Marwan S. Al-Dulaimy College of Medicine, University of Tikrit

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1 Distribution of blindness and low vision among patients attending out patient clinic in Tikrit Marwan S. Al-Dulaimy College of Medicine, University of Tikrit Abstract The magnitude and geographical distribution of blindness and low vision are greatly unknown. The current study aimed to estimate the distribution of blindness and low vision, identify the main causes of blindness and low vision, and estimate targets for blindness prevention programs. A cross-sectional study of randomly selected patients aged 5 years and above attending ophthalmological out patient clinic in tikrit teaching hospital was conducted from December 2008 to May Vision status was defined using World Health Organization categories of visual impairment based on presenting visual acuity. 2,499 (84.6%) were examined. Prevalence of blindness (presenting VA of less than 3/60 in the better eye) was 4.1%; prevalence of low vision (presenting VA of at least 3/60 but less than 18/60 in the better eye) was 7.7%; whereas prevalence of monocular visual impairment (presenting VA of at least 18/60 in better eye and VA of less than 18/60 in other eye) was 4.4%. Prevalence of blindness and low vision increased in both male and female with age. The main causes of blindness were considered to be cataract (41.2%) and glaucoma (35.3%), whereas low vision was mainly caused by glaucoma (58.1%) and cataract (29.3%).causes of monocular visual were trachoma and other causes (32.1%), cataract (22.0%). Visual impairment due to cataract and trachoma increased markedly with increasing age.other causes of visual impairment were more common in persons aged less than 30 years compared to those aged 30 years and above. Blindness is a public health problem in Salah alddin, and there is urgent need to implement comprehensive blindness prevention programs. Further surveys are essential to confirm these tragic findings and estimate prevalence of blindness and low vision in the entire region of Salah-alddin in order to facilitate planning of VISION 2020 objectives. Introduction The World Health Organization (WHO) estimates that the number of people with visual impairment worldwide in 2002 was in excess of 161 million, of whom about 37 million were blind [1]. More than 90% of the world's visually impaired live in developing countries [2]. In these settings, blindness is associated with considerable disability ; resulting in huge economic and social consequences [3]. However, 75% of this visual impairment is estimated to be avoidable (preventable and curable) [4]. In 1999, the WHO Prevention of Blindness Program launched VISION 2020: The Right to Sight Initiative with the objective of assisting member states in eliminating avoidable blindness by the year 2020 [5,6]. The global target is to ultimately reduce blindness prevalence to less than 0.5% in all countries, or less than 1.0% in any community [7,8]. There are many causes of blindness, including cataract, glaucoma, injury, diabetic retinopathy, infections, malnutrition, age related macular degeneration [9, 10]. It is estimated that 75% of the cases of blindness in these countries could have been prevented but in situations where people are poor and live in remote locations both prevention and treatment efforts are extremely difficult. In times of war and civil conflict, the problems become even more severe; in these situations it is very hard even to get an idea of the number of people who are blind. Surveys to find this out are important as a first step toward providing prevention and treatment services, Surveys play an essential part in international efforts to fight blindness [9, 10]. The WHO classification of visual impairment was used to define vision status for study participants. Blindness was defined as a presenting VA of less than 3/60 in the

