DEMOGRAPHICS OF COLLABORATORS INVESTIGATING THE NIGERIAN MEDICAL AND DENTAL INTERNS: A MEDICAL INTERNSHIP TRAINING IN NIGERIA (MINTING) STUDY COLLABORATION.

Introduction: The internship period is a peculiar time in a doctor's career, and some have described it as a "nuisance year" during which the junior doctor assumes many roles at the same time. Junior doctors especially house officers are faced with many unique challenges; this is even more pronounced in poor resource settings like Nigeria. This study aimed to unravel and improve understanding of the challenges faced by medical and dental interns in Nigeria. Methodology: A nine-member House officers Research and Statistics Committee (HRSC) was immediately set up to include three senior colleagues - Senior Registrars and Registrar. To carry out her responsibility efficiently the committee created the House Officers Research Collaboration Network (HRCN), a 103- member team comprising medical and dental interns from across Nigeria under a collaborative - Medical INternship Training in Nigeria (MINTING) study. Results: Out of a total of the 103 House Officers Research Collaboration Network, 80 of them participated in this survey giving a 78% response rate. Ten of the intern Collaborators had additional qualification and seven of them had BSc as an initial degree. About 66 % of the Collaborators have never authored any publication. Of the 27 that have published an article; three collaborators are said to have published 15, 13, 16 articles respectively. Male collaborators where more likely to have published at least one article in the past. Thirty one of the 80 Collaborators have never been in a research collaborative group prior to this MINTING collaborative. Conclusion: This commentary is set out to describe in detail Nigerian House Officers initiative in terms of the structure, functions, operational modalities, and to investigate the demographics of the HRCN collaborators which showed that over two third of collaborators have never authored any publication and about a third of them have never been involved in collaborative research. We also believe the findings will serve as policy guide and benchmark in training the critical medical health force.

Ivermectin shows clinical benefits in mild to moderate COVID19: a randomized controlled double-blind, dose-response study in Lagos.

INTRODUCTION: In vitro studies have shown the efficacy of Ivermectin (IV) to inhibit the SARS-CoV-2 viral replication, but questions remained as to in-vivo applications. We set out to explore the efficacy and safety of Ivermectin in persons infected with COVID19. METHODS: We conducted a translational proof of concept randomized, double blind placebo controlled, dose response and parallel group study of IV efficacy in RT-polymerase chain reaction proven COVID 19 positive patients. Sixty-two patients were randomized to three treatment groups. (A) IV 6 mg regime, (B) IV 12 mg regime (given Q84 h for 2 weeks) (C, control) Lopinavir/Ritonavir. All groups plus standard of Care. RESULTS: The Days to COVID negativity (DTN) was significantly and dose dependently reduced by IV (P = 0.0066). The DTN for Control were, = 9.1+/-5.2, for A 6.0 +/- 2.9 and for B 4.6 +/-3.2. Two way repeated measures ANOVA of ranked COVID 19 +/- scores at 0, 84, 168 and252h showed a significant IV treatment effect (P = 0.035) and time effect (P < 0.0001). IV also tended to increase SPO2% compared to controls, P = 0.073, 95% CI-0.39 to 2.59 and increased platelet count compared to C (P = 0.037) 95%CI 5.55-162.55 × 103/ml. The platelet count increase was inversely correlated to DTN (r = -0.52, P = 0.005). No SAE was reported. CONCLUSIONS: 12mg IV regime given twice a week may have superior efficacy over 6mg IV given twice a week, and certainly over the non IV arm of the study. IV should be considered for use in clinical management of SARS-COV2, and may find applications in prophylaxis in high risk areas.

Onchocerciasis as a risk factor for night blindness.

