Outer retinal layer thickness in patients with glaucoma with horizontal hemifield visual field defects

Abstract

Background/aims: To determine the effect of glaucoma on outer retinal layer thickness in eyes with horizontal hemifield visual field (VF) defects.

Methods: We conducted a cross-sectional study in glaucomatous eyes with repeatable (in three or examinations) horizontal hemifield VF (programme 24-2) defect defined as: all five nasal VF locations immediately either above or below the horizontal midline abnormal in the pattern deviation plot with p<0.5%; no mirror-image adjacent 5 VF locations abnormal in the pattern deviation plot and no non-edge VF locations in the non-affected hemifield abnormal in the pattern deviation plot with p<1%. We used optical coherence tomography to measure thickness of each retinal layer in the temporal macula (12° horizontally and 24° vertically) and computed the absolute (µm) and relative (%) intraindividual asymmetry between the perimetrically normal and abnormal hemimacula.

Results: We included 10 eyes of 8 patients with median age of 67 years and median VF mean deviation of -8.85 dB. The nerve fibre, ganglion cell and inner plexiform layers were significantly thinner in the perimetrically abnormal hemimacula (median asymmetry of -6.4, -11.5 and -3.8 µm, (corresponding to -27.7, -40.5 and -15.7 %), respectively, all p≤0.01). The inner nuclear layer was slightly thicker in the perimetrically abnormal hemimacula (median asymmetry of 1.3 µm (5.0 %), p=0.01). The outer plexiform, outer nuclear and photoreceptor layers asymmetry values were negligible.

Conclusion: Our study showed no evidence that glaucoma has an effect on the outer retinal layer thickness. In contrast, a large impact was observed in inner layer thickness.

Keywords: glaucoma; imaging; retina.