The Tema Eye Survey (TES), an international effort carried out by investigators from the United Kingdom, United States, and Ghana, was undertaken because of the recognized scarcity of comprehensive eye disease information from Africa as a whole and no data from West Africa.

Gathering such data can help Ghana’s Ministry of Health plan for future eye care needs in the country and the region to correctly appropriate resources. 

Donald L. Budenz, MD, MPH, the Kittner Distinguished Professor and chairman of the Department of Ophthalmology at the University of North Carolina School of Medicine in Chapel Hill, and other investigators hypothesized that this region has the highest glaucoma prevalence in the world.



In large population-based studies, such as the Baltimore Eye Survey

 studies, glaucoma has been shown to pose a triple threat compared with other ethnic groups to individuals of African heritage with an increased prevalence, younger age of onset, and more severe disease course. 

Previous studies in East and South Africa

 have reported a lower prevalence of primary angle-closure glaucoma (POAG) compared with the North American studies.


The TES was randomly sampled, was population-based, and, importantly, did not rely on elevated IOP in its case definitions, Budenz said. 

Before the TES, only 1 glaucoma survey had been performed in East Africa, 2 in South Africa, and none in West Africa.

The primary goal of the TES was to determine the prevalence rates of blindness, visual disability, glaucoma, and other ocular diseases in adults in Tema, Ghana.

The survey included 5600 randomly sampled adults who were 40 years and older. The survey design required a random sampling of clusters of 400 to 600 individuals of voting age for a total of 30 to 40 clusters.

The investigators had to map the communities because of the absence of census data and used voting rolls to identify potential participants. 

The clusters were randomly selected, and field examinations were performed on 5600 participants. Individuals who failed the field examinations then underwent clinic evaluations. 

The criteria for a referral for a full dilated clinic examination were visual acuity below 20/40, 2 failures on frequency-doubling technology testing, IOP greater than 20 mm Hg, narrow chamber, and cup-to-disc ratio greater than 0.7. 

Glaucoma was defined according to the standard definition developed by Foster and colleagues,

Another challenge was that the local staff required training in all instrumentation, including the SITA Fast Humphrey VF Analyzer, because these evaluations had never been performed in this location.


Budenz reported that a census was done of 6806 individuals, and field examinations were performed on 5607 individuals (response rate, 82.2%). 

A total of 1869 failed the field examination, and 1538 underwent clinic examinations (response rate, 82.2%). 

The prevalence rate of glaucoma in this population was 6.5%. When the data were adjusted for age and gender, the total POAG prevalence rate increased to 6.8%.

“The glaucoma types identified were primarily POAG in 94.5%, chronic narrow-angle glaucoma in 2.5%, traumatic glaucoma in 1.9%, and others that included uveitic, mixed-mechanism, steroid-induced, and unspecified glaucoma in 1.1%,” he said, noting the absence of pseudoexfoliation glaucoma

A comparison of the total prevalence of POAG in this study population with the other studies showed that the prevalence was similar to rates reported from Barbados and St Lucia and almost double those found in East Africa, South Africa, and the US.

“We believe that the study population is very similar to the Caribbean populations in glaucoma prevalence, which is likely due to migration from West Africa to the Caribbean during the slave-trading years and lack of admixture,” Budenz said. “These populations are unique in the high prevalence of glaucoma.”

A noteworthy finding of the current study was that only approximately 3% of the patients identified with glaucoma were aware that they had the disease, which is in marked contrast with similar studies conducted in developed countries in which 50% of patients identified with glaucoma were aware they had the disease. 

The prevalence of undiagnosed glaucoma in the TES study was 97%.

was to identify the incidence of glaucoma and the rates of progression among the original patients after 10 years.

Investigators examined 1200 individuals who had tested normal previously using the same methods, and they also tried to reexamine the original 362 individuals in the clinic who had received a diagnosis of glaucoma.

The incidence per 100 individuals of OAG was 4.7 per year. When results
were compared with those of other studies with gender and age adjustment, the incidence rates of OAG in the TES survey and the Barbados Eye Study were “considerably higher.” 

The population in Ghana is severely underserved by medical professionals, Budenz said. There are only 53 ophthalmologists to provide care for 27 million individuals; in contrast, there is 1 ophthalmologist for every 10,000 individuals in the US.


“The next steps in this population are to improve case detection of glaucoma through screening, train eye care providers in sub-Saharan Africa
to diagnose and manage glaucoma, and find the best treatments for this population, which include selective laser trabeculoplasty, trabeculectomy with mitomycin C, glaucoma tube implants, and cyclophotocoagulation,” Budenz concluded. “We are not sure how medications fit into this algorithm, in that they are expensive and not sustainable in this population.” 