PURPOSE: In the Kaduna State Nigeria Onchocerciasis focus, the prevalence of reported night blindness (RNB) was 12.9%, higher than the national average (1%), and a control non-onchocercal community (0.83%, P < 0.0001). Risk factors for RNB were explored. METHODS: This was an analysis of baseline data from the phase three ivermectin trials in Kaduna (1988-1995). 6831 subjects in the onchocercal zone and 1563 in the control zone were examined. Ordinal logistic regression was used to assess the relationship between microfilaria load (uninfected, low (<10 mf/mg), moderate (10-49 mf/mg) and high (50+ mf/mg)) and likelihood of RNB. RESULTS: Ocular evidence of vitamin A deficiency (Bitot spots or xerophthalmia) was absent in both populations. The excess risk of nightblindness attributable to domicile in this onchocerciasis-endemic area was 11.9% with a population attributable fraction of 92.2%. The prevalence of RNB and age-adjusted odds ratio increased with higher microfilaria load (P < 0.0027.) Subjects with onchocerciasis-related ocular lesions such as optic nerve disease (OND; age-adjusted OR 2.29, 95% confidence interval, CI, 1.86-2.83), sclerosing keratitis (OR 2.75, 95% CI 2.10-3.50), and onchocercal chorioretinitis (OR 1.66, 95% CI 1.22-2.26) were significantly more likely to report night blindness. Overall, subjects with a primary diagnosis of 'ocular onchocerciasis' were 50% more likely to report night blindness. OND, cataract and trachoma together accounted for 52% of all RNB but OND (onchocerciasis-related in 80% of cases) emerged as the single most common associated pathology in 30% of cases. CONCLUSIONS: Onchocercal infection probably accounted for the excess of RNB in this focus.

African programme for Onchoceriasis control: ophthalmological findings in Bushenyi, Uganda.

BACKGROUND: The overall prevalence of blindness from Onchoceriasis in Bushenyi is relatively low, most of which is to be found in the elderly. Onchoceriasis is a major health problem in Africa. The Community-Directed treatment with invermectin is a control strategy to address the problem, but baseline data are generally lacking in several countries. OBJECTIVE: To describe baseline ophthalmological data in order to assess the impact of Community-Directed with Ivermectin (CDTI) in Uganda. METHODS: The study site was in Bushenyi, Western Uganda. In a cross-sectional study, 367 persons aged 10 years or older from seven selected villages received eye examination using a standardised protocol and Wu-Jones Motion Sensitivity Testing (MSST). Besides MSST, other information sought included visual acuity, slit lamp examination, testicular opacities and intraocular presence. RESULTS: Of the 367 subjects, 219(57.2%) were males. Subjects less than 25 years of age were 104(28.3). The prevalence of blindness were 1.9% while 4.1% was visually impaired by acuity criteria alone. A further 9.1% had moderate visual field loss while 2.8% had severe field loss. There was no case of anterior chamber microfilaria but dead microfilariae were seen in two cases. Punctate keratitis was present in 1.8% with sclerosing keratitis was twice as common at 3.8%. Optic atrophy was also relatively common at 12.4%, while chorioretinitis was present in 3.3%. CONCLUSION: There was an apparent paucity of acute onchocerciasis-related lesions but a significant presence of irreversible onchocerciasis-related lesions. The most significant problem requiring intervention would appear to be cataract.

The peculiar challenges of blindness prevention in Nigeria: a review article.

AIM: To describe the challenges peculiar to Nigeria in the implementation of vision 2020: the right to sight and to proffer solutions as to the way forward METHOD: A review of the recently completed national blindness survey, current literature, and the advocacy experience of the Ophthalmological Society of Nigeria. FINDINGS: The prevalence of blindness in Nigeria is 0.78%. Over 43% of these are blind from cataracts and a further 9% from uncorrected aphakia or complications of couching. 50% of all cataract interventions are carried out by itinerant couchers. Other major causes of blindness are glaucoma (16%) corneal opacities (12%), trachoma (4%), optic atrophy (3%) onchocerciasis (1%) and macular disease (1%). 70% of these are either preventable or reversible. Nigeria has a relatively favourable ophthalmologist/population ratio of about 2.8 per million, but has a low Cataract surgical rate of 300 per million per year. The reasons for this include a lack of ownership of blindness prevention programs, a lack of political will and parlous state of funding for vision 2020. There is an abdication of responsibility for both training and services on the part of government to the International NonGovernmental organisations. Teaching hospitals no longer generate enough patient surgical load to support training. We estimate it would cost N8.5 billion ($56.8 million) to sustain the WHO recommended Cataract Surgical Rate of 3000 per million per year in Nigeria. CONCLUSIONS: Nigeria is not headed in the direction of meeting Vision 2020 targets. Advocacy involving funding through the MDGs, needs to be intensified.

