Optic Disc Hemorrhages and Laminar Disinsertions in Glaucoma

Long-Term Follow-Up of Myopic Glaucoma: Progression Rates and Associated Factors

PRCIS

In the group of glaucoma patients with myopia, the more severe the degree of myopia, the faster the loss of visual acuity and central visual field defect.

DESIGN

Longitudinal observational study.

OBJECTIVE

To investigate the progression rate of myopic glaucoma and associated factors by long-term analysis of its clinical course.

METHODS

Patients who had had at least 5 years of follow-up and a spherical equivalent of -0.5 diopters or less were included in this study. They were divided into 3 myopia groups according to myopic grade, namely mild myopia (-0.5 to -3.0 diopters), moderate myopia (-3.0 to -6.0 diopters), and high myopia (-6.0 diopters or more), and the clinical course, progression rate, and associated factors were compared among the groups and analyzed.

RESULTS

A total of 121 eyes of 121 patients with glaucoma with myopia were included in the study. The average follow-up period was 10.4 ± 2.9 years. In the analysis of progression rate, the change rate of average retinal nerve fiber layer (RNFL) thickness (-0.75 μm/y in mild myopia, -0.82 μm/y in moderate myopia, -0.84 μm/y in high myopia) and the mean deviation change (-0.30 dB/y in mild myopia, -0.37 dB/y in moderate myopia, -0.39 dB/y in high myopia) both tended to be faster as the myopic grade increased. In a Kaplan-Meier survival analysis, the high myopia groups demonstrated a significantly faster VA loss (of more than 3 lines) and a higher incidence of newly developed central visual field defect (CVFD) than did the mild and moderate myopia groups. Longer axial length (odds ratio: 1.72, CI: 1.03-3.07, P = 0.047) and RNFL defect extending to the macula (odds ratio: 4.14, CI: 1.54-12.30, P = 0.007) were significantly associated with newly developed CVFD.

CONCLUSIONS

In patients with myopic glaucoma, the higher the degree of myopia, the faster the rate of visual acuity loss and CVFD occurrence. Occurrence of CVFD was associated with longer axial length and widening of RNFLr defect to the macula.

Biomechanical Correlations Between the Cornea and the Optic Nerve Head

Purpose

A thin cornea is a potent risk factor for glaucoma. The underlying mechanisms remain unexplained. It has been postulated that central corneal thickness (CCT) may be a surrogate for biomechanical parameters of the posterior eye. In this study, we aimed to explore correlations of biomechanical responses between the cornea and the optic nerve head (ONH) and the peripapillary sclera (PPS) to elevated intraocular pressure (IOP), the primary risk factor of glaucoma.

Methods

Inflation tests were performed in nine pairs of human donor globes. One eye of each pair was randomly assigned for cornea or posterior eye inflation. IOP was raised from 5 to 30 millimeters of mercury (mmHg) at 0.5 mmHg steps in the whole globe and the cornea or the ONH/PPS was imaged using a 50 MHz ultrasound probe. Correlation-based ultrasound speckle tracking was used to calculate tissue displacements and strains. Associations of radial, tangential, and shear strains at 30 mmHg between the cornea and the ONH or PPS were evaluated.

Results

Corneal shear strain was significantly correlated with ONH shear strain (R = 0.857, P = 0.003) and PPS shear strain (R = 0.724, P = 0.028). CCT was not correlated with any strains in the cornea, ONH, or PPS.

Conclusions

Our results suggested that an eye that experiences a larger shear strain in the cornea would likely experience a larger shear strain in its ONH and PPS at IOP elevations. The strong correlation between the cornea's and the ONH's shear response to IOP provides new insights and suggests a plausible explanation of the cornea's connection to glaucoma risk.

Retrolaminar Demyelination of Structurally Intact Axons in Nonhuman Primate Experimental Glaucoma

Purpose

To determine if structurally intact, retrolaminar optic nerve (RON) axons are demyelinated in nonhuman primate (NHP) experimental glaucoma (EG).

Methods

Unilateral EG NHPs (n = 3) were perfusion fixed, EG and control eyes were enucleated, and foveal Bruch's membrane opening (FoBMO) 30° sectoral axon counts were estimated. Optic nerve heads were trephined; serial vibratome sections (VSs) were imaged and colocalized to a fundus photograph establishing their FoBMO location. The peripheral neural canal region within n = 5 EG versus control eye VS comparisons was targeted for scanning block-face electron microscopic reconstruction (SBEMR) using micro-computed tomographic reconstructions (µCTRs) of each VS. Posterior laminar beams within each µCTR were segmented, allowing a best-fit posterior laminar surface (PLS) to be colocalized into its respective SBEMR. Within each SBEMR, up to 300 axons were randomly traced until they ended (nonintact) or left the block (intact). For each intact axon, myelin onset was identified and myelin onset distance (MOD) was measured relative to the PLS. For each EG versus control SBEMR comparison, survival analyses compared EG and control MOD.

Results

MOD calculations were successful in three EG and five control eye SBEMRs. Within each SBEMR comparison, EG versus control eye axon loss was -32.9%, -8.3%, and -15.2% (respectively), and MOD was increased in the EG versus control SBEMR (P < 0.0001 for each EG versus control SBEMR comparison). When data from all three EG eye SBEMRs were compared to all five control eye SBEMRs, MOD was increased within the EG eyes.

Conclusions

Structurally intact, RON axons are demyelinated in NHP early to moderate EG. Studies to determine their functional status are indicated.

Acute Onset Optic Disc Hemorrhage Following Pharmacologic Mydriasis

PURPOSE

To report two unusual cases of optic disc hemorrhage occurring following pharmacologic mydriasis.

