Primary angle-closure glaucoma is significantly more common than primary open-angle glaucoma in the East, whereas in Africa and Europe the reverse is true. In order to study the role of ethnic background in the frequency of primary angle-closure glaucoma in Cape Town and, in particular, in people of mixed ethnic background, the so-called 'coloureds', we retrospectively reviewed all patients with primary glaucoma who attended the glaucoma clinic at Groote Schuur Hospital during a 30-month period. Primary angle-closure glaucoma was diagnosed in 11 of 63 (17%) whites, 11 of 85 (13%) blacks and 114 of 244 (46,7%) coloureds with primary glaucoma; the difference is statistically highly significant (P &lt; 0,001). The human leucocyte antigen frequencies in 97 coloured patients with primary angle-closure glaucoma were similar to those found in a control group of individuals with a similar ethnic background. This study highlights the fact that coloureds are more predisposed to primary angleclosure glaucoma than whites or blacks. Because of their strong historical and genetic ties with south-east Asia, this greater prevalence of primary angle-closure glaucoma might be explained by an Eastern influence on the ocular structures of the eye, as opposed to an African or European influence

Martell, R

Salmon, J.F.

English

AJOL - African Journals Online

rThe staff were particularly interested in data on adherenceto treatment. Non-compliance remains the predominantproblem in the management of tuberculosis. With regard tothe third aim, the implementation of the system on a widescale, there were mixed feelings. Although the project wasinitially received with enthusiasm by the staff, who enjoyedthe access to epidemiological data that the systemprovided, the prospect of additional routine administrativework outweighed their positive feelings. A subsequentinvestigation into the workload of clinic nurses in a westernCape urban clinic confirmed the heavy administrativeworkload: 48% of clinic nurses' time is spent on indirectpatient care.s Much of this time is spent on the collection ofdata for statistical purposes. The punchcard could simplifythis process. It would concurrently provide the relevantinformation to clinic staff for management purposes.Although the plethora of forms may well reflect thecomplexity of the treatment and management oftuberculosis, a comprehensive epidemiological profileremains essential to efficient planning.ConclusionA simple and accurate means of collecting health dataremains a priority in the evolving primary health care system.The punchcard system provides an easy, efficient, 'hands-on' tool for this task. No similar system appears to bedescribed or implemented elsewhere. The implementationof the method on a wide and routine basis would not bepossible without rationalisation of the existing administrativeload.REFERENCES1. KOslner HGV. Editorial. Epidemiological Comments 1991; 18(1): 3-15.2. KOstner HGV. Tuberculosis control programme - 1988. EpidemiologicalComments 1990; 17(1): 3-13.3. Youngleson SM. The accessibility and validity of demographic treatment andcompliance data at Ravensmead Clinic. Unpublished report. Parowvallei, GP:CERSAlMRC, 1989.4. Dick J. Developing a case register for tuberculosis in the western Cape. Reporton the pilot study in Atlantis. Parowvallei, CP: CERSAlMRC, 1989.5. Dick J, Pekeur P. An investigation into the workload of clinic nurses at a localauthority clinic. Unpublished report. Parowvallei, CP: NPTB/MRC, 1992.Accepted 1 Sep 1993.SAMJARTICLESThe role of