Computerized motion sensitivity screening tests in a multicountry rural onchocercal community survey in Africa.

PURPOSE: To determine whether the Wu-Jones Motion Sensitivity Screening Test (MSST) accurately reflects the burden of optic nerve disease in several onchoendemic communities in Africa. MATERIALS AND METHODS: The MSST was used to evaluate subjects in the communities of Raja in Sudan, Bushenyi in Uganda, Morogoro in Tanzania, and Ikon, Olomboro, and Gembu in Nigeria. Motion sensitivity was expressed as a percentage of motion detected in the individual eye, and this was averaged for the community. A perfectly normal eye would detect all motion and score 100%. RESULTS: In this study, 3858 eyes of 2072 subjects were tested. The test was completed in 76% of respondents. Acceptability was high. Average test time was 120.4 s. The overall mean motion sensitivity of all eyes tested was 88.49%, ±17.49. Using a cutoff level of 50%, 6.4% of all subjects tested were subnormal. The highest proportion of subnormals recorded was in Morogoro at 12.7%. Severe defects in a community best correlated with optic nerve disease prevalence, while the proportion of the defect from a higher cutoff level best correlated with overall ocular morbidity. A repeat examination in the next 5 years following ivermectin treatment will show the influence, if any, on community-wide MSST performance. CONCLUSION: A wide range in community scores reflected disease diversity. The MSST appears to be a useful test in community-wide screening and diagnosis as it reflects the general level of ocular pathology and specifically, optic nerve disease.

Utility and effectiveness of computerised motion sensitivity screening tests in rural onchocercal community survey.

BACKGROUND: Non-invasive tool of community diagnosis for onchocercal endemicity needs to be identified and ascertained for their utility and effectivity in order to facilitate the control of onchocerciacis in sub-Saharan Africa OBJECTIVE: To determine the utility and effectiveness of the Wu-Jones Motion Sensitivity Screening Test (MSST) in detecting optic nerve diseases in onchocercal-endemic rural Africa. METHODS: MSST was applied to sampled subjects in the selected communities of Raja in Sudan; Bushenyi in Uganda; Morogoro in Tanzania; and of Ikom, Olamaboro and Gashaka in Nigeria. Basically, six points within the central field of vision were repeatedly tested at 1/3 meter from the screen of a laptop computer in a room darkened. Motion sensitivity was expressed as a percentage of motion detected in the individual eye and this was averaged for the community. RESULTS: A total of 3,858 eyes of 2,072 patients were examined. Seventy-six percent of the subjects completed the test, at an average test time of 120.4 (66.7) seconds. The overall mean motion sensitivity of all eyes tested was 88.49 (17.49%). At a cut-off point of 50%, 6.4% of all subjects tested were subnormal, while at 70% cutoff, 13.3% were subnormal. The highest proportion of 50% cutoff sub-normality was recorded at Morogoro at 12.7%. CONCLUSION: Motion Sensitivity Screening Test was widely accepted and easily administered to the rural and largely illiterate subjects studied. Our data suggest that the proportion of severe field defects by MSST in a community, with cutoff at 33%, best correlates with optic nerve disease prevalence, while proportion of defect from a higher cut-off level at about 50%, best correlates with overall ocular morbidity.