Read the Glaucoma 360: 2021 Highlights digital edition


This article was adapted from the Shaffer-Hetherington-Hoskins Lecture titled “Glaucoma at the Center of the Earth,” which Budenz delivered at the 25thannual Glaucoma Symposium of the Glaucoma Research Foundation. He has no financial interest in this subject matter. The second phase of TES was supported by a Shaffer Grant from the Glaucoma Research Foundation.



1. Tielsch JM, Sommer A, Katz J, Royall RM, Quigley HA, Javitt J. Racial variations in the prevalence of primary open-angle glaucoma. The Baltimore Eye Survey. 

2. Leske MC, Connell AM, Schachat AP, Hyman L. The Barbados Eye Study. Prevalence of open angle glaucoma. 

. 1994;112(6):821-829. doi:10.1001/archopht.1994.01090180121046

3. Mason RP, Kosoko O, Wilson R et al. National survey of the prevalence and risk factors of glaucoma in St. Lucia, West Indies. Part I. Prevalence findings. 

. 1989;96(9):1363-1368. doi:10.1016/s0161-6420(89)32708-4

4. Buhrmann RR, Quigley HA, Barron Y, West SK, Oliva MS, Mmbaga BB. Prevalence of glaucoma in a rural East African population. 

5. Rotchford AP, Kirwan JF, Muller MA, Johnson GJ, Roux P. Temba glaucoma study: a population based cross-sectional survey in urban South Africa. 

. 2003;110(2):376-382. doi:10.1016/S0161-6420(02)01568-3

6. Foster PJ, Buhrmann R, Quigley HA, Johnson GJ. The definition and classification of glaucoma in prevalence surveys.

. 2002; 86(2):238-242. doi:10.1136/bjo.86.2.238

7. Budenz DL, Barton K, Whiteside-de Vos J, et al. Prevalence of glaucoma in an urban West African population: the Tema Eye Survey. 

2013;131(5):651-658. doi:10.1001/jamaophthalmol.2013.1686

8. Mwanza JC, Tulenko SE, Barton K, et al. Eight-year incidence of open-angle glaucoma in the Tema Eye Survey. 

 2019;126(3):372-380. doi:10.1016/j.ophtha.2018.10.016

Articles

Region may have world’s highest rate, investigators say.

Survey sheds light on glaucoma prevalence in West Africa

Investigators from various companies described their diagnostic offerings at the Glaucoma Research Foundation’s 2021 New Horizons Forum. 

The advances, mostly centered on artificial intelligence (AI), are highlighted here.

PERG: Useful for detecting very early glaucoma damage


Pattern electroretinography (PERG) is being elevated to the next level, that is, out of the laboratory setting and into the clinic as a useful technology that can detect early metabolic changes, said Matthew Emmer, vice president of business development and clinical affairs, Diopsys Inc.

“The goal was to make PERG easier to use and less demanding for the physician and technicians, with testing times shorter than 1 minute per eye,” he said.

The company has developed reference ranges and reports that are easily interpretable. 

Trend graphs also have been developed, making PERG useful for objective, functional understanding of early disease dysfunction such as early retinal ganglion cell (RGC) dysfunction, Emmer explained.

Numerous studies have reported that PERG is very sensitive for detecting functional loss and provides a window of opportunity before apoptosis
occurs. 

PERG can detect decreased RGC function years before structural loss in glaucoma suspects and is more sensitive than optical coherence tomog­raphy for detecting dysfunction in affected cells before damage is irreversible in ocular hypertension.

PERG also can predict visual field loss and disease progression and monitor treatment efficacy.

Diopsys first introduced ERG sensors that facilitated the development of a grading system for the average patient pattern responses to stimuli. 

In the presence of early disease, the signal becomes less reproducible and markedly different from a normal sinus­oidal response. 

The grading system allows clinicians to assign a number to the degree of dysfunction detected by the sensors considering the response size, response speed, and reproducibility along with a reference range. 

A trend plot shows changes over time.

“All of this information precedes structural changes,” Emmer explained.

Recent investigations are indicating a strong correlation between PERG and the RGC count and between the PERG retinal vessel count and retinal vascular integrity, he pointed out. 

The company is releasing software that incorporates AI based on data from 800 patients; application of the data algorithm to a patient subset is showing better sensitivity and specificity.



Kaushal Solanki, PhD, CEO and founder of Eyenuk Inc, is dedicated to detecting glaucoma early to prevent vision loss.

Eyenuk is marketing an AI platform that can screen, diagnose, and monitor diseases based on ophthal­mic images. With imaging, AI can instant­ly
produce an actionable report without the need to dilate the majority of patients.

“A number of disease indications can be detected through this platform,” he emphasized.

Use of AI and automation are the only ways we can accomplish the goal of preventing vision loss, Solanki said.

The platform incorporates 3 components: EyeScreen, EyeArt, and EyeMark. 