OBSERVATION

A 78-year old woman and 60-year old man with primary open angle glaucoma developed optic disc hemorrhages shortly after pupillary dilation.

CONCLUSION AND IMPORTANCE

Cycloplegia may cause subtle shifts in vitreous and lamina cribrosa position that may result in the formation of optic disc hemorrhages in susceptible glaucomatous eyes.

Elucidation of the role of the lamina cribrosa in glaucoma using optical coherence tomography

Glaucoma is a chronic and progressive optic neuropathy characterized by the death of retinal ganglion cells and corresponding visual field loss. Despite the growing number of studies on the subject, the pathogenesis of the disease remains unclear. Notwithstanding, several studies have shown that the lamina cribrosa (LC) is considered an anatomic site of glaucomatous optic nerve injury, thus having a key role in the pathophysiology of glaucoma development and progression. Different morphological alterations of the LC have been described in vivo in glaucomatous eyes after the evolution of optical coherence tomography (OCT) devices. The most relevant findings were the reduction of laminar thickness, the presence of localized defects, and the posterior LC displacement. These new laminar parameters documented through OCT are not only promising as possible additional tools for glaucoma diagnosis and monitoring, but also as predictors of disease progression. In spite of the advance of technology, however, proper evaluation of the LC is not yet viable in all eyes. We describe OCT-identified LC changes related to the development and progression of glaucoma and provide future directions based on a critical data analysis, focusing on its clinical relevance and applicability.

Risk Factors Associated with Structural Progression in Normal-Tension Glaucoma: Intraocular Pressure, Systemic Blood Pressure, and Myopia

Purpose

To determine risk factors associated with structural progression in medically treated normal-tension glaucoma (NTG).

Methods

This retrospective cohort study included 166 NTG patients (average age, 56.5 years; average mean deviation, −4.2 dB). The structural progression endpoint was determined by optical coherence tomography; significant thickness differences in the peripapillary retinal nerve fiber layer (RNFL) or macular ganglion cell inner plexiform layer (GCIPL) that exceeded baseline test-retest variability were identified with event-based guided-progression analysis. Intraocular pressure and systemic blood pressure (BP) were measured at each visit throughout the follow-up period, and the risk for progression was evaluated with Cox regression. Myopic disc features and antihypertensives were also analyzed. Tree analysis was used to determine the cutoff values and elucidate influential risk factors.

Results

Structural progression, defined as progressive peripapillary RNFL or macular GCIPL thinning, was identified in 62 eyes. Occurrence of disc hemorrhages, presence of diabetes, and lower minimum systolic BP were associated with progression (hazard ratio [HR]: 2.116, P = 0.005; HR: 1.998, P = 0.031; HR: 0.968, P = 0.005; respectively). The cutoff value derived from the tree analysis of minimum systolic BP was 108 mm Hg. The tree analysis revealed systolic and diastolic BP to be the most influential risk factors for progressive peripapillary RFNL thinning and progressive macular GCIPL thinning, respectively.

Conclusions

Low BP measured during follow-up correlated with structural progression in medically treated NTG eyes, indicating that the evaluation of hypotension is required during the management of NTG patients. The tree analysis identified BP target values that may help prevent glaucoma progression.

Disc Hemorrhages Are Associated With the Presence and Progression of Glaucomatous Central Visual Field Defects

PRECIS

In this prospective cohort study, disc hemorrhages were associated with more severe central damage on 24-2 and 10-2 visual fields (VFs), and faster progression globally on 24-2 VFs and centrally on 10-2 VFs.

PURPOSE

To study the relationship between disc hemorrhage (DH) and the presence and progression of glaucomatous central VF damage.

METHODS

Cross-sectional and longitudinal analyses were performed on data from the African Descent and Glaucoma Evaluation Study (ADAGES) cohort. Two masked investigators reviewed disc photographs for the presence and location of DH. 24-2 central VF damage was based on the number of test locations within the central 10 degrees of the 24-2 field pattern deviation and their mean total deviation (MTD). 10-2 central VF damage was based on pattern deviation and MTD. Main outcome measures were the association between DH and presence of central VF damage and between DH and worsening of VF.

RESULTS

DH was detected in 21 of 335 eyes (6.2%). In the cross-sectional analysis, DH was significantly associated with more severe central damage on 24-2 [incidence rate ratio=1.47; 95% confidence interval (CI)=1.02-2.12; P=0.035] and 10-2 VFs (incidence rate ratio=1.81; 95% CI=1.26-2.60; P=0.001). In the longitudinal analysis, DH eyes progressed faster than non-DH eyes based on 24-2 global MTD rates (difference in slopes, β=-0.06; 95% CI=-0.11 to -0.01; P=0.009) and 10-2 MTD rates (β=-0.10; 95% CI=-0.14 to -0.06; P< 0.001), but not 24-2 central MTD rates (β=-0.02; 95% CI=-0.078 to 0.026; P=0.338).

CONCLUSION

DH was associated with the presence and progression of central VF defects. DH identification should prompt intensive central VF monitoring and surveillance with 10-2 fields to detect progression.

Characterization of Prelaminar Wedge-Shaped Defects in Primary Open-Angle Glaucoma

PURPOSE

To determine the clinical relevance of prelaminar wedge defects (PLWDs) detected by swept-source optical coherence tomography (SS-OCT) in primary open-angle glaucoma (POAG).

MATERIALS AND METHODS

In this retrospective case-control study, PLWDs were defined as triangular-shaped defects at the surface of the optic nerve prelaminar tissue, not adjacent to blood vessels, present on cross-sectional SS-OCT scans. Two observers masked to diagnosis independently reviewed scans to detect PLWDs and lamina cribrosa defects. History of disc hemorrhage, occurring within 2 years prior to imaging, was obtained from chart review. One eye per subject was randomly selected. Two-sided t-tests, analysis of variance with Bonferroni correction, and multivariable logistic regression analysis were performed to explore demographic and clinical features associated with PLWDs.