Utility and Effectiveness of Computerised Motion Sensitivity Screening Tests in Rural Onchocercal Community Survey

BACKGROUND: Non-invasive tool of community diagnosis for onchocercal endemicity needs to be identified and ascertained for their utility and effectivity in order to facilitate the control of onchocerciacis in sub-Saharan Africa OBJECTIVE: To determine the utility and effectiveness of the Wu-Jones Motion Sensitivity Screening Test (MSST) in detecting optic nerve diseases in onchocercal-endemic rural Africa. METHODS: MSST was applied to sampled subjects in the selected communities of Raja in Sudan; Bushenyi in Uganda; Morogoro in Tanzania; and of Ikom; Olamaboro and Gashaka in Nigeria. Basically; six points within the central field of vision were repeatedly tested at 1/3 meter from the screen of a laptop computer in a room darkened. Motion sensitivity was expressed as a percentage of motion detected in the individual eye and this was averaged for the community. RESULTS: A total of 3;858 eyes of 2;072 patients were examined. Seventy-six percent of the subjects completed the test; at an average test time of 120.4 (66.7) seconds. The overall mean motion sensitivity of all eyes tested was 88.49 (17.49). At a cut-off point of 50; 6.4of all subjects tested were subnormal; while at 70cutoff; 13.3were subnormal. The highest proportion of 50cutoff sub-normality was recorded at Morogoro at 12.7. CONCLUSION: Motion Sensitivity Screening Test was widely accepted and easily administered to the rural and largely illiterate subjects studied. Our data suggest that the proportion of severe field defects by MSST in a community; with cutoff at 33; best correlates with optic nerve disease prevalence; while proportion of defect from a higher cut-off level at about 50; best correlates with overall ocular morbidity

A comparison of the Goldmann applanation and non-contact (Keeler Pulsair EasyEye) tonometers and the effect of central corneal thickness in indigenous African eyes.

UNLABELLED: The Keeler Pulsair EasyEye non-contact tonometer (NCT) was introduced into practice at Rachel Eye Center Abuja, Nigeria, where the patients are indigenous Africans. This was compared to the 'gold standard' Goldmann applanation tonometer (GAT) to determine if the instrument was accurate in Africans, with particular reference to the influence of central corneal thickness (CCT). PATIENTS AND METHODS: 174 eyes of 88 patients were analysed. Pachymetry was performed using Sonomed PacScan AP300, and GAT with the Haag Streit R-900. Pachymetric corrections of NCT (NCTc) and GAT (GATc) were carried out with the Sonomed algorithm. Pearson's correlation r, linear regression analysis, Student t-test and Bland-Altman analysis were used to compare the instruments. RESULTS: Mean NCT readings were similar (17.36 mmHg) to mean GAT (17.42 mmHg; p = 0.769). GAT/NCT correlation coefficient, r, was 0.883 as compared with 0.868 for GATc/NCTc. The linear regression equation was GAT = 2.79 + 0.84*NCT (r(2) = 0.78). Forty-five per cent of differences were within 1 mmHg, while 79% were within 3 mmHg. This was similar to findings in some studies on Caucasians. Bland-Altman analysis however suggested that the spread of differences was wider than in those studies. Outliers (differences more than 5 mmHg) sometimes reflected difficulties encountered with GAT in routine practice. Mean CCT was 537.9 microm, (S.D. 38.4, 95% confidence interval 532.1-543.7 microm) and CCT appeared lower than in Caucasians. Both GAT and NCT IOP tended to rise with increasing CCT but NCT had a greater tendency to do so. Regression analysis suggested that NCT IOP increased by 0.6 mmHg for every 10 mum increase in CCT, compared to 0.4 mmHg for GAT. Thirty-eight per cent of the patients preferred NCT as opposed to 25% GAT. CONCLUSIONS: The Keeler Pulsair EasyEye gives reliable measurements of IOP in African eyes but is significantly affected by CCT. Particularly in borderline cases where management decisions have to be taken, it may be necessary to have pachymetric corrections based on an NCT algorithm, which appears steeper than the GAT algorithm.

