APOC impact assessment studies Phase II, Morogoro Tanzania: ophthalmology report

I i APOC IMPACT ASSESSMENT STUDIES PHASE II, MOROGORO TANZANIA: OPHTHALMOLOGY REPORT By Professor Rich E. Umeh (External Ophthalmologist) Dr Habibu T.Z. Yongolo (Internal Ophthalmologist) Dr Anna J. Sanyiwa (Internal Ophthalmologist) Dr Magdalena S. Ponera (Wu-Jones Assistant) JUNE 2OO4 It COMPOSITION OF OPHTHALMOLOGY TEAM The Ophthalmology team consisted of four experts, namely, one external ophthalmologist, two National ophthalmologists and one assistant medical officer in Ophthalmology who operated the Wu-Jones computerized Motion Sensitivity Screening Test (MSST). She was assisted by one of the data entry clerks. All members of the team except one understood and spoke the local language so it was easy to explain the various procedures to the subjects. I.GENERAL OBJECTIVE To evaluate the ophthalmological impact of onchocerciasis control (CDTI) in APOC countries. 1. 1 SPECIFIC OBJECTIVES 1. To determine the changes in prevalence of onchocercal eye lesions, visual field defects and blindness using the standard clinical methods for eye examination and the Wu-Jones computerized visual function test (CVFT). 2.1 Study Area The study was carried out in Mngazi, in the Morogoro district of Tanzania. Morogoro is a semi-mountainous /lowland with an altitude of 800 - 1,200.It lies between latitude 8 and 10 degrees South of the equator and between longitudes 37 and 38 degrees East of Greenwich. The district has an area of 19,250 sq km which is about 26.5% of the total area of Morogoro Region which ts 72,973 sq km. Morogoro Region is located in the Eastern part of Tan zania and has four other districts that are all covered by 2 previous CDTI projects namely Mahenge and Kilosa. Estimated population of the district is 528,760 with an average growth rate of 2.6%o based on the 1988 census. Population density was projected as 28 persons /sq km with the higher mountainous areas being much more densely populated than the lowlands. The district is a rich agricultural area with many cash crops produced in the fertile valleys e.g. rice, cotton, sunflower, simsim etc. The religion is predominantly Christian (47%) while Muslim (26%) and Traditional religion (27%) constitute a little more than the other half. According to the 200112002 REA result,Mngazi is hyper endemic for onchocerciasis infection. The two study 2 lI villages in Mngazi community , - Mngazi and Vigolegole have estimated populations of 2,331 and 3,606 respectively. Subjects for the study were drawn from two contiguous villages, Mngazi and Vigolegole separated by a river. The people share the same language, culture and social characteristics. The villages are compact and their main occupation is subsistence farming. Main source of drinking water is tap water but domestic activities are carried out mainly in the river. There is no electricity in the area. Two health facilities, a dispensary and a Health Centre sub serve the villages. 2.2 Study Population Every subject aged l0 years and above who was examined by the dermatologist, went through the Wu-Jones MSST procedure. This translated to a total of 690 individuals. More than half of this number, i.e.432 randomly selected, had the detailed standard eye examination. Details of the sampling method have been reported in the baseline Impact Assessment study report (APOC, May, 2000). 3. METHODS 3.1 Visual Acuity Visual acuity was measured by one of the data entry clerks and two other members of the team all trained by the ophthalmologist to conduct the test. Snellen's illiterate "E" chart for distance was used for all the subjects. The chart was placed at 6 meters from the subject in broad daylight with the subject seated in a position backing the source of sunlight. After the test had been fully explained in the local language and demonstrated using a single cardboard letter "E", each eye of the subject was tested in turn while the fellow eye was occluded. J f3.2 Wu -Jones Motion Sensitivity Screening Test (MSST) Two laptop microcomputers were used for the test. The