Angle closure: classification, concepts, and the role of ultrasound biomicroscopy in diagnosis and treatment

Whole Exome Sequencing Reveals Novel Candidate Genes in Familial Forms of Glaucomatous Neurodegeneration

Glaucoma is the largest cause of irreversible blindness with a multifactorial genetic etiology. This study explores novel genes and gene networks in familial forms of primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) to identify rare mutations with high penetrance. Thirty-one samples from nine MYOC-negative families (five POAG and four PACG) underwent whole-exome sequencing and analysis. A set of prioritized genes and variations were screened in an independent validation cohort of 1536 samples and the whole-exome data from 20 sporadic patients. The expression profiles of the candidate genes were analyzed in 17 publicly available expression datasets from ocular tissues and single cells. Rare, deleterious SNVs in AQP5, SRFBP1, CDH6 and FOXM1 from POAG families and in ACACB, RGL3 and LAMA2 from PACG families were found exclusively in glaucoma cases. AQP5, SRFBP1 and CDH6 also revealed significant altered expression in glaucoma in expression datasets. Single-cell expression analysis revealed enrichment of identified candidate genes in retinal ganglion cells and corneal epithelial cells in POAG; whereas for PACG families, retinal ganglion cells and Schwalbe's Line showed enriched expression. Through an unbiased exome-wide search followed by validation, we identified novel candidate genes for familial cases of POAG and PACG. The SRFBP1 gene found in a POAG family is located within the GLC1M locus on Chr5q. Pathway analysis of candidate genes revealed enrichment of extracellular matrix organization in both POAG and PACG.

Development and validation of methods to visualize conventional aqueous outflow pathways in canine primary angle closure glaucoma

PURPOSE

Angle closure glaucoma (PACG) is highly prevalent in dogs and is often refractory to medical therapy. We hypothesized that pathology affecting the post-trabecular conventional aqueous outflow pathway contributes to persistent intraocular pressure (IOP) elevation in dogs with PACG. The goal of this study was to determine the potential for aqueous angiography (AA) and optical coherence tomography (OCT) to identify abnormalities in post-trabecular aqueous outflow pathways in canine PACG.

METHODS

AA and anterior segment OCT (Spectralis HRA + OCT) were performed ex vivo in 19 enucleated canine eyes (10 normal eyes and 9 irreversibly blind eyes from canine patients enucleated for management of refractory PACG). Eyes were cannulated and maintained at physiologic IOP (10-20 mmHg) prior to intracameral infusion of fluorescent tracer. OCT scleral line scans were acquired in regions of high and low perilimbal AA signal. Eyes were then perfusion fixed and cryosections prepared from 10/10 normal and 7/9 PACG eyes and immunolabeled for a vascular endothelial marker.

RESULTS

Normal canine eyes showed segmental, circumferential limbal AA signal, whereas PACG eyes showed minimal or no AA signal. AA signal correlated with scleral lumens on OCT in normal dogs, but lumens were generally absent or flattened in PACG eyes. Collapsed vascular profiles were identified in tissue sections from PACG eyes, including those in which no lumens were identified on AA and OCT.

CONCLUSIONS

In canine eyes with PACG, distal aqueous outflow channels are not identifiable by AA, despite normalization of their IOP, and intra-scleral vascular profiles are collapsed on OCT and histopathology.

Assessment of Post-Operative Pseudophakic Glaucoma by Ultrasound Biomicroscopy

Purpose

Pseudophakic glaucoma is a secondary glaucoma in which intra-ocular pressure is elevated following cataract removal. The current study aimed to evaluate the role of ultrasound biomicroscopy (UBM) in assessing post-operative pseudophakic glaucoma.

Patients and Methods

This is a case series, prospective, observational and analytical study. It included 29 eyes of 29 patients with post-operative pseudophakic glaucoma. The patients were evaluated by medical history, detailed ophthalmologic examination and UBM.

Results

UBM examination has unmasked different causes of pseudophakic glaucoma. The detected causes were classified into 3 main groups, including intraocular lens (IOL)-related causes, lens remnants and intra-ocular inflammation. Haptic-related causes were present in 9 eyes, while 6 eyes had decentered or tilted IOLs. Soemmering's ring was the main cause in 3 eyes while in one eye the cause was lens particle in the anterior chamber (AC). Silicone oil in AC with seclusio pupillae was the main cause in one eye. Peripheral anterior synechiae were detected in 8 eyes while, posterior synechiae were evident in 7 eyes. Uveitis induced by anterior chamber IOL (ACIOL) was found in 3 eyes and one eye had peripheral anterior synechiae due to neovascular glaucoma.