RESULTS

40 POAG and 23 control eyes were included. PLWDS were found in 27.5% of POAG (n = 11) and 4.3% of controls (n = 1, p = .04). Eyes with repeat SS-OCT imaging (7 POAG and 0 controls) had persistent PLWDs. More POAG eyes with PLWDs had a history of disc hemorrhage (45.5%) than POAG eyes without PLWDs (3.4%, p = .004). On multivariable analysis, compared to POAG without PLWDs, POAG with PLWDs had increased odds of observed disc hemorrhage (OR = 21.6, 95% CI, 2.2-589.0, p = .02) after adjusting for age, gender, visual field mean deviation and maximum intraocular pressure (IOP). POAG with PLWDs had more lamina cribrosa defects (45.5%) than POAG without PLWDs (3.4%, p = .01) but did not differ significantly from controls (8.7%, p = .07). Compared to all patients without PLWDs, patients with PLWDs had increased odds of having lamina cribrosa defects (OR = 44.8; 95% CI, 6.3-703.6, p < .001) after adjusting for age, gender, and maximum IOP.

CONCLUSIONS

PLWDs were more frequently found in POAG than control eyes and were associated with a history of disc hemorrhage and lamina cribrosa defects. PLWDs may be a useful imaging biomarker of glaucomatous damage.

Effect of systemic blood pressure on optical coherence tomography angiography in glaucoma patients

BACKGROUND

The association between retinal microvascular structure and glaucoma has been revealed in multiple studies using optical tomography angiography (OCTA), but limited information on the macular vessel density (mVD) in patients with glaucoma is available. In this study, we tried to identity the factors that affected macular VD (mVD) in glaucomatous eyes.

METHODS

This retrospective cross-sectional study evaluated OCT and OCTA images from 92 eyes from 58 healthy subjects and 179 eyes from 103 glaucoma patients using the SD-OCT database from July 2017 to July 2018. Glaucomatous eyes were further divided into two groups according to history of disc haemorrhage (DH). Association between mVD and demographic characteristics, ganglion cell-inner plexiform layer (GCIPL) thickness, visual field mean deviation (MD) and systemic blood pressure was analysed in each group.

RESULTS

In both healthy and glaucomatous eyes, mVD was inversely associated with age (β = -0.035, P = 0.025; β = -0.039, P = 0.018). In the glaucomatous eyes, mVD was significantly decreased, as the MD value was worse (β = 0.109, P = 0.002). In glaucomatous eyes with DH, mVD decreased as blood pressure increased (β = -0.111, P = 0.003) CONCLUSIONS: Reduced mVD is more common in older individuals in both healthy and glaucomatous eyes, and correlates with functional deterioration than structural damage in glaucomatous eyes. In glaucomatous eyes with DH, high systemic BP is associated with a reduction in mVD. This may indicate that glaucoma patients with DH are more susceptible to vascular damage secondary to hypertension.

Optic disc hemorrhage in nonglaucomatous eyes: A cross-sectional study with average 8-year follow-up

Purpose

To characterize changes in the retinal nerve fiber layer (RNFL) and peripapillary vessel density (VD) at the site of disc hemorrhage (DH) in nonglaucomatous eyes.

Materials and methods

This retrospective cross-sectional study included nonglaucomatous eyes diagnosed with unilateral DH. The change of DH was recorded using disc photography. Both anatomical data and functional visual field (VF) data were collected using optical coherence tomography angiography and Humphrey VF examination.

Results

Sixteen patients were included with average follow-up duration of 95 months. Almost half of DH episodes was initially presented at the inferotemporal area of the optic disc. Pigment formation at the previous DH site after resolution was noted in 12.5% of eyes. Sectoral radial peripapillary VD at the DH site was significantly lower in DH eyes than in the control group; however, the sectoral RNFL thickness at the DH site was not significantly decreased. Progression of the VF defect corresponding to the DH site was found in 81.3% of eyes despite regular use of antiglaucoma agents. The mean change in the VF mean deviation was –0.64 dB/year in DH eyes.

Conclusion

During long follow-up periods, decreased peripapillary VD at the DH site and progression of the VF defect corresponding to the DH site were detected in nonglaucomatous eyes. Retinal pigmentation with an RNFL defect is a clue for DH, although RNFL showed no significant change. Antiglaucoma treatment may not prevent the deterioration of visual function.

Artificial intelligence and deep learning in glaucoma: Current state and future prospects

Over the past few years, there has been an unprecedented and tremendous excitement for artificial intelligence (AI) research in the field of Ophthalmology; this has naturally been translated to glaucoma-a progressive optic neuropathy characterized by retinal ganglion cell axon loss and associated visual field defects. In this review, we aim to discuss how AI may have a unique opportunity to tackle the many challenges faced in the glaucoma clinic. This is because glaucoma remains poorly understood with difficulties in providing early diagnosis and prognosis accurately and in a timely fashion. In the short term, AI could also become a game changer by paving the way for the first cost-effective glaucoma screening campaigns. While there are undeniable technical and clinical challenges ahead, and more so than for other ophthalmic disorders whereby AI is already booming, we strongly believe that glaucoma specialists should embrace AI as a companion to their practice. Finally, this review will also remind ourselves that glaucoma is a complex group of disorders with a multitude of physiological manifestations that cannot yet be observed clinically. AI in glaucoma is here to stay, but it will not be the only tool to solve glaucoma.

