Temporal Relation Between mGCIPL and pRNFL Loss in Glaucoma
Ophthalmology, July 2017
In a longitudinal study of patients with glaucoma, Kim et al. confirmed that thinning of the inferior macular ganglion cell–inner plexiform layer (mGCIPL) can be detected before defects are apparent in the peripapillary retinal nerve fiber layer (pRNFL). However, they cautioned that this finding may relate to high sensitivity of the mGCIPL map.
This 3-year retrospective study involved 151 patients (mean age, 51 years) with primary open-angle glaucoma and a visual field mean deviation of –1.5 to –5.5 decibels. Spectral-domain optical coherence tomography (OCT) mGCIPL and pRNFL deviation maps, obtained at baseline and follow-up, were superimposed onto RNFL photography using vascular landmarks to produce an integrated map. The pRNFL changes were further subdivided by location (i.e., macular vulnerability zone and inferoinferior portion). The primary outcome was temporal sequence of inferior mGCIPL loss with a corresponding pRNFL defect observed on the integrated deviation map.
At baseline, 99 (66%) of the 151 eyes showed inferior mGCIPL loss. Inferoinferior pRNFL defects were more common than pRNFL defects in the macular vulnerability zone (MVZ; 112 eyes [74%] and 5 eyes [3%], respectively). Three years later, 112 eyes (74%) demonstrated inferior mGCIPL loss, 123 eyes (82%) had inferoinferior pRNFL defects, and 25 eyes (17%) had pRNFL defects in the macular vulnerability zone. Among the 94 eyes that initially exhibited inferior mGCIPL thinning but no MVZ-pRNFL defect, 19 (20%) showed this defect at follow-up. Of the 52 eyes without evidence of mGCIPL loss at baseline, only 1 (2%; p < .001) subsequently demonstrated an MVZ-pRNFL defect.
Although inferoinferior pRNFL defects could be detected before inferior mGCIPL changes on the OCT deviation map in some eyes, no MVZ-pRNFL defects were identified before inferior mGCIPL changes. The authors deduced that change in the macular retinal ganglion cells precedes change in the corresponding pRNFL. They recommended adding macular OCT imaging when assessing structural loss in patients with early-stage glaucoma.
The original article can be found here.