2 better eye. Low vision was defined as presenting VA of at least 3/60 but less than 6/18 in the better eye. Monocular visual impairment, which is not a WHO definition, was derived to represent participants who had normal or near-normal vision in the better eye (VA of at least 6/18) and visual impairment in the other eye (VA less than 6/18) [11]. Subjects and Methods A cross-sectional study of randomly selected patients aged 5 years and above attending ophthalmological out patient clinic in tikrit teaching hospital was conducted from December 2008 to May The study was conducted among persons aged 5 years and above. This target group was included because anecdotal data showed that blindness was common in both adults and children. The minimum age for visual acuity testing was predetermined to be 5 years. There are no reliable data on blindness prevalence in salah alddin on which to base sample-size calculations. The current study calculated sample size assuming an expected blindness prevalence of 2.0% and worst acceptable prevalence of 1.0%., we estimated that at least 2,104 persons aged 5 years and above were to be examined. A complete history including age, sex, ocular and medical history, compliance to ocular medications, commitment to regular follow up visits, previous eye surgeries and family history was taken from all patients. Ophthalmic examination included snellens E chart visual acuity testing, anterior segment examination via slitlamp, intraocular pressure (IOP) measurement via goldmanns applanation tonometry,refraction, posterior segment examination after mydriasis via indirect ophthalmoscope.visual acuity (VA) testing was conducted using the Snellen E chart at 6 m in adequate daylight, outdoors. In participants with VA less than 6/60, VA was evaluated with the Snellen chart at 3 m. Further VA assessment was done in participants with VA less than 3/60 by counting fingers, hand movement, and light perception, as appropriate. Basic eye examination was done in all persons after VA testing. Using a torch and a 2.5 magnifying binocular loupe and slit lamp, each eye was examined separately for inturned lashes (trichiasis), the cornea was then inspected for corneal opacities, and the lens examined for cataract and IOP measurement done shiotz and applanation tonometry. Data were recorded on a customized form, and the cause of visual impairment determined for all patients with a presenting VA of less than 6/18 for each eye separately. Patients who required surgical intervention or further assessment were referred to attend a surgical unit that was organized and conducted after the survey. After the survey, this study determined the principal disorder responsible for blindness or low vision for the patients, taking into account the main cause for each individual eye. In the instance when different causes had been identified for each eye separately in a given individual, the principal disorder was chosen to be the one that was most readily curable or, if not curable, most easily preventable.sensitivity analysis of the prevalence estimates was undertaken by including all the enumerated persons in the denominator under the assumption that the absentees had no visual impairment; and the size of the change in prevalence estimates assessed Inter-rater agreement of eye examination (VA and determination of cause) was assessed using the kappa (κ) statistic. To derive population estimates of burden, prevalence estimates were adjusted for age and sex according to the sample population structure. Results Sample study. A total of 2,499 persons aged 5 years and above underwent VA testing and basic eye examination, a response rate of 84.6%. Of the 2,499 persons included in the analysis, 1,038 (41.5%) were males and 1,461 (58.5%) were females figure 1, Table 1. The age and sex distribution among the 454 persons not examined was the same; however, there were more females than males aged 15 y and above among persons examined (p-value = 0.001). The age range was 5 years 80 years, with a mean age of 23.9 y (SD = 16.6).

3 Prevalence of Blindness, Low Vision, and Monocular Visual Impairment. The age/sex-specific and overall prevalence of blindness, low vision, and monocular visual impairment found in this study are shown in figure 2. Table 2 Overall prevalence of blindness (VA of less than 3/60 in the better eye) was 4.1%. Prevalence of low vision (VA of at least 3/60 but less than 6/18 in the better eye) was 7.7% ; whereas prevalence of monocular visual impairment (VA of at least 6/18 in the better eye and VA less than 6/18 in the other eye) was 4.4%. Prevalence of blindness and low vision increased in both males and females with age. Sensitivity analysis of prevalence estimates by including 454 absentees in the denominator under the assumption that they had no visual impairment. kappa statistic was Causes of Blindness, Low Vision, and Monocular Visual Impairment: The age/sex-specific and overall prevalence of blindness, low vision, and monocular visual impairment found in this study are shown in Figures 3-6, and Table 3. Cataract was the leading cause of blindness (41.2%), followed by glaucoma (35.3%), diabetic retinopathy (18.6%), and trachoma and other causes (4.9%). Low vision was caused mainly by glaucoma (58.1%),and cataract (29.3%) ; whereas diabetic retinopathy and trachoma plus other causes accounted for 6.8% and 5.8% of low vision, respectively. Causes of monocular visual impairment were trachoma (37.6%), other causes (31.2%),, cataract (22.0%), Visual impairment due to cataract and trachoma increased markedly with increasing age. Other causes of visual impairment were more common in persons aged less than 30 years compared to those aged 30 years and above. Discussion The main causes of visual impairment in this study was cataract (41.2%), followed by glaucoma (35.3%), and diabetic retinopathy (18.6%), trachoma and other causes (4.9%). Like in other developing countries, cataract constitutes the main cause of blindness and it is prevalence in rural population than in urban population.. Therefore keefe JE et al found the main causes of blindness in eastern mediaerran countries to be cataract (45.2%) trachoma (25.7%) glaucoma (5.7%) others ( 23.4%)[ 12]. Keefe et al reported that the transition from where cataract predominate as a major cause of visual loss to one where age related retinal disease account for most vision results from high cataract surgery rates in developing countries but also the aging of population. we think that relative low incidence of blindness caused by cataract in western countries is attributed to easy assess to surgery, early surgery, fewer complications. In our community, especially in rural areas, cataract patients are used to present late due to false believe that the cataract should only be extracted when it become mature.this false belief should be discouraged in order to decrease the incidence of blindness attributed to cataract [ 12]. In my study Glaucoma was the second commonest cause of blindness (35.3%) greatly exceed Keefe et al that found the glaucoma (5.7%) [12]. And is consistent with that reported in study in south Pakistan (32.2 %) [13]. Many patients with glaucoma present late as they are not aware of having it.some patients were not committed to their regular follow up visits, while some others were not compliant to their ocular medications due to poor understanding of disease process or from unavailability of expensive eye drops. I think that a screening program for patients at high risk of developing glaucoma is important in preventing blindness from this irreversible blinding disorder. The WHO considers blindness to be public health problem when the prevalence of blindness in general population exceeds 1% [14]. The prevalence of blindness revealed in Tikrit teaching hospital in Salah alddin greatly exceed with this WHO parameter and is consistent with that reported in study in south india (3.2 %) [15].Blindness prevalence in salah alddin also exceeds that reported in other setting like Gambia (0.7%) [16], Nigeria (0.3%_ 0.9%) [17] tazania (1.3%) [18]. Diabetic retinopathy contribute (18.6%) this exceed that in Turkmenistan (8.3% ) [ 19] Ireland ( 5.8%) [20 ]

