Gonioscopy findings and prevalence of occludable angles in a Burmese population: the Meiktila Eye Study

Applications of Artificial Intelligence and Deep Learning in Glaucoma

Diagnosis and detection of progression of glaucoma remains challenging. Artificial intelligence-based tools have the potential to improve and standardize the assessment of glaucoma but development of these algorithms is difficult given the multimodal and variable nature of the diagnosis. Currently, most algorithms are focused on a single imaging modality, specifically screening and diagnosis based on fundus photos or optical coherence tomography images. Use of anterior segment optical coherence tomography and goniophotographs is limited. The majority of algorithms designed for disease progression prediction are based on visual fields. No studies in our literature search assessed the use of artificial intelligence for treatment response prediction and no studies conducted prospective testing of their algorithms. Additional challenges to the development of artificial intelligence-based tools include scarcity of data and a lack of consensus in diagnostic criteria. Although research in the use of artificial intelligence for glaucoma is promising, additional work is needed to develop clinically usable tools.

Prevalence and risk factors for primary angle-closure disease spectrum: The Colombian glaucoma study

PURPOSE

To estimate the prevalence and risk factors associated with the primary angle-closure disease spectrum in participants of the Colombian Glaucoma Study.

METHODS

A cross-sectional study in subjects older than 50 years with a diagnosis of diabetes mellitus or/and systemic hypertension was conducted in Colombia to estimate glaucoma prevalence. This study included 1749 patients and classified them using gonioscopy into either open-angle or primary angle-closure disease spectrum groups. The patients in the primary angle-closure disease spectrum group were then subdivided into the following categories: primary angle-closure suspect, primary angle-closure, and primary angle-closure glaucoma. A logistic regression model was carried out to identify factors related to the primary angle-closure disease spectrum, including age, sex, height, and refraction.

RESULTS

The prevalence of primary angle-closure disease spectrum was 19.3% (338) (95% CI: 17.5-21.2). The prevalence of primary angle-closure suspect, primary angle-closure, and primary angle-closure glaucoma was 8.0% (140) (95% CI: 6.8-9.4), 10.1% (176) (95% CI: 8.7-11.6), and 1.2% (22) (95% CI: 0.8-1.9), respectively. In the multivariate analysis, advanced age (+80 years), female sex, and high hyperopia (p = 0.000, 0.021, and 0.001, respectively) were identified as independent factors related to the primary angle-closure disease spectrum.

CONCLUSION

A high prevalence of primary angle-closure disease spectrum was found in Colombian patients with a diagnosis of diabetes mellitus or/and systemic hypertension, especially primary angle-closure and primary angle-closure glaucoma. Age, female sex, and high hyperopia were identified as risk factors for the primary angle-closure disease spectrum.

The prevalence and break down of narrow anterior chamber angle pathology presenting to a general ophthalmology clinic

To approximate the breakdown of narrow anterior chamber angle conditions, on general ophthalmology clinics, in the predominantly white population of the South East Kent region in the United Kingdom.A review was done of all patients attending a secondary care ophthalmology general clinic over a 3-year period. Patients were assessed with: slitlamp biomicroscopy with indentation gonioscopy; SD optical coherence tomography, Humphrey visual field analyzer, and high frequency ultrasound and categorized into various narrow angle conditions. These were: narrow Van Herrick but open angle; primary narrow angle but nonoccludable; primary angle closure suspect; primary angle closure; chronic narrow angle glaucoma; plateau iris configuration; plateau iris syndrome, and phacomorphic narrow angle.A total of 14,520 patients were referred to the clinic, of those 10,491 attended and were analyzed. Six hundred seventy four (6.4%) of the patients had some form of narrow angle condition in at least 1 eye. The majority of these patients were at relative low risk of pathology such as nonoccludable narrow angles (359/53.3%) and narrow Van Herrick but open angles (93/13.8%). 8.8% of all the narrow angle patients had primary angle closure suspect or primary angle closure. Plateau iris pathology was seen in 68 (10.1%) of patients with 18 (26%) having confirmed plateau iris syndrome after peripheral iridotomy. Phacomorphic pathology was confirmed in 75 (11.1%) patients.Narrow angle patients form a significant proportion (6.4%) of those attending general ophthalmology clinic in the predominantly white population in the South East Kent Region of the United Kingdom. The majority of these (67.1%) are at a relatively low risk of developing acute or chronic angle closure glaucoma. Of the remaining patients 8.8% have primary angle closure suspect or primary angle closure and 2.9% have already progressed to chronic narrow angle closure glaucoma. Plateau iris pathology and phacomorphic glaucoma account for the remainder of the presentations.

