Although early diagnosis and treatment reduce the risk of blindness from glaucoma, the decision on whether or not to begin treatment in patients with suspected glaucoma is often a dilemma because the majority of patients never develop definite glaucoma. A growing body of evidences suggests that posterior bowing of the lamina cribrosa (LC) is the earliest structural change preceding the retinal nerve fiber layer (RNFL) loss in glaucomatous optic neuropathy. Based on this notion, we conducted a prospective study enrolling 87 eyes suspected of having glaucoma to investigate whether the future rate of RNFL loss is associated with the baseline LC curve evaluated by measuring the LC curve index (LCCI) using enhanced depth imaging optical coherence tomography. A faster rate of RNFL loss was significantly associated with greater LCCI (P < 0.001;standardized coefficient beta = -0.392), older age (P = 0.008;beta = -0.314), and greater vertical cup-to-disc ratio (P = 0.040;beta = -0.233). Assessment of LC morphology may help predict the disease outcome in eyes with suspected glaucoma.

Purpose

To determine using swept-source optical coherence tomography (SS-OCT) whether there are differences in the location of the anterior lamina cribrosa insertion (ALI) in primary open-angle glaucoma (POAG) patients and healthy subjects.

Methods

Fifty three eyes from 53 patients with POAG, and 53 eyes from 53 age-matched healthy subjects were included prospectively in Seoul National University Bundang Hospital. Twelve radial line B-scans centered on the optic disc in every half-clock-hour meridian were acquired using SS-OCT. The ALI position was assessed by measuring two parameters: (1) ALI distance (ALID)--the distance from the anterior scleral canal opening (ASCO) to the ALI; and (2) marginal anterior lamina cribrosa surface depth (mALCSD)--the perpendicular distance from the ASCO plane to the anterior lamina cribrosa surface. These parameters were compared between the two groups for each meridian.

Results

Both ALID (256 ± 54 vs. 209 ± 37 µm, mean ± SD, p < 0.001) and mALCSD (232 ± 63 vs. 187 ± 40 µm, p < 0.001) were significantly greater in the POAG group than in the normal group. The largest difference was observed at the 6.5 o'clock and 11.5 o'clock meridians for both ALID and mALCSD. Multiple regression analysis revealed a negative correlation between age and both ALID and mALCSD in the control group, and a negative correlation between mean deviation of the visual field test and both ALID and mALCSD in the POAG group.

Conclusions

The ALI was displaced posteriorly in eyes with POAG compared to those of healthy controls. This finding suggests that the posteriorly located lamina cribrosa insertion is an important component of glaucomatous optic nerve excavation.

Purpose

To evaluate the in vivo changes in the Schlemm's canal (SC) in patients with primary angle-closure glaucoma (PACG) after trabeculectomy using spectral-domain optical coherence tomography (SD-OCT).

Methods

Forty eyes of 40 patients with PACG who underwent trabeculectomy were included. All participants underwent SD-OCT. The diameter and area of SC were examined and measured before and within 1 month after trabeculectomy. All SD-OCT images were processed using adaptive compensation algorithm to improve contrast and image quality. Multivariate linear regression analysis was performed for predictors of percentage change in the mean SC diameter and area.

Results

The mean age of participants was 60.5 ± 14.6 years. Adaptive compensation significantly increased the percentage of sections in which SC was observable in the subjects studied from 52.5% (21/40) to 75.0% (30/40), which has acceptable intraobserver and interobserver repeatability. There was a significant increase in the SC diameter and area at the follow-up examination compared with the baseline value (SC diameter: 34.2 ± 6.2 μm vs. 28.4 ± 6.1 μm; SC area: 8117 ± 1942 μm(2) vs. 5200 ± 996 μm(2); all P < 0.001). After multivariate analysis, the only variable related to changes in SC was percentage change in IOP (SC diameter, P = 0.002; SC area, P < 0.001). In addition, the magnitude of the change in the SC area also correlated with angle opening distance at 750 μm from the scleral spur at baseline.

Conclusions

Expansion of SC was observed after trabeculectomy in PACG patients. The degree of SC expansion was related to the extent of the IOP decrease.