4 Malaysia ( 4.2 %). [ 21 ]and consistent with south afagnstan ( 15.3 %).[ 22] Blindness caused by diabetes mellitus is considered to be preventable and curable if promptly dealt with, patient with diabetes should be referred to ophthalmologist as soon as they are discovered for regular follow up and to detect and manage any abnormality before developing advanced diabetic retinopathy.a substantial number of patients do not believe in the benefits of laser treatment, and others find it difficult to travel long way to receive laser treatment if it is not available in their region. this lack of knowledge and ignorance of diabetic patient constitute a major cause of loss vision, which can be reduced by educating the patient about complications of diabetes mellitus and benefit of laser treatment. In present study trachoma and other causes contribute (4.9%). Trachoma also important cause of blindness and was leading cause of all forms of visual impairment the proportion of blindness due to trachoma by far exceeds what been observed in other countries where trachoma is endemic :: Mali (12.1%) [23], Kenya (18.7%) [24], Ethiopia (20.6%) [25], and Tanzania (26%) [26]. In salah alddin, trachomatous trichiasis (TT) has been documented in children as young as 4 years, overall (all ages) TT prevalence was prevalence of bilateral trachomatous corneal opacity [27]. Nontrachomatous corneal opacity cause visual impairment. Although the etiology of such corneal scarring in adults is often difficult to ascertain, the histories obtained suggested that ocular trauma, vitamin A deficiency, measles, and corneal infections were the most likely causes. I observed a lower than expected prevalence of monocular visual impairment and a low ratio of blindness to low vision. This atypical picture may partly be explained by severe and early onset of blinding trachoma, accumulation of blindness in the absence of eye care services, as well as over sampling of blind people. There are several studies on blindness in childen. With retinal degeneration, congenital cataract, congenital glaucoma and corneal scar being the most common etiologies. Blindness in childhood has reaching implications for the affected child and family and throughout life it profoundly influence educational employment personal and social aspects,thus, the control of childhood blindness has identified as priority to WHO global initiative for avoidable blindness by year [28 ] The study area has blindness of severe public health magnitude with over 4-fold prevalence compared to WHO parameters. The high prevalence of low vision and monocular visual impairment predicts a greater prevalence of blindness in the study area in the future. There is urgent need to target blindness prevention interventions in this population. This will involve setting up cataract surgical services, trachoma control programs, vitamin A supplementation, and optometry services. There is also need to put in place interventions to rehabilitate persons whose blindness is not reversible, especially those blinded by trachoma. conclusions 1. There were more females than males aged 15 years and above among persons examined. 2. The overall prevalence of blindness ( VA of less than 3/60 in better eye ) was 4.1%. 3. Prevalence of low vision ( VA of at least 3/60 but less than 6/18 in better eye was 7.7%. 4. Prevalence of blindness and low vision increased in both males and females with age 5. There are no difference between sexes in the odds of blindness 6. The main cause of visual impairement was cataract ( 41.2%) followed by glaucoma (35.3%), diabetic retinopathy ( 18.6% ) and trachoma plus other causes ( 4.9% ) 7. Low vision was caused mainly by glaucoma (58.1%) and cataract (29.3%) where as diabetic retinopathy and trachoma plus other causes accounted for 6.8% and 5.8% of low vision respectively. 8. Causes of monocular visual impairment were trachoma ( 37.6), other causes (31.2 % ), cataract ( 22.0 %) and non trachomatous corneal opacity ( 8.3%)

