The RUSH2A Study: Dark-Adapted Visual Fields in Patients With Retinal Degeneration Associated With Biallelic Variants in the USH2A Gene

for the Foundation Fighting Blindness Consortium Investigator Group

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


PURPOSE. To measure visual fields using two-color dark-adapted chromatic perimetry in a subset of participants in the Rate of Progression of USH2A-related Retinal Degeneration (RUSH2A), a study of USH2A-mediated syndromic (USH2) and autosomal recessive nonsyndromic retinitis pigmentosa, determine percentage retaining rod function, and explore relationships between dark-adapted visual fields (DAVF) and rod function from ERG and full-field stimulus thresholds (FST). METHODS. Full-field rod mean sensitivity, number of rod loci, maximum sensitivity, DAVF full-field hill of vision (DAVF VTOT), and 30° hill of vision (DAVF V30) were measured in one eye for DAVF ancillary study participants (n = 49). Loci where cyan relative to red sensitivity was more than 5 dB on dark-adapted chromatic perimetry were considered rod mediated. Correlation coefficients between the DAVF measures and standard clinical measures were estimated, as were kappa statistics (κ) for agreement between DAVF and other measures of rod function. RESULTS. Of 49 participants tested with DAVF, 38 (78%) had evidence of rod function, whereas 15 (31%) had measurable rod ERGs. DAVF maximum sensitivity was highly correlated with FST white thresholds (r = −0.80; P < .001). Although not statistically significant, the number of rod loci and DAVF VTOT were lower in eyes with longer disease duration by 0.82 (95% confidence interval, −1.76, 0.12) loci/year and 0.59 (95% confidence interval, −1.82, 0.64) dB-steradians/year, respectively. CONCLUSIONS. Rod-mediated function on FST and DAVF is present in many patients with symptomatic USH2A-related retinal degeneration, including some without measurable rod ERGs. RUSH2A longitudinal data will determine how these measures change with disease progression and whether they are useful for longitudinal studies in inherited retinal degenerations.

Original languageEnglish (US)
Article number17
JournalInvestigative Ophthalmology and Visual Science
Issue number3
StatePublished - Mar 2022


  • Usher syndrome type 2
  • autosomal recessive retinitis pigmentosa
  • dark adaptation
  • full-field stimulus test
  • visual fields

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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