MSST was conducted in a room darkened black curtains to cut out the natural light from the windows. Only a tiny source of light was allowed to enable the subjects observe the computer screen as well as move about safely in the dark room. In addition the examiner needed light to record the results. When the subject was seated comfortably in front of the computer, the test was carefully explained to him in his local language and a test run conducted before the actual test to ensure subject fully understood the procedure. Details of the procedure are same as recorded in the previous report (Long term Impact Assessment of APOC operations, May 2000). 3.3 Clinical methods Detailed standard eye examination was carried out in another room darkened with black curtains to enable effective use of the Slit lamp biomicroscope and the ophthalmoscope. 3.3.lAnterior Segment Examination As in previous report (APOC, May 2000), each subject was first asked to bend his head between his knees for about 2 minutes to allow for the emergence of microfilaria, if any. into the anterior chamber. The eyes were then examined using the Slit lamp biomicroscope (x25 magnification). Microfilaria in the cornea or anterior chamber were examined for and counted. Cornea was also checked for presence of punctate and/or sclerosing keratitis. Other corneal pathologies were noted if these were present. Pupil response to light as well as size and shape of the pupil were noted. Anterior chamber, iris and lens were scrutinized for any signs of inflammation, atrophy or opacity, respectively. Photographs of anterior segment lesions were taken, where necessary. 4 a3.3.2 Post Segment Examination All the subjects, with the exception of those whose ocular media did not allow, had fundus examination. Funduscopy under mydriasis was carried out in subjects with visual acuity less than 6/9. Tropicamide 1o/o and /or cyclopentolate lo/o were used for dilatation of the pupil. Details of the disc and retina were noted. Signs checked for included colour and cup: disc ratio of the optic disc, typical onchocercal chorioretinitis, and non-oncho related retinal lesions. Fundus photographs were not taken due to unavailability of fundus camera 4. DATA MANAGEMENT Data were collected using questionnaire specially designed for the research. (Appendix l) and preliminary cleaning carried out before these were entered into the computer using the SPSS programme (SPSS version 10.1 package). Analysis of data involved calculation of age-specific prevalence of the variables of interest to enable comparison with results of previous impact assessment survey. For ease of analysis, and the fact that the pathology in the right and left eyes was almost similar, only findings in the right eye were used for all the variables. 5. RESULTS A total of 432 subjects, two hundred and four males (47 .2%) and 228 females (52.8%) had full standard eye examination. 5.lAge/Sex Distribution of 432 study subjects The age and sex specific distribution of the subjects are shown in Table 1. Children aged l0 to l4 years constituted the largest group, 79 (183%) followed closely by the next age group, 15 to 24 with 65 (15.1%) individuals. The elderly, aged 65 years and above had the least number, 53 (12.3%) although a relatively high when compared to the other 5 agroups. Significant difference in sex is noted only among the age group 25 - 34 where the females were more than twice the number of males (44f : l9m) and 65 years & above where this is reversed (34m : l9f). There were slightly more females than males. The difference in the sex is not significant. 5.2 Microfilaria (mf) counts in Cornea or Anterior Chamber Dead microfilaria in the cornea (DMFC) was found in only 4 individuals giving an overall prevalence of 1.0 %. This was found only in one subject in each of the following age groups- 15-24,25-34,35-44, and 55-64. Thus the age specific prevalence in any of the groups was only 2o/o. Thus the overall prevalence is lower than the baseline figure of 6.r%. Table 2 shows the age - specific distribution of microfilaria in the anterior chamber (MFAC). A total of 63(15.0%) individuals had MFAC. Those aged 55 to 64 had the highest age specific count 18(29.0%) followed by the younger age group 15 to 24 years with 1 I (17.5%). All other age groups had almost similar counts. Overall prevalence of MFAC was 63(15.0Yo) again lower than the prevalence at baseline (21.4%). 