Angle-closure assessment in anterior segment OCT images via deep learning

Precise characterization and analysis of anterior chamber angle (ACA) are of great importance in facilitating clinical examination and diagnosis of angle-closure disease. Currently, the gold standard for diagnostic angle assessment is observation of ACA by gonioscopy. However, gonioscopy requires direct contact between the gonioscope and patients' eye, which is uncomfortable for patients and may deform the ACA, leading to false results. To this end, in this paper, we explore a potential way for grading ACAs into open-, appositional- and synechial angles by Anterior Segment Optical Coherence Tomography (AS-OCT), rather than the conventional gonioscopic examination. The proposed classification schema can be beneficial to clinicians who seek to better understand the progression of the spectrum of angle-closure disease types, so as to further assist the assessment and required treatment at different stages of angle-closure disease. To be more specific, we first use an image alignment method to generate sequences of AS-OCT images. The ACA region is then localized automatically by segmenting an important biomarker - the iris - as this is a primary structural cue in identifying angle-closure disease. Finally, the AS-OCT images acquired in both dark and bright illumination conditions are fed into our Multi-Sequence Deep Network (MSDN) architecture, in which a convolutional neural network (CNN) module is applied to extract feature representations, and a novel ConvLSTM-TC module is employed to study the spatial state of these representations. In addition, a novel time-weighted cross-entropy loss (TC) is proposed to optimize the output of the ConvLSTM, and the extracted features are further aggregated for the purposes of classification. The proposed method is evaluated across 66 eyes, which include 1584 AS-OCT sequences, and a total of 16,896 images. The experimental results show that the proposed method outperforms existing state-of-the-art methods in applicability, effectiveness, and accuracy.

Deep learning algorithms to isolate and quantify the structures of the anterior segment in optical coherence tomography images

BACKGROUND/AIMS

Accurate isolation and quantification of intraocular dimensions in the anterior segment (AS) of the eye using optical coherence tomography (OCT) images is important in the diagnosis and treatment of many eye diseases, especially angle-closure glaucoma.

METHOD

In this study, we developed a deep convolutional neural network (DCNN) for the localisation of the scleral spur; moreover, we introduced an information-rich segmentation approach for this localisation problem. An ensemble of DCNNs for the segmentation of AS structures (iris, corneosclera shell adn anterior chamber) was developed. Based on the results of two previous processes, an algorithm to automatically quantify clinically important measurements were created. 200 images from 58 patients (100 eyes) were used for testing.

RESULTS

With limited training data, the DCNN was able to detect the scleral spur on unseen anterior segment optical coherence tomography (ASOCT) images as accurately as an experienced ophthalmologist on the given test dataset and simultaneously isolated the AS structures with a Dice coefficient of 95.7%. We then automatically extracted eight clinically relevant ASOCT measurements and proposed an automated quality check process that asserts the reliability of these measurements. When combined with an OCT machine capable of imaging multiple radial sections, the algorithms can provide a more complete objective assessment. The total segmentation and measurement time for a single scan is less than 2 s.

CONCLUSION

This is an essential step towards providing a robust automated framework for reliable quantification of ASOCT scans, for applications in the diagnosis and management of angle-closure glaucoma.

National and subnational prevalence and burden of glaucoma in China: A systematic analysis

Background

Glaucoma, the second leading cause of blindness, affects approximately 64.3 million individuals worldwide. In China, demographic ageing is in rapid progress. Yet detailed and up-to-date estimates of the scale of glaucoma are rare. We aimed to quantify and understand the prevalence and burden of glaucoma in China from 1990 to 2015, with projections until 2050.

Methods

For this systematic review and meta-analysis, we searched China National Knowledge Infrastructure (CNKI), Wanfang, Chinese Biomedicine Literature Database (CBM-SinoMed), PubMed, Embase and Medline using comprehensive search strategies to identify all relevant articles that have reported the prevalence of glaucoma in the general Chinese population. We used a multilevel mixed-effect meta-regression to estimate the prevalence rates of primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG), and a random-effects meta-analysis to pool the overall prevalence of secondary glaucoma. United Nations population data were used to estimate and project the number of people with glaucoma from 1990 to 2050. Univariable and multivariable meta-regressions were conducted to assess the association between the prevalence of POAG and PACG and relevant demographic and geographic factors. The national burden of POAG and PACG in the years 2000 and 2010 were distributed to six geographic regions accordingly.