APOC impact assessment studies: baseline ophthalmological findings in Morogoro, Tanzania.

The goal of the African Programme for Onchocerciasis Control (APOC) is to eliminate Onchocerciasis as a disease of public Health significance and an important constraint to socio-economic development in the 19 none OCP (Onchocerciasis Control Project) countries covered through Community-Directed Treatment with Ivermectin, CDTI. In 1998, impact assessment studies were carried out in Morogoro, Tanzania during which baseline ophthalmological parameters were established. The hypothesis being tested is that CDTI will prevent or delay progression of onchocercal eye lesions and blindness. A total of 425 subjects aged 10 years or more from 14 villages within Bwakira district ofMorogoro region in Tanzania were examined for Snellen visual acuity, ocular microfilaria, lens opacities, uveitis and posterior segment disease especially chorioretinitis and optic nerve disease. Motion Sensitivity Screening Test (MSST) was carried out as well. Microfilaria was present in the anterior chamber of nearly half (49.2%) of all subjects examined. Prevalence of blindness was extremely high at 15.2%. Onchocercal lesions were responsible for blindness in 41.5% of these, followed by cataracts (27.7%), glaucoma (10.8%) and trachoma (6.2%). The main pathway to onchocercal blindness in this population was anterior uveitis with or without secondary cataracts. There is an urgent need to get CDTI underway and institute other horizontal primary eye care measures, especially cataract backlog reduction, in order to reduce the excessive burden of avoidable blindness in this community.

Ocular morbidity from sickle cell disease in a Nigerian cohort.

UNLABELLED: Sickle cell Retinopathy is increasingly being recognised as a cause of significant ocular morbidity and blindness in Africa south of the Sahara. This study looked for retinopathy in a cohort of 90 Nigerians with Sickle Cell Disease (SCD). METHOD: The cohort consisted of black Nigerians from the Hausa-Fulani, Ibo and Yoruba, as well as other minority ethnic groups resident in the Federal Capital Territory aged between 5-36 yr. 88 patients were SS and only 2 SC. RESULTS: SCD related posterior lesions were seen in 22 patients (24%). Of these, 19 cases (21%) had Non Proliferative Sickle Retinopathy (NPSR) while 5 (5.6%) had Proliferative Sickle Retinopathy (PSR) in various stages of development, and 2 had both PSR and NPSR. Patients with PSR are at risk of blindness from vitreous haemorrhage and tractional retinal detachment. A 14-year-old male with arterio-venous anastomosis was the youngest with PSR while the most advanced PSR lesion was a sea fan in a 25-year-old female. CONCLUSIONS: standard treatment consisting of photocoagulation and/or vitrectomy is not available in many eye centres in sub-Saharan Africa and steps need to be taken to improve this situation. The role of anti-sickling remedies, if any, is the subject of ongoing investigations. Our findings with NIPRISAN, a phytomedicinal preparation currently undergoing trials, will be reported subsequently.

The problem of trachoma within an onchocerciasis-endemic zone in Kaduna: need for a multilateral approach?

INTRODUCTION: Within the mesoendemic onchocerciasis belt of Kaduna State, Northern Nigeria, there were other causes of ocular morbidity as well. We investigated the contribution of trachoma. METHODS: A total of 6831 individuals were examined for eye disease, including signs of trachoma. RESULTS: The overall prevalence of trachoma was 4.5% (577 eyes of 310 individuals), making it the second most common cause (1 in 5) of ocular morbidity after cataracts. Of the 577 eyes, 405 (70.2%) had cicatrizing disease while the rest had active disease. Overall, the prevalence of TF was 1.1% (1.3% in those < 10 years of age), TI 0.2%, TS 3%, CO 0.5% and TT 1.1% (4.3% and 3.5% in subjects aged > 55 and > 40 years, respectively). The prevalence of trachoma increased with age. The overall prevalence of blindness in the whole population was 2.7%. Trachoma accounted for 11% of this. On the other hand, onchocerciasis accounted for 3.1% of the overall ocular morbidity (less than trachoma) and 39% of the blindness. CONCLUSIONS: There appears to be a clear need to retrain middle cadre ivermectin workers in trachoma rapid assessment and SAFE strategy intervention methods in order to further impact blindness prevention in these 'onchocerciasis-endemic' zones.

