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

The application of artificial intelligence in glaucoma diagnosis and prediction

Artificial intelligence is a multidisciplinary and collaborative science, the ability of deep learning for image feature extraction and processing gives it a unique advantage in dealing with problems in ophthalmology. The deep learning system can assist ophthalmologists in diagnosing characteristic fundus lesions in glaucoma, such as retinal nerve fiber layer defects, optic nerve head damage, optic disc hemorrhage, etc. Early detection of these lesions can help delay structural damage, protect visual function, and reduce visual field damage. The development of deep learning led to the emergence of deep convolutional neural networks, which are pushing the integration of artificial intelligence with testing devices such as visual field meters, fundus imaging and optical coherence tomography to drive more rapid advances in clinical glaucoma diagnosis and prediction techniques. This article details advances in artificial intelligence combined with visual field, fundus photography, and optical coherence tomography in the field of glaucoma diagnosis and prediction, some of which are familiar and some not widely known. Then it further explores the challenges at this stage and the prospects for future clinical applications. In the future, the deep cooperation between artificial intelligence and medical technology will make the datasets and clinical application rules more standardized, and glaucoma diagnosis and prediction tools will be simplified in a single direction, which will benefit multiple ethnic groups.

Opportunistic Eye Screening Among First-Degree Relatives of Glaucoma Patients at a Suburban Tertiary Center in Malaysia

Background and objective

The majority of glaucoma patients are asymptomatic and are usually diagnosed at an advanced stage of the disease. This study aimed to assess the outcomes of glaucoma screening among known first-degree relatives of primary glaucoma patients.

Materials and methods

This study involved primary angle-closure glaucoma (PACG), primary open-angle glaucoma (POAG), and juvenile open-angle glaucoma (JOAG) patients who attended the glaucoma clinic at the Hospital Universiti Sains Malaysia between January 2014 and December 2015. First-degree relatives of the patients underwent a preliminary eye-screening evaluation, including visual acuity (Snellen chart), intraocular pressure (IOP) measurement (air-puff tonometry), and non-mydriatic fundus photography. Patients with visual acuity worse than 6/12, IOP measuring more than 21 mmHg or a difference of more than 3 mmHg between the eyes, and a vertical cup-disc ratio (VCDR) of 0.7 or higher were given a comprehensive eye examination.

Results

Seventy indexed glaucoma patients were recognized, and 368 first-degree relatives were identified. Forty-five relatives underwent the preliminary screening. Of these, 29 showed normal findings (62%), one had corneal pathology (2%), and 16 (36%) underwent a complete eye examination after failing the initial screening. Among the indexed JOAG group, five relatives (11%) were diagnosed as having JOAG; two were treated medically, while the remaining three required surgical intervention.

Conclusion

Opportunistic glaucoma screening of high-risk groups, especially JOAG is a feasible and cost-effective way to detect early glaucoma and prevent irreversible blindness. However, improvement in our healthcare system, including the involvement of multicentre clinics in other states in screening initiatives, is required to promote and facilitate the response to screening opportunities.

The Role of Artificial Intelligence in the Diagnosis and Management of Glaucoma

Glaucomatous optic neuropathy is the leading cause of irreversible blindness worldwide. Diagnosis and monitoring of disease involves integrating information from the clinical examination with subjective data from visual field testing and objective biometric data that includes pachymetry, corneal hysteresis, and optic nerve and retinal imaging. This intricate process is further complicated by the lack of clear definitions for the presence and progression of glaucomatous optic neuropathy, which makes it vulnerable to clinician interpretation error. Artificial intelligence (AI) and AI-enabled workflows have been proposed as a plausible solution. Applications derived from this field of computer science can improve the quality and robustness of insights obtained from clinical data that can enhance the clinician's approach to patient care. This review clarifies key terms and concepts used in AI literature, discusses the current advances of AI in glaucoma, elucidates the clinical advantages and challenges to implementing this technology, and highlights potential future applications.

