The effect of trabeculectomy surgery on the central visual field in patients with glaucoma using microperimetry and optical coherence tomography

Purpose To determine the functional and structural effects of trabeculectomy surgery on patients with advanced glaucoma and central visual field defects in the early post-operative period. Methods Thirty consecutive adult subjects with advanced glaucoma requiring trabeculectomy surgery and an established visual field defect within 10° of fixation underwent microperimetry (MAIA MP-1, CenterVue, Padova, Italy) and optic disc optical coherence tomography (OCT) imaging (Spectralis, Heidelberg Engineering, Germany) pre-operatively, and 1 month and 3 months following trabeculectomy surgery. Main outcome measures were post-trabeculectomy change in mean threshold on microperimetry and nerve fibre layer thickness on OCT. Fellow eyes were used as controls. Results The mean change in MP average threshold values from pre-operative to post-operative was 0.6 ± 1.9 dB for treated eyes and 0.1 ± 1.3 dB for control eyes ( p = 0.14) at 1 month and 0.2 ± 2.3 and −0.3 ± 1.6 dB at 3 months ( p = 0.22). Mean change in global nerve fibre layer thickness was −0.6 and −0.5 µm for operated and control eyes, respectively ( p = 0.83), at 1 month and 0.8 and −0.4 µm at 3 months ( p = 0.88). The kappa agreement for structure–function correlation between OCT and MP was 0.735 (confidence interval 0.59–0.88) ( p < 0.005). Conclusions Central visual function and retinal nerve fibre layer thickness appear to be preserved in glaucoma patients with central visual field defects undergoing trabeculectomy surgery in the early post-operative period. These data may inform glaucoma surgeons considering trabeculectomy surgery in this patient group.