Prevalence of glaucoma in the lsraeli Arab population

INTRODUCTION

Glaucoma is a major disease that causes irreversible vision loss[1]. The prevalence of glaucoma and its types have been found to vary greatly with ethnicity and geography[2-3]. This suggests that genetic and environmental factors may play significant roles in the etiology of the disease.African Americans, Asians and Hispanics are populations that have been studied in particular[2-3]. Primary open angle glaucoma (POAG) has been found to be highly prevalent among persons from African descent[4-5]; and primary angle-closure glaucoma (PACG) among Asians, other than Japanese[3]. The risk of glaucoma increases with age, and most studies have found female gender to be a risk factor[3]. In Arab populations, high prevalence rates and genetic associations have been found for juvenile-onset glaucoma[6-7]; and genetic factors have been found to associate with adult-onset types of glaucoma[8-9]. However, searching PubMed, we did not find any studies that assessed the prevalence of adult-onset glaucoma in Arab populations. We set out to assess the rates of diagnosed glaucoma and its types in a defined Arab population.

METHODS

The study population comprised residents of Tira, a Muslim Arab town in the Triangle region in Israel, who are insured by Clalit Health Services, the largest health maintenance organization in Israel. Clalit Health Services insures more than half the Israeli population, and 18 600 of the 22 600(82%) residents of Tira. Individuals diagnosed with glaucoma were identified from patient files. Data accessed included the type of glaucoma, age at diagnosis, the types of medications prescribed to treat glaucoma, the number of individuals who underwent surgery as treatment for glaucoma, and the number of those legally blind as a result of glaucoma.Individuals were classified with POAG if they met any of the following diagnostic criteria: cup-to-disk ratio (CDR) ＞0.5 with asymmetry between the eyes and damage to the field of vision; intraocular pressure (IOP) ＞23 mm Hg; damage to the field of vision without CDR asymmetry, but with IOP＞23 mm Hg; CDR asymmetry ＞0.5 with damage to the field of vision, independent of IOP; CDR asymmetry ＞0.2 and damage to the field of vision, with or without increased IOP; damage to the field of vision as defined by the following characteristics of glaucomatous field defects: asymmetry across the horizontal midline (in early/moderate cases), location in the midperiphery (in early/moderate cases), clustering in neighboring test points, and reproducibility on at least two occasions.In addition, the condition should not be explainable by any other disease and should be considered a valid representation of an individual's functional status (based on performance indices such as false positive rate). The conduct of this study conformed to the principles outlined in the Declaration of Helsinki.

RESULTS AND DISCUSSION

Medical records were available for 15 122 (81%) of the residents in Tira who were insured by Clalit Health Services,comprising 67% of the total population of Tira. Overall prevalence was 3.9%, which compares with a reported prevalence of 2.2% in the general Israel population[10-11]. Of the total number of glaucoma cases, POAG comprised 77%,prevalences of POAG and PACG were 3.0% and 0.42%,respectively. Studies conducted in Japanese, black, Hispanic and white populations also reported considerably higher rates of POAG than PACG. This contrasts with studies of Asian populations, other than Japanese, which reported higher rates of PACG than POAG[3]. Advances in diagnostic technology may explain, at least in part, the increasing gap in prevalence rates between POAG and PACG[3]. On one hand, POAG is now diagnosed more easily; on the other hand, criteria for diagnosis of PACG have become more stringent.

We report increasing prevalence of all types of glaucoma with age. The prevalence of PACG peaked at age 60-69y. Of all the individuals with glaucoma in our population, 62% were women. Prevalence was greater for men than for women for all types of glaucoma, for the age groups 60-69y and 70-79y.For the age group 30-39y there was no difference between the genders in the prevalence of PACG. For all other age groups,prevalences were higher for women than for men. Prevalences for women were 135% that of men for all types of glaucoma,143% for POAG, and 96% for PACG.

Our prevalence of PACG is similar to that reported in western Europe[12]. We report POAG prevalence among individuals 40y and older of 8.4% (868/10 296), 10.1% (554/5476) among women and 7.3% (314/4320) among men. This compares with prevalences of 2.1%, 1.4%, and 4.2% reported for white, Asian and black populations in the UK, respectively[13]. More recently conducted studies also reported lower prevalences for POAG in the ≥40y population than did ours, 2.0% in Myanmar[14]and 2.3% in Sri Lanka[15]. In those studies, the mean ages were 56.2 and 57y, respectively, while in our study the mean age was 62y. This difference can explain our higher rate of glaucoma,since the risk of developing glaucoma is higher at an older age.Other studies showed higher prevalences, 3.5% in an Asian population[16]and up to 8% in west Africa[17].