ethnicity inprimary angle-closureglaucomaJ. F. Salmon, R. MartellPrimary angle-closure glaucoma is significantly morecommon than primary open-angle glaucoma in the East,whereas in Africa and Europe the reverse is true. In orderto study the role of ethnic background in the frequency ofprimary angle-closure glaucoma in Cape Town and, inparticular, in people of mixed ethnic background, theso-called 'coloureds', we retrospectively reviewed allpatients with primary glaucoma who attended theglaucoma clinic at Groote Schuur Hospital during a30-month period. Primary angle-closure glaucoma wasdiagnosed in 11 of 63 (17%) whites, 11 of 85 (13%) blacksand 114 of 244 (46,7%) coloureds with primary glaucoma;the difference is statistically highly significant (P < 0,001).The human leucocyte antigen frequencies in 97 colouredpatients with primary angle-closure glaucoma were similarto those found in a control group of individuals with asimilar ethnic background. This study highlights the factthat coloureds are more predisposed to primary angle-closure glaucoma than whites or blacks. Because of theirstrong historical and genetic ties with south-east Asia, thisgreater prevalence of primary angle-closure glaucomamight be explained by an Eastern influence on the ocularstructures of the eye, as opposed to an African orEuropean influence.s Atr Med J 1994; 84: 623-626.In western Europe and North America, primary angle-closureglaucoma is significantly less commqn than chronic open-angle glaucoma.'-3 The situation is reversed in east andsouth-east Asia, however, where primary angle-closureglaucoma has been reported to be more common thanprimary open-angle glaucoma:>-lO (Fig. 1). It is interesting tonote that the ethnic group with the highest prevalence ofprimary angle-closure glaucoma are the Eskimos, aMongoloid people thought to be related to the people ofeast Asia.3 ,11-13 The distinction between the two forms ofglaucoma is important to the clinkian, because the twoconditions are treated differently.In the western Cape the so-called 'coloured' people ofmixed ancestry have strong genetic links with the Eastwhich can be traced back to the 17th century when theDepartment of Ophthalmology, Groote Schuur Hospital andUniversity of Cape TownJ. F. Salmon, M.D., F.R.C.S.Provincial Library for Tissue Immunology, Cape TownR. Marten. M.B. CH.B., F.G.P. (SA)SAMJ Volume 84 No. 9 September 1994%Human leucocyte antigens were determined in the 97coloured patients with primary angle-closure glaucoma.HLA-A, -B and -C typing WE;lre performed by means of theNIH complement-dependent microdroplet Iymphocytetoxicity technique.17 B-cells, separated from peripheral bloodby the nylon-wool method, were used for HLA-DR and -DOtyping performed by means of the technique agreed upon forthe Seventh International Histocompatibility Workshop.'B.'9Local antisera as well as sera obtained by exchange withother laboratories were used. A control group was drawnfrom people with the same ethnic background and consistedof 3 716 individuals for the comparison of the HLA class Iantigen frequencies and 549 individuals for the com~arisonof HLA class 11 antigen frequencies. Frequencies werecompared between patients and controls at 16 A-locus, 29B-Iocus, 8 C-Iocus, 10 DR-Iocus and 3 DO-locus HLAs; theChi-square test was used for proportions with Yates'correction. The P-values were multiplied by the number ofcomparisons made, as there was no prior reason Jo suspectthat any significant differences would be found. A correctedP-value of <0,05 was considered statistically signiflcant.The Chi-square test was used to compare the freq'uency ofprimary angle-closure glaucoma in the three ethnic groups.Burma Philippines JapanGao Alsbirk Genic GaoChinaSunHungTaiwanUrnSingaporeLoho4020100 r----------------------,8080Fig. 1. Estimates of the relative frequency of primary angle-closure glaucoma among patients with primary glaucoma in Asia(hospital-based case series).