Progressive loss of retinal ganglion cell function precedes structural loss by several years in glaucoma suspects
Michael R Banitt, Lori M Ventura, William J Feuer, Eleonore Savatovsky, Gabriel Luna, Olga Shif, Brandon Bosse, Vittorio Porciatti, Michael R Banitt, Lori M Ventura, William J Feuer, Eleonore Savatovsky, Gabriel Luna, Olga Shif, Brandon Bosse, Vittorio Porciatti
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.
Conflict of interest statement
Disclosure: M.R. Banitt, None; L.M. Ventura, None; W.J. Feuer, None; E. Savatovsky, None; G. Luna, None; O. Shif, None; B. Bosse, None; V. Porciatti, None
Figures
Source: PubMed