Results

From 1990 to 2015, the prevalence of all glaucoma ranged from 2.59% (95% CI = 1.96-3.49) to 2.58% (95% CI = 1.94-3.47). For different subtypes of glaucoma, the overall prevalence of POAG ranged from 1.03% (95% CI = 0.67-1.58) in 1990 to 1.02% (95% CI = 0.67-1.57) in 2015, PACG from 1.41% (95% CI = 1.18-1.68) to 1.40% (95% CI = 1.17-1.68). The overall prevalence of secondary glaucoma was 0.15% (95% CI = 0.10-0.23) during this period. The number of people with all glaucoma in China was 5.92 million (95% CI = 4.47-7.97) in 1990, and 13.12 million (95% CI = 9.88-17.68) in 2015. This increasing trend was also witnessed in different subtypes of glaucoma. The number of people affected by POAG increased from 2.35 million (95% CI = 1.54-3.60) in 1990 to 5.22 million (95% CI = 3.40-7.98) in 2015, PACG from 3.22 million (95% CI = 2.70-3.84) to 7.14 million (95% CI = 5.97-8.53), and secondary glaucoma from 0.34 million (95% CI = 0.23-0.53) to 0.76 million (95% CI = 0.51-1.17). In 2015, more than half (54.42%) of the glaucoma cases were PACG, followed by POAG (39.79%) and secondary glaucoma (5.79%). By 2050, the number of all glaucoma cases in China will be 25.16 million (95% CI = 18.96-33.86). In the multivariable meta-regressions, the odds ratio (OR) for each decade's increase in age was 1.43 (95% CI = 1.33-1.55) for POAG, and 1.65 (95% CI = 1.51-1.80) for PACG; males were more likely to have POAG (OR 1.36, 95% CI = 1.17-1.59), but less likely to have PACG (OR 0.53, 95% CI = 0.46-0.60) compared with females. After adjustment of age and gender, people living in urban areas were more likely to have POAG compared with those in rural areas (OR 1.54, 95% CI = 1.02-2.35). People in Northeast China were at a higher risk (OR 1.77, 95% CI = 1.07-2.94) of having PACG than people in East China. Among the six regions, East China owed the most POAG and PACG cases, whereas Northwest China owed the least.

Conclusions

This systematic review and meta-analysis suggests a substantial burden of glaucoma in China, with great variances among the different age groups, genders, settings and geographic regions. With the dramatic ageing trend in the next three decades, the prevalence and burden of glaucoma will continue to increase. More elaborate epidemiological studies are needed to optimise public health strategies for mitigating this important health problem.

Proportion of undetected narrow angles or angle closure in cataract surgery referrals

OBJECTIVE

To determine the proportion of patients referred for cataract surgery consultation who had undetected narrow angles (primary angle closure suspect [PACS], primary angle closure [PAC], or primary angle closure glaucoma [PACG]).

DESIGN

Retrospective chart review.

PARTICIPANTS

Phakic patients referred by eye care providers (optometrists and ophthalmologists) to a tertiary centre for cataract management between July 1, 2010 and June 30, 2012 were identified and reviewed.

METHODS

Demographic, referral, and specialist assessment information, as well as biometric data, including anterior segment optical coherence tomography, were collected. Patients with undetected narrow angles were identified. Univariate tests and multivariable analyses were performed to determine risk factors for narrow angles or angle closure.

RESULTS

A total of 1229 patients were included. The mean patient age was 67.8 ± 13.0 years, 53.9% of patients were female, and 26.8% were Asian or South Asian. Of the sample population, 139 (11.3%) patients had PACS, 7 (0.6%) had PAC, and 12 (1.0%) had PACG. Overall, 158 (12.9%) patients had narrow angles or angle closure. Multivariable logistic regression using generalized estimating equations confirmed 3 independent predictors of PACS/angle closure: Asian race (odds ratio 2.82, p < 0.001), shorter axial length (AL) (odds ratio 1.25, p = 0.03), and smaller anterior chamber depth (ACD; odds ratio 33.3, p < 0.001). A patient of Asian race referred for cataract surgery with ACD <2.8 mm and AL <23 mm had a 52% probability of having PACS/angle closure (range 42%-62%) versus 3% if these 3 factors were not present.

CONCLUSIONS

Of patients referred for cataract surgery, 1.5% were found to have undetected narrow angles or angle closure, implying that gonioscopy may not be adequately performed in this patient population.