Measures of disease activity in glaucoma

Glaucoma is the leading cause of irreversible blindness globally which significantly affects the quality of life and has a substantial economic impact. Effective detective methods are necessary to identify glaucoma as early as possible. Regular eye examinations are important for detecting the disease early and preventing deterioration of vision and quality of life. Current methods of measuring disease activity are powerful in describing the functional and structural changes in glaucomatous eyes. However, there is still a need for a novel tool to detect glaucoma earlier and more accurately. Tear fluid biomarker analysis and new imaging technology provide novel surrogate endpoints of glaucoma. Artificial intelligence is a post-diagnostic tool that can analyse ophthalmic test results. A detail review of currently used clinical tests in glaucoma include intraocular pressure test, visual field test and optical coherence tomography are presented. The advanced technologies for glaucoma measurement which can identify specific disease characteristics, as well as the mechanism, performance and future perspectives of these devices are highlighted. Applications of AI in diagnosis and prediction in glaucoma are mentioned. With the development in imaging tools, sensor technologies and artificial intelligence, diagnostic evaluation of glaucoma must assess more variables to facilitate earlier diagnosis and management in the future.

Aspects of Tertiary Prevention in Patients with Primary Open Angle Glaucoma

The purpose of the study is to assess the health of patients in the activity of tertiary prevention dedicated to preventing blindness caused by POAG (primary glaucoma with open angle and high tension) and NTG (primary glaucoma with open-angle and statistically normal tension-particular form of glaucoma with open angle) and preservation of the remaining visual function. The design of the study is epidemiological, observational, descriptive and retrospective, and uses only the data recorded in the existing records in the archives of the Ophthalmology office within the Integrated Outpatient Clinic of the Emergency Clinical Hospital of Oradea (IOCECHO) during the years 1999-2019 (anamnestic data; objective examination and paraclinical examination: intraocular pressure-IOP and visual field-VF). The methods of the study included the standardized protocol: anamnesis, physical ophthalmological examination, IOP determination, and computerized perimetry with the "Fast Threshold" strategy performed with the "Opto AP-300" perimeter. The obtained results were statistically processed with a specialized software (S.P.S.S.-I.B.M. Statistics version 22). The study examined the available data of 522 patients of which 140 were men (26.8%) and 382 were women (73.2%). The gender ratio was 0.37. In the period 1999-2019, 150,844 people with ophthalmic pathology were consulted in the Ophthalmology office of IOCECHO out of which 522 patients (0.35%) were diagnosed with primitive open-angle glaucoma, 184 people (35.2%) presented high IOP (POAG), and 338 people (64.8%) had statistically normal IOP (NTG). The annual proportion of cases diagnosed with glaucoma in the total number of patients examined was between 0.1% (2005; 2008; 2010) and 2.4% in 2012, when 101 people were detected. In the studied records, no cases of uni- and/or bilateral blindness were mentioned. The mean age of glaucoma patients at the first consultation was 60.81 ± 12.14 years with high frequencies in the 55-69 age groups and at the last consultation it was 66.10 ± 12.47 years with high frequencies in the age groups between 60-74 years. Monitoring and treatment of glaucoma patients was beneficial; IOP decreased statistically significantly: in patients with POAG by 46.16%, from 30.50 ± 7.98 mmHg to 16.42 ± 3.01 mmHg (p = 0.000) and in those with NTG by 17.44%, at 16.39 ± 3.66 mmHg at 13.53 ± 1.92 mmHG (p = 0.000). The duration of treatment and monitoring was on average 5.1 ± 3.4 years, for 184 patients (35.2%) with POAG and 5.1 ± 3.8 years for 338 patients (64.8%) with NTG. Tertiary prevention of glaucoma, by providing specialized care, ensures effective control of IOP and implicitly of the long-term evolution of the disease. IOP is the only modifiable risk factor in patients with POAG and NTG and its decrease prevents the progression of the disease and emphasizes the importance of early diagnosis and treatment. The management of the glaucoma patient consisted of: complete ophthalmological examination (subjective and objective), paraclinical examination with IOP, and VF measurement (valuable ophthalmological diagnostic tool) for disease detection and effective assessment of disease progression in order to improve the process of therapeutic decision making.