We considered whether a reason for our high prevalence of POAG compared to other populations could be due to the absence of medical records for 3480 individuals insured by Clalit Health Services. However, even if we consider an extreme scenario, and assume that all these persons were above age 40y and none had glaucoma, the calculated prevalence rate for glaucoma would still be high, 6.3% (868/13 776). Neither do lenient diagnostic criteria explain the relatively high rates of glaucoma in our study. Rather, compared to other studies[14-15],our diagnostic criteria were quite stringent. Another possible explanation for the high rate of glaucoma in our study is that once a year we conduct a screening day for glaucoma in which we enthusiastically promote patients to be examined. Since older persons are more available than younger ones, this may explain the higher prevalence in older patients. Lastly, the continued, though decreasing prevalence of consanguineous marriages in the Israeli Arab Community[18]could also contribute to the high rate of POAG in our study, since positive family history is a risk factor for POAG[19].

For 548 of 909 individuals (60.3%) with POAG, records of prescriptions of medications were available. Of patients prescribed one medication, 72 (29.2%) were prescribed beta blocker eye drops, 86 (35.0%) eye drops that combined beta blockers and carbonic anhydride inhibitors, 82 (33.3%)prostaglandin eye drops, and 6 (2.4%) alpha blocker eye drops. The preference for prostaglandins, though without statistical significance, apparently results from the means of administration; once daily rather than twice, as with the combined medications.

Of 79 patients who underwent surgery to treat glaucoma, 68 underwent trabeculectomy and 11 Ex-Press (Alcon Inc., TX,USA) shunt surgeries. Following trabeculectomy, 27 (39.7%)required medications for treatment of glaucoma. Of them,21 were prescribed one medication, 11 only beta blocker eye drops, 4 only prostraglandin eye drops, and 6 a combination of beta blockers and carbonic anhydride inhibitors. Following Ex-Press surgery, 3 (27.3%) were prescribed medication, all of them one type of eye drop: a combination of beta blockers and carbonic anhydride inhibitors.

During the last three years, 16 (1.3%) of our patients with POAG were recorded as legally blind (field of vision reduced to 10 degrees or visual acuity of less than 6/60) as a result of glaucoma. According to the Israel Registry of the Blind,glaucoma accounted for 11.8% to 14.3% of the new incidences of blindness in Israel between the years 1998 and 2003[20].In Israel, the prevalence of blindness from leading causes,such as age-related macular degeneration, glaucoma, diabetic retinopathy and maculopathy, optic atrophy and cataract was assessed as similar to that in other western populations[20].

The data from the current study are based on the medical records of two-thirds of the residents of one Arab village.Due to the respective design, we were not able to diagnose the prevalence of undiagnosed glaucoma in our population.Another limitation of the study is that the information regarding medications is based on prescription data only, no data were available regarding the purchase of medications or compliance with taking them. In another study of this population, we found compliance with medication prescriptions for glaucoma to be only about 50%[21]. In conclusion, the prevalence of glaucoma in an Arab town in Israel appears high compared to other populations of different ethnicities and geography. More studies are needed to discern the risk for glaucoma in Arab and Middle Eastern populations.

ACKNOWLEDGEMENTS

Conflicts of Interest: Chassid O, None; Epstein I, None;Sharabi-Nov A, None; Pikkel J, None.

REFERENCES

1 Resnikoff S, Pascolini D, Etya’ale D, Kocur I, Pararajasegaram R,Pokharel GP, Mariotti SP. Global data on visual impairment in the year 2002. Bull World Health Organ 2004:82(11):844-851.

2 Wadhwa SD, Higginbotham EJ. Ethnic differences in glaucoma:prevalence, management, and outcome. Curr Opin Ophthalmol 2005;16(2):101-106.

3 Cedrone C, Mancino R, Cerulli A, Cesareo M, Nucci C. Epidemiology of primary glaucoma: prevalence, incidence, and blinding effects. Prog Brain Res 2018;173:3-14.

