Determining Progression of VF Loss by Baseline Thickness of Macular Ganglion Cell Complex
Previous studies reported that the thickness of the macular ganglion cell complex (mGCC) showed good diagnostic ability for detecting glaucoma. However, its impact on the progression of visual field loss in primary open angle glaucoma (POAG) is unknown. In this study, researchers assessed whether baseline mGCC thickness was associated with the progression of visual field loss in POAG. They determined that baseline mGCC thickness can be predictive of progressive visual field loss in patients with POAG.
They included 56 patients with POAG in the study, all of whom were followed for more than two years after baseline optical coherence tomography (OCT) measurements. They had at least five reliable Humphrey visual field tests with 30–2 Swedish Interactive Threshold Algorithm standard tests during the follow-up period. The researchers divided subjects into two groups according to the slope of the mean deviation (MD): the fast progression group (MD slope < –0.4 dB/y) and the slow progression group (MD slope ≥ –0.4 dB/y). Factors compared between the groups were as follows: age, baseline intraocular pressure (IOP), mean IOP during the follow-up, refraction, baseline MD, pattern standard deviation (PSD), and baseline OCT measurements.
The study researchers found no significant differences between the two groups in age, baseline IOP, mean IOP during the follow-up, refraction, baseline MD or PSD, average thickness of retinal nerve fiber layer (RNFL), or disc parameters. However, they did note that the baseline mGCC thickness (average and inferior hemifield) was significantly thinner in the fast progression group than in the slow progression group (74.0 ± 7.2 µm vs. 80.3 ± 8.6 µm; 68.0 ± 6.6 µm vs. 78.2 ± 11.6 µm, respectively). Moreover, global loss volume and focal loss volume, which are parameters of mGCC, showed significantly higher rates in the fast progression group than in the slow progression group. In multivariate analysis, only mGCC thickness of the inferior hemifield was associated with disease progression (p=0.007).