Comparison of vertical cup-to-disc ratio estimates using stereoscopic and monoscopic cameras

BACKGROUND

The use of monoscopic cameras for glaucoma screening is increasing due to their portability, lower cost, and non-mydriatic capabilities. However, it is important to compare the accuracy of such devices with stereoscopic cameras that are used clinically and are considered the gold standard in optic disc assessment. The aim of this study is to compare vertical cup-to-disc ratio (VCDR) estimates obtained using images taken with a monoscopic and stereoscopic camera.

METHODS

Participants were selected from the Tema Eye Survey. Eligible subjects had images of at least one eye taken with two cameras. They were classified as meeting the glaucoma threshold if an eye had a VCDR estimate >97.5th percentile, corresponding to >0.725 for this population. Hence, we used 0.725 as the cutoff to group eyes into two categories: positive and negative. We calculated sensitivity, specificity, and predictive values of VCDR assessed by expert readers at a reading center for monoscopic photos using stereoscopic photos as the gold standard.

RESULTS

Three hundred and seventy-nine eyes of 206 participants were included in the study. Most participants were female (60.2%) and the most common age group was 50-59 years (36.4%). Sixteen eyes met the glaucoma threshold (VCDR > 0.725). Of these, the VCDR estimates of 14 eyes (87.5%) disagreed on the glaucoma threshold from the two cameras. The sensitivity to detect glaucoma with the monoscopic camera was 14.3% (95% CI: 4.0, 40.3).

CONCLUSIONS

The low sensitivity of monoscopic photos suggests that stereoscopic photos are more useful in the diagnosis of glaucoma.

Comparison of Outcomes of Glaucoma Screening in Primary Care and Community Settings

Purpose: To compare outcomes of glaucoma screening in primary care and community settings, including the follow-up rates of subjects with positive screening results. Methods: This was a comparative, prospective, non-randomized study. Subjects were recruited by medical students in community-based and primary care settings and screened for glaucoma using the same screening strategy. Results: Two hundred and fifteen total patients were screened, 117 in community settings and 98 in primary care settings. Positive screenings were seen in 34% of patients in the community setting group (n = 40) and 40% of patients in the primary care setting group (n = 39). Of the patients who screened positive, 74% completed their initial follow-up appointment in the primary care setting group compared with 47.5% in the community-based setting group (p = .015). In the primary care setting, 18% were lost to follow up compared with 42.5% in the community-setting (P = .018). African-Americans were more likely to follow-up (P = .025) and less likely to be lost to follow-up (P = .033) in the primary care setting compared with the community-based setting. Conclusion: Patients with a positive glaucoma screening result in a primary care setting are more likely to follow up than those in a community-based setting.

Cost-effectiveness of glaucoma screening in cataract camps versus opportunistic and passive screening in urban India: A study protocol

India has an estimated 12 million people affected with glaucoma; however, no organised screening programme exists. Cases are usually detected opportunistically. This study documents the protocol for detecting glaucoma in suspects in cataract camps conducted by Shroff Charity Eye Hospital in North India. We report a cost-effectiveness alongside prospective study design of patients attending cataract camps where glaucoma screening will be integrated. The eligible population for glaucoma screening is non-cataract patients. Patients will undergo glaucoma screening by a trained optometrist using a pre-determined glaucoma screening algorithm. Specific diagnostic cut-off points will be used to identify glaucoma suspects. Suspected patients will be referred to the main hospital for confirmatory diagnosis and treatment. This group will be compared to a cohort of patients arriving from cataract camps conducted by the institute in similar areas and undergoing examination in the hospital. The third arm of the study includes patients arriving directly to the hospital for the first time. Cost data will be captured from both the screening components of cataract-only and glaucoma screening-integrated camps for screening invitation and screening costs. For all three arms, examination and treatment costs will be captured using bottom-up costing methods at the hospital. Detection rates will be calculated by dividing the number of new cases identified during the study by total number of cases examined. Median, average and range of costs across the three arms will be calculated for cost comparisons. Finally, cost-effectiveness analysis will be conducted comparing cost per case detected across the three arms from a quasi-societal perspective with a time horizon of 1 year . Ethics approval for the study has been obtained from the institutional ethics committee of the hospital. The study protocol will be useful for researchers and practitioners for conducting similar economic evaluation studies in their context.

