Offset of openings in optic nerve head canal at level of Bruch’s membrane, anterior sclera, and lamina cribrosa

We compared the central retinal vascular trunk (CRVT) position, as a surrogate of lamina cribrosa (LC) offset, with the anterior scleral opening (ASCO) offset from the Bruch’s membrane opening (BMO). Based on the BMO-centered radial scans, the BMO and ASCO margins were demarcated, and each center was determined as the center of the best-fitted ellipse for each margin. The ASCO/BMO offset was defined as the offset between each center. Angular deviations and the extent of ASCO and CRVT offsets from the BMO center were compared directly. Incomplete demarcation of ASCO was found in 20%, which was associated with a larger BMO area and a larger ASCO offset from the BMO. The angular deviation of ASCO offset was associated with that of CRVT offset and that of the longest externally oblique border. The ASCO offset was smaller than the CRVT offset, and, unlike the CRVT offset, it was rarely deviated to the inferior side. The complete ASCO margin might not be demarcatable when determined on BMO-centered radial scans in the presence of an offset. Also, the ASCO, which reflects only the superficial scleral layer, might not reflect the LC position, because the LC might be shifted further from the ASCO.

Repeatability of Bruch’s Membrane Opening-minimum Rim Width in Age-related Macular Degeneration and Diabetic Macular Edema

Purpose: To evaluate the repeatability of retinal nerve fiber layer (RNFL) thickness and Bruch’s membrane opening-minimum rim width (BMO-MRW) measurements by spectral-domain optical coherence tomography (SD-OCT) in wet age-related macular degeneration (wAMD) and diabetic macular edema (DME).Methods: This was a prospective study. The RNFL thickness and BMO-MRW parameters for each sector and global average were measured twice by SD-OCT. Repeatability was evaluated using the intraclass correlation coefficient (ICC) and coefficient of variation (CV). If the optic disc membrane was confirmed, it was analyzed by dividing it into three groups based on severity.Results: A total of 99 eyes (48 with wAMD, 51 with DME) were included in the analysis. The ICCs of the global RNFL thickness and global BMO-MRW measurements were 0.996 and 0.997, respectively, in wAMD and 0.994 and 0.996, respectively, in DME eyes. The CV values of global RNFL thickness and BMO-MRW were 0.60% and 0.73%, respectively, in wAMD eyes and 1.10% and 1.21%, respectively, in DME eyes. The disc membrane on the optic nerve head significantly affected global BMO-MRW repeatability (B = 0.814, p < 0.001).Conclusions: Both RNFL thickness and BMO-MRW measurements showed good repeatability in eyes with wAMD and DME. The severity of the optic disc membrane significantly affected the repeatability of BMO-MRW measurements in eyes with wAMD and DME. Therefore, physicians should examine the BMO-MRW in eyes with severe optic disc membrane.

Bruch's membrane opening – minimum rim width measurement after acute primary angle-closure

Purpose To evaluate Bruch's membrane opening – minimum rim width (BMO-MRW) and peripapillary retinal nerve fiber layer thickness (RNFLT) following an acute primary angle-closure attack (APAC). Materials and methods Nine consecutive patients with unilateral APAC were included. Patients with a bilateral attack, with signs of glaucomatous optic nerve damage or evidence of a previous APAC in either eye were excluded. Three months after the attack, all eyes underwent BMO-MRW and RNFLT measurements with SDOCT. APAC eyes were compared to the contralateral eyes. Results Three months after the attack, mean BMO-MRWs were 281.22 ± 56.88 μm and 313.78 ± 43.48 μm ( P = 0.009) and mean RNFLTs were 78 ± 15.36 μm vs 95.78 ± 10.81 μm ( P = 0.008) in the APAC and contralateral eyes, respectively. RNFLT and BMO-MRW measurements had a strong positive correlation ( R = 0.7436, P = 0.013). APAC eyes had a shorter axial length (21.85 ± 1.21 vs 22 ± 1.07, P = 0.042) and shallower anterior chamber depth (2.29 ± 0.21 vs 2.41 ± 0.12, P = 0.039) than contralateral eyes. IOP at presentation showed a strong negative correlation with both BMO-MRW ( R = −0.7669, P = 0.009) and RNFLT measurements ( R = −0.7723, P = 0.008). Conclusion BMO-MRW and RNFLT measurements are significantly reduced 3 months after an APAC when compared to the contralateral eye. IOP at presentation may have an impact on the reduction of these parameters.

Pattern Electroretinogram Parameters Are Associated with Optic Nerve Morphology in Preperimetric Glaucoma after Adjusting for Disc Area

