Normative reference ranges for binocular summation as a function of age for low contrast letter charts.

Journal Article (Journal Article)

PURPOSE: Binocular summation (BiS), defined as the superiority of binocular over monocular viewing on visual threshold tasks, is most often studied in laboratory settings. Few studies have evaluated BiS with readily available clinical tools. Low contrast acuity (LCA) charts are increasingly popular in clinical research, yet their utility in detecting BiS has not been evaluated. METHODS: 129 normal subjects aged 3 to 85 years were prospectively enrolled and underwent monocular and binocular testing using 2.5% and 1.25% Sloan LCA charts and Pelli-Robson (PR) contrast sensitivity (CS) charts at an academic institution. Subjects also underwent similar testing with Early Treatment Diabetic Retinopathy Study (ETDRS) VA charts. BiS was calculated as the difference between the better eye and binocular scores. RESULTS: Monocular and binocular scores decreased with increasing age for all metrics. The mean (±SD) BiS scores for 2.5% and 1.25% Sloan LCA were 6±4.5 and 3±5 letters, respectively. BiS score was 4.5±7 letters for PR charts and 2±3 letters for ETDRS VA. There was a significant effect of age on BiS for the low contrast metrics (P≤0.001 for all), but not for high-contrast ETDRS VA. Linear regression revealed significant associations between increased interocular difference (IOD) in acuity and decreased BiS for all tests, and associations between increasing age and decreased BiS for the LCA tests. CONCLUSION: Of the clinical tests evaluated, 2.5% and 1.25% Sloan LCA charts most readily demonstrated BiS in young normal subjects. BiS declined with increasing age and increased IOD. Median values presented in this study may be useful for future clinical studies utilizing LCA.

Full Text

Duke Authors

Cited Authors

  • Pineles, SL; Velez, FG; Yu, F; Demer, JL; Birch, E

Published Date

  • December 2014

Published In

Volume / Issue

  • 22 / 4

Start / End Page

  • 167 - 175

PubMed ID

  • 25283818

Pubmed Central ID

  • 25283818

Electronic International Standard Serial Number (EISSN)

  • 1744-5132

Digital Object Identifier (DOI)

  • 10.3109/09273972.2014.962751


  • eng

Conference Location

  • England