4 Ntim-Amponsah CT, Amoaku WM, Ofosu-Amaah S, Ewusi RK,Idirisuriya-Khair R, Nyatepe-Coo E. Adu-Darko M. Prevalence of glaucoma in an African population. Eye (Lond) 2004:18(5):491-497.

5 Leske MC, Connel AM, Schachat AP, Hyman L. Prevalence of open angle glaucoma. Arch Ophthalmol 1994:112(6):821-829.

6 Bar-Yosef U, Levy J, Elbedour K, Ofir R, Carmi R, Birk OS. Congenital glaucoma: CYP1B1 mutations in Israeli Bedouin kindreds. J Glaucoma 2010;19(1):35-38.

7 Bayat B, Yazdani S, Alavi A, Chiani M, Chitsazian F, Tusi BK.Contributions of MYOC and CYP1B1 mutations to JOAG. Mol Vis 2008;14:508-517.

8 Abu-Amero KK, Morales J, Bosley TM, Mohamed GH, Cabrera VM.The role of mitochondrial haplogroups in glaucoma: a study in an Arab population. Mol Vis 2008;14:518-522.

9 Abu-Amero KK, Morales J, Mohamed GH, Osman MN, Bosley TM.Glutathione S-transferase M1 and T1 polymorphisms in Arab glaucoma patients. Mol Vis 2008;14:425-430.

10 Levkovitch-Verbin H, Goldshtein I, Chodick G, Zigman N, Shalev V.The Maccabi Glaucoma Study: prevalence and Incidence of glaucoma in a large Israeli health maintenance Am J Ophthalmol 2014;158(2):402-408.e1.

11 Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol 2006;90(3):262-267.

12 Day AC, Baio G, Gazzard G, Bunce C, Azuara-Blanco A, Munoz B, Friedman DS, Foster PJ. The prevalence of primary angle closure glaucoma in European derived populations: a systematic review. Br J Ophthalmol 2012;96(9):1162-1167.

13 Rudnicka AR, Mt-Isa S, Owen CG, Cook DG, Ashby D. Variations in primary open-angle glaucoma prevalence by age, gender, and race:a Bayesian meta-analysis. Invest Ophthalmol Vis Sci 2006;47(10):4254-4261.

14 Casson RJ, Newland HS, Muecke J, McGovern S, Abraham L, Shein WK, Selva D, Aung T. Prevalence of glaucoma in rural Myanmar: the Meiktila Eye Study. Br J Ophthalmol 2007;91(6):710-714.

15 Sia DI, Eudssuriya K, Sennanayake S, Senaratne T, Selva D, Casson RJ. Prevalence of and risk factors for primary open-angle glaucoma in central Sri Lanka: the Kandy Eye Study. Ophthalmic Epidemiol 2010;17(4):211-216.

16 Chan EW, Li X, Tham YC, Liao J, Wong TY, Aung T, Cheng CY.Glaucoma in Asia: regional prevalence variations and future projections.Br J Ophthalmol 2016;100(1):78-85.

17 Budenz DL, Barton K, Whiteside-de Vos J, Schiffman J, Bandi JR,Nolan W, Herndon L, Kim H, Hay-Smith G, Tielsch JM; Tema Eye Survey Study Group. Prevalence of glaucoma in an urban West African population: the Tema Eye Survey. JAMA Ophthalmol 2013;131(5):651-658.

18 Sharkia R, Mahajnah M, Athamny E, Khatib M, Sheikh-Muhammad A, Zalan A. Changes in marriage patterns among the Arab Community in Israel over a 60-year period. J Biosoc Sci 2016;48(2):283-287.

19 Hollands H, Johnson D, Hollands S, Simel DL, Jinapriya D, Sharma S. Do findings on routine examination identify patients at risk for primary open-angle glaucoma? The rational clinical examination systematic review. JAMA 2013;309(19):2035-2042.

20 Avisar R, Friling R, Snir M, Avisar I, Weinberger D. Estimation of prevalence and incidence rates and causes of blindness in Israel, 1998-2003. Isr Med Assoc J 2006;8(12):880-881.

21 Masoud M, Sharabi-Nov A, Pikkel J. Noncompliance with ocular hypertensive treatment in patients with chronic open angle glaucoma among Arab population in Israel: a cross sectional descriptive study. J Ophthalmol 2013;2013:405130.