ABSTRACT.Purpose: To evaluate the changes of peripapillary and subfoveal choroidal thickness (CT) after trabeculectomy. Methods: Prospective longitudinal study included 37 eyes with open-angle glaucoma. The subfoveal and peripapillary CT was measured using enhanced depth imaging spectral domain optical coherence tomography before trabeculectomy and 1 week, 3 and 6 months postoperatively. The associations between changes in the CT, intraocular pressure (IOP) and axial length were analysed. Results: The medium subfoveal CT (IQR) increased from 182 (97) lm at baseline to 267 (107) lm 1 week, 213 (97) lm 3 months and 207 (91) lm 6 months postoperatively (p < 0.001). The peripapillary CT increased in all four quadrants at all follow-ups (p < 0.05). The subfoveal and peripapillary choroidal thickening correlated with the magnitude of IOP reduction (p < 0.05) and axial length shortening (p < 0.01) during whole follow-up period. There was a peripapillary CT increase of 2.9 lm per mmHg of IOP reduction (p < 0.001, CI 1.5-4.4) and 4.8 lm per mm of baseline axial length (p = 0.049, CI 0.03-9.6) 1 week postoperatively after adjustment for baseline IOP. Six months postoperatively, the decrease in axial length was the only factor associated with peripapillary choroidal thickening (p = 0.031; regression coefficient: 73.29 lm/mm, CI 7.1-139.5). Conclusion: Intraocular pressure (IOP) reduction after trabeculectomy caused the increase in subfoveal and peripapillary CT for at least 6 months postoperatively correlating with greater IOP reduction and axial length shortening. In the long term, the decrease in axial eye length, but not IOP, was the only factor to be associated with peripapillary choroidal thickening.

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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.Clinically, reduction of intraocular pressure (IOP) remains the only proven treatment for glaucoma 1-3 . Landmark glaucoma randomized clinical trials have confirmed the value of lowering IOP in delaying visual field (VF) progression 1-5 . Interestingly, recent studies 6-8 have reported that the surgical lowering of IOP in glaucoma can result in the improvement of VF, which lends support to the preliminary data reported by Katz and Spaeth, who demonstrated reversal of structural change and field loss in newly diagnosed patients after commencement of treatment 9,10 .Apart from functional changes, others have examined structural changes after trabeculectomy and their potential association with functional changes. The association between structural glaucomatous damage with VF decline after trabeculectomy is complex. The MoreFlow Medical Research Council 5-Fluorouracil (5-FU) study reported that out of 250 eyes, 20 eyes showed structural progression, 35 eyes showed VF progression, and 15 eyes showed both over a five years period 11 . In the Collaborative Initial Glaucoma Treatment Study (CIGTS), VF worsening was significantly associated with enlargement of the optic cup, but reversal of cupping was not associated with improvement of the VF 12 . Other studies reported an early increase in retinal nerve fiber layer (RNFL) thickness after trabeculectomy, but did not investigate the relation with VF changes [13][14][15][16][17] . Also, these studies have used the older time-domain optical coherence tomography (OCT) 14,16 , stereoscopic optic disc photographs 12,15 scanning laser polarimetry 17 , or Heidelberg Retina Tom...