%ResultsFig. 2. Frequency of primary angle-closure glaucoma 1n threeethnic groups at the glaucoma clinic, Groote Schuur Hospital.Whiteo Open·angleGlaucomafZZi Angle-closu reGlaucomaBlack130N=244Mixed RacePrimarY open-angle glaucoma was almost twice as commonas primary angle-closure glaucoma at this clinic. When theethnic background of the patients was evaluated, it wasfound that 11 of 63 (17,5%) whites, 11 of 85 (12,9%) blacksand 114 of 244 (46,7%) coloureds had primary angle-closureglaucoma (Fig. 2). The prevalence of primary angle-closureglaucoma at this clinic was significantly greater in colouredsthan in whites or blacks (P < 0,001).When HLA frequencies in patients and controls werecompared, no statistically significant differences were notedbetween the groups (Table I).N=392100802568040200PrimaryGlaucomaCape was governed by the Dutch East India Company.'4Their ancestors were mainly south-east Asians (fromIndonesia and Malaysia) and indigenous Africans (Khoi-Khoiand San), and to a lesser extent east Africans (fromMadagascar and Mozambique), west Africans andEuropeans. They form an anthropologically distinctpopulation, whose relatively recent origin is the result ofearly gene mixing at the Cape.'5We wondered whether because of their Eastern ancestrythis group would show a greater predisposition to primaryangle-closure glaucoma than whites or blacks in CapeTown. We therefore assessed all patients with primaryglaucoma who attended the glaucoma clinic at GrooteSchuur Hospital during a 30-month period. The ratio ofprimary angle-closure glaucoma to primary open-angleglaucoma was determined in three distinct ethnic groups:whites, blacks and coloureds. In addition, the frequencies ofthe histocompatibility antigens were evaluated in 97coloured patients with primary angle-closure glaucoma.Patients and methodsAll patients with primary glaucoma who attended theglaucoma clinic at Groote Schuur Hospital from July 1988 toDecember 1990 were retrospectively ·reviewed. Of the 392patients, 244 (62%) were coloured, 85 (22%) were black and63 (16%) were white.Primary angle-closure glaucoma was diagnosed if theintra-ocular pressure was> 21 mmHg in the presence of apartially or totally occluded angle in at least one eye, andwas made irrespective of the optic nerve appearance. Mostpatients had chronic angle-closure glaucoma. '6 Secondarycauses of angle closure such as iris neovascularisation, lensintumescence and subluxation, trauma and uveitis werespecifically excluded. Primary open-angle glaucoma wasdiagnosed if an open angle was found on gonioscopy in apatient with glaucomatous disc cu'pping and acorresponding visual field loss.Volume 84 No. 9 September 1994 SAMJSAMJARTICLESTable I. HLA phenotype frequency in patients of mixed ancestry with primary angle-closure glaucoma, and controlsPACG* ControlsAntigen Positive Negative Positive Negative Yates P-valueA1 21 76 610 3106 1,5154 0,200 < P < 0,300A2 24 73 1 160 2556 1,5607 0,200 < P < 0,300A3 14 83 552 3164 0,0009 0,950 < P < 0,980A10 20 77 559 3157 1,8695 0,100 <P<O,200A11 17 80 469 3247 1,6276 0,200 < P < 0,300A23 4 93 427 3289 4,4093 0,020 < P < 0,050A24 23 74 701 3015 