.026 LogMAR per year. Kinetic VF sensitivity was available for 107 eligible subjects (age 7-82 years) and decreased with age. There was a statistically significant age-effect interaction by VF test type for both the I4e and V4e stimuli for each of the left and right eyes (p<0.001). A 1-year increase in age decreased the I4e visual field by approximately 10.4 sum total meridian degrees for the left and right eyes; the V4e visual field decreased by approximately 24.3 sum total meridian degrees for the left and right eyes.

Conclusions : In a cohort of genetically confirmed CHM patients, VF deterioration occurs at a higher rate than visual acuity early in the disease, whereas VA decreases are more profound in the later stages.

This is a 2021 ARVO Annual Meeting abstract.