5 9. Visual impairment due to cataract and trachoma increased markedly with increased age 10. Other causes of visual impairment were more common in person aged less than 30 years compare to those aged 30 years and above 11. Burden estimated that blindness affected persons.low vision affected 2,291 persons where as 1,556 persons had monocular visual impairment. References 1. Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, et al. Global data on visual impairment in the year Bull World Health Organ. 2004;82: Thylefors B. A simplified methodology for the assessment of blindness and its main causes. World Health Stat Q. 1987;40: Frick KD, Foster A. The magnitude and cost of global blindness : An increasing problem that can be alleviated. Am J Ophthalmol. 2003;135: World Health Organization. VISION 2020: The right to sight The global initiative for the elimination of avoidable blindness. Magnitude and causes of visual impairment. Fact Sheet No Geneva: World Health Organization; Thylefors B. A global initiative for the elimination of avoidable blindness. Am J Ophthalmol. 1998;125: World Health Organization. Global initiative for the elimination of avoidable blindness. WHO document WHO/PBL/97.61Rev.2. Geneva: World Health Organization; World Health Organization. Strategies for the prevention of blindness in national programmes a primary health care approach. Geneva: World Health Organization; World Health Organization. Prevention of blindness and visual impairment World Health Organization. Training for mid-level managers: The EPI coverage survey. WHO document WHO/EPI/MLM/ Geneva: World Health Organization; STARBASE. WHO Polio Campaign: NIDs nd round results World Health Organization. Methods of assessment of avoidable blindness. Geneva: World Health Organization; keefe JE, Konyamak, Taylor HR. vision impairment in specific region. Br J ophthalmol 2002; 86: Pakistan Institute of Community Ophthalmology, Kyber Institute of Ophthalmic Medical Sciences, Peshawar, Pakistan. 14. International Centre for Eye Health. Epidemiology in practice: Sample size calculation for eye surveys: a simple method. Community Eye Health Journal. 1997;10: Nrmalan PK, Thulasira RD, Maneksha V, et al.apopulation based eye survey of older adults in Tirunelveli district of south india : blindness,cataract surgery and visual outcomes.br J Ophthalmol 2002;86: Faal H, Minassian D, Sowa S, Foster A. National survey of blindness and low vision in the Gambia: Results. Br J Ophthalmol. 1989;73: Adeoye A. Survey of blindness in rural communities of south-western Nigeria. Trop Med Int Health. 1996;1: Rapoza PA, West SK, Katala SJ, Taylor HR. Prevalence and causes of vision loss in central Tanzania. Int Ophthalmol. 1991;15: Amansakhatov S, volokhovskayazp,afanasyeva AN,et al. diabetic retinopathy in Turkmenistan: result of anational survey.br J opthalmol 2002;86: Munier A, Gunning T, Kenny D, O Keef m. causes of blindness in the adult population of Republic of

