Rate of three-dimensional neuroretinal rim thinning in glaucomatous eyes with optic disc haemorrhage

Optic nerve head anatomy in myopia and glaucoma, including parapapillary zones alpha, beta, gamma and delta: Histology and clinical features

The optic nerve head can morphologically be differentiated into the optic disc with the lamina cribrosa as its basis, and the parapapillary region with zones alpha (irregular pigmentation due to irregularities of the retinal pigment epithelium (RPE) and peripheral location), beta zone (complete RPE loss while Bruch's membrane (BM) is present), gamma zone (absence of BM), and delta zone (elongated and thinned peripapillary scleral flange) within gamma zone and located at the peripapillary ring. Alpha zone is present in almost all eyes. Beta zone is associated with glaucoma and may develop due to a IOP rise-dependent parapapillary up-piling of RPE. Gamma zone may develop due to a shift of the non-enlarged BM opening (BMO) in moderate myopia, while in highly myopic eyes, the BMO enlarges and a circular gamma zone and delta zone develop. The ophthalmoscopic shape and size of the optic disc is markedly influenced by a myopic shift of BMO, usually into the temporal direction, leading to a BM overhanging into the intrapapillary compartment at the nasal disc border, a secondary lack of BM in the temporal parapapillary region (leading to gamma zone in non-highly myopic eyes), and an ocular optic nerve canal running obliquely from centrally posteriorly to nasally anteriorly. In highly myopic eyes (cut-off for high myopia at approximately -8 diopters or an axial length of 26.5 mm), the optic disc area enlarges, the lamina cribrosa thus enlarges in area and decreases in thickness, and the BMO increases, leading to a circular gamma zone and delta zone in highly myopic eyes.

Comparison of Rate of Change between Bruch's Membrane Opening Minimum Rim Width and Retinal Nerve Fiber Layer in Eyes Showing Optic Disc Hemorrhage

PURPOSE

To investigate and compare the longitudinal rate of change of Bruch's membrane opening minimum rim width (BMO-MRW) and peripapillary retinal nerve fiber layer (RNFL) thickness in eyes showing optic disc hemorrhage(DH).

DESIGN

Observational case series.

METHODS

A total of 82 subjects(82 eyes) showing DH who had undergone more than five reliable spectral-domain optical coherence tomography (OCT) tests were included. BMO-MRW and RNFL were measured with OCT at 3-month intervals. The rates of change in global and each Garway-Heath sector were calculated with a linear mixed-effects model after adjusting for age, sex, and BMO area.

RESULTS

The mean follow-up period was 21.57 ± 7.88 months with a mean number of 7.88 ± 2.39 OCT tests. Baseline demographics were age (58.37 ± 10.65 y); 46.3% were female; and the mean deviation was -4.41 ± 5.04 dB. The global rate of change in BMO-MRW was -3.507 ± 0.675 μm/y and in -1.404 ± 0.208 μm/y in RNFL. The rate of change was the greatest in the inferotemporal sector, which was -9.141 ± 1.254 μm/y in BMO-MRW and -4.204 ± 0.490 μm/y in the RNFL. The rate of change was significantly greater in BMO-MRW than in the RNFL in all sectors, except for the nasal sector (P < .05). Percentage of reduction was significantly greater in BMO-MRW than in RNFL in the inferotemporal and superotemporal sectors (P < .05).

CONCLUSIONS

BMO-MRW showed a significantly greater rate of change than RNFL in eyes showing DH, especially in the inferotemporal and superotemporal sectors in percentage of reduction. Thus, it may be more advantageous to detect glaucomatous progression earlier in BMO-MRW than in the RNFL in eyes showing DH that are more likely to progress.