5.3 Punctate Keratitis Forty-four individuals had puntate keratitis. The age-specific frequency of punctate keratitis in the cornea of the study subjects is illustrated in Table 3a. The highest number of affected individuals was found in the age between 10-14 and25-34. The youngest age group had the highest age-specific prevalence of 31.8o/o followed by those aged between 35-44 with an age-specific prevalence of 15.9o/o. Overall prevalence of punctate keratitis was 10. 4%o.The present result is higher compared to the baseline prevalence of 9.7Yo. 6 5.4 Sclerosing Keratitis Sclerosing keratitis was noted in a total of 34 (7 .9%) out of the 432 subjects. The highest age -specific prevalence of 38.2o/o and 35.3Yo was noted in the older age groups- 55-64 and people aged 65 years and above, respectively. Age specific distribution of the lesion is shown in Table 3b. This is high compared to the previous rate of 4.7%o. 5.5 Iridocyclitis Iridocyclitis was diagnosed in l8 individuals mainly in people aged from between 55 and 64 and the elderly subjects, 65 years and above. This gives an overall prevalence of 4.2Yo; much lower than the prevalence obtained at baseline, 139%. If the number of people who had lots of pigment in the anterior chamber but without any other signs of inflammation were added, that is 48, then this number will increase to 66 giving an overall prevalence of 15.3Yo. These pigments were seen mainly in people from the age of 45 years. 5.6 Cataract The age and sex- specific frequency of subjects who had cataract is shown in Table 4. Out of a total of 228 females, 3l (13.6%) had bilateral cataracts while among 204 males, cataract was diagnosed in 33 (16.2%) individuals. As expected, frequency increased as age increased with a peak in the oldest age group. Overall prevalence of cataract for both sexes was 15.1%. 5.7 Optic atrophy Primary optic atrophy as a main cause of ocular pathology was diagnosed in only three subjects, one aged between 35 and 44 and two others were in the age group 65 years and above. This translated to a prevalence of 0.7o/o. 7 5.8 Oncho chorioretinitis Chorioretinal changes, typical of onchocerciasis infection were found in only three individuals giving a prevalence of 0.7Yo (Table 5). This figure is only about 1/3 of the prevalence noted in the baseline study (2.6%). 5.9 Intra retinal deposit There was no difference between the prevalence of intra retinal deposit (0.2%) found in this study and the baseline study (0.2%o). On both occasions the lesion was found in only Anterior onchopathology as a main cause of ocular pathology was noted in l0 individual 5 males (2.5%) and 5 females (2.2%). The overall prevalence was 2.3Yo. In contrast posterior onchopathology contributed only 0.7%. 6. 0 Distribution of Ocular Lesions Table 6 shows the distribution of ocular lesions found in 432 subjects. Cataract topped the list followed by onchopathology. 7.0 VISUAL ACUITY The frequency of visual acuity measurements are illustrated in table 7. 7.1 Visual Impairment It was possible to obtain visual acuity measurements in all the study subjects. A total of 44 individuals (10.2%) had visual impairment. All age groups were affected with the youngest age group recording a prevalence of 2.3Yo and the elderly topping the list with an age specific prevalence of 38.6.o/o. The numbers of people with impaired visual acuity increased with age. 8 7.2 Blindness A total of 28 people were blind in both eyes from all causes giving an overall prevalence of 6.5Yo. This indicates an increase of l% in the prevalence obtained in the baseline survey (5.7%). Fourteen out of these people were blind from typical onchocercal lesions giving a prevalence of 3.2%o from oncho blindness, half of the total blind. 