Abstract
Purpose::
To compare the thickness of selected macular regions and retinal nerve fiber layer (RNFL) thickness in early glaucoma patients (EGPs) by means of optical coherence tomography (OCT) at baseline and one year thereafter
Methods::
Twelve eyes with early glaucoma (standard automated perimetry [SAP] mean deviation [MD] -2.32±5.21 dB) of 12 patients (mean age 59.74±19.72 years, 5F and 7M) were studied. All patients had visual acuity (VA)≥20/25 and ametropia < 2D and presented no systemic or ocular disease other than glaucoma. Twelve eyes from 12 healthy age-matched subjects were used as control eyes (CEs). Clinical examination (VA, biomicroscopy with +90 D lens, SAP) and OCT evaluation were performed at baseline (T0) and 12 months thereafter (T1). Retinal morphology was studied with OCT3 using Fast Macula and Fast RNFL programs. Fast Macula analyzes the macular region with a radius of 3 mm centred in the fixation point (FP); this region is divided into 3 concentric areas: central area (0-0.5 mm radius), inner ring (IR)(0.5 -1.5 mm radius) and outer ring (OR)(1.5-3 mm radius). Total macular volume (TMV) and mean thickness of each area were calculated. Fast RNFL analyzes the RNFL peripapillary thickness using a circular scan with 1.73 mm diameter. Data were analysed by one-way ANOVA. A level of p<0.05 was accepted as statistically significant
Results::
In EGPs both IR and OR mean macular thickness were found to be significantly different comparing T0 vs T1 (IR: 289.33±17.51 vs 286.94±15.82 µm, P=0.041 and OR: 240.62±19.87 vs 246.33±25.35 µm, P=0.044); particularly, OR mean thickness increased in 5 of 12 eyes. No significant difference was found in mean RNFL thickness, central macular thickness and MD comparing T0 vs T1. In CEs no significant difference was found in any of the parameters comparing T0 vs T1
Conclusions::
Different kind of histological changes can occur in the macular region of EGPs. Besides a well known thinning, a thickening (41.6% of eyes) of the outer macular region is detected; this represents an interesting finding. As no changes in the peripapillary RNFL is observed, we suppose that a transient oedema of perimacular cell bodies could occur during the glaucomatous optic neuropathy.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea • retina: proximal (bipolar, amacrine, and ganglion cells)