Harry A. Quigley

THE NUMBER OF PEOPLE WITH GLAUCOMA WORLDWIDE IN 2010 AND 2020

Aim: To estimate the number of people with open angle (OAG) and angle closure glaucoma (ACG) in 2010 and 2020. Methods: A review of published data with use of prevalence models. Data from population based studies of age specific prevalence of OAG and ACG that satisfied standard definitions were used to construct prevalence models for OAG and ACG by age, sex, and ethnicity, weighting data proportional to sample size of each study. Models were combined with UN world population projections for 2010 and 2020 to derive the estimated number with glaucoma. Results: There will be 60.5 million people with OAG and ACG in 2010, increasing to 79.6 million by 2020, and of these, 74% will have OAG. Women will comprise 55% of OAG, 70% of ACG, and 59% of all glaucoma in 2010. Asians will represent 47% of those with glaucoma and 87% of those with ACG. Bilateral blindness will be present in 4.5 million people with OAG and 3.9 million people with ACG in 2010, rising to 5.9 and 5.3 million people in 2020, respectively. Conclusions: Glaucoma is the second leading cause of blindness worldwide, disproportionately affecting women and Asians.

Number of people with glaucoma worldwide.

AIM: To estimate the prevalence of glaucoma among people worldwide. METHODS: Available published data on glaucoma prevalence were reviewed to determine the relation of open angle and angle closure glaucoma with age in people of European, African, and Asian origin. A comparison was made with estimated world population data for the year 2000. RESULTS: The number of people with primary glaucoma in the world by the year 2000 is estimated at nearly 66.8 million, with 6.7 million suffering from bilateral blindness. In developed countries, fewer than 50% of those with glaucoma are aware of their disease. In the developing world, the rate of known disease is even lower. CONCLUSIONS: Glaucoma is the second leading cause of vision loss in the world. Improved methods of screening and therapy for glaucoma are urgently needed.

The definition and classification of glaucoma in prevalence surveys

This review describes a scheme for diagnosis of glaucoma in population based prevalence surveys. Cases are diagnosed on the grounds of both structural and functional evidence of glaucomatous optic neuropathy. The scheme also makes provision for diagnosing glaucoma in eyes with severe visual loss where formal field testing is impractical, and for blind eyes in which the optic disc cannot be seen because of media opacities.

Retinal Ganglion Cell Atrophy Correlated With Automated Perimetry in Human Eyes With Glaucoma

We measured the number and size of retinal ganglion cells from six human eyes with glaucoma. In each, the histologic findings were correlated with visual field results. Five age-matched normal eyes were studied for comparison. In general, there were fewer remaining large ganglion cells in retinal areas with atrophy. In the perifoveal area, however, no consistent pattern of cell loss by size was found. Our estimates suggest that visual field sensitivity in automated testing begins to decline soon after the initial loss of ganglion cells. Throughout the central 30 degrees of the retina, 20% of the normal number of cells were gone in locations with a 5-dB sensitivity loss, and 40% cell loss corresponded to a 10-dB decrease. There were some remaining ganglion cells in areas that had 0-dB sensitivity in the field test.

Global Prevalence of Glaucoma and Projections of Glaucoma Burden through 2040 A Systematic Review and Meta-Analysis

PURPOSE Glaucoma is the leading cause of global irreversible blindness. Present estimates of global glaucoma prevalence are not up-to-date and focused mainly on European ancestry populations. We systematically examined the global prevalence of primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG), and projected the number of affected people in 2020 and 2040. DESIGN Systematic review and meta-analysis. PARTICIPANTS Data from 50 population-based studies (3770 POAG cases among 140,496 examined individuals and 786 PACG cases among 112 398 examined individuals). METHODS We searched PubMed, Medline, and Web of Science for population-based studies of glaucoma prevalence published up to March 25, 2013. Hierarchical Bayesian approach was used to estimate the pooled glaucoma prevalence of the population aged 40-80 years along with 95% credible intervals (CrIs). Projections of glaucoma were estimated based on the United Nations World Population Prospects. Bayesian meta-regression models were performed to assess the association between the prevalence of POAG and the relevant factors. MAIN OUTCOME MEASURES Prevalence and projection numbers of glaucoma cases. RESULTS The global prevalence of glaucoma for population aged 40-80 years is 3.54% (95% CrI, 2.09-5.82). The prevalence of POAG is highest in Africa (4.20%; 95% CrI, 2.08-7.35), and the prevalence of PACG is highest in Asia (1.09%; 95% CrI, 0.43-2.32). In 2013, the number of people (aged 40-80 years) with glaucoma worldwide was estimated to be 64.3 million, increasing to 76.0 million in 2020 and 111.8 million in 2040. In the Bayesian meta-regression model, men were more likely to have POAG than women (odds ratio [OR], 1.36; 95% CrI, 1.23-1.52), and after adjusting for age, gender, habitation type, response rate, and year of study, people of African ancestry were more likely to have POAG than people of European ancestry (OR, 2.80; 95% CrI, 1.83-4.06), and people living in urban areas were more likely to have POAG than those in rural areas (OR, 1.58; 95% CrI, 1.19-2.04). CONCLUSIONS The number of people with glaucoma worldwide will increase to 111.8 million in 2040, disproportionally affecting people residing in Asia and Africa. These estimates are important in guiding the designs of glaucoma screening, treatment, and related public health strategies.