1,1459 0,200 < P < 0,300A28 16 81 586 3130 0,0027 0,950 < P < 0,980A29 5 92 326 3390 1,1382 0,200 < P < 0,300A30 16 81 679 3037 0,0989 0,700 < P < 0,800A31 2 95 84 3632 0,0467 0,800 < P < 0,900A32 1 96 220 3496 3,2922 0,050 < P < 0,100A33 7 90 242 3474 0,0048 0,900 < P < 0,950A36 2 95 32 3684 0,4830 0,300 < P < 0,500A43 7 90 207 3509 0,2227 0,500 < P < 0,700A74 1 96 140 3576 1,2939 0,200 < P < 0,300B7 14 83 756 2960 1,6995 0,100 < P< 0,200B8 8 89 350 3366 0,0459 0,800 < P < 0,900B13 3 94 147 3569 0,0280 0,800 < P < 0,900B14 10 87 255 3461 1,2449 0,200 < P < 0,300B15 16 81 440 3276 1,5280 0,200 < P < 0,300B18 12 85 367 3349 0,4082 0,500 < P < 0,700B22 2 95 42 2456 0,0134 0,900 < P < 0,950B27 6 91 172 3544 0,2245 0,500 < P < 0,700B35 16 81 425 3291 1,8958 0,100 < P < 0,200B37 2 95 64 3652 0,0199 0,800 < P < 0,900B38 2 95 91 3625 0,0080 0,900 < P < 0,950B39 3 94 143 3573 0,Q132 0,900 < P < 0,950B41 3 94 161 3555 0,1161 0,700 < P < 0,800B42 3 94 231 3485 1,1050 0,200 < P < 0,300B44 14 83 627 3089 0,2469 0,500 < P < 0,700B45 4 93 198 3518 0,0861 0,700 < P < 0,800B46 0 97 4 2494 0,8538 0,300 < P < 0,500B47 4 93 79 3637 0,9580 0,300 < P < 0,500B48 0 97 3 2495 1,3938 0,200 < P < 0,300B49 0 97 70 3646 0,9631 0,300 < P < 0,500B50 3 94 22 3694 5,6437 0,010 < P < 0,020B51 7 90 182 3534 0,6429 0,300 < P < 0,500B52 10 87 148 3568 7,9999 0,001 < P < 0,010B53 3 94 96 3620 0,0001 0,990 < P < 1,000B57 12 85 313 3403 1,4175 0,200 < P < 0,300B58 6 91 614 3102 6,6797 0,001 < P < 0,010B60 3 94 166 3550 0,1596 0,500 < P < 0,700B61 7 90 178 3538 0,7374 0,300 < P < 0,500B70 8 89 580 3136 3,3830 0,050 < P < 0,100C1 3 94 125 3591 0,0194 0,800 < P < 0,900C2 8 89 609 3107 4,0389 0,020 < P < 0,050C3 11 86 586 3130 1,0892 0,200 < P < 0,300C4 33 64 866 2850 5,4447 0,010 < P < 0,020C5 2 95 141 3575 0,3795 0,500 < P < 0,700C6 33 64 1 162 2554 0,2168 0,500 < P < 0,700C7 40 57 1536 2180 0,0072 0,900 < P < 0,950C8 10 87 259 3457 1,1389 0,200 < P < 0,300DR1 13 80 61 488 0,3908 0,500 < P < 0,700DR2 39 54 189 360 1,6440 0,100 < P< 0,200DR3 16 77 114 435 0,4234 0,500 < P < 0,700DR4 21 72 117 432 0,Q193 0,800 < P < 0,900DR5 28 65 158 391 0,0189 0,800 < P < 0,900DR6 22 71 113 436 0,2861 0,500 < P < 0,700DR7 20 73 138 411 0,3864 0,500 < P < 0,700DR8 6 87 29 520 0,0451 0,800 < P < 0,900DR9 5 88 10 539 2,9842 0,050 < P < 0,100DR10 3 90 9 540 0,3977 0,500 < P < 0,700DQ1 71 22 363 186 3,3430 0,050 <P<O,100DQ2 28 65 149 400 0,2178 0,500 < P < 0,700DQ3 50 43 240 309 2,8487 0,050 < P< 0,100• PACG = primary angle-elosure glaucoma.SAMJ Volume 84 No. 9 September 1994DiscussionPrevious studies have shown that the prevalence of primaryangle-closure glaucoma is influenced by the ethnicbackground of the population studied'.2·''''3,20-'' (Table 11). Inthe East, primary angle-closure glaucoma is significantlymore common than primary open-angle glaucoma.3In ourglaucoma clinic, we had the opportunity to compare therelative frequency of this form of glaucoma in three distinctethnic groups and, in particular, were able to determine therelationship between primary angle-closure glaucoma andprimary open-angle glaucoma in people of mixed ancestry.Table 11. Prevalence (%) of primary angle-closure glaucoma inindividuals over the age of 40 years in different ethnic groups(population-based studies)'Country Author PrevalenceWales Hollows' 0,1Sweden Bengtsson' 0,1Israel Hyams20 0,5Greenland} Clemmesen1t 5,0Canada Eskimo Orance" 2,9Alaska Arkell13 2,7China Hu21 1,3Japan Shiose22 0,3South AfricaTswana Oavid23 1,0Pondo Bartholomew" 0,25Coloureds Salmon30 2,3• Figures for