Prevalence of Primary Glaucoma as Diagnosed by Study Optometrists of L. V. Prasad eye Institute - Glaucoma Epidemiology and Molecular Genetics Study

PURPOSE

To report the prevalence of primary glaucoma as identified by study optometrists of the L. V. Prasad Eye Institute - Glaucoma Epidemiology and Molecular Genetics Study (LVPEI-GLEAMS).

METHODS

Two study optometrists and a total number of 3833 individuals participated in the LVPEI-GLEAMS. All subjects underwent a complete medical history and comprehensive eye examination including slit lamp photography, imaging of anterior and posterior segment, frequency doubling technology and standard automated perimetry including gonioscopy with a Sussman 4 mirror goniolens, post dilated evaluation of the optic disc and fundus was done with a 90 D lens by the study optometrist. A diagnosis of primary open angle glaucoma (POAG), primary angle closure suspect (PACS), primary angle closure (PAC), primary angle closure glaucoma (PACG), normal tension glaucoma (NTG), glaucoma/disc suspect or no glaucoma was made based on the clinical examination.

RESULTS

Estimated prevalence of OAG (POAG and NTG) was 1.07% (0.74-1.39), PACS 2.03% (1.58-2.48), PAC 1.77% (1.35-2.19), PACG 0.21% (0.06-0.35) as identified by the study optometrists on site.

CONCLUSIONS

Prevalence of all the categories of primary glaucoma, as reported by the study optometrists of LVPEI-GLEAMS was comparable to previous findings of other regions in South India.

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.

Predictive role of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in normal-tension glaucoma

As a type of primary open-angle glaucoma, normal-tension glaucoma (NTG) is a health problem that manifests itself with low intraocular pressure (IOP) levels and preserves its importance for public health care. In population-based screenings, which take the IOP levels of 21mmHg as a cut-off for the diagnosis of glaucoma, the diagnosis is usually delayed, and the treatment is started in an advanced stage by the referred ophthalmologists. NTG is associated with some autoimmune conditions and systemic diseases, such as paraproteinemia, nocturnal hypotension, and migraine. Recently, a simple and cheap test (namely the hemogram) was defined as measure of systemic inflammation, measuring the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR). A recent study displayed an altered platelet function in NTG patients. We hypothesize that an automated hemogram analysis for NLR together with IOP measurements may be used to screen NTG patients who are admitted to primary care clinics if any relationship between NTG and NLR could be demonstrated in future researches.

Efficacy of automated computer-aided diagnosis of retinal nerve fibre layer defects in healthcare screening

BACKGROUND/AIMS

To evaluate the efficacy of a new automatic computer-aided detection (CAD) system for mass screening of retinal nerve fibre layer (RNFL) defects in a large population using fundus photographs.

METHODS

Among the fundus photographs of 1200 consecutive subjects who visited a healthcare centre, a total of 2270 photographs appropriate for analysis were tested. The photographs were first reviewed by two expert ophthalmologists for detection of RNFL defects (gold standard manual detection). The images were then analysed using an automatic CAD system for detecting RNFL defects in various cases of glaucomatous and non-glaucomatous optic neuropathy. A free-response receiver operating characteristics curve was generated to evaluate the validity of the CAD system. The results of the automatic detection were compared with those of manual detection, and sensitivity and specificity of the CAD system were calculated.