Progressive retinal nerve fibre layer thinning and choroidal microvasculature dropout at the location of disc haemorrhage in glaucoma

BACKGROUND/AIMS

To investigate whether parapapillary choroidal microvasculature dropout (MvD) is associated with progressive retinal nerve fibre layer (RNFL) thinning in eyes with primary open-angle glaucoma (POAG) and disc haemorrhage (DH).

METHODS

Parapapillary microvasculature was evaluated by swept-source optical coherence tomography (OCT) angiography (OCTA) in 50 eyes with POAG and DH, 1 year before, at the time of and 1 year after the detection of DH. MvD was defined as an area in the parapapillary deep layer of focal sectoral dropout with no visible microvascular network. Progressive changes in OCT RNFL thickness were compared in groups of eyes with and without MvD.

RESULTS

Cumulative prevalence of MvD was 76.0% (38 eyes) at 1 year after detection of DH. All MvDs were detected in the same sectoral locations as DH. In eyes with MvD, global RNFL thickness and sectoral RNFL thickness at the location of DH were significantly reduced, both from 1 year before to the time of DH detection (both p<0.001) and from DH detection to 1 year later (both p<0.001). In eyes without MvD, however, the reductions in global (p=0.011) and sectoral (p=0.007) RNFL thickness were significant only from DH detection to 1 year later.

CONCLUSION

In eyes with POAG, RNFL thinning was spatially consistent and progressive at the location of MvD accompanied by subsequent DH and continued to progress after the occurrence of DH. When DH was not accompanied by MvD, progressive RNFL thinning was more likely to occur after the detection of DH.

Choroidal Microvascular Dropout in Primary Open-angle Glaucoma Eyes With Disc Hemorrhage

PURPOSE

The main purpose of this study was to compare the prevalence of choroidal microvascular dropout (CMvD) in primary open-angle glaucoma (POAG) eyes with and without disc hemorrhage (DH).

METHODS

In a cross-sectional study, 44 eyes of 44 control subjects, 32 eyes of 32 POAG patients with DH, and 41 eyes of 41 POAG patients without DH underwent visual fields (VFs), optical coherence tomography (OCT) and OCT angiography (OCTA). Presence of CMvD was evaluated on the choroidal OCTA slab. VF defect in the glaucoma eyes were classified into initial nasal defect, initial parafoveal scotoma, and combined nasal and parafoveal defect.

RESULTS

CMvD was detected in 17 POAG eyes with DH (53.1%) and 13 POAG eyes without DH (31.7%; P=0.06). On univariate analysis, CMvD in POAG eyes was associated with DH [odds ratio (OR): 2.44, P=0.06] and measures of glaucoma severity: VF mean deviation (OR: 0.85, P=0.02), retinal nerve fiber layer thickness (OR: 0.95, P=0.03), and peripapillary vessel density (OR: 0.94, P=0.09). On multivariate models that accounted for the measures of glaucoma severity, CMvD in POAG eyes was statistically significantly associated with DH (OR≥3, P<0.05). CMvD was more frequently seen in eyes with initial parafoveal scotoma than initial nasal defect both in POAG eyes with DH (P=0.06) and POAG eyes without DH (P<0.001).

CONCLUSIONS

Prevalence of CMvD was significantly greater in POAG eyes with DH compared with POAG eyes without DH. CMvD in POAG eyes was also significantly associated with central VF defects and greater severity of glaucomatous damage.

Positive predictive value of optic disc haemorrhages for open angle glaucoma

OBJECTIVES

To determine the positive predictive value (PPV) of disc haemorrhages (DHs) for the diagnosis of open angle glaucoma (OAG).

METHODS

A retrospective review of 618 consecutive new referrals by community optometrists to a hospital glaucoma service, including 54 patients with DHs. All patients had a comprehensive eye examination. The primary outcome was whether the patient was diagnosed with OAG in either eye, with a secondary outcome of whether they were discharged at the first visit (first visit discharge rate, FVDR).

RESULTS

54 of 618 patients (8.7%) had a DH noted at the time of referral, including 21 referred with DH alone. 29 patients with DHs were diagnosed with OAG for a PPV of 54% (95% CI 40-67%), falling to 24% (95% CI 8-47%) in those with DH alone. The overall FVDR was 35%, increasing to 57% in those referred due to DH alone. The FVDR for those referred with DH alone was significantly higher than the FDVR of 25% among the 564 patients referred with suspected glaucoma without a DH (P = 0.001). The FVDR decreased to 35% for patients with a DH plus one other feature of glaucoma and to 0% for patients with a DH and at least two other features suggestive of glaucoma.

CONCLUSIONS

Almost 60% of patients referred due to isolated DHs were discharged at the first visit to the glaucoma clinic, however almost one in four was diagnosed with OAG. Patients with DH and other features suggestive of glaucoma had a higher probability of glaucoma diagnosis.

Mechanical Deformation of Human Optic Nerve Head and Peripapillary Tissue in Response to Acute IOP Elevation

Purpose

To measure the deformation of the human optic nerve head (ONH) and peripapillary tissue (PPT) in response to acute intraocular pressure (IOP) elevation.

Methods

The ONH and PPT of 14 human donor globes were imaged with high-frequency ultrasonography during inflation testing from 5 to 30 mm Hg. A correlation-based speckle tracking algorithm was used to compute tissue displacements, and the through-thickness, in-plane, and shear strains were calculated by using least-squares strain estimation methods. The ONH and PPT were segmented along the anterior-posterior direction and the nasal-temporal direction. Regional displacements and strains were analyzed and compared.