Purpose. We examined the relationships between pattern electroretinogram and optical coherence tomography derived optic nerve head measurements, after controlling for disc area. Methods. Thirty-two eyes from 20 subjects with preperimetric glaucoma underwent pattern electroretinogram and optical coherence tomography. Pattern electroretinogram parameters (Magnitude, MagnitudeD, and MagnitudeD/Magnitude ratio) and optic nerve head measurements (rim area, average cup to disc ratio, vertical cup to disc ratio, cup volume, retinal nerve fiber layer thickness sectors, and Bruch’s membrane opening-minimum rim width thickness sectors) were analyzed after controlling for disc area. Results. Magnitude and MagnitudeD were significantly associated with rim area (r ≥ 0.503, p ≤ 0.004 ). All pattern electroretinogram parameters significantly correlated with Bruch’s membrane opening-minimum rim width sectors—temporal superior and nasal inferior (r = 0.400, p = 0.039 )—and retinal nerve fiber layer sectors—superior, nasal superior, and inferior (r ≥ 0.428, p ≤ 0.026 ). Magnitude and MagnitudeD explained an additional 26.8% and 25.2% of variance in rim area (B = 0.174 (95% CI: 0.065, 0.283), p = 0.003 , and B = 0.160 (95% CI: 0.056, 0.265), p = 0.004 ), respectively. MagnitudeD and MagnitudeD/Magnitude ratio explained an additional 13.4% and 12.8% of the variance in Bruch’s membrane opening-minimum rim width global (B = 38.921 [95% CI: 3.872, 73.970], p = 0.031 , and B = 129.024 (95% CI: 9.589, 248.460), p = 0.035 ), respectively. All Bruch’s membrane opening-minimum rim width sectors and retinal nerve fiber layer sectors (nasal superior, nasal inferior, and inferior) were significantly correlated with rim area (r ≥ 0.389, p ≤ 0.045 ). Conclusion. PERG abnormalities can predict rim area loss in preperimetric glaucoma after controlling for disc area. We recommend controlling for disc area to increase diagnostic accuracy in early glaucoma.

Diagnostic Classification of Bruch's Membrane Opening-Minimum Rim Width and Retinal Nerve Fiber Layer Thickness in Myopic Eyes by Optical Coherence Tomography

Purpose: This study was conducted in order to compare the diagnostic classification of Bruch's membrane opening-minimum rim width (BMO-MRW) and RNFL thickness in normal myopic subjects by using optical coherence tomography (OCT).Methods: This cross-sectional study involved 75 healthy myopic subjects [spherical equivalent (SE) ≤ −0.5D] from April 2019 to January 2020. One eye of each subject was randomly selected for examination. BMO-MRW and peripapillary RNFL thickness were measured by spectral-domain OCT (Spectralis, Heidelberg Engineering GmbH, Heidelberg, Germany). All the subjects were divided into three groups: low myopic group (SE &gt; −3D), moderate myopic group (−6D &lt; SE ≤ −3D), and high myopic group (SE ≤ −6D). A nonparametric test was used to analyze the difference among groups. Linear regression was used to analyze the relationship between BMO-MRW/RNFL thickness and axial length/spherical equivalent. McNemar test was used to compare the diagnostic classification between BMO-MRW and RNFL thickness.Results: The RNFL thickness classified a significantly higher percentage of eyes as outside normal limits/borderline in at least 1 quadrant (BMO-MRW, 4%; RNFL thickness, 34.67%; p &lt; 0.01). There was no significant correlation between BMO-MRW/RNFL thickness and AL/SE. The low myopia (SE &gt; −3D) had a significantly lower percentage of eyes classified as outside normal limits/borderline in at least 1 quadrant than the moderate myopia (−6D &lt; SE ≤ −3D) and high myopia (SE ≤ −6D) (low myopia, 12.5%; moderate/high myopia, 42.42%/50%; p &lt; 0.05).Conclusion: BMO-MRW had a lower percentage of eyes classified as outside normal limits/borderline in at least 1 quadrant than RNFL thickness in normal myopic subjects. When referring to the diagnostic classification of RNFL thickness in myopic subjects, caution should be exercised in interpreting positive results. Further studies are needed to compare the diagnostic accuracy of these two measurements in myopic glaucoma patients.

Factors Associated with Increased Neuroretinal Rim Thickness Measured Based on Bruch’s Membrane Opening-Minimum Rim Width after Trabeculectomy

Purpose: To investigate the factors associated with an increase in the neuroretinal rim (NRR) thickness measured based on Bruch’s membrane opening-minimum rim width (BMO-MRW) after trabeculectomy in patients with primary open-angle glaucoma (POAG). Methods: We analyzed the BMO-MRW using spectral-domain optical coherence tomography (SD-OCT) of patients with POAG who underwent a trabeculectomy for uncontrolled intraocular pressure (IOP) despite maximal IOP reduction treatment. The BMO-MRW was measured before and after trabeculectomy in patients with POAG. Demographic and systemic factors, ocular factors, pre- and post-operative IOP, and visual field parameters were collected, together with SD-OCT measurements. A regression analysis was performed to investigate the factors that affected the change in the BMO-MRW after the trabeculectomy. Results: Forty-four eyes of 44 patients were included in the analysis. The IOP significantly decreased from a preoperative 27.0 mmHg to a postoperative 10.5 mmHg. The mean interval between the trabeculectomy and the date of post-operative SD-OCT measurement was 3.3 months. The global and sectoral BMO-MRW significantly increased after trabeculectomy, whereas the peripapillary retinal nerve fiber layer thickness did not show a difference between before and after the trabeculectomy. Younger age and a greater reduction in the IOP after the trabeculectomy were significantly associated with the increase in the BMO-MRW after trabeculectomy. Conclusions: The NRR thickness measured based on the BMO-MRW increased with decreasing IOP after trabeculectomy, and the increase in the BMO-MRW was associated with the young age of the patients and greater reduction in the IOP after trabeculectomy. Biomechanically, these suggest that the NRR comprises cells and substances that sensitively respond to changes in the IOP and age.