Conclusion

UBM is a helpful diagnostic tool to evaluate causes of pseudophakic glaucoma through adequate visualization of different angle structures.

Bilateral Angle Closure Following the Infusion of a Monoclonal Antibody to Treat Relapsing Multiple Myeloma

PURPOSE

We describe a case of bilateral angle closure glaucoma following the infusion of daratumumab, a monoclonal antibody used to treat relapsing multiple myeloma.

METHODS

This is an interventional case report.

RESULTS

A 59-year-old woman presented with bilateral angle closure glaucoma one day following her first infusion of daratumumab. B-scan echography showed ciliochoroidal effusions in both eyes. Cycloplegia was implemented given the suspicion for drug-induced angle closure, which resulted in prompt deepening of the anterior chambers and normalization of intraocular pressures. The ciliochoroidal effusions resolved 16 days following the cessation of daratumumab.

CONCLUSIONS

Daratumumab may be associated with drug-induced secondary angle closure glaucoma.

Angle Closure Scoring System (ACSS)-A Scoring System for Stratification of Angle Closure Disease

Purpose

To evaluate the angle closure scoring system (ACSS) for stratifying primary angle course disease.

Methods

This observational cross sectional institutional study included patients with primary open angle glaucoma suspects (n = 21) and primary angle closure disease (primary angle closure, PAC, n = 63 and primary angle course glaucoma, PACG, n = 58 (defined by International society of Geographical and Epidemiological Ophthalmology, ISGEO). Two independent examiners blinded to clinical details, graded good quality pre-laser goniophotographs of the patients incorporating quadrants of peripheral anterior synechieae (PAS), non-visibility of posterior trabecular meshwork (PTM) and blotchy pigments (ranging from 1–4 quadrants), iris configuration, angle recess (sum of above depicting ACSS_g) and lens thickness/axial length ratio (LT/AL), cup disc ratio and baseline intraocular pressure (IOP) to give total score (ACSS_t).

Result

There were significant differences in ACSSg scores within the same ISGEO stage of PAC and PACG between eyes that required nil or >1medicines after laser iridotomy, p<0.001. The ACSSg was associated with need for >1 medicines in both PAC and PACG eyes, p<0.001. An ACSSg score>12 and 14 in PAC (odds ratio = 2.7(95% CI-1.7–5.9) and PACG (Odds ratio = 1.6(95%CI-1.19–2.2) predicted need for single medicines while ACSSg scores >14 and 19 predicted need for ≥2 medicines in PAC and PACG eyes, respectively. The LT/Al ratio, IOP score or cup disc score did not influence the need for medical treatment independently.

Conclusion

The ACSS can be a useful clinical adjunct to the ISGEO system to predict need for medicines and prognosticate each stage more accurately.

Uveal Effusion: Clinical Features, Management, and Visual Outcomes in a Retrospective Case Series

PURPOSE

To present the experience of a tertiary care ophthalmic institution in the assessment and management of uncommon causes of uveal effusion and related complications.

MATERIALS AND METHODS

A retrospective chart review was conducted of 12 patients diagnosed with uveal effusion and managed at our institution between 1996 and 2012. The presenting features, investigations, management, and outcomes were analyzed for each case.

RESULTS

The case series encompasses a variety of clinical conditions that cause uveal effusion including inflammatory, hydrostatic, and idiopathic mechanisms. Two thirds of the patients presented with secondary angle closure. Half of the patients had serous retinal detachment. Modern imaging techniques including ultrasound biomicroscopy and high-resolution magnetic resonance imaging were critical in making the diagnosis. Seven of the 12 patients responded to medical treatment and 4 required scleral surgery. Uveal effusions resolved in all patients after treatment.

CONCLUSIONS

Uveal effusion is a complex and poorly understood clinical entity with significant visual morbidity and is caused by a range of ocular and systemic diseases. Effective management is critically dependent on the underlying cause.

Evaluation of the efficacy of laser peripheral iridoplasty in reversing the darkroom provocative test result in Chinese patients with primary angle closure status post laser iridotomy

AIM

To investigate the efficacy and safety of krypton laser peripheral iridoplasty (LPIP) for Chinese patients with primary angle closure (PAC) or primary angle-closure glaucoma (PACG) status post laser iridotomy in reversing the positive results of the dark room provocative test (DRPT).

METHODS

This study was prospective, noncomparative, interventional case series. Thirty-three patients (thirty-eight eyes) with PAC or PACG status post patent laser iridotomy and maintained normal intraocular pressure (IOP) but with positive DRPT results were enrolled. All the subjects were treated with krypton LPIP. DRPT was repeated after krypton LPIP. Results of DRPT were recorded. The visual acuity, IOP and gonioscopy were analyzed before and after krypton LPIP. A minimum time limit for follow-up was 6mo.