EyeScreen is a human plus AI diagnostic service with which human graders review images as usual with AI performing a background check and flagging potential errors. 

EyeArt is autonomous AI that enables screening at the point of care without requiring a specialist. 

EyeMark is “superpower” AI that performs an analysis to detect abnormalities and longitudinal monitoring that detects and quantifies changes to create biomarkers that human experts cannot produce, he explained.

Thus far, Eyenuk has launched the platform targeting diabetic retinopathy; EyeScreen and EyeArt are launched and EyeMark will launch in 2021.

He reported that EyeArt is the first FDA-cleared autonomous AI technol­ogy for detecting more than mild diabetic retinopathy and vision-threatening diabetic retinopathy. 

Regarding glaucoma, EyeScreen and EyeArt are being marketed and EyeMark is under development.

“AI will play an instrumental role to enable timely detection and monitoring of glaucoma via EyeScreen, EyeArt, and EyeMark. Using this platform, we hope to significantly reduce vision loss from glaucoma,” Solanki concluded.


AI-driven platform for diagnostics and augmentation


Millions of patients worldwide have visual field (VF) defects and/or double vision from glaucoma, stroke, macular degeneration, diabetes, and retinitis pigmentosa. The current treatments do not restore vision and only provide visual aids.

Heru has developed a cloud-based AI platform combined with downloadable apps on augmented and virtual reality headsets to provide both autonomous vision diagnostics and personalized vision augmentation, according to Mohamed Abou Shousha, PhD, MD, MS, FRCS, CEO and founder, Heru, and associate professor, Bascom Palmer Eye Institute, Miami, Florida.

The company’s diagnostic suite includes the following downloadable apps: autonomous VF, autonomous strabismus, visual distortion, eye imaging, and remote eye examination.

The VF app, a registered medical device with the FDA, is self-administered, easy to use, portable, and cost-effective.

“One headset plus software performs multiple tests,” he said, explaining that the test uses patients’ natural interactions to light stimuli presented
in the glasses to allow the app to map and quantify the vision autonomously.

Telemedicine applications include VF, remote eye examination, and eye imaging capabilities; following testing, the results are sent to a portal for review.

The AI platform goes a step further by augmenting patient vision. In addition to diagnosing visual defects, the visual distortion and double vision can be corrected and the customized VF corrected and expanded based on the patient profile.

“The user’s vision is augmented and enhanced and the surrounding environment enhanced, providing increased safety and functionality to the patient,” Shousha said.

A clinical trial at Bascom Palmer that compared the Heru VF measurements with Humphrey VF showed the 2 are comparable in healthy and diseased eyes with excellent reproducibility.


Elina Ianchulev, MBA, chief business officer at KeepYourSight, described the company’s eye care platform for remote physiologic monitoring and telehealth.

Telehealth provides the opportunity for remote diagnosis and care management of chronic ocular diseases, which is important because 50% of glaucoma and diabetic retinopathy cases are diagnosed late, and in 50% of patients with age- related macular degeneration (AMD), treatment is late, she explained.

The KeepYourSight platform provides clinical applications to remotely assess optic nerve/macula/acuity function and, later in 2021, ocular motility, the ocular surface tear film, and others. 

The tests, all of which are software-based, can be self-administered on tablets, personal computers, and smartphones.

In addition to monitoring existing patients, this platform offers clinicians the opportunity to expand their practices through screening in the community and among friends and family and referring channels, Ianchulev said.


Ocutrx Vision Technologies is dedicated to providing augmented vision to
patients with AMD and low vision.

The Oculenz augmented reality technology uses pixel manipulation to allow ophthalmic patients to see around their scotoma, according to Linda Lam, MD, MBA, chief scientific and strategy officer.

The technology works by first mapping the scotoma during a VF test. Eye-tracking follows the patient’s gaze as the image and text are moving around the scotoma.

Data transmission to the clinician and telemedicine are also possible with this device, which facilitates following scotoma enlargement and possible disease progression and
earlier intervention.

In addition to remote care, Ocutrx developed the OR-Bot, which is useful in the operating room to address challenges with ergonomics, space constraints imposed by current surgical systems and digital cameras, and poor resolution and 3D glasses limitations. 

The instrument offers a virtual reality microscope, 3D mon­itor, and augmented reality headset. 

Investigators from various companies described their diagnostic offerings at the Glaucoma Research Foundation’s 2021 New Horizons Forum. 

New Horizons Forum: Diagnostic advances in glaucoma

 changed the world in many ways, notably in how physicians practice medicine. 

The need to social distance to prevent spread of the coronavirus provided the perfect moment for telemedicine to flourish, according to Terri-Diann Pickering, MD, a clinical instructor at California Pacific Medical Center and a member of the board of directors of the Glaucoma Research Foundation.

Before the virus arrived, the use of telemedicine was relatively limited to patients who lived in isolated areas far from medical centers. 

