Progressive loss of retinal ganglion cell function precedes structural loss by several years in glaucoma suspects

Invest Ophthalmol Vis Sci. 2013 Mar 28;54(3):2346-52. doi: 10.1167/iovs.12-11026.

Abstract

Purpose: We determined the time lag between loss of retinal ganglion cell function and retinal nerve fiber layer (RNFL) thickness.

Methods: Glaucoma suspects were followed for at least four years. Patients underwent pattern electroretinography (PERG), optical coherence tomography (OCT) of the RNFL, and standard automated perimetry testing at 6-month intervals. Comparisons were made between changes in all testing modalities. To compare PERG and OCT measurements on a normalized scale, we calculated the dynamic range of PERG amplitude and RNFL thickness. The time lag between function and structure was defined as the difference in time-to-criterion loss between PERG amplitude and RNFL thickness.

Results: For PERG (P < 0.001) and RNFL (P = 0.030), there was a statistically significant difference between the slopes corresponding to the lowest baseline PERG amplitude stratum (≤50%) and the reference stratum (>90%). Post hoc comparisons demonstrated highly significant differences between RNFL thicknesses of eyes in the stratum with most severely affected PERG (≤50%) and the two strata with least affected PERG (>70%). Estimates suggested that the PERG amplitude takes 1.9 to 2.5 years to lose 10% of its initial amplitude, whereas the RNFL thickness takes 9.9 to 10.4 years to lose 10% of its initial thickness. Thus, the time lag between PERG amplitude and RNFL thickness to lose 10% of their initial values is on the order of 8 years.

Conclusions: In patients who are glaucoma suspects, PERG signal anticipates an equivalent loss of OCT signal by several years.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Analysis of Variance
  • Electroretinography
  • Female
  • Glaucoma / pathology
  • Glaucoma / physiopathology*
  • Humans
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Retinal Ganglion Cells / pathology
  • Retinal Ganglion Cells / physiology*
  • Time Factors
  • Tomography, Optical Coherence
  • Visual Fields / physiology