RESULTS

Thirty-three patients (thirty-eight eyes) were followed for 17.7±8.37mo (range 7-41mo) after LPIP. Positive results of DRPT decreased from 38 eyes to 9 eyes (23.7%) after LPIP. Peripheral anterior synechiae of angle in 34 of 38 eyes (89.5%) remained unchanged at dynamic gonioscopy throughout the follow-up period after LPIP.

CONCLUSION

LPIP decreased positive rates of the DRPT significantly. The mechanism may be that LPIP minimized contact between the peripheral iris and trabecular meshwork, which is a key factor for developing peripheral anterior synechiae.

Unilateral angle-closure glaucoma with ciliochoroidal effusion after the consumption of cannabis: a case report

A 35-year-old male patient, diagnosed with acute angle-closure glaucoma, did not improve despite intensive treatment with antiglaucoma medications. Ultrasound biomicroscopy revealed a ciliochoroidal effusion. Due to his past history of drug abuse, a urine test was analyzed and found to be positive for cannabis. After topical cycloplegia and oral steroid therapy, his symptoms improved substantially. The present case highlights the role of ultrasound biomicroscopy in evaluating patients with acute angle-closure glaucoma and the role of cannabis abuse in the development of ciliochoroidal effusion.

Understanding the causation of primary angle closure disease using the sufficient component cause model

BACKGROUND

Several risk factors have been associated with primary angle closure disease, but their actual role in causation of an individual case is not clear.

DESIGN

Concept paper.

PARTICIPANTS/SAMPLES

No patient participation.

METHODS

The sufficient component cause model is briefly explained in the context of primary angle closure disease. The framework is used to conceptualize the role of individual mechanisms of disease. The possibility of personalized treatment for primary angle closure disease is discussed in this context.

MAIN OUTCOME MEASURES

Qualitative concepts in disease causality may refine research and treatment in primary angle closure disease.

RESULTS

The minimum set of conditions that are sufficient for primary angle closure disease to occur is considered the sufficient component cause model for that individual case. Described risk factors (including genes) as well as currently unknown influences play a role in the model. There may be many such models and all complementary components in any sufficient-cause model must be present for disease to occur. Interruption of any one component in that model can be used for treatment. Pupillary block is likely a component of most such models and may currently be considered a universally necessary component of these models.

CONCLUSIONS

The sufficient component cause model can be used as a framework to explain the role of individual mechanisms of causation and treatment of primary angle closure disease. It also aids understanding of the proportion of disease due to specific causes.

Increased iris-lens contact following spontaneous blinking: mathematical modeling

The purpose of this work was to study in silico how iris root rotation due to spontaneous blinking alters the iris contour. An axisymmetric finite-element model of the anterior segment was developed that included changes in the iris contour and the aqueous humor flow. The model geometry was based on average values of ocular dimensions. Blinking was modeled by rotating the iris root posteriorly and returning it back to the anterior. Simulations with maximum rotations of 2°, 4°, 6°, and 8° were performed. The iris-lens contact distance and the pressure difference between the posterior and anterior chambers were calculated. When the peak iris root rotation was 2°, the maximum iris-lens contact increased gradually from 0.28 to 0.34mm within eight blinks. When the iris root was rotated by 6° and 8°, the pressure difference between the posterior and anterior chambers dropped from a positive value (1.23Pa) to negative values (-0.86 and -1.93Pa) indicating the presence of reverse pupillary block. Apparent iris-lens contact increased with steady blinking, and the increase became more pronounced as posterior rotation increased. We conclude that repeated iris root rotation caused by blinking could maintain the iris in a posterior position under normal circumstances, which would then lead to the clinically observed anterior drift of the iris when blinking is prevented.

Non-steroidal drug-induced glaucoma

Numerous systemically used drugs are involved in drug-induced glaucoma. Most reported cases of non-steroidal drug-induced glaucoma are closed-angle glaucoma (CAG). Indeed, many routinely used drugs that have sympathomimetic or parasympatholytic properties can cause pupillary block CAG in individuals with narrow iridocorneal angle. The resulting acute glaucoma occurs much more commonly unilaterally and only rarely bilaterally. CAG secondary to sulfa drugs is a bilateral non-pupillary block type and is due to forward movement of iris-lens diaphragm, which occurs in individuals with narrow or open iridocorneal angle. A few agents, including antineoplastics, may induce open-angle glaucoma. In conclusion, the majority of cases with glaucoma secondary to non-steroidal medications are of the pupillary block closed-angle type and preventable if the at-risk patients are recognized and treated prophylactically.