The technology provided remote monitoring that was facilitated by portable imaging devices.

Clearing hurdles to large scale telemedicine adoption

In ophthalmology, telemedicine has facilitated screening for diabetic retinopathy, corneal and external ocular diseases, and pediatric ophthalmology. 

Telecommunication also has facili­tated international collaborations among specialists and in develop-ing countries to cover rural patients. 

However, activity was limited before COVID-19. This changed in early 2020.

Li Wenliang, MD, was the first ophthalmologist to die from the virus in February 2020 after examining an infected patient with glaucoma. 

Roughly 5 weeks later the American Academy of Ophthalmology recommended postponing elective procedures and office visits. 

A public health emergency was declared soon after and telemedicine privacy requirements were waived in the United States. 



showed that ophthalmology lost more patient volume as the result of the pandemic than any other specialty,” Pickering reported.

This was the point at which ophthalmology practices went virtual, both to provide nonemergent patient care and peace of mind to patients and staff with social distancing. 

She pointed out that patient volume decreased by 97% for cataract care and 88% for glaucoma.

 

Overall, 81% of the ophthalmology volume was lost during March and April 2020 compared with the same period the previous year.


The areas in ophthalmology for which telemedicine is especially beneficial are for treating diabetic retinopathy, retinopathy of prematurity, and corneal and external disease. 

Pickering also said the technology is good for triaging because it can reduce the number of office visits and costs.

Unfortunately, telemedicine has been less helpful in glaucoma because of the difficulty in measuring IOP. “It is just not the same as an in-person examination,” she emphasized.

However, virtual examinations grew out of necessity, and the available technology was called into use. 

Pearls to educate patients about ocular telemedicine options



When conducting a virtual eye examination, physicians can use online charts to measure visual acuity. 

IOP can be measured using the iCare Home monitoring device, and the optic nerve head theoretically can be evaluated using mobile phones and adaptors; a Triggerfish contact lens sensor (Sensimed) is another potentially useful device for measuring IOP, although setting up this technology might be difficult for patients at home, she noted.

A low-tech visual field examination can be performed by showing patients how to perform confrontational visual fields. 

Phone and online apps, virtual reality headsets, and other devices such as the ForeseeHome (Notal Vision) and Eyecatcher (HP Inc) also are available. 

However, these devices may not detect early visual field loss. A pocket-sized fundus camera or a phone app with an adaptor can be used to evaluate the optic nerve head, but this requires dilation and an assistant.

Emerging opportunities — and risks — with telehealth in a pandemic

The GlobeChek Kiosk is a relatively new device that performs 11 tests in less than 10 minutes without need for dilation. 

"This was devised to help address the lack of a comprehensive eye examination, especially for patients with diabetes,” she said.


When the pandemic started, slit-lamp examinations were considered high-risk procedures for disease transmission, but now that is not the case. 

As Pickering explained, no severe ophthalmic-related outbreaks have occurred since masks and other protocols were put into place. 

As a result, use of telemedicine has decreased significantly or stopped altogether.

A survey conducted by Glaucoma Research Foundation found that most patients prefer to wait 6 weeks for an in-office appointment instead of a virtual office appointment in 2 weeks.

By June 2020, most practices had reopened and were resuming appointments, and telemedicine appointments decreased markedly. By October, outpatient visits had returned to baseline.

COVID-19 creates disruption, opportunity for ophthalmology


Pickering remarked that in the future, physicians will need readily available hardware. 

That list could include wireless or easy-to-use implantable IOP sensors; smart contact lenses; the ability to perform imaging of the angle; online or app-based visual field testing; a home visual field device; and a handheld, portable optical coherence tomography scanner for optic nerve evaluation.

According to Pickering, teleglaucoma is here to stay because of the concept of crisis readiness.

“Advances in technology will help to improve accuracy and diagnosis,” Pickering concluded. “The expansion
of medical and nonmedical use of online programs due to COVID-19 will increase patient and physician acceptance.” 

tp@glaucomasf.com
Pickering is a consultant to Aerie.

1. Analysis: ophthalmology lost more patient volume due to COVID-19 than any other specialty. Strata Decision Technology. May 11, 2020. Accessed 
July 1, 2021. https://eyewire.news/articles/analysis-55-percent-fewer-americans-sought-hospital-care-in-march-april-due-to-covid-19/

2. Leonard C. Telemedicine in the time of COVID-19. 

. May 6, 2020. Accessed July 1, 2021. https://www.reviewofophthalmology.com/article/telemedicine-in-the-time-of-covid19

Telemedicine provides readiness in time of crisis.

Glaucoma 360: Highlights from 2021

Survey sheds light on glaucoma prevalence in West Africa

New Horizons Forum: Diagnostic advances in glaucoma

Teleglaucoma: Practice survival in the COVID-19 era

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