America, continental Europe and south-east Asia are not available.A diagnosis of primary angle-closure glaucoma was madein 17% of white and 13% of black patients with primaryglaucoma. Although selection bias may play a role in ourstudy, these figures correlate well with those from a 1973Johannesburg stUdy, when it was reported that 17% ofblacks and 20% of whites with primary glaucoma attendingthe glaucoma clinic had primary angle-closure glaucoma.'5These percentages are significantly lower than the 46,7%found in coloureds in this study.The fact that coloured people are more likely to haveprimary angle-closure glaucoma than blacks and whites wasnoted in a 1964 study of the types of glaucoma treated at aGroote Schuur Hospital c1inic.'6 Although the criteria for thediagnosis of primary angle-closure glaucoma are notrecorded and no comment was made on ethnic differences -in the frequency of primary angle-closure glaucoma in thisearly study, it can be calculated from the associated tablethat 68 of 112 (61 %) coloureds, 23 of 98 (23,5%) whites and8 of 41 (19,5%) blacks with primary glaucoma had primaryangle-closure glaucoma.'6 This fact was not recognised byMann27 and was not included in a recent major review on theepidemiology of primary angle-closure glaucoma.3Our study shows no differences in the histocompatibilityantigen profile of patients with primary angle-closureglaucoma and controls. This indicates a lack of associationbetween primary angle-closure glaucoma andhistocompatibility antigens and supports the findings ofRitch" (20 patients) and Gieser" (35 patients) in the USA. Italso confirms that the coloured patients in this study aresignificantly different genetically from white and black SouthAfricans and that the sample of patients is representative ofthe ethnic background from which they were drawn.'5In conclusion, this study confirms that coloureds aresignificantly more predisposed to primary angle-closureglaucoma than whites and blacks. Because of their stronghistorical and genetic ties with south-east Asia, thispredisposition might be explained by an Eastern influenceon the ocular structure of these paients, as opposed to anAfrican or European influence. The frequency of primaryangle-closure glaucoma at a glaucoma clinic may not be thesame as that in a population-based study.3 For this reason, aprevalence study has been undertaken among the people ofthe village of Mamre, near Cape Town, and will be reportedin detail in a separate study.30This study was supported by grants from the South AfricanMedical Research Council and the University of Cape Town.REFERENCES,. Hollows Fe, Graham PA. lntraocular pressure, glaucoma and glaucoma suspectsin a defined population. Br J Ophtha/mo/ 1966; 50: 570·586. :2. Bengtsson B. The prevalence of glaucoma. Br J Ophthalmo/1981i-65: 46-49.3. Congdon N, Wang F, Tielsch JM. Issues in the epidemiology and population-based screening of primary angle-closure glaucoma. Surv Ophtha/mol 1992; 36:411-423.4. Loh PCK. The problem of glaucoma in Singapore. Singapore Med j 1968; 9: 76-80.5. Urn ASM. PACG in Singapore. Aust J Ophtha/mo/ 1979; 7: 23-30.6. Hung PT. Aetiology and mechanism of PACG. Asian Pac J aphthalmol 1990; 2:82·84.7. Sun SJ, Guan JX, Hu AH, Wang XV. A statistical and family-history-basedanalysis of primary glaucoma. Chin J aphthalmol 1985; 21: 32-34.8. Gao PW. Kubota T. SUjino K, et al. A statistical comparison of glaucoma in theThird Affiliated Hospital of China Medical College and Kyushu University (Japan).Acta Soc Ophtha/mo/ Jpn 1989; 93: 