Results

The ONH displaced more posteriorly than the PPT in response to an acute IOP increase. Scleral canal expansion was minimal but correlated with ONH posterior displacement at all IOP levels. Through-thickness compression was concentrated in the anterior of both the ONH and the PPT. Shear was concentrated in the vicinity of the canal with higher shear in the peripheral ONH than the central ONH and higher shear in the PPT near the scleral canal than that further away from the canal.

Conclusions

High-resolution ultrasound speckle tracking showed a displacement mismatch between the ONH and the PPT, larger compressive strains in the direction of IOP loading in the anterior ONH and PPT, and higher shear strains in the periphery of ONH in response to acute IOP elevation in the human eye. These findings delineate the deformation patterns within and around the ONH and may help understand IOP-associated optic nerve damage.

Optic disk hemorrhage and vitreous hemorrhage after phacoemulsification in a normal tension glaucoma patient: A case report

RATIONALE

Optic disk hemorrhage has been closely correlated with glaucoma for its development and progression. Phacoemulsification surgery results in large intraocular pressure (IOP) fluctuation. We report a case of optic disk hemorrhage and consequently progressive vitreous hemorrhage after an unsuccessful phacoemulsification surgery in an advanced normal tension glaucoma (NTG) patient.

PATIENT CONCERNS

An advanced NTG patient of 82 years old with chronic hypertension underwent an unsuccessful phacoemulsification surgery complicated by posterior capsule rupture. During the postoperative 2 weeks, recurrent episodes of fresh hyphema occurred and B ultrasonography scan revealed the progressive vitreous hemorrhage. The IOP went out of control under the maximum tolerable IOP-lowering medications.

DIAGNOSIS

Vitreous hemorrhage after phacoemulsification in an advanced NTG patient.

INTERVENTIONS

Vitrectomy was performed to search for the cause of the progressive vitreous hemorrhage. After removal of the thick vitreous hemorrhage, a fresh spot of optic disk hemorrhage was detected at the nasal margin of the significantly-cupping disk.

OUTCOMES

Postoperatively, the hemorrhagic vitreous opacity gradually resolved and the IOP remained stable at 10 ∼13 mmHg with topical prostaglandin analogue drops. Fundus examination revealed the dilated disk vessel with localized angiomatous change at the nasal disk margin.

LESSONS

Severe optic disk hemorrhage may occur after phacoemulsification in advanced glaucoma patients. Systemic vascular factors, such as chronic hypertension and old age, and surgical complications, such as posterior capsule rupture and postoperative IOP elevation, would further increase the risk. For phacoemulsification in advanced glaucoma cases, extra care should be taken to control intraoperative IOP fluctuations and monitor postoperative IOP.

Association between focal lamina cribrosa defects and optic disc haemorrhage in glaucoma

BACKGROUND/AIMS

To explore the relationship between focal lamina defect (LD) size and optic disc haemorrhages (DH) in glaucomatous eyes.

METHODS

Radial B-scan images at 15° intervals obtained using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (OCT) were performed on a group of subjects previously assessed for DH every 3 months over a period of 5 years. EDI-OCT scans were assessed for the presence of focal lamina cribrosa defects by a single observer.

RESULTS

119 eyes from 62 subjects (44 females, 18 males) were analysed. 44 eyes (37%) were noted to have at least 1 LD, and of those, eight eyes had more than one defect. 68 eyes (57%) were observed to have at least one DH occur over the course of monitoring. 48 eyes (40%) had recurrent DH, with a mean of 5.17 haemorrhages over the 5-year period. Type 1 focal LD (p=0.0000, OR 7.17), glaucoma progression (p=0.0024, OR 0.32) and ArtDiff (p=0.0466, OR 1.04) were significantly associated as predictors of DH. No correlation between the size of the LD and DH occurrence (p=0.6449, Spearman rank correlation) was found.

CONCLUSION

Focal lamina cribrosa hole-type defects were significantly associated with an increase in DH occurrence over the preceding 5 years. The lack of association between defect size and DH suggests that DH and lamina defects may have separate links to the glaucomatous process.

The impact of disc hemorrhage studies on our understanding of glaucoma: a systematic review 50 years after the rediscovery of disc hemorrhage

PURPOSE OF REVIEW

To trace the influence of disc hemorrhage studies on our understanding of glaucoma.

SOURCES

Major articles published during the last 50 years since the rediscovery of disc hemorrhage were identified. A total of 196 articles were selected from 435 articles retrieved using the keywords glaucoma and disc hemorrhage as of August 9 2018 from PubMed.

RECENT FINDINGS

The main characteristics of disc hemorrhage, including its morphology, recurrence rate, duration, increased incidence in glaucoma, and role in the progression of normal tension glaucoma was well understood by the year 2000. Since then, studies have focused on more sophisticated and accurate methods of elucidating both structural and functional progression, with special attention to the role of the lamina cribrosa. Nevertheless, both the mechanism of disc hemorrhage development and its fuller relationship with glaucoma remain unclear. Disc hemorrhage research requires careful study of glaucomatous optic neuropathy. This has been facilitated by recent advances in optical coherence tomography (OCT) angiography and other OCT technologies. Furthermore, animal studies of disc hemorrhage promise new insights into glaucomatous optic neuropathy.

A Phenotype of Primary Open-angle Glaucoma With Systemic Vasospasm

PURPOSE

Primary open-angle glaucoma (POAG) patients constitute a heterogenous group. Identification of phenotypic subtypes among these patients may provide a deeper understanding of the disease and aid associations with genotypes. We describe a phenotype of POAG patients associated with a constellation of systemic disorders; patients with this phenotype seem to be vulnerable to optic nerve damage at low intraocular pressures.

MATERIALS AND METHODS

In this retrospective study, we evaluated the medical records of active Jules Stein Eye Institute glaucoma patients from January 1996 to 2017 and included subjects with POAG, acquired pits of the optic nerve (APON), and at least one of the following: systolic blood pressure persistently ≤100 mm Hg, history of migraine headaches or migraine variant, and the Raynaud syndrome.