The motion sensitivity screening test in clinical practice in abuja, Nigeria: affordable automated perimetry for the third world?

Perimetry is essential in the clinical management and evaluation of glaucoma patients and other patients with diseases impacting on visual fields, but automated equipment may be too expensive for many practitioners in the developing world. I have used the Wu-Jones automated motion sensitivity system in a medium sized practice in Nigeria, a developing country, and hereby present an audit of our experience with it. The Wu-Jones Motion Sensitivity screening test is a lap-top computer based test which integrates a number of components including a test program and reporting facility, a self organizing neural network, a database management mechanism, and a menu-mouse-windowing user interface. The test is available on the public domain and is small enough (194 mb) to fit into a diskette. This test has been used at the Rachel Eye Center in Abuja since 1998, and has been applied to 339 individuals, 298 of whom are included in this analysis. Patients tested fell into four main groups: those with clinical glaucoma (intraocular pressure > 20 mmHg on at least one occasion and optic cup/disc ratio of 0.5 or more), glaucoma suspects, (i.e. ocular hypertensives >20 mmHg or c/d ratio of 0.5 or more and first degree relatives of glaucoma patients) patients undergoing routine tests for pre-employment ('normals'), and 'others'. These 'normals' were used as controls. Records are available for 531 eyes. It took an average of two minutes to complete the test. Significant field defects (Motion sensitivity less than 50%) were detected overall in 15.6% of tested eyes, 7.2% of normals but in 32.6% of glaucoma eyes. Using the 'normals' as controls, the sensitivity of the test in our hands varied from 33% to 72% and specificity from 57% to 93% at motion sensitivity cut off points from 50% to 97%. At the 83% cut off point, positive and negative predictive values were 86.0% and 47.5% respectively. Reliability averaged 70%. I find the test easy to administer and understand by patients. Results can be recalled without difficulty, facilitating the longitudinal follow up process. This test will be of value to practices in the third world unable to afford more expensive equipment in the third world. The main investment would be in form of a laptop computer and a diskette. It can also be a useful adjunct for office practice in the western world.

Trachoma: an Ancient and Contemporary Scourge

Trachoma is an ancient yet contemporary scourge. It is a specific kerato-conjunctivitis caused by certain serovars of Chlamydia trachomatis. It affects an estimated 84 million people and remains the commonest communicable cause of blindness in 6 million people. WHO has introduced the SAFE strategy which needs to be implemented with more determination in Nigeria if the level of trachoma blindness is to be positively impacted. This is particularly in the area of identification of communities in need of intervention through more widespread application of Rapid assessment methods. The challenges in trachoma research remain to improve the accurate diagnosis of active disease; to monitor emergence of antibiotic resistance and to improve the understanding of transmission and reservoirs of the infectious agent

Free-floating melanin particles in the anterior chamber: a normal finding in African eyes?