RESULTS

In manual detection of 2270 photographs, 41 RNFL defects from 36 photographs (1.6%) were detected, and no RNFL defects were found in 2234 photographs (98.4%). The sensitivity of the CAD system for detecting RNFL defects was 90.2% (37/41 RNFL defects) and the specificity was 72.5% (1620/2234 photographs with no RNFL defects) at a false-positive rate of 0.36 per image.

CONCLUSIONS

The new CAD system successfully detected RNFL defects during mass screening of fundus photographs in a large population who visited a healthcare centre. The proposed algorithm can be useful for clinicians in screening RNFL defects in healthcare centres. The false-positive rate is still unsatisfactory, although improved compared with the previous study. Further studies are needed to enhance the speed and specificity of image analysis using the CAD system.

Is Prevention of Glaucoma Possible in Bosnia and Herzegovina?

Introduction:

Glaucoma is the second leading cause of blindness in the world and represents a significant social and health problem. Early detection of glaucoma enables early initiation of treatment and may delay disease progression. The aim of this work is to determine whether it is possible to detect glaucoma in early stages.

Methods:

A public awareness campaign was carried out in University Clinic Center (UCC) in Tuzla, Bosnia and Herzegovina (B&H) during 2012, 2013, 2014 and 2015 Glaucoma Week, with one-day, free of charge screening of individuals. This screening program was composed of getting brief medical history, slit-lamp examination including intraocular pressure and anterior chamber dept evaluation and non-mydriatic fundus exam with evaluation of the cup/disk ration.

Results:

A total of 682 individuals were screened, 277 were male and 405 were female. The youngest individual was 8 years old and the oldest individual was 84 years old. The mean age was 57.6 years. Intraocular pressure higher then 21,9 mmHg was found in 83 patients.

Conclusion:

Glaucoma is a disease that affects visual acuity and gradually leads to blindness. It occurs in all age groups in both sexes and in all races. Early detection of disease and proper treatment can prevent permanent loss of vision. Detection and early treatment of glaucoma must become one of the leading public health programs in B&H.

A comparative study on the efficacy, safety, and cost-effectiveness of bimatoprost/timolol and dorzolamide/timolol combinations in glaucoma patients

Aim:

This study was designed to compare the bimatoprost/timolol combination and dorzolamide/timolol combination in glaucoma for efficacy, safety, and cost-effectiveness in a local population of Trichy in the state of Tamilnadu.

Materials and Methods:

Eight-week, randomized, parallel group, open-label study was conducted on 48 patients of open angle glaucoma or ocular hypertension. After initial clinical assessment and baseline investigations, bimatoprost/timolol combination (Group A) was prescribed to 22 patients (2 patients lost after initial assessment) and dorzolamide/timolol combination (Group B) to 24 patients. The patients were reviewed after second and eighth weeks for cure rate and adverse drug reaction monitoring.

Results:

At the end of 8 weeks, the mean reduction in intraocular pressure from baseline was 13.04 mmHg (95% confidence interval (CI): 10.67–14.70) with bimatoprost/timolol combination once daily (P < 0.01) and 9.46 mmHg (95% CI: 7.47–10.5) with dorzolamide/timolol combination twice daily. Both the treatments were safe. Cost-effective range of bimatoprost/timolol combination was lower than that of dorzolamide/timolol combination.

Conclusion:

The fixed combination of bimatoprost/timolol was slightly more effective than that of dorzolamide/timolol combination in reducing IOP, and both treatments were generally well tolerated. Bimatoprost/timolol combination was more cost-effective (cost-effective analysis) than dorzolamide/timolol combination.

