Short-term changes in Bruch's membrane opening-based morphometrics during the first week after trabeculectomy

Susceptibility of optic nerve head in children with posture-related elevation of intraocular pressure

BACKGROUND/AIMS

This work aimed to investigate changes in optic nerve head (ONH) morphometry based on Bruch membrane opening in children with extensive nocturnal intraocular pressure (IOP) elevations.

METHODS

The course of Bruch membrane opening-based optic nerve head (ONH) morphometry was analysed in thirty-two patients younger than 18 years with evaluable SD-OCT examinations of the ONH and nocturnal posture-dependent IOP elevation above 25 mmHg. Longitudinal changes in neuroretinal rim tissue, as measured by Bruch Membrane opening minimum rim width (BMO-MRW) and peripapillary retinal nerve fiber layer (RNFL) thickness, were assessed.

RESULTS

One year after the 24 h IOP measurement, global BMO-MRW (- 1.61 ± 16.8 µm, n.s.; p = 0.611) and RNFL (+ 0.64 ± 3.17 µm; n.s.; p = 0.292) measurements were not significantly different from the baseline. No significant BMO-MRW reduction (- 3.91 ± 24.3 µm; n.s. p = 0.458) or deviation in RNFL thickness (+ 1.10 ± 3.52 µm) was observed at the four-year follow-up. Absolute IOP values measured in the supine position did not correlate with changes in global BMO-MRW or RNFL thickness.

CONCLUSION

Posture-dependent IOP elevations do not seem to influence retinal nerve fibre layer thickness or Bruch membrane opening-based morphometric data in childhood.

Optic Nerve Head Changes After Intraocular Pressure-Lowering Glaucoma Surgeries Using Optical Coherence Tomography

PRCIS

Optic nerve head (ONH) changes were detected with swept-source optical coherence tomography (SS-OCT) after intraocular pressure (IOP)-lowering glaucoma surgeries.

PURPOSE

The aim of this study was to detect changes in the ONH with SS-OCT after IOP-lowering procedures.

PATIENTS AND METHODS

Patients with progressing glaucoma who were referred for IOP-lowering procedures were included. The participants underwent a 24-2 visual field test and SS-OCT (DRI OCT Triton Plus; Topcon). IOP and SS-OCT scans were obtained during the preoperative period and up to 7 days and 30-90 days postoperatively. ONH parameters were measured with a B -scan at the center of the optic disc and an average of 5 central B -scans. The hypotenuse of the ONH cup (HOC) was calculated using the Pythagorean theorem: hypotenuse 2 = leg1 2 + leg2 2 , considering the length and depth of the cup as the legs of a right triangle. We also evaluated changes in Bruch membrane opening (BMO)-to-BMO diameter. Statistical analysis was performed using generalized estimating equations.

RESULTS

A total of 15 eyes were included. The mean patient age was 70 (SD, 11.04) years. The mean circumpapillary retinal nerve fiber layer was 60.13 (SD, 23.21) µm and the visual field mean deviation was -13.29 (SD, 8.5) dB. The mean IOP at each visit was: 20.5 (SD, 4.99); 11 (SD, 4.95), and 15.7 (SD, 5.04), respectively. The mean HOC, the mean depth and length of the ONH cup, and the BMO-to-BMO diameter decreased significantly after the IOP-lowering procedures.

CONCLUSIONS

The HOC evaluated with SS-OCT significantly decreased after IOP-lowering surgeries. This parameter was useful for evaluating short-term changes in the ONH.

Neuroretinal Rim Response to Transient Intraocular Pressure Challenge Predicts the Extent of Retinal Ganglion Cell Loss in Experimental Glaucoma

Purpose

To determine if the optic nerve head (ONH) response to transient elevated intraocular pressure (IOP) can predict the extent of neural loss in the nonhuman primate experimental glaucoma model.

Methods

The anterior chamber pressure of 21 healthy animals (5.4 ± 1.2 years, 8 female) was adjusted to 25 mm Hg for two hours followed by 10 mm Hg for an additional two hours. For the duration of IOP challenge the ONH was imaged using radial optical coherence tomography (OCT) scans at five-minute intervals. Afterward, a randomized sample of 14 of these subjects had unilateral experimental glaucoma induced and were monitored with OCT imaging, tonometry, and ocular biometry at two-week intervals.

Results

With pressure challenge, the maximum decrease in ONH minimum rim width (MRW) was 40 ± 10.5 µm at 25 mm Hg and was correlated with the precannulation MRW, Bruch's membrane opening (BMO) position, and the anterior lamina cribrosa surface position (P = 0.01). The maximum return of MRW at 10 mm Hg was 16.1 ± 5.0 µm and was not associated with any precannulation ONH feature (P = 0.24). However, healthy eyes with greater thickness return at 10 mm Hg had greater loss of MRW and retinal nerve fiber layer (RNFL) at a cumulative IOP of 1000 mm Hg · days after induction of experimental glaucoma. In addition, MRW and RNFL thinning was correlated with an increase in axial length (P < 0.01).

Conclusion

This study's findings suggest that the ONH's response to transient changes in IOP are associated with features of the ONH and surrounding tissues. The neural rim properties at baseline and the extent of axial elongation are associated with the severity of glaucomatous loss in the nonhuman primate model.

Changes of Optical Coherence Tomography Parameters after Cataract Surgery in Primary Open-Angle Glaucoma Eyes

PURPOSE

To investigate the impact of uncomplicated cataract surgery on the measurement of Bruch's membrane opening-minimum rim width (BMO-MRW) and retinal nerve fiber layer thickness (RNFLT) using spectral domain optical coherence tomography (SD-OCT) in primary open-angle glaucoma (POAG) patients.

METHODS

This retrospective study included 63 eyes of 63 patients, including 32 POAG eyes and 31 normal eyes who underwent uneventful cataract surgery and follow-up for at least 6 months. Using SD-OCT, BMO-MRW and RNFLT were measured preoperatively and postoperatively at 6 months. Paired t-test was used to compare intraocular pressure (IOP), BMO-MRW, RNFLT, and image quality before and after surgery. These parameters and their changes were compared between POAG and normal groups. Univariate and multivariate linear regression analyses were performed to determine the factors associated with the postoperative change (Δ) in RNFLT and BMO-MRW.

RESULTS

BMO-MRW and RNFLT were significantly increased and IOP was decreased after phacoemulsification in both groups (p < 0.001, respectively). The ΔRNFLT was significantly greater in POAG eyes compared with the normal eyes (p < 0.001). The ΔRNFLT was associated with the postoperative IOP reduction and glaucoma diagnosis (p < 0.001 and p = 0.001, respectively). In the normal group, only the ΔIOP had a significant influence on the ΔRNFLT (p = 0.003), but in the POAG group, not only the ΔIOP (p = 0.044) but also preoperative visual field mean deviation (p = 0.029) showed a significant influence. The ΔBMO-MRW showed no difference between POAG and normal eyes.

CONCLUSIONS

The postoperative increase of RNFLT was significantly greater in the POAG group, and the postoperative increase of RNFLT was associated with the preoperative visual field mean deviation and ΔIOP in POAG eyes and with the ΔIOP in normal eyes. Our results imply that RNFLT is more affected than BMO-MRW in POAG eyes compared to normal eyes by cataract surgery.