Prevalence of angle closure in siblings of patients with primary angle-closure glaucoma

PURPOSE

To determine the frequency of angle closure in siblings of patients with primary angle-closure glaucoma (PACG).

METHODS

In this cross-sectional observational study, siblings of consecutive patients with PACG underwent a comprehensive ophthalmologic examination, including slit-lamp biomicroscopy, measurement of intraocular pressure, stereoscopic optic nerve head examination, and dynamic gonioscopy. Ultrasonic pachymetry was obtained in all subjects; peripapillary retinal nerve fiber layer thickness measurement by optical coherence tomography and standard achromatic perimetry were performed in subjects with angle closure, categorized as primary angle-closure suspect (PACS), primary angle closure (PAC), and PACG, or any suspicion of glaucoma in the presence of open angles.

RESULTS

Overall, 95 siblings from 47 families with at least 1 subject affected with PACG participated in the evaluations; 55 (57.9%) individuals were categorized within the spectrum of angle closure, including 34 (35.8%) subjects with PACS, 7 (7.4%)individuals with PAC, and 14 (14.7%) cases of PACG. Nine (9.5%) individuals with open angles demonstrated other abnormal features, these included 3 (3.2%) subjects with suspicious discs, 5 (5.3%) cases of primary open-angle glaucoma, and 1 patient (1.1%) with normal-tension glaucoma. The remaining 31 individuals (32.6%) had no evidence of glaucoma.

CONCLUSIONS

Our findings indicate familial segregation of angle closure. Siblings of PACG patients are at high risk for the condition, such that two thirds of them demonstrate clinical findings related to glaucoma. These observations suggest a hereditary basis for angle closure; therefore, siblings of patients affected with angle closure should undergo targeted screening for glaucoma.

Angle closure in Caucasians--a pilot, general ophthalmology clinic-based study

PURPOSE

To assess the rate of clinically significant angle closure in a predominantly Caucasian, clinic-based population, and consequently find out whether gonioscopy should be included in the routine ophthalmic examination.

METHODS

Patients aged ≥40 years with hyperopia ≥1 D were consecutively recruited in a community general ophthalmology clinic. Detailed darkroom gonioscopy was done, and primary angle closure was diagnosed if there was iridotrabecular apposition >180 degrees not secondary to an identifiable ocular disorder. Biometric parameters were measured and compared between the eyes with and without angle closure.

RESULTS

Eighty-four eyes from 84 patients (aged 61.3±8.9 y) were enrolled. There were 52 female (62%) and 32 male. Fourteen patients (16.7%) were diagnosed with angle closure. A statistically significant difference was observed between the eyes with and without angle closure in mean axial length (22.07±0.72 vs. 22.61±0.97, P=0.028), anterior chamber depth (ACD) (2.45±0.33 vs. 2.89±0.32, P<0.001), and lens thickness (4.97±0.3 vs. 4.62±0.4, P=0.002). Degree of hyperopia was marginally significant (3.13±2.3 vs. 2.45±1.5, P=0.09). In a logistic regression model, only ACD remained statistically significantly different (P=0.016). We tested the ability of ACD to distinguish eyes with angle closure. The area under the receiver operating characteristic curve was 0.824; using a cutoff ACD value of 2.65 mm, sensitivity was 0.786 with a specificity of 0.812.

CONCLUSIONS

Clinically significant angle closure, mandating close follow-up or preventive procedures, may be more common in Caucasians than currently thought. We recommend that gonioscopy should be included in the routine ophthalmic examination of all adults with hyperopia.

The heritability and sibling risk of angle closure in Asians

PURPOSE

To describe the heritability and sibling risk for angle closure.

DESIGN

Prospective clinical study.

PARTICIPANTS

Probands with primary angle closure (PAC) and primary angle-closure glaucoma (PACG) and their first-degree relatives.

METHODS

One hundred probands with PAC and PACG and their first-degree relatives were examined prospectively. All subjects underwent an ophthalmic evaluation that included slit-lamp examination, optic disc evaluation, and gonioscopy. An angle was classified as narrow if the posterior (usually pigmented) trabecular meshwork could be seen for less than 180° of the angle circumference. The heritability of narrow angles was calculated by threshold models. The sibling recurrence and relative risk of having narrow angles compared with the general population was calculated using estimation of sibling genetic risk parameters, corrected for single ascertainment bias.

MAIN OUTCOME MEASURES

Heritability and sibling risk for narrow angles.

