Glaucoma is a multifactorial disease whose precise mechanism remains elusive. Although increased intraocular pressure (IOP) is recognized as the greatest risk factor for the development¹ and progression^2-4 of glaucoma, vascular factors are also thought to play a role in the pathogenesis of glaucoma.^5-10

Purpose: To determine microvasculature changes in the deep optic nerve head (ONH) and peripapillary tissues after trabeculectomy, and to correlate these with changes in the lamina cribrosa (LC) curvature. Methods: Fifty-six eyes with primary open-angle glaucoma that underwent trabeculectomy were included. The optic nerve and peripapillary microvasculature were evaluated in en face images obtained using optical coherence tomography (OCT) angiography (OCTA) before and 3 months after trabeculectomy. The OCTA-derived vessel density (VD) was calculated in each layer segmented into the prelaminar tissue (PLT), LC, peripapillary retina (PR), and peripapillary choroid (PPC). Swept-source OCT volume scanning of ONH was performed on the same day as OCTA to examine the change in LC curvature quantified as the LC curve index (LCCI). Results: At 3 months postoperative, the IOP and LCCI had significantly decreased (both P < 0.001). OCTA images revealed a significant increase in VD in the LC (P = 0.006), but not in the PLT, PR, or PPC. Twenty-six eyes showed both significant LCCI decrease and VD increase based on 95% Bland-Altman limits of agreement. The VD increase in the LC was significantly associated with larger percentage reductions in IOP (P = 0.040) and LCCI (P < 0.001) in the univariate analysis. Multivariate analysis revealed that only the LCCI reduction was a significant factor affecting the VD increase in the LC. Conclusions: A significant increase in VD was observed at the level of the LC after trabeculectomy. The VD increase was more strongly associated with the reduction in the LC curvature than with the reduction of IOP.

Purpose: To investigate whether the lamina cribrosa (LC) curvature is decreased after trabeculectomy. Methods: Thirty-nine eyes of 39 patients with primary open-angle glaucoma who underwent trabeculectomy were included. Optic nerves were scanned by using enhanced-depth-imaging spectral-domain optical coherence tomography before and after trabeculectomy. The LC curvature was assessed by measuring the LC curvature index (LCCI) in seven horizontal B-scan images in each eye. Results: The LCCI was significantly smaller at postoperative 6 months than at the preoperative level in all seven planes (all P < 0.001). Preoperative LCCI was associated with younger age at superior midperiphery, midhorizontal plane, inferior midperiphery (all P ≤ 0.005) and higher preoperative intraocular pressure (IOP) at superior and inferior midperiphery (both P = 0.039). Younger age and larger preoperative LCCI were associated with a larger reduction of the LCCI at all three locations (P = 0.003 and 0.031 at superior midperiphery, P = 0.011 and 0.001 at midhorizontal plane, and P = 0.014 and 0.005 at inferior midperiphery, respectively), whereas the percentage IOP lowering was associated at superior and inferior midperiphery (P = 0.017 and 0.047, respectively). Conclusions: Lamina cribrosa curvature was reduced after trabeculectomy. This finding suggests that LC curvature may have value as a parameter relevant to optic nerve head biomechanics.

To compare the abilities of spectral-domain optical coherence tomography (OCT) (SD-OCT; Spectralis, Heidelberg Engineering) and swept-source OCT (SS-OCT; DRI-OCT1 Atlantis system, Topcon) for analyzing the macular inner retinal layers in diagnosing glaucoma. The study included 60 patients with primary open-angle glaucoma (POAG) and 60 healthy control subjects. Macular cube area was scanned using SD-OCT and SS-OCT on the same day to assess the thicknesses of the macular retinal nerve fiber layer (mRNFL), ganglion cell layer plus inner plexiform layer (GCIPL), and total retinal layer in nine subfields defined by the Early Treatment Diabetic Retinopathy Study (ETDRS). The abilities of the parameters to discriminate between the POAG and control groups were assessed using areas under the receiver operating characteristic curves (AUCs). Glaucoma-associated mRNFL and GCIPL thinning was more common in the outer zones than inner zones for both SD-OCT and SS-OCT. The mRNFL and GCIPL measurements showed distinct pattern differences between SD-OCT and SS-OCT in each ETDRS subfield. Although the glaucoma-diagnosis ability was comparable between SD-OCT and SS-OCT for most of the parameters, AUC was significantly larger for SD-OCT measurements of the GCIPL thickness in the outer temporal zones (p = 0.003) and of the mRNFL thickness in the outer nasal zones (p = 0.001), with the former having the largest AUC for discriminating POAG from healthy eyes (AUC = 0.894). Spectralis SD-OCT and DRI SS-OCT have similar glaucoma-diagnosis abilities based on macular inner layer thickness analysis. However, Spectralis SD-OCT was potentially superior to DRI SS-OCT in detecting GCIPL thinning in the outer temporal zone, where the glaucomatous damage predominantly occurs.