Racial Differences in the Cause-Specific Prevalence of Blindness in East Baltimore

BACKGROUND Bilateral blindness unrelated to simple refractive error is twice as prevalent among blacks as among whites, although the difference narrows among the elderly. The reasons for this race- and age-related pattern are uncertain. METHODS AND RESULTS A randomly selected, stratified, multistage cluster sample of 2395 blacks and 2913 whites 40 years of age and older in East Baltimore underwent detailed ophthalmic examinations by a single team. We identified 64 subjects who were blind in both eyes. The leading causes of blindness were unoperated senile cataract (accounting for blindness in 27 of the total of 128 eyes), primary open-angle glaucoma (17 eyes), and age-related macular degeneration (16 eyes). Together, these three disorders accounted for 47 percent of all blindness in this sample. Unoperated cataract accounted for 27 percent of all blindness among blacks, among whom it was four times more common than among whites; whites were almost 50 percent more likely than blacks to have undergone cataract extraction before the age of 80 (P less than 0.002). Primary open-angle glaucoma accounted for 19 percent of all blindness among blacks; it was six times as frequent among blacks as among whites and began 10 years earlier, on average. By contrast, age-related macular degeneration resulting in blindness was limited to whites, among whom it was the leading cause of blindness (prevalence, 2.7 per 1000; 95 percent confidence interval, 1.2 to 5.4); it affected 3 percent of all white subjects 80 years of age or older. CONCLUSIONS The pattern of blindness in urban Baltimore appears to be different among blacks and whites. Whites are far more likely to have age-related macular degeneration, and blacks to have primary open-angle glaucoma. The high rate of unoperated cataracts among younger blacks and among elderly subjects of both races suggests that health services are underused. Half of all blindness in this urban population is probably preventable or reversible.

Neuronal death in glaucoma

Glaucoma is recognized to have its major detrimental effect upon the eye by killing retinal ganglion cells. The process of cell death appears to be initiated at the optic nerve head, though other sites of injury are possible but unsubstantiated. At present the injury at the nerve head seems related to the level of the eye pressure, but its detailed mechanism is as yet unexplained. There is a greater loss of ganglion cells from some areas of the eye, and this feature of glaucoma seems related to the regional structure of the supporting connective tissues of the optic nerve head. Larger retinal ganglion cells have been consistently shown to have somewhat greater susceptibility to injury in glaucoma, though all cells are injured, even early in the process. Ganglion cells die by apoptosis in human and experimental glaucoma, opening several potential areas for future therapies to protect them from dying. Neurotrophin deprivation is one possible cause of cell death and replacement therapy is a potential approach to treatment.

Morphologic Changes in the Lamina Cribrosa Correlated with Neural Loss in Open-Angle Glaucoma

We divided 25 glaucomatous human eyes into three groups representing mild (Group 1, seven eyes), moderate (Group 2, 11 eyes), and severe (Group 3, six eyes) optic nerve damage, based on visual field testing or remaining number of optic nerve fibers. The optic nerve head of each eye was examined by scanning electron microscopy. Compression of the successive lamina cribrosa sheets was the earliest detected abnormality, occurring in some eyes before the detection of visual field loss. Backward bowing of the entire lamina cribrosa was a later change and involved its upper and lower poles more than the mid-nerve head. The diameter of the scleral opening at the level of Bruchs membrane did not enlarge in these adult glaucomatous eyes. Mechanical compression of the nerve head occurred early enough to be considered a primary pathogenetic event in glaucomatous damage.

An Evaluation of Optic Disc and Nerve Fiber Layer Examinations in Monitoring Progression of Early Glaucoma Damage

From annual examinations of 813 ocular hypertensive eyes, the authors compared optic disc and nerve fiber layer photographs in 2 age-matched subgroups: 37 eyes that converted to abnormal visual field tests at the end of a 5-year period and 37 control eyes that retained normal field tests. Disc change was detected in only 7 of 37 (19%) converters to field loss and in 1 of 37 (3%) controls. Progressive nerve fiber layer atrophy was observed in 18 of 37 (49%) converters and in 3 of 37 (8%) controls. Serial nerve fiber layer examination was more sensitive than color disc evaluation in the detection of progressive glaucoma damage at this early stage of glaucoma. The evaluation of cup-to-disc ratio or of the nerve fiber layer appearance in the initial photograph taken 5 years before field loss were equally predictive of future field damage. The position of nerve fiber layer defects was highly correlated with the location of subsequent visual field loss.

Chronic Human Glaucoma Causing Selectively Greater Loss of Large Optic Nerve Fibers

Eighteen eyes of 12 persons with chronically elevated intraocular pressure (IOP) were studied histologically to determine the number and diameter of optic nerve fibers. In some eyes, automated perimetry had been performed. Optic nerve fibers larger than the mean diameter were killed more rapidly than smaller fibers, although no fiber size was completely spared at any stage of atrophy. The number of optic nerve fibers varies considerably among normal eyes. The authors confirmed that the death of a substantial proportion of optic nerve fibers precedes detectable visual field loss.