RESULTS

Of 87 patients (125 eyes) with APON, 37 patients (55 eyes) met the study criteria. In total, 34 patients were female (92%). The median age at the time of diagnosis was 55 years. Nineteen patients (73%) had low systolic blood pressures, same number had Raynaud syndrome, and 25 (68%) had a history of migraine.

CONCLUSIONS

We describe a POAG subtype with APON and systemic vascular instability, predominantly female in their sixth decade of life who demonstrate progressive glaucomatous visual field damage at low intraocular pressure. We suggest that this clinical picture represents an important phenotype of POAG, and that identification and further study of it will help guide diagnosis and development of individualized treatments.

Association between Rates of Retinal Nerve Fiber Layer Thinning and Previous Disc Hemorrhage in Glaucoma

PURPOSE

To investigate the relationship between previous disc hemorrhage (DH) and subsequent rates of retinal nerve fiber layer (RNFL) thinning.

DESIGN

Longitudinal, observational cohort study.

PARTICIPANTS

Twenty-eight patients with glaucoma and patients with suspected glaucoma who had a history of DH in 1 eye (unilateral DH), but not in the fellow eye, enrolled in the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study were included.

METHODS

All subjects underwent annual optic disc photography and semiannual spectral-domain OCT RNFL thickness measurements. Multivariable linear mixed-effects models were used to investigate the relationship between the presence of previous DH and RNFL thinning rates while adjusting for potential confounding factors, such as race, age, mean intraocular pressure (IOP), baseline disease severity, and central corneal thickness (CCT). The relationship between the timing of DH and the rates of RNFL thinning also was investigated in eyes with a history of DH.

MAIN OUTCOME MEASURES

Rates of global and local RNFL thinning.

RESULTS

Previous DH was significantly associated with faster RNFL thinning rates globally (-0.39 μm/year faster, P = 0.010), in DH quadrants (-0.77 μm/year faster, P = 0.012), and non-DH quadrants (-0.49 μm/year faster, P = 0.038) after adjustment for race, mean IOP, baseline age, baseline standard automated perimetry mean deviation, and CCT. Higher IOP was also significantly associated with faster thinning rates globally (-0.07 μm/year faster per 1 mmHg higher, P = 0.047) and in DH quadrants (-0.10 μm/year faster per 1 mmHg higher, P = 0.044). In eyes with a history of DH, the time elapsed from the latest DH episode to the first OCT examination was not significantly associated with the rate of RNFL thinning.

CONCLUSIONS

A history of DH is an independent risk factor for faster rates of RNFL thinning in non-DH quadrants and in DH quadrants; this risk is present even in eyes that exhibited DH several years earlier.

Finite Element Biomechanics of Optic Nerve Sheath Traction in Adduction

Historical emphasis on increased intraocular pressure (IOP) in the pathogenesis of glaucoma has been challenged by the recognition that many patients lack abnormally elevated IOP. We employed finite element analysis (FEA) to infer contribution to optic neuropathy from tractional deformation of the optic nerve head (ONH) and lamina cribrosa (LC) by extraocular muscle (EOM) counterforce exerted when optic nerve (ON) redundancy becomes exhausted in adduction. We characterized assumed isotropic Young's modulus of fresh adult bovine ON, ON sheath, and peripapillary and peripheral sclera by tensile elongation in arbitrary orientations of five specimens of each tissue to failure under physiological temperature and humidity. Physical dimensions of the FEA were scaled to human histological and magnetic resonance imaging (MRI) data and used to predict stress and strain during adduction 6 deg beyond ON straightening at multiple levels of IOP. Young's modulus of ON sheath of 44.6 ± 5.6 MPa (standard error of mean) greatly exceeded that of ON at 5.2 ± 0.4 MPa, peripapillary sclera at 5.5 ± 0.8 MPa, and peripheral sclera at 14.0 ± 2.3 MPa. FEA indicated that adduction induced maximum stress and strain in the temporal ONH. In the temporal LC, the maximum stress was 180 kPa, and the maximum strain was ninefold larger than produced by IOP elevation to 45 mm Hg. The simulation suggests that ON sheath traction by adduction concentrates far greater mechanical stress and strain in the ONH region than does elevated IOP, supporting the novel concept that glaucomatous optic neuropathy may result at least partly from external traction on the ON, rather than exclusively on pressure on the ON exerted from within the eye.

Macular Vessel Density in Glaucomatous Eyes With Focal Lamina Cribrosa Defects

PURPOSE

To compare optical coherence tomography angiography (OCTA) measured macular vessel density and spectral domain optical coherence tomography (SDOCT) measured macular ganglion cell complex (GCC) thickness in primary open-angle glaucoma eyes with and without focal lamina cribrosa (LC) defects.

METHODS

In this cross-sectional, case-control study of patients with primary open-angle glaucoma, 46 eyes of 46 patients with LC defects and 54 eyes of 54 patients without observable LC defects were included. OCTA and SDOCT imaging were performed on the same day by the same operator. Perimetry and swept-source OCT testing used to identify LC defects were conducted within 6 months of OCTA and SDOCT testing. Global and local parafoveal vessel density and macular GCC thickness were compared between study groups.

RESULTS

Glaucoma severity was similar between groups (SAP mean deviation=-5.63 and -4.64 dB for eyes with and without LC defects, respectively; P=0.40). Global and local measured parafoveal vessel density was similar between groups (all P≥0.11). GCC focal loss volume was higher in eyes with LC defects than eyes without LC defects (7.2% and 4.97%, respectively; P=0.03). In addition, GCC focal loss volume was topographically related to defect location in LC defect eyes.