PURPOSE: Pigment dispersion syndrome (PDS) is a well-described entity with Krukenberg's spindle, heavy trabecular pigmentation and retroilluminating iris defects. We have observed a group of patients in mesoendemic onchocercal communities of Kaduna State, Nigeria, with significant amounts of free-floating melanin in the anterior chamber, normal angle pigmentation and absence of iris defects. A pseudo-Krukenberg spindle forms when the patients are asked to maintain a 2 min head-down posture as is often done when examining eyes for the presence of anterior chamber microfilaria. This spindle gradually disappears (tumbles back) after about 2 min of return to the erect posture. This paper describes this finding, which does not appear to fit into accepted notions of pigment dispersion. METHODS: As part of the seventh annual ivermectin dosing exercise during which evidence of optic nerve damage was sought, 455 patients were examined for the presence of microfilaria in the anterior chamber. A total of 352 had been selected for signs of optic nerve disease during an earlier screening exercise, while 103 belonged to a random sample of 5 years and above. Signs of onchocerciasis were sought, while gonioscopy and intraocular pressure measurements were carried out. RESULTS: Of the 455 (11%) individuals examined, 53 demonstrated this phenomenon. Within the random sample, the prevalence was 20%. These tumbling Krukenberg positive (TK+) individuals are significantly younger than TK- individuals and the prevalence, highest in the first decade, dropped steadily to zero levels over the age of 75. Sex distribution was about equal. There was no difference in intraocular pressure, cup-disc ratio and angle pigmentation. Distributions of sclerosing keratitis and chorioretinitis were not statistically different. Optic nerve disease was more common in TK- but this was attributable to the older age distribution. Five TK+ were re-examined after a period of 7 years and had not developed PDS or glaucoma. Four of the five remained TK+. A familial tendency was noted and hereditary factors may be at play, possibly autosomal recessive. The same phenomenon was noted in two of 44 patients in an ophthalmic clinic in Abuja, Nigeria, an urban, non-endemic city south of Kaduna. CONCLUSIONS: This phenomenon does not fit into accepted notions of PDS and may well be a normal finding.

Blindness: how to assess numbers and causes?

BACKGROUND: Traditionally, blindness surveys have modelled themselves on the "gold standard" of a census and examination of a whole population. Blindness, however, is a relatively rare condition even in badly affected communities; hence, large sample sizes are required to gain adequate estimates of prevalence, particularly by cause. METHODS: Three assessments of blindness prevalence and aetiology in the same communities are reported. One involved asking individuals questions concerning their visual status during a census (perceived visual status, PVD), one involved examination of all ostensibly visually disabled people presenting to a central point within each community (examination of the visually disabled, EVD), and the final assessment involved a gold standard examination of the whole population (whole community examination, WCE). RESULTS: In a population of 8139 the blindness prevalence was 2.7% PVS, 3.6% EVD, and 3.1% WCE. Attributed causes of blindness were not representative in the PVS except for cataract. The END yielded cause specific estimates not far from those found at WE except for a relative under-representation of glaucoma and optic atrophy. CONCLUSION: Since cataract is, by a significant margin, the most common cause of blindness in the world such a simple method as asking individuals if they are blind and what they believe to be the cause may yield adequate estimates of the problem for planning eye care strategies for this condition. Alternatively, an ophthalmologist visiting villages and examining allcomers for visual disability may provide reasonably accurate cause specific prevalence estimates without the expense of a major blindness survey.

Corneal changes of uncertain etiology in mesoendemic onchocercal communities of Northern Nigeria.

