One year structural and functional glaucoma progression after trabeculectomy

Abstract

We evaluated the changes in visual field mean deviation (VF MD) and retinal nerve fibre layer (RNFL) thickness in glaucoma patients undergoing trabeculectomy. One hundred patients were examined with VF and spectral-domain optical coherence tomography (OCT) before trabeculectomy and 4 follow-up visits over one year. Linear mixed models were used to investigate factors associated with VF and RNFL. VF improved during the first 3 months of follow-up (2.55 ± 1.06 dB/year) and worsened at later visits (-1.14 ± 0.29 dB/year). RNFL thickness reduced by -4.21 ± 0.25 µm/year from 1st month of follow-up. Eyes with an absence of initial VF improvement (β = 0.64; 0.30-0.98), RNFL thinning (β = 0.15; 0.08-0.23), increasing intraocular pressure (IOP; β = -0.11; -0.18 to -0.03) and severe glaucoma (β = -10.82; -13.61 to -8.02) were associated with VF deterioration. Eyes with VF deterioration (β = 0.19; 0.08-0.29), increasing IOP (β = -0.09; -0.17 to -0.01), and moderate (β = -6.33; -12.17 to -0.49) or severe glaucoma (β = -19.58; -24.63 to -14.52) were associated with RNFL thinning. Changes in RNFL structure and function occur over a 1-year follow-up period after trabeculectomy. Early VF improvement is more likely to occur in patients with mild/moderate glaucoma, whereas those with severe glaucoma show greater decline over one year. Our findings indicate that progression is observable using OCT, even in late-stage glaucoma.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

Identification of eligible glaucoma patients who underwent trabeculectomy. Of the 124 patients enrolled, 100 were included in the analysis. Of which, majority were examined at 7 visits whereas 10 missed one follow-up visit. Visual field tests were performed for 5 visits (visit 1, 4–7) and OCT/IOP were performed at all 7 visits.

Figure 2

Changes in (A) intraocular pressure, (2) visual field mean deviation and (3) retinal nerve fibre layer thickness after trabeculectomy. *Data shown at each time point are expressed as mean and P values were obtained using comparison with the previous follow-up using linear mixed model.

Figure 3

Scatterplot of the change in visual field mean deviation (VF MD) from baseline to 3rd month follow-up versus the change in VF MD from 1 year after surgery compared with before, stratified by glaucoma severity. Eyes having mild glaucoma were indicated with dark filled circle, those having moderate glaucoma in green hollow diamond and severe glaucoma in black hollow triangle. The VF before trabeculectomy and the VF postoperatively (3 months after surgery) were used for the calculation of VF worsening (r = 0.32; P = 0.005).