CONCLUSIONS

Although OCTA macular vessel density was not significantly different between eyes with and without LC defects, focal GCC loss in eyes with LC defects was different. This highlights the importance of not relying solely on vessel density measurements for determining macular changes for diagnosing and detecting glaucomatous progression.

Impact of optic disc hemorrhage on subsequent glaucoma progression in mild-to-moderate myopia

PURPOSE

To investigate optic disc hemorrhage (DH)'s clinical implications to subsequent progression of primary open-angle glaucoma (POAG) in cases of mild-to-moderate myopia.

DESIGN

Retrospective comparative study.

PARTICIPANTS

(1) Fifty-nine (59) myopic (26.5 mm > axial length [AXL] ≥ 24.0 mm) POAG patients with DH and (2) 59 age-, AXL-, and mean deviation (MD) of visual field (VF)-matched controls without DH were evaluated over the course of a minimum 3.5 years of follow up. For clear assessment of the effect of DH on progression of glaucoma, the patients selected for inclusion in the study were those with stable IOP (i.e., those showing an at least 20% reduction relative to the baseline IOP) whose IOP-lowering medication was not increased, supplemented or changed during the follow-up period.

METHODS

The patients' optic disc/retinal nerve fiber layer (RNFL) photographs were independently evaluated by three glaucoma specialists for structural progression of glaucoma. Event-based analysis with Guided Progression Analysis (GPA) software was used to determine their functional progression. The durations of structural and functional progression were compared by Kaplan-Meier life survival analyses.

MAIN OUTCOME MEASURES

Optic disc/RNFL progression and VF progression.

RESULTS

The mean follow-up periods between the DH and non-DH groups were not significantly different: in the DH group, 5.6±2.7 years; in the non-DH group, 5.4±2.6 years (P = 0.588). In the DH group, 30 (50.8%) of 59 eyes manifested optic disc/RNFL deterioration; in the non-DH group, however, only 17 (28.8%) of 59 eyes showed structural progression. For the DH group, the cumulative probability of structural glaucoma progression was significantly greater than for the non-DH group (P = 0.001; log rank test). Interestingly, the two groups did not significantly differ in the cumulative probability of functional progression (P = 0.79; log rank test): in the DH group, VF progression was observed in 14 eyes (23.7%); in the non-DH group, in 12 eyes (20.3%).

CONCLUSIONS

DH was associated with a greater probability of structural progression in medically well-controlled-IOP POAG eyes with mild-to-moderate myopia. However, the relevance of DH to VF progression was not clear over the course of the average 5.5-year duration of the study.

Clinical Implications of In Vivo Lamina Cribrosa Imaging in Glaucoma

The lamina cribrosa (LC) is a multilayered, collagenous, sieve-like structure at the deep optic nerve head, and is presumed to be the primary site of axonal injury. According to biomechanical theory, intraocular pressure-induced posterior deformation of the LC causes blockage of axonal transport and alters the ocular blood flow, so that the axons of the retinal ganglion cells lead to apoptosis, which results in glaucomatous optic disc change. Although most of the research on the LC to date has been limited to experimental animal or histologic studies, the recent advances in optical coherence tomography devices and image processing techniques have made possible the visualization of the LC structure in vivo. LC deformation in glaucoma typically has been evaluated in terms of its position from a structural reference plane (LC depth), entire curvature or shape, thickness, or localized structural change (focal LC defects or LC pore change). In this review, we highlight the methods of assessing LC deformation from in vivo optical coherence tomography scans, and we discuss the clinical implications of the recent investigations of the in vivo structure of LC in glaucoma.

In vivo analysis of glaucoma-related features within the optic nerve head using enhanced depth imaging optical coherence tomography

Structural differences between optic nerve head (ONH) parameters in glaucomatous and non-glaucomatous eyes has been documented, however the association between such parameters in patients with different disease stages is yet to be elucidated. We investigated the relationship between different laminar and prelaminar ONH structures using enhanced depth imaging spectral-domain optical coherence tomography (EDI OCT) in a population with and without glaucoma. In this observational case-control study, we prospectively enrolled healthy individuals and glaucomatous patients with different disease stages. All participants underwent EDI OCT imaging (Heidelberg Engineering). Following ONH parameters were measured on serial vertical B-scans by two examiners masked to patient’s clinical data: lamina cribrosa (LC) and prelaminar neural tissue (PLNT) thicknesses, Bruch’s membrane opening (BMO) and cup depth. Associations between cup depth, and laminar and prelaminar parameters were evaluated controlling for possible confounding factors such as axial length and disc size. Sixty-four eyes of 64 patients were included (30 with glaucoma and 34 controls). Eyes with glaucoma had significantly lower mean LC and PLNT thickness, and greater mean cup depth than controls (p<0.01). There was a significant negative association between PLNT thickness and cup depth in glaucomatous eyes (R² = 0.158, p = 0.029). In addition, LC thickness correlated significantly with cup depth (R² = 0.135, p = 0.045). Eyes with thinner LCs presented deeper cups. Overall, cup depth and BMO had the best and LC thickness had the worst intraobserver and interobserver reproducibility grading. In conclusion, significant associations were seen between cup depth, LC and PLNT thickness. Eyes with deeper cups not only had less neural tissue, but also thinner LCs, independent of disc size and axial length. Best reproducibility was found for prelaminar parameters compared to deeper ONH structures.

Comparison of Glaucoma Progression Between Unilateral and Bilateral Disc Hemorrhage Eyes and Associated Risk Factors for Progression

PURPOSE

To compare glaucoma progression between unilateral and bilateral disc hemorrhage (DH) eyes and to determine the associated risk factors.