7.3 Motion Sensitivity Screening Test A total of 690 people were available for the test but only 600 could do the test successfully. Out of these, 555 (92.5%) had full visual fields, 25 (4.2%) had moderate field loss while 20 (3.3%) persons had severe visual field loss. 8.COMPARISON OF BASELINE AND FOLLOW UP RESULTS The details of the prevalence of the variables of interest are listed in Table 8 9. DISCUSSION There was a hundred percent response with regard to the study sample. All the age groups were relatively equally represented though children under l5 tended to be more in number. There was no remarkable sex predilection in the study. Prevalence of the different variables shared a lower trend than was found in the baseline studies in the same community five years ago. For example, prevalence of dead microfilaria on the cornea and live micrifilaria in the anterior chamber were lower by as much as two thirds of the previous figures. However, when the rate of puntate keratitis, a lesion indicating disintegrating dead microfilaria on the cornea, is added on, the prevalence increases by as much as2o/o suggesting a worsening of the eye oncho problem. For a lesion like onchochoriorenitis, the low prevalence figure may be attributed 9 to the high number of corneal pathology and blind cataract, which prevented fundoscopy. In addition, it may be that the oncho species affect the anterior segment more than the posterior segment. This is a well-known pattern proven by other studies. In contrast, the prevalence of sclerosing keratitis, another indicator of anterior segment onchopathology was twice as high as baseline figures, just as the punctate keratitis. This suggests a serious problem posed by onchocercisis infection in the study area. Similarly the frequency of torpid iridocyclitis noted among study subjects support the fact that the infection is taking its toll on the eye health of the people. It is well known that iridocyclitis predisposes the eye to conditions like secondary cataract and glaucoma which are pathways to blindness. This may have contributed to the high prevalence of cataract documented in the study. It is likely that optic atrophy may have been due to onchocerciasis but there is no concrete evidence from the study to support this view. The prevalence of visual impairment and blindness in this study is noteworthy especially as the rates exceed the figures obtained in the previous study. This result may suggest a worsening in whatever condition precipitating visual disability in this area. Onchocerciasis must be a significant contributing factor since, 3.2Yo of all blind is due to oncho related lesion. With regard to the visual field measured with the MSST, majority of the normal sighted people had full fields. The moderate and severe field defects were relatively few. This is in agreement with the suggestion that oncho eye here is a predominantly anterior segment problem. 10. CONCLUSION There are indications that the study area might have a savannah-type oncho eye lesion that is, predominantly anterior segment onchopathology caused by a yet-to-be identified species of O. Volvulus.The more worrying aspect is the fact that eye oncho signs start as early as below 15 years where, for example, the age-specific prevalence of puntate keratitis was as high as 31.8%. From all indications it is clear that onchocerciasis poses a serious threat to the eye health of this population. This situation demands an urgent, l0 asystematic and sustained intervention. Fortunately treatment with ivermectin started while the team was there. This trend needs to be sustained. 1 1. COMMENTS/RECOMMENDATION l. Start of the fieldwork was delayed by a couple of days owing to the unavailability of APOC eye examination equipment. Up to the moment of writing this report, the equipment never reached the team. All eye equipment used were kindly provided by the two National ophthalmologists who deprived their hospitals of these facilities for the period of the field work. Photographs of anterior segment of the eye were taken with the dermatology team's camera. No fundus photographs were taken as a result of this problem. 