RESULTS

One hundred probands (consisting of 76 subjects with PACG and 24 with PAC) were examined together with 327 first-degree relatives. There were 76 female probands and 24 male probands. Of the first-degree relatives, 146 were male and 181 were female. Of the 327 first-degree relatives, 105 (32.1%) had narrow angles. The heritability of narrow angles was 58.8% overall, with the genetic variance being 2.30 and the phenotypic variance being 3.91. Of the 515 sibling pairs examined, 171 (33.1%) pairs had both siblings unaffected, 113 (21.9%) pairs had both siblings affected, 231 (45.0%) pairs had 1 sibling affected. The sibling recurrence risk for having narrow angles was 49% (95% confidence interval, 41.6%-56.8%), whereas the sibling relative risk for narrow angles was 7.57 (95% confidence interval, 6.41-8.74).

CONCLUSIONS

A high heritability of narrow angles of almost 60% was found. Siblings of Chinese patients with PAC or PACG have almost a 50% probability of having narrow angles and are more than 7 times more likely to have narrow angles than the general population.

High prevalence of narrow angles among Chinese-American glaucoma and glaucoma suspect patients

PURPOSE

To evaluate the prevalence of gonioscopically narrow angles in a Chinese-American population with glaucoma or glaucoma suspicion.

PATIENTS AND METHODS

Charts from all Chinese-American patients seen in a comprehensive ophthalmology clinic in the Chinatown district of San Francisco in 2002 were reviewed. One eye from each patient with glaucoma or glaucoma suspicion that met inclusion criteria was included (n=108). Data were collected for sex, age, race (self-declared), refraction (spherical equivalent), intraocular pressure, gonioscopy, and vertical cup-to-disk ratio.

RESULTS

Sixty percent (n=65) of Chinese-American eyes with glaucoma or glaucoma suspicion had gonioscopically narrow angles (Shaffer grade < or = 2 in 3 or more quadrants). Those with narrow angles were significantly older (P=0.004) than their open angle counterparts, but the 2 groups did not differ in terms of sex, refraction, intraocular pressure, or cup-to-disk ratio (all, P > or = 0.071). In a multivariate model including age, sex, and refraction as predictors of angle grade (open or narrow), only age was a significant predictor of angle grade (P=0.004).

CONCLUSIONS

A large proportion of Chinese-Americans in our study population with glaucoma or glaucoma suspicion had gonioscopically narrow angles. In multivariate analysis, patients with narrow angles were older than those with open angles but did not differ from them in terms of sex or refraction. Continued evaluation of angle closure glaucoma risk among Chinese-Americans is needed.

Causes of blindness in rural Myanmar (Burma): Mount Popa Taung-Kalat Blindness Prevention Project

Purpose

This study is a review of the major causes of visual impairment (VI) and severe visual impairment/blindness (SVI/BL) in Mount Popa Taung-Kalat, a rural region in Myanmar (Burma).

Methods

A review of our clinical records of consecutive patients attending clinics was conducted. Participants of all ages (n = 650) of the population of Mount Popa Taung-Kalat and villages in its vicinity underwent ophthalmic interview and a detailed dilated ocular evaluation by trained Australian ophthalmologists and ophthalmic nurses. This evaluation included anterior segment examination with a slit lamp, intraocular pressure recording, and direct or indirect ophthalmoscopy. VI and SVI/BL were defined by the World Health Organization (WHO) criteria.

Results

Six hundred fifty subjects were screened, with a mean age of 49.0 ± 20.6 years (range, 1–99). One hundred five patients (16.2%) were children (ages 1–18). Five hundred thirty-one eyes of the total 1,300 eyes (39.5%) had VI/SVI/BL, and 40 eyes of the children (38.1%) (average age 15.3 ± 13.3) had VI/SVI/BL. The leading causes of VI/SVI/BL were cataract with 288 cases (54.2%), glaucoma with 84 cases (15.8%), and corneal pathology with 78 cases (14.7%). Of all the VI/SVI/BL cases, 8.4% were preventable, 81.9% were treatable, and total of 90.5% were avoidable.

Conclusions

In the current study, cataracts were the major cause of blindness and visual impairment, and most of the ophthalmic pathology causing blindness is avoidable. These results highlight the lack of basic ophthalmologist eye care and optician resources in rural regions in Myanmar.

Prevention of primary angle-closure glaucoma in Asia

Focused research is needed to reduce the prevalence of glaucoma in Asia