BACKGROUND: We report an unusual type of corneal change in some communities mesoendemic for onchocerciasis in Kaduna State of Northern Nigeria. METHODS: Thirty-four villages with an overall average microfilarial skin snip positivity rate of 71% and a total population of about 10,000 were included in a controlled trial of ivermectin for onchocerciasis. Detailed slit lamp examination of 806 persons within this population revealed at least 27 individuals with these lesions. There were 11 women and 16 men, aged between 5 and 70 years with a mean age of 45 years and a SD of 15 years. Drawings and photographs of 22 of these individuals were available for assessment. RESULTS: The lesions were peripheral, silvery white, and of two main types: the first group's lesions were flaky, refractile, and crystalline in appearance; the second group's lesions were more cylindrical in outline and were crisscrossed, giving a lattice-like pattern. There were indeterminate forms in between these polar topographies. Of the 25 subjects who had skin snips performed, 23 were microfilaria-positive. There was no accompanying inflammation and the posterior segments showed no evidence of crystalline deposits or retinitis pigmentosa, as is found in Bietti's dystrophy. The lesions coexisted with typical sclerosing keratitis in six individuals, and changes noted in the posterior pole of ten individuals were typical of onchocercal chorioretinitis. The evidence for consanguinity was not compelling. Differences between and similarities to Bietti's and Schnyder's crystalline corneal dystrophy, which are known to be composed of cholesterol crystals, are discussed. The lesions are also compared with lattice dystrophy known to be composed of amyloid. These lesions may be related to onchocercal infection. CONCLUSIONS: We describe some unusual peripheral corneal changes in individuals living within areas of Northern Nigeria mesoendemic for onchocerciasis. These changes take the form of flaky crystals or lattice within the anterior stroma and are common in middle-aged individuals. This may be related to onchocercal infection.

When should children and young adults with sickle cell disease be referred for eye assessment?

Children and young adults who suffer from sickle cell disease (SCD) are at risk of blindness from retinopathy and other complications. The incidence of proliferative retinopathy in SCD patients varies from 5 to 10% depending on the genotype, being commoner in SC than SS and S-thal. 'Sudden' blinding sequelae such as vitreous haemmorrhage and tractional retinal detachment can eventuate from vasculo-proliferative retinal lesions, known as sea fans, in otherwise 'quiet' eyes. This risk can be minimised considerably if the lesions are detected in a timely fashion and treated, usually with laser photocoagulation and possibly with cryotherapy. This communication aims, by a review of relevant literature and through our original data, to highlight a time frame for the development of proliferative sickle retinopathy to enable paediatricians decide on an appropriate time of referral for ophthalmic assessment. Ninety patients with SCD (88 SS, 2 SC) aged 5-36 years were examined for anterior and posterior ocular signs of SCD using dilated binocular indirect ophthalmoscopy. Other relevant literature was reviewed. Twenty-four percent of these patients had some form of SCD related posterior pathology, 5.6% of which was pre-proliferative or proliferative. This included a 14-year-old SS patient with arterio-venous anastomosis. The literature reveals that patients begin to exhibit evidence of proliferative retinopathy from about the age of 10 and the frequency tends to increase with age. However, though rare, vitreous haemmorhage has been known to occur below the age of 20. Children with SCD should, from about the age of ten, be referred for at least biennial dilated binocular indirect ophthalmoscopy preferably with fluorescein angiography if such facilities are available, so that neovascular lesions can be treated before blinding sequelae occur. From the age of 20, the frequency of eye examination should increase to yearly. Antisickling remedies, such as NIPRISAN may be beneficial in prophylaxis.

Glaucoma prevalence may not be uniformly high in all 'black' populations.

Epidemiological data on the prevalence of glaucoma are generally presented for populations described as "whites" or "blacks". "Black" populations appear to have a higher glaucoma preva lence than "white" populations. We describe a population-baseed survey for glaucoma in rural Northern Nigeria. A total of 1563 Hausa/Fulani individuals aged 5 years and above, underwent an extensive screening test and a detailed ophthalmological examination was performed on individuals who failed the test. The overall prevalence of open angle glaucoma in this population was 1.02% (0.12 to 3.64, 95% confidence interval) in individuals 45 years of age and older. This is lower than the prevalence rates reported for other "black" populations. The low prevalence of glaucoma detected in this African population may be, to some extent, a reflection of the age structure of the population studied or methodological differences in ophthalmic examinations performed. It is also possible that the prevalence of glaucoma varies considerably between "black" populations due to genetic heterogeneity or the effect of some unidentified environmental exposure. The use of the simple description of populations as 'black' (or 'white'), which focuses on a commonality, tends to obscure the potential heterogeneity within and between populations and thus may be unhelpful in some circumstances.