Loss of visual function may precede retinal layer thinning in glaucoma: Study

USA: True functional change precedes thinning of retinal nerve fiber layer (RNFL) in glaucoma, suggests a recent study in the journal Investigative Ophthalmology & Visual Science.

Previous studies have suggested structural change to be detectable before functional change in glaucoma. However, this may be related to the lower variability and hence narrower limits of structural tests. In this study, Stuart K. Gardiner, Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States, and colleagues determined whether a time lag exists between the true rates of change in structure and function, regardless of clinical detectability of those changes.

For the purpose, the researchers used structural equation model in order to determine whether the rate of change in function (mean linearized total deviation, AveTDLin) or structure (RNFLT) was predicted by the concurrent or previous rate for the other modality. Rates were calculated over 1135 pairs of consecutive visits from 318 eyes of 164 participants in the Portland Progression Project, with mean 207 days between visits.