Determinants of glaucoma awareness and knowledge in urban Chennai.

AIM: To assess the awareness and knowledge levels about glaucoma and its determinants in an urban population of Chennai in south India. MATERIALS AND METHODS: Chennai glaucoma study (CGS) was a population based prevalence study to estimate the prevalence of glaucoma in a rural and urban south Indian population. A total of 3850 subjects aged 40 years or above participated in the urban arm of CGS. A systematic random sample of 1926 (50.0%) subjects completed a questionnaire that assesses their awareness and knowledge level of glaucoma. Respondents "having heard of glaucoma" even before they were contacted/recruited for the study were defined as "aware" and respondents having some understanding of the eye disease were defined as "knowledgeable". RESULTS: Overall 13.5% were aware of glaucoma, the age-gender adjusted rate for awareness was 13.3% (95% CI: 11.57 to 15.03). Two clinicians graded knowledge on glaucoma, based on the subject's knowledge of risk factors, definitions and treatment aspects of glaucoma. Overall 8.7% had some knowledge about glaucoma. Among those who had knowledge 0.5% had good knowledge about glaucoma, 4% had fair knowledge and 4.2% had poor knowledge. We observed a very good agreement between the clinicians in grading knowledge (k =0.92). Determinants of glaucoma awareness and knowledge were higher levels of education, females, age, religion and family history of glaucoma. CONCLUSION: Awareness and knowledge about glaucoma was very low among the urban population of Chennai. We have found that younger subjects and men were less aware of glaucoma. Subjects with lower levels of education were less aware and knew less about glaucoma than their counterparts. The study findings stress the need for health education for effective prevention of blindness due to glaucoma.

Comparison of Humphrey MATRIX and Swedish interactive threshold algorithm standard strategy in detecting early glaucomatous visual field loss.

PURPOSE: The aim of this study was to compare the Humphrey MATRIX visual field (frequency doubling technology threshold) and Swedish interactive threshold algorithm (SITA) standard strategy white on white perimetry in detecting glaucomatous visual field loss. MATERIAL AND METHODS: Twenty-eight adult subjects, diagnosed to have glaucoma at a tertiary eye care hospital, who fulfilled the inclusion criteria, were included in this prospective study. All subjects underwent a complete ophthalmic examination. Subjects with glaucomatous optic disc changes underwent repeat perimetric examination on the same day with the Humphrey visual field analyzer (HFA II) and Humphrey MATRIX, the order of testing being random. Only reliable fields, where the HFA results corresponded to the disc changes were considered for analysis. A cumulative defect depth in each hemifield in both HFA and MATRIX reports was calculated. RESULTS: Thirty-seven eyes of 24 subjects had reliable fields corresponding to optic disc changes. The mean age of the subjects was 56 +/- 12 years. There were 12 males and 12 females. The test duration was significantly less on the MATRIX, mean difference in test duration was -81 +/- 81.3 sec ( p p = 0.55, p = 0.64 respectively) and a positive correlation coefficient of 0.63 and 0.72 respectively. Poor agreement was found with the glaucoma hemifield test. CONCLUSION: The Humphrey MATRIX takes less time in performing the test than SITA Standard and shows good correlation for mean deviation and pattern standard deviation. However, the glaucoma hemifield test showed poor agreement. The Humphrey MATRIX diagnoses were similar to established perimetric standards.

Prevalence of retinitis pigmentosa in South Indian population aged above 40 years.

PURPOSE: The study was undertaken to evaluate the prevalence of retinitis pigmentosa (RP) in rural and urban South India. METHODS: Seven thousand seven hundred and seventy four subjects aged 40 years or more from rural and urban Tamil Nadu, underwent comprehensive ophthalmic examination out of 9576 enumerated (81.17%). After a thorough ophthalmic examination, fundus photographs were taken for documentation. Statistical analysis was done using SPSS for Windows (ver 14). RESULTS: 7461 (95.9%) subjects had fundus details seen in both eyes. Thirteen subjects (0.17%; 4 males, 9 females) were diagnosed as retinitis pigmentosa. Retinitis pigmentosa in the urban population was seen in approximately 1 in 930 persons, while 1 in 372 of rural subjects had the disorder. This figure is greater than other reports from the western populations and that of the conservative estimate of 1 in 4000. The age and gender adjusted prevalence rate of retinitis pigmentosa to national census 2001 was 0.155%. Eight subjects (61.53%) had visual acuity less than 3/60. CONCLUSION: Prevalence of RP in South India appears to be alarmingly higher in comparison to those seen in other parts of the world.