2. In future it would help a lot if the necessary equipment were delivered to the site well ahead of the arrival of the team. 12. ACKNOWLEDGEMENT The authors will like to thank the Director, Dr A. Seketeli and the members of APOC Management for giving us the opportunity to participate in this very interesting study. Our profound gratitude also goes to the village leaders and the people of Mngazi for their cooperation. 1t TABLE 1. AGE AND SEX DISTRIBUTION OF 432 SUBJECTS EXAMINED Age group (yrs) Sex Total "h M '/, F.h 10-14 t5-24 25-34 35-44 45-54 55-64 >65 14.0 8.3 32 44 31 33 32 t9 42 33 t9 30 )) 24 34 20.5 16.2 9.3 14.7 10.8 11.8 16.7 37 16.2 t4.t 19.3 31.6 14.5 79 18.3 65 15.1 63 14.6 61 t4.t 55 12.7 56 13.0 s3 12.3 TOTAL 204 47.2 288 52.8 432 100 +VI-Visual impairement t2 tTABLE 2 AGE -SPECIFIC DISTRIBUTION OF MFAC** AMONG 432 SUBJECTS Total 'Age group (Yrs) Present o//o Absent o//o 10-14 t5-24 25-34 35-44 45-54 55-64 6 7 8 9.5 18 6>65 7 11 11.1 17.5 9.5 11.1 13.0 29.0 o5 63 60 55 50 53 72 54 JI 53 45 36 45 20.0 14.9 15.7 14.6 12.4 10.0 12.4 79 18.6 15.3 14.8 t4.t 12.9 13.2 12.5 TOTAL 63 14.8 362 83.8 42s 98.4 *7(1.6" ) unable to assess **MFAc-Microfilaria in the anterior chamber 13 tTABLE 3a. AGE -SPECIFIC DISTRIBUTION OF PUNCTATE KERATITIS IN 432 SUBJECTS Age group (Yrs) Present o//o Absent o//o Total 'h 18.6 15.3 14.9 14.4 13.0 12.5 12.0 63 65 63 6l 55 53 51 65 63 55 53 47 50 47 4.5 t7.l 16.6 14.5 13.9 12.4 13.2 12.4 t4 31.8 18.2 15.9 13.6 6.8 9.1 1 8 7 6 3 4 10-14 t5-24 25-34 3s-44 45-54 55-64 >65 TOTAL 44 10.4 380 89.6 424 98.0 * 8 Unable to assess t4 aTABLE 3b AGE- SPECIFIC DISTRIBUTION OF SCLEROSING KERATITIS (N:432) Age group (Yrs) Present oh Absent o//o Total ' 18.3 15.0 14.6 t4.t 12.7 13.0 12.3 79 65 63 61 55 50 53 79 o5 60 60 50 43 4t 19.8 16.3 15.1 15.1 12.6 10.8 10.3 0.0 0.0 8.8 2.9 0 0 3 I 5 10-14 t5-24 25-34 3s-44 45-54 55-64 >65 14.7 38.2 35.3 13 t2 TOTAL 34 7.9 398 92.1 432 r00 l5 aTABLE 4 AGE AND SEX - SPECIFIC FREQUENCY OF CATARACT (N:425) Age group (Yrs) Sex Total No "/"MohFoh 10-14 15-24 25-34 35-44 45-54 55-64 >65 1 0 0 1 1 5 6.3 0 0.0 0.0 0 0.0 11 1 1.6 0.0 1.6 7.8 32.8 56.2 0.0 0.0 12.9 51.6 35.4 0 0 4 t6 0.0 6.3 6.3 28.3 75.7 0 0 I 5 0.0 25 2l 36 TOTAL 33 51.6 31 48.4 64 14.8 16 a aTABLE 5 AGE -SPECIFIC DISTRIBUTION OF ONCHOCHORIORETINITIS IN 402 SUBJECTS Age group (yrs) Present 'h Absent o//o Unable oh Total 'h to asses 10-14 t5-24 25-34 35-44 45-54 55-64 >65 0.0 0.0 33.3 0.0 0.0 33.3 33.3 0 0 I 0 0 I I 79 65 62 6r 50 4t 4t 19.8 0 0.0 79 18.3 16.3 0 0.0 65 15.0 15.5 0 0.0 63 14.6 15.3 0 0.0 61 t4.l 12.5 5 t6.7 55 12.7 10.3 t4 46.7 s6 13.0 10.3 11 36.7 53 12.3 TOTAL 3 0.7 399 92.4 30 6.9 432 100 17 ITABLE 6. DISTRIBUTION OF OCULAR LESIONS **AMONG 432 SUBJECTS PATHOLOGY NO. o//o Anterior onchopathology Posterior onchopathology Primary optic atropy Cataract Glaucoma Pthisis bulbi Trachoma Others* 11 3 3 64 2.3 3 5 4 0.7 0.7 14.8 0.7 1.2 1.0 2.8t2 *Other (ARMD,Toxoplasmosis scar,macular hole,band keratopathy) **An individual may have more than one lesion. 18 tf TABLE 7. AGE- SPECIFIC DISTRIBUTION OF VISUAL ACUITY (N:432) Age group (yrs) Normal oh VI* '/" Blind " Total "/, 10-14 t5-24 25-34 35-44 45-54 55-64 >65 78 21.7 t 2.3 0 0 79 18.3 62 62 58 44 30 26 17.2 3 6.8 0 0 65 15.0 17.2 t 2.3 0 0 63 14.6 16.2 3 6.8 0 0 6r t4.t 6 t4 5 17.9 55 12.712.2 8.3 13 29.5 13 46.4 56 13.0 7.2 t7 38.6 10 35.7 53 12.3 TOTAL 360 83.3 44 10.2 28 6.5 432 100 t9 aTABLE 8. COMPARISON OF PREVALENCE OF OCULAR CONDITIONS IN MOROGORO SITE Type of lesion Baseline (1999) N=425 No "h Follow up (2004) N:432 No t/" DMFC* MFAC* PK* SK* Iridocyclitis Onchochoriorenitis Intraretinal deposit Visual Imp BIind 26 6.1 81 21.4 4t 9.7 4.7 13.9 2.6 15 3.5 f,./ 4 1.0 63 14.6 10.2 7.920 59 11 1 44 34 66 3 I 44 28 15.3 0.7 0.2 0.2 10.2 24 6.5 *DMFC- Dead microfilaria on the cornea * MFCA- Microfilaria in the anterior chamber *PK-Punctate keratitis *SK-Sclerosing keratitis 20 It Names of team members Signature Professor Rich E. Umeh Dr HabibuT.Z. Yongolo Dr Anna J. Sanyiwa Dr Magdalena S. Ponera 2t