METHODS

A total of 78 bilateral primary open-angle glaucoma (POAG) patients who had shown one or more occurrences of DH (48 eyes of 38 unilateral DH patients and 30 eyes of 30 bilateral DH patients) were included. Glaucoma progression was defined by visual field (VF) deterioration. The mean VF global indices progression rates in the pre-DH, post-DH and total follow-up periods were compared between the unilateral and bilateral DH groups. The cumulative probability of glaucoma progression between the 2 groups was compared by the Kaplan-Meier survival analysis. Univariate and multivariate Cox proportional hazard models were used to identify the risk factors for glaucoma progression.

RESULTS

Among the mean VF global indices progression rates, only the mean pattern standard deviation progression rate showed a statistically significant difference between the groups (unilateral DH group: 0.30±0.38 dB/y; bilateral DH group: 0.13±0.27 dB/y) (P=0.042). The Kaplan-Meier analysis revealed a greater cumulative probability of progression in the unilateral than in the bilateral DH group (P=0.008). The multivariate Cox's proportional hazard model indicated unilaterality of DH to be a factor associated with glaucoma progression (hazard ratio, 2.587; P=0.030).

CONCLUSIONS

In bilateral POAG patients with DH, unilaterality of DH is associated with glaucoma progression. Therefore, clinicians need to perform careful and frequent follow-up on bilateral POAG patients showing DH in only 1 eye during the follow-up period.

Optic Disc Hemorrhage and Lamina Cribrosa Defects in Glaucoma Progression

Both disc hemorrhages (DH) and focal lamina cribrosa (LC) defects are recently considered as a progression factor in glaucoma. However, the clinical relevance of the presence of LC findings at the site of the DH has not yet been determined. We conducted a prospective study enrolling a total of 98 glaucoma eyes with DH and 37 OAG eyes with focal LC defect without DH to determine whether visual field (VF) progression differs according to the findings of the LC that had been evaluated by enhanced depth imaging (EDI) of optical coherence tomography (OCT) and its relationship with DH. Only the presence of focal LC defects was significantly different between the progressing and stable patients (P < 0.001). Baseline intraocular pressure (hazard ratio [HR], 1.076; P = 0.098) and the presence of focal LC defects at the DH site (HR, 2.620; P = 0.002) were found to be associated with VF progression. Glaucoma eyes with DH at the site of focal LC defects showed frequent and faster VF progression compared with DH not accompanied by LC alterations or LC alterations not accompanied by DH. Evaluating LC alterations in glaucoma eyes with DH may be important in predicting the progression of glaucoma.

Optic disk hemorrhage in health and disease

Optic disk hemorrhage occurs in all age groups from neonates to the elderly. Optic disk hemorrhage is best known for its association with visual field loss and progression in patients with glaucoma; however, it may occur in conjunction with other ocular or systemic conditions as well as in healthy individuals. It may also be the first sign of a sight-threatening condition. Variations in the shape, location, and size of the optic disk hemorrhage, as well as associated ocular and systemic signs or symptoms, may help determine the underlying pathology. We address the epidemiology, demographics, pathophysiology, clinical presentations and implications, differential diagnoses, and management of eyes with optic disk hemorrhage in diseased and healthy subjects.

Lamina cribrosa in glaucoma

PURPOSE OF REVIEW

This article presents, summarizes, and interprets the most recent advances in the study and understanding of the lamina cribrosa in glaucoma, in the context of previous work.

RECENT FINDINGS

The lamina is an active living structure that responds to strain by changing morphology at the micro-scale and macro-scale in glaucoma. Changes in lamina cribrosa morphology in glaucoma include posteriorization of the laminar insertion into the sclera, increased cupping or depth of the lamina cribrosa, and the development of focal lamina cribrosa defects. These lamina cribrosa changes are associated with disk hemorrhages and visual field damage, and are detectable with clinical imaging techniques such as optical coherence tomography. Glaucomatous changes in the lamina cribrosa are thought to be driven by cellular processes mediated by focal cyclical mechanical strain. Strain is eye specific and mediated by intraocular pressure, cerebrospinal fluid pressure, scleral and lamina cribrosa morphology, and structural stiffness; deleterious lamina cribrosa strains can occur at all levels of mean intraocular pressure.

SUMMARY

Laminar morphology is ever changing in health and disease, and recent studies have identified several promising morphological changes that are indicative of glaucoma susceptibility, onset, and progression.

Optic disc hemorrhage in glaucoma: pathophysiology and prognostic significance

PURPOSE OF REVIEW

This article reviews the recent findings with regard to the pathophysiology and clinical significance of optic disc hemorrhage in glaucoma.

RECENT FINDINGS

Even though the pathophysiology of disc hemorrhage has been investigated in depth, its underlying mechanism remains unclear. The key disc hemorrhage mechanisms currently under discussion are mechanical vascular disruption and associated vascular susceptibilities. Recent technical advances in spectral-domain optical coherence tomography have yielded more compelling evidence of mechanical vascular disruption behind the pathogenesis of disc hemorrhage in glaucoma. Studies show that disc hemorrhage is associated with structural and functional glaucoma progression. Furthermore, recent findings suggest that disc hemorrhage can have different significances according to its location, recurrence, and associated underlying mechanism.

SUMMARY

The underlying mechanism of disc hemorrhage is complex like that of glaucoma. The ongoing controversy respecting the role of disc hemorrhage as a risk factor for glaucoma progression notwithstanding, special attention entailing closer follow-up and/or treatment escalation is recommended for patients with disc hemorrhage. Further studies investigating the unrevealed pathogenesis of disc hemorrhage and its prognostic value in glaucoma are warranted.