Disruption of the podosome adaptor protein TKS4 (SH3PXD2B) causes the skeletal dysplasia, eye, and cardiac abnormalities of Frank-Ter Haar Syndrome

Frank-Ter Haar syndrome (FTHS), also known as Ter Haar syndrome, is an autosomal-recessive disorder characterized by skeletal, cardiovascular, and eye abnormalities, such as increased intraocular pressure, prominent eyes, and hypertelorism. We have conducted homozygosity mapping on patients representing 12 FTHS families. A locus on chromosome 5q35.1 was identified for which patients from nine families shared homozygosity. For one family, a homozygous deletion mapped exactly to the smallest region of overlapping homozygosity, which contains a single gene, SH3PXD2B. This gene encodes the TKS4 protein, a phox homology (PX) and Src homology 3 (SH3) domain-containing adaptor protein and Src substrate. This protein was recently shown to be involved in the formation of actin-rich membrane protrusions called podosomes or invadopodia, which coordinate pericellular proteolysis with cell migration. Mice lacking Tks4 also showed pronounced skeletal, eye, and cardiac abnormalities and phenocopied the majority of the defects associated with FTHS. These findings establish a role for TKS4 in FTHS and embryonic development. Mutation analysis revealed five different homozygous mutations in SH3PXD2B in seven FTHS families. No SH3PXD2B mutations were detected in six other FTHS families, demonstrating the genetic heterogeneity of this condition. Interestingly however, dermal fibroblasts from one of the individuals without an SH3PXD2B mutation nevertheless expressed lower levels of the TKS4 protein, suggesting a common mechanism underlying disease causation.

Glaucoma screening: current trends, economic issues, technology, and challenges

PURPOSE OF REVIEW

Glaucoma is one of the leading causes of irreversible blindness worldwide. Early glaucoma detection and treatment are currently the only known methods for preventing blindness and low vision resulting from this frequently asymptomatic disease.

RECENT FINDINGS

New technologies for detecting early glaucomatous damage are important in diagnosing optic nerve disease, not only in community screening settings but also in clinics. Imaging of the optic nerve head and macula and retinal nerve fiber layer analysis can provide quick, automated, and quantitative measurements in agreement with clinical estimates of optic disc structure and visual function. In the area of perimetry, frequency-doubling technology is a promising and feasible mass-screening method with reasonable sensitivity for detecting visual field loss. Central corneal thickness has emerged as a new risk factor for the development and progression of glaucoma, thereby complicating the role of tonometry and measurement of intraocular pressure as screening parameters for glaucoma. Along with technological advances, strides are also being made with public policy and legislative efforts to bring glaucoma onto the national and global health care agenda. These initiatives incorporate vision-screening goals into national disease prevention programs emphasizing the need for early glaucoma detection and treatment.

SUMMARY

Glaucoma awareness needs to be increased through better education, and compliance with follow-up care needs to be improved to decrease the economic and social costs from glaucoma. In addition, screening models need to be developed that will be effective in developing countries where the risk of blindness from glaucoma is highest.

Phacoemulsification and intraocular lens implantation for acute angle closure not treated or previously treated by laser iridotomy

PURPOSE

To determine the effect of phacoemulsification, aspiration, and intraocular lens (IOL) implantation in eyes with acute angle closure or eyes with prior laser iridotomy for acute angle closure.

SETTING

Department of Ophthalmology, Oita Prefectural Hospital, Oita, Japan.

METHODS

Eighteen eyes with acute angle closure and 8 eyes with cataracts that had a prior acute angle closure treated by laser iridotomy had phacoemulsification, aspiration, and IOL. A third group that had phacoemulsification, aspiration, and IOL for cataracts only served as controls. The preoperative and postoperative intraocular pressures (IOPs), visual acuities, and number of antiglaucoma medications were compared between these 3 groups.

RESULTS

The mean IOPs in the eyes with phacoemulsification, aspiration, and IOL alone and the eyes with prior acute angle closure treated by laser iridotomy were decreased significantly after phacoemulsification, aspiration, and IOL. The mean IOPs in the control group also decreased, but not significantly. There was no significant difference in the postoperative IOP between the 3 groups. The postoperative visual acuities were improved significantly in the 3 groups, and the differences in the final visual acuities were not significant. Postoperatively, the antiglaucoma medication was not needed in the phacoemulsification, aspiration, and IOL-alone group, but medication was necessary in eyes treated previously with laser iridotomy.

CONCLUSION

Phacoemulsification with IOL implantation lowered IOP, improved visual acuity, and diminished the need for antiglaucoma medication in eyes with acute angle closure and with a prior acute angle closure treated by laser iridotomy.