6 Ireland.Br J Opthalmol 1998; 82: Zainal m, Ismail SM, Ropilah AR, et al.prevelancess of blindness and low vision Malaysian population : results from national Eye survey 1996.Br J Ophthalmol 2002; 86: Ngondi J, Ole-Sempele F, Onsarigo A, Matende I, Baba S, et al. Blinding trachoma in post-conflict southern afagnstan. PLoS Med doi: /journal.pmed Kortlang C, Koster JC, Coulibaly S, Dubbeldam RP. Prevalence of blindness and visual impairment in the region of Segou, Mali. A baseline survey for a primary eye care programme. Trop Med Int Health. 1996;1: Whitfield R, Schwab L, Ross- Degnan D, Steinkuller P, Swartwood J. Blindness and eye disease in Kenya: Ocular status survey results from the Kenya Rural Blindness Prevention Project. Br J Ophthalmol. 1990;74: Zerihun N, Mabey D. Blindness and low vision in Jimma Zone, Ethiopia: Results of a population-based survey. Ophthalmic Epidemiol. 1997;4: Rapoza PA, West SK, Katala SJ, Taylor HR. Prevalence and causes of vision loss in central Tanzania. Int Ophthalmol. 1991;15: International Centre for Eye Health. Epidemiology in practice: Sample size calculation for eye surveys: a simple method. Community Eye Health Journal. 1997;10: Rahi JS, Gilbert CE, Foster A, Minassian D.Measuring the burden of childhood blindness. Br J opthalmol 199; 83: Table (1) demographic characteristic of sample study Total Female Male Age NO % NO % NO % < > Total 26(18.8) 25(16.8) Mean(SD) X2 = 20.41, df = 3, p value = (significant)

7 Table (2): Prevalence of blindness, low vision, and monocular visual impairment by age group and sex Sex & age group Vision status Vision status Vision status Male Overall Female Overall Total overall a-blind n(%) 5(0.7) 6(3.3) 24(20.7) 35(3.4) 4(0.4) 25(6.9) 38(24.5) 67(4.6) 9(0.5) 31(5.7) 62(22.9) 102(4.1) b-low vision n(%) 14(1.9) 19(10.6) 42(36.2) 75(7.2) 16(1.7) 35(9.6) 66(42.6) 117(8.0) 30(1.8) 54(9.9) 108(39.9) 192(7.7) c-monocular visual impairment n(%) 22(3.0) 13(7.2) 13(11.2) 48(4.6) 19(2.0) 29(8.0) 13(8.4) 61(4.2) 41(2.4) 42(7.7) 26(9.6) 109(4.4) a-presenting VA of less than 3/60 in the better eye b-presenting VA of at least 3/60 but less than 6/18 in the better eye c-presenting VA of at least 6/18 in the better eye and VA of less than 6/18 in other eye Table 3. Main causes of blindness, low vision, and monocular visual impairment by age group. Total,n (%) Monocular visual impairmen Low vision blindness Age group years Cause 10(12.5) 4(9.8) 4(13.3) 2(22.2) 5-29 Cataract 33(26.0) 9(21.4) 15(27.8) 9(29.0) (40.5) 11(42.3) 37(34.6) 31(50.0) (30.3) 24(22.0) 56(29.3) 42(41.2) overall 34(42.5) 14(34.1) 18(60.0) 2(22.2) 5-29 Glaucoma 66(52.0) 22(52.4) 33(61.1) 11(35.5) (45.1) 5(19.2) 60(56.1) 23(37.1) (46.8) 41(37.6) 111(58.1) 36(35.3) overall 6(7.5) 2(4.9) 3(10.0) 1(11.1) 5-29 Diabetic retinopathy 18(14.2) 4(9.5) 3(5.6) 11(35.5) (8.7) 3(11.5) 7(6.5) 7(11.3) (10.2) 9(8.3) 13(6.8) 19(18.6) overall 30(37.5) 21(51.2) 5(16.7) 4(44.4) 5-29 Trachoma and other 10(7.9) 7(16.7) 3(5.6) (5.6) 7(26.9) 3(2.8) 1(1.6) (12.7) 35(32.1) 11(5.8) 5(4.9) overall

8 _ _ Male Female a-blindness b-low visio c-monocular visual impairmen Fig. (2) Prevalence of blindness, low vision, and monocular visual impairment by age group and sex.

9 _29 30_ blindness Low vision Monocular visual impairmen Fig. (3) visual impairment by age group among cataract _29 30_ blindness Low vision Monocular visual impairmen Fig. (4) visual impairment by age group among Glaucoma _29 30_ blindness Low vision Monocular visual impairmen Fig. (5) visual impairment by age group among Diabetic retinopathy

10 _29 30_ blindness Low vision Monocular visual impairmen Fig. (6) visual impairment by age group among Trachoma and other causes