458-465.9. Alsbirk PH. Prevention and control of visual impairment and blindness (Withspecial reference to glaucoma) in Burma. World Health Organisation. ConsultantReport, SE Asia Region/OphthaJmo/ 1984; 78 (5).10. Genio CA. Gavino BC. Glaucoma profile at the Philippines General Hospital.Philippines J Ophtha/mo/ 1983; 15: 1-2.11. Clemmesen V, Alsbirk PH. Primary angle closure glaucoma in Greenland. ActaOphtha/mo/1971; 49: 47-58.12. Orance SM. Angle closure glaucoma among Canadian Eskimos. Can JOphthaJmo/ 1973; 8: 252-255.13. Arkell SM. Ughtman OA, Sommer A. Taylor HA, Korshin OM, Tielsch JM. Theprevalence of glaucoma among Eskimos of Northwest Alaska. Arch aphtha/mol1987; 105: 482-485.14. Marais JS. The Cape Coloured People 1652-1937. 1st ed. Johannesburg:Witwatersrand University Press, 1957; 1-31.15. Botha MC. Blood group gene frequencies. An indication of the geneticconstitution of population samples in Cape Town. S Atr Med J 1972; 46: suppl,1-27. .16. Salmon JF. The presenting features of primary angle-closure glaucoma in patientsof mixed ethnic background. S Air Med J 1993; 83: 594-597.17. Terasaki Pt. McClelland J, Park MS. McCurdy B. Microdroplet lymphocytecytotOXicity test. In: Aay JG, Hare OB, Petersen PO, Kayhoe DE, eds. Manual ofTissue Typing Techniques. Bethesda Md: NIH, 1974.18. Oanilovs JA, Ayoub G. Terasaki PI. B lymphocyte isolation by thrombin-nylonwool. In: Terasaki PI. ed. Histocompatibility Testing 1980. Los Angeles: UCLAPress, 1980; 287.19. Bodmer JG, Pickbourne P, Aichards S. Joint report 1a serology. In: Bodmer WF.Batchelor JA, Bodmer JG. Festenstein H, Morris PJ, eds. HistocompatibilityTesting 1977. Copenhagen: Munksgaard. 1977; 35.20. Hyams SW. Keroub C, Pokotilo E. The computer in clinical research. Prevalenceof glaucoma. Doc Ophtha/mo/ 1977; 43: 17-21.21. Hu Z. Zhao ZL, Oong FT. An epidemiological investigation of glaucoma in Beijingand Shun-yi County. Chin J Ophtha/mo/1989; 25: 115-118.22. Shiose Y, Kitazawa Y, Tsukuhara S, et al. Epidemiology of glaucoma in Japan: anationwide glaucoma survey. Jpn J Ophtha/mol 1991; 35: 133-155.23. Oavid R. Stone O. The prevalence of glaucoma in a homogeneous Africanpopulation. In: Oavid A, Ticho V, eds. Recent Advances in Glaucoma. New York:Elsevier Science Publishers BV. 1984; 145-153.24. Bartholomew AS. Glaucoma in a South African black population. A populationstudy on the Panda tribe of South Africa. S Afr Arch Ophthalmol 1976; 3: 135-150.25. Luntz MH. Primary angle-closure glaucoma in urbanised South African Caucasoidand Negroid communities. Br J aphtha/mol 1973; 57: 445-456.26. Sacks S. The glaucomas at the Cape. S Air Med J 1964; 38: 594-595.27. Mann I. Culture. Race, Climate and Eye Disease. Springfield, Ill.: Charles CThomas, 1966: 540.28. Ritch A, Podos SM, Henley W, Moss A, Southren AL. Fotino M. Lack ofassociation of histocompatibility antigens with primary open angle glaucoma.Arch Ophtha/mo/ 1978; 96: 2204-2206.29. Gieser OK, Wilensky JT. HLA antigens and acute angle-closure glaucoma. Am JOphtha/mo/1979; 88: 232-235.30. Salmon JF, Mermoud A, Ivey A, Swanevelder SA, Hoffman M. The prevalence ofprimary angle-closure and open-angle glaucoma in Mamre, Western Cape, SouthAfrica. Arch Ophthaimo/1993; 111: 1263-1269.Accepted 3 Aug 1993.Volume 84 No.9 September 1994 SAMJ

The role of ethnicity in primary angle-closure glaucoma

https://www.ajol.info/index.php/samj/article/download/149416/138912

The role of ethnicity in primary angle-closure glaucoma

Abstract

Similar works

Full text

Available Versions

AJOL - African Journals Online