As will be demonstrated in this article, glaucoma screening protocols recommended by both governmental and non-governmental organizations vary significantly (Table 1). While access to proper ophthalmic care is a limitation to effective screening worldwide, particularly in developing countries, the variability in recommended glaucoma screening protocols in developed countries is, in part, due to a lack of conclusive evidence demonstrating the benefit of population-based screening. Given the imperfect sensitivity and specificity of screening tests, combined with an overall low glaucoma prevalence in the general population, many authors and organizations argue that screening is not justified.^13–16 Nevertheless, glaucoma is asymptomatic and not screening means that many will lose vision owing to not knowing they have the condition.

The American Academy of Ophthalmology (AAO) is the world’s largest organization of eye physicians and surgeons and currently recommends screening for glaucoma, among other eye diseases, at age 40. Certain factors that should prompt an individual to be screened earlier include: “diabetes, high blood pressure, or a family history of eye disease.”¹ While there are multiple tools available to the ophthalmologist to screen for glaucoma, including optical coherence tomography, standard automated perimetry, intraocular pressure measurements, and the appearance of the optic nerve head, the AAO does not specify which tests should be used to screen patients.¹⁷

In February 2019, in conjunction with the International Council of Ophthalmology (ICO), a group of high-level ophthalmologists representing all regions of Sub-Saharan Africa convened in Ethiopia to create a practical “Toolkit for Glaucoma Management in Sub-Saharan Africa.” In their toolkit, the committee referenced a screening program still in its pilot stages but recommended that eye doctors institute community and hospital-based screening for glaucoma of the general population over the age of 35 at every eye visit.¹⁰ In contrast to both the AAO and Sub-Saharan Africa Guidelines, many other institutional bodies operating principally within the United States, Central and South America, and Europe do not recommend screening the general population for glaucoma.

The United States Preventive Services Task Force (USPSTF) is an organization funded by the United States Department of Health and Human Services and is tasked with systematically evaluating and issuing screening recommendations for a variety of clinically preventable diseases.² Both in 2013 and more recently in 2022, the USPSTF did not recommend screening of the general population for glaucoma given the lack of scientific evidence of clinical utility for any combination of structural and functional testing strategies.^3–5 The task force has a stringent methodology for recommending screening and requires randomized trials comparing screened to unscreened populations that show long-term improvement in outcomes for the group to recommend screening. For similar reasons, the United Kingdom’s National Screening Committee also does not advocate for screening of the general population for glaucoma.⁶ Similarly, the European Glaucoma Society has concluded that there are no guidelines for glaucoma screening that have been shown to have a beneficial link between screening and improved clinical outcomes.⁷

In their 2019 guide to open angle glaucoma, the Pan-American Association of Ophthalmology (PAAO), coordinating with the International Council of Ophthalmology (ICO) and the International Agency for the Prevention of Blindness, concluded that there is no single screening test or even a combination of tests that currently offer sufficient sensitivity and specificity to justify a regional screening program. The authors highlight the potential usefulness of employing primary care providers in screening efforts of the general population although they indicate a trained eye-care provider is needed for many components of testing and result analysis. Indeed, the authors conclude that public education at the primary care level regarding the danger of vision loss from glaucoma should be a key prevention strategy for preventing glaucoma-related vision loss in the asymptomatic individual. The authors allude to the potential utility of telemedicine screening, but once again conclude no such protocol is at this time recommended for the general population. They further comment that any such telemedicine screening must be accompanied by ancillary testing of vision, pressure, and optic nerve assessment by a trained medical professional to be considered an adequate screening. Similar to recommendations from other previously mentioned organizations, the PAAO recommends focusing screening efforts principally on at-risk populations that are broadly defined and include “older adults, those with genetic predispositions, or those with untreated ocular hypertension.”⁸

Similar to the USPSTF, European Glaucoma Society, and PAAO, the ICO’s 2015 Glaucoma Eye-Care Task Force completed a review of glaucoma eye-care protocols and concluded that general population screening was of limited utility, although an assessment of glaucoma risk factors and evaluation for clinical signs of glaucoma should be undertaken in an effort to rule out glaucoma at each initial patient visit.⁹ Their review includes a comprehensive list of pertinent history data to collect, examination techniques, treatment options, laser treatment protocols, ongoing management recommendations, and indicators of progression for both open and closed-angle glaucoma. Their guidelines include clinical disc photos and demonstrative visual field defects corresponding to glaucomatous optic nerve damage. The authors conclude that while proactive mass screening is not currently recommended, screening for glaucoma at a comprehensive eye examination when a patient arrives at an ophthalmologist’s office is recommended and first-degree relatives of individuals with glaucoma should also be screened regularly.

In its most recent review, the World Glaucoma Society assessed the merits and shortcomings of current screening methodologies for both open and primary angle closure glaucoma. In their assessment of screening protocols and technologies for open angle glaucoma, the authors reviewed nearly 900 articles and concluded that at the time of publication, there was insufficient evidence in the literature to suggest a clear benefit of screening the general population for open angle glaucoma. Furthermore, as has been alluded to previously, the authors highlighted that while numerous studies discuss and assess the benefits of newer screening technologies, these studies are prone to certain biases, including selection biases, inherent to assessing certain subgroups of the population, a “disease severity” bias, study setting (eg, a specific country, or in a hospital setting vs community-setting), and a general loss of power in the studies’ results given subgroup analyses with insufficient population size.¹¹ The authors concluded that while specificity for certain open angle glaucoma screening tests or combinations of tests approached 90%, the evidence supporting any one combination of functional and structural tests is currently insufficient. Unlike their recommendation for open angle glaucoma, the World Glaucoma Society postulated that tests, such as limbal anterior chamber depth, the oblique flashlight test, and central anterior chamber depth by optical pachymetry, may have a future use in worldwide screening for angle closure glaucoma.¹¹ However, the authors offer no formal consensus on who should be screened, when, how often, or what method should be utilized.

Similar to other institutions previously mentioned, the World Health Organization does not consider general population screening to be cost-effective; however, they do recommend routine eye examinations for “high-risk” populations.^12,18 The World Health Organization defines high-risk populations in its World Report on Vision in broad and nonspecific terms. More specifically, they along with others highlight women and marginalized populations (eg, the unhoused), as groups that should in general undergo routine eye examinations to increase equity of identification and treatment of common vision-impairing conditions.^12,18

In summary, general population screening for glaucoma has been adopted as a recommendation by only a few organizations and only in such situations, as in the case of the AAO, where a certain age has been met, or in the case of the Sub-Saharan African Guidelines where a population is recommended to be assessed en masse over age 35 years old because of an elevated risk of developing open angle glaucoma. This brings up the question of whether a targeted screening protocol should be recommended globally. The screening of such high-risk populations, already illustrated by a number of prior studies and recommended screening protocols, will be discussed fully in subsequent sections of this supplement.^14,19–22 It is the screening of such high-risk populations that has been demonstrated to be not only clinically useful in diagnosing and treating larger proportions of the general population benefiting from a higher positive-predictive value for screening protocols in these groups but also cost-effective.^23,24