The role of advanced glycation end products in retinal ageing and disease

The retina is exposed to a lifetime of potentially damaging environmental and physiological factors that make the component cells exquisitely sensitive to age-related processes. Retinal ageing is complex and a raft of abnormalities can accumulate in all layers of the retina. Some of this pathology serves as a sinister preamble to serious conditions such as age-related macular degeneration (AMD) which remains the leading cause of irreversible blindness in the Western world. The formation of advanced glycation end products (AGEs) is a natural function of ageing but accumulation of these adducts also represents a key pathophysiological event in a range of important human diseases. AGEs act as mediators of neurodegeneration, induce irreversible changes in the extracellular matrix, vascular dysfunction and pro-inflammatory signalling. Since many cells and tissues of the eye are profoundly influenced by such processes, it is fitting that advanced glycation is now receiving considerable attention as a possible pathogenic factor in visual disorders. This review presents the current evidence for a pathogenic role for AGEs and activation of the receptor for AGEs (RAGE) in initiation and progression of retinal disease. It draws upon the clinical and experimental literature and highlights the opportunities for further research that would definitively establish these adducts as important instigators of retinal disease. The therapeutic potential for novel agents that can ameliorate AGE formation of attenuate RAGE signalling in the retina is also discussed.

Comparing Central Corneal Thickness in a Sub-Saharan Cohort to African Americans and Afro-Caribbeans

PURPOSE

To evaluate the central corneal thickness (CCT) of Africans in a glaucoma practice in a university teaching hospital in West Nigeria, Africa, and compare results with similar studies carried out in African American and Afro-Caribbean populations.

METHODS

CCT was measured by means of ultrasound pachymetry (pachymeter used was Micropach 200 P+ Pachymeter; Sonomed) in only African participants with either glaucomatous or healthy eyes. After instillation of topical anesthetic, 3 measurements of corneal thickness were taken, and the average thickness for each was calculated. The relationship between CCT and age was studied using correlation analyses and t tests. A total of 70 eyes were included for analysis.

RESULTS

The mean CCT of all participants was 532.00 microm. Glaucoma suspects and patients with glaucoma had corneas thinner than those of normal participants (527.36 and 536.91 microm, respectively); however, the difference was not significant (P = 0.296). Decreasing values of CCT were significantly related to older age (P = 0.002). Men had a significantly higher CCT than women (P = 0.035).

CONCLUSIONS

CCT values in African populations are less than those of whites. Decreasing values of CCT are significantly related to older age, and men have thicker corneas than women. There is a suggestion that CCT is lower in patients with glaucoma than in nonglaucomatous controls; however, the difference is not statistically significant. Comparing our results to other studies in literature, it seems that average CCT is similar between populations living in sub-Saharan Africa and African Americans and Afro-Caribbeans.

Telemedicine-friendly, portable tonometers: an evaluation for intraocular pressure screening

PURPOSE

To evaluate the intraocular pressure (IOP) readings from two portable, telemedicine-friendly tonometers for suitability in glaucoma screening.

METHODS

213 eyes of 107 consenting patients attending an eye clinic were tested with an I-care tonometer and a Pulsair-Easy Eye puff-air tonometer. Gold standard IOP was measured with a Goldmann applanation tonometer (GAT). Effect of central corneal thickness, anterior chamber depth and refractive errors on IOP measurements were also analysed.

RESULTS

The mean difference of IOP by GAT and both the portable tonometers was +/- 2.2 mmHg. The analysis indicates minimal difference between IOP readings of both the portable tonometers. The mean difference between two consecutive readings by I-care was 0.01 mmHg. Using 21 mmHg as a threshold for suspected glaucoma, both the portable digital tonometers reported a sensitivity of 38% and specificity of >95%. In the subjects studied, central corneal thickness had statistically significant influence on IOP measurements while refractive errors and anterior chamber depth had no significant influence on IOP measurements with any tonometry.

CONCLUSION

The IOP readings by both portable tonometers are comparable and were within clinically acceptable range from GAT. These portable tonometers are useful tools for IOP screening.