This article is more than 5 years old. Information may no longer be current.
Study: RNFL thinning occurs before visual field defects
Researchers used a broken stick analysis to estimate the tipping point at which retinal nerve fiber layer thickness values are associated with visual field defects. It was found that in open angle glaucoma, substantial retinal nerve fiber layer thinning appears to be necessary before functional visual field defects are detected.
The study, published in the American Journal of Ophthalmology, included one eye per 87 healthy and 108 glaucoma participants. The abstract stated that the comparison of retinal nerve fiber layer (RNFL) thickness values with visual field threshold values showed a plateau of visual field threshold values at high RNFL thickness values and then a sharp decrease at lower RNFL thickness values.
It was found that the mean retinal RNFL thickness value that was associated with initial visual field loss was 89 µm. The superior RNFL thickness value that was associated with initial corresponding inferior VF loss was 100 µm. The inferior RNFL thickness value that was associated with initial corresponding superior VF loss was 73µm.
Researchers concluded that in open angle glaucoma, substantial RNFL thinning or structural loss appears to be necessary before functional visual field defects become detectable.