Comparison of refractive errors and factors associated with spectacle use in a rural and urban South Indian population.

PURPOSE: To compare the prevalence of refractive errors and factors associated with spectacle use in a rural and urban south Indian population. MATERIALS AND METHODS: Four thousand eight hundred subjects (age> 39 years) each from rural and urban Tamil Nadu were enumerated for a population-based study. All participants underwent a complete ophthalmic evaluation including best-corrected visual acuity (BCVA), objective and subjective refraction. Out of 3924 rural responders 63.91% and out of 3850 urban responders 81.64% were phakic in the right eye with BCVA of 20/40 or better and were included in the study. Association of spectacle use and refractive errors with different parameters were analysed using logistic regression. STATISTICAL ANALYSIS: Chi square, t test, Chi square for trend and Pearson's correlation coefficient were used for analysis. RESULTS: Spectacle use was significantly higher and positively associated with literacy and employment in the urban population. The age and gender-adjusted prevalence of emmetropia, myopia of spherical equivalent (SE) < or =-0.50 diopter sphere (DS), high myopia (SE < or =-5.00DS), hyperopia (SE> 0.50DS) and astigmatism < or = 0.50 diopter cylinder (DC) were 46.8%, 31.0%, 4.3%, 17.9% and 60.4% respectively in the rural population and 29.0%, 17.6%, 1.5%, 51.9%, 59.1% respectively in the urban population. The prevalence of emmetropia decreased with age ( p p = 0.001) and were associated with nuclear sclerosis ( p = 0.001) in both populations. Hyperopia was commoner among women than men ( p = 0.001); was positively associated with diabetes mellitus ( p = 0.008) in the rural population and negatively with nuclear sclerosis ( p = 0.001) in both populations. CONCLUSION: Spectacle use was found to be significantly lower in the rural population. The pattern of refractive errors was significantly different between both populations.

Genetic homogeneity for inherited congenital microcoria loci in an Asian Indian pedigree.

PURPOSE: Congenital microcoria is a rare autosomal dominant developmental disorder of the iris associated with myopia and juvenile open angle glaucoma. Linkage to the chromosomal locus 13q31-q32 has previously been reported in a large French family. In the current study, a three generation Asian Indian family with 15 congenital microcoria (pupils with a diameter <2 mm) affected members was studied for linkage to candidate microsatellite markers at the 13q31-q32 locus. METHODS: Twenty-four members of the family were clinically examined and genomic DNA was extracted. Microsatellite markers at 13q31-q32 were PCR amplified and run on an ABI Prism 310 genetic analyzer and genotyped with the GeneScan analysis. Two point and multipoint linkage analyses were performed using the MLINK and SUPERLINK programs. RESULTS: Peak two point LOD scores of 3.5, 4.7, and 5.3 were found co-incident with consecutive markers D13S154, DCT, and D13S1280. Multipoint analysis revealed a 4 cM region encompassing D13S1300 to D13S1280 where the LOD remains just over 6.0 Thus we confirm localization of the congenital microcoria locus to chromosomal locus 13q31-q32. In addition, eight individuals who had both microcoria and glaucoma were screened for glaucoma genes: myocilin (MYOC), optineurin (OPTN) and CYP1B1. Using direct sequencing a point mutation (144 G>A) resulting in a Q48H substitution in exon 1 of the MYOC gene was observed in five of the eight glaucoma patients, but not in unaffected family members and 100 unrelated controls. CONCLUSIONS: We have confirmed the localization of the congenital microcoria locus (MCOR) to 13q31-q32 in a large Asian Indian family and conclude that current information suggests this is a single locus disorder and genetically homogeneous. When combined with the initial linkage paper our haplotype and linkage data map the MCOR locus to a 6-7 cM region between D13S265 and D13S1280. The DCT locus, a member of the tyrosinase family involved in pigmentation, maps within this region. Data presented here supports the hypothesis that congenital microcoria is a potential risk factor for glaucoma, although this observation is complicated by the partial segregation of MYOC Q48H (1q24.3-q25.2), a mutation known to be associated with glaucoma in India. Fine mapping and candidate gene analysis continues with the hope that characterizing the micocoria gene will lead to a better understanding of microcoria and glaucoma causation. The relationship between microcoria, glaucoma, and the MYOC Q48H mutation in this family is discussed.