Biomedical subjects

R K John

Publications and source records attributed to R K John.

8 recordsLinked to original sources

PubMed2003

Awareness of eye diseases in an urban population in southern India.

OBJECTIVE: To assess the level of awareness of eye diseases in the urban population of Hyderabad in southern India. METHODS: A total of 2522 subjects of all ages, who were representative of the Hyderabad population, participated in the population-based Andhra Pradesh Eye Disease Study. Of these subjects, 1859 aged > 15 years responded to a structured questionnaire on cataract, glaucoma, night blindness and diabetic retinopathy to trained field investigators. Having heard of the eye disease in question was defined as "awareness" and having some understanding of the eye disease was defined as "knowledge". FINDINGS: Awareness of cataract (69.8%) and night blindness (60.0%) was moderate but that of diabetic retinopathy (27.0%) was low, while that of glaucoma (2.3%) was very poor. Knowledge of all the eye diseases assessed was poor. Subjects aged > or = 30 years were significantly more aware of all eye diseases assessed except night blindness. Multivariate analysis revealed that women were significantly less aware of night blindness (odds ratio (OR) = 0.78; 95% confidence interval (CI) = 0.63-0.97). Education played a significant role in awareness of these eye diseases. Study subjects of upper socioeconomic status were significantly more aware of night blindness (OR = 2.20; 95% CI = 1.29-3.74) and those belonging to upper and middle socioeconomic strata were significantly more aware of diabetic retinopathy (OR = 2.79; 95% CI = 2.19-3.56). Muslims were significantly more aware of cataract (OR = 2.36; 95% CI = 1.84-3.02) and less aware of night blindness (OR = 0.52; 95% CI = 0.42-0.64). The major source of awareness of the eye diseases was a family member/friend/relative suffering from that eye disease. CONCLUSION: These data suggest that there is a need for health education in this Indian population to increase their level of awareness and knowledge of common eye diseases. Such awareness and knowledge could lead to better understanding and acceptance of the importance of routine eye examinations for the early detection and treatment of eye diseases, thereby reducing visual impairment in this population.

Adolescent↗

PubMed2001

Blindness in the Indian state of Andhra Pradesh.

PURPOSE: To determine the current prevalence and causes of blindness in the Indian state of Andhra Pradesh to assess if blindness has decreased since the last survey of 1986-1989. METHODS: A population-based epidemiology study, using a stratified, random, cluster, systematic sampling strategy, was conducted in the state of Andhra Pradesh in India. Participants of all ages (n = 10,293), 87.3% of the 11,786 eligible, from 94 clusters in one urban and three rural areas representative of the population of Andhra Pradesh, underwent interview and a detailed dilated ocular evaluation by trained professionals. Blindness was defined as presenting distance visual acuity < 6/60 or central visual field < 20(o) in the better eye. RESULTS: Two hundred seventy-five participants were blind, a prevalence of 1.84% (95% confidence interval, 1.49%-2.19%) when adjusted for the age, sex, and urban-rural distribution of the population in 2000. The causes of this blindness were easily treatable in 60.3% (cataract, 44%; refractive error, 16.3%). Preventable corneal disease, glaucoma, complications of cataract surgery, and amblyopia caused another 19% of the blindness. Blindness was more likely with increasing age and decreasing socioeconomic status, and in female subjects and in rural areas. Among the 76 million population of Andhra Pradesh, 714,400 are estimated to have cataract-related blindness (615,600 cataract, 53,200 cataract surgery-related complications, 45,600 aphakia), and 228,000 refractive error-related blindness (159,600 myopia, 22,800 hyperopia, 45,600 refractive error-related amblyopia). If 95% of the cataract and refractive error blindness in Andhra Pradesh had been treated effectively, 3.4 and 7.4 million blind-person-years, respectively, could have been prevented. If 90% of the blindness due to preventable corneal disease and glaucoma had been prevented, another 2.7 million blind-person-years could have been prevented. CONCLUSIONS: The prevalence of blindness in this Indian state has increased from 1.5% in the late 1980s to 1.84% currently, as against the target of the National Program for Control of Blindness to reduce the prevalence to 0.3% by 2000. The number of people with cataract-related blindness has not reduced even with the eye care policy focus on cataract. Reduction of blindness in India will require strategies that are more effective than those that have been pursued so far.

Adolescent↗

PubMed2000

Angle-closure glaucoma in an urban population in southern India. The Andhra Pradesh eye disease study.

OBJECTIVE: To assess the prevalence and features of angle-closure glaucoma (ACG) in an urban population in southern India. DESIGN: A population-based, cross-sectional study. PARTICIPANTS: A total of 2522 (85.4% of those eligible) persons of all ages, including 1399 persons 30 years of age or older, from 24 clusters representative of the population of Hyderabad city. TESTING: The participants underwent an interview and detailed eye examination that included logarithm of minimum angle of resolution visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, and gonioscopy; pupil dilatation and stereoscopic fundus evaluation was performed if the risk of angle-closure as a result of dilatation was not believed to be imminent. Humphrey threshold 24-2 visual fields (Humphrey Instruments Inc., San Leandro, CA) were performed when indicated by standardized criteria for disc damage or if intraocular pressure (IOP) was 22 mmHg or more. MAIN OUTCOME MEASURES: An occludable angle was defined as pigmented posterior trabecular meshwork not visible by gonioscopy in three quarters or more of the angle circumference. Manifest primary angle-closure glaucoma (PACG) was defined as IOP of 22 mmHg or more or glaucomatous optic disc damage with visual field loss in the presence of an occludable angle. An IOP of 22 mmHg or more or glaucomatous optic disc damage in the presence of an occludable angle secondary to an obvious cause was defined as secondary ACG. RESULTS: Manifest PACG and occludable angles without ACG were present in 12 and 24 participants, respectively, with age- and gender-adjusted prevalence (95% confidence interval [CI]) of 0.71% (0.34%-1.31%) and 1.41% (0.73%-2.09%) in participants 30 years of age or older, and 1.08% (0.36%-1.80%) and 2.21% (1.15%-3.27%) in participants 40 years of age or older, respectively. With multivariate analysis, the prevalence of these two conditions considered together increased significantly with age (P < 0.001); although not statistically significant, these were more common in females (odds ratio 1.70; 95% CI, 0.82-3.54) and in those belonging to lower socioeconomic strata as compared with middle and upper strata (odds ratio, 1.82; 95% CI, 0.88-3.74). The odds of manifest PACG were higher in the presence of hyperopia of more than 2 diopters ([D]; odds ratio, 3.69; 95% CI, 0.89-15.2). Only four of 12 participants (33.3%) with manifest PACG had been previously diagnosed, and one of 12 (8.3%) had peripheral iridotomy performed previously. Manifest PACG had caused blindness in one or both eyes in five of these 12 participants (41.7%); best-corrected distance visual acuity less than 20/400 in one or both eyes in four patients, and acuity less than 20/200 in one eye in another patient. Most (83.3%) of those with manifest PACG could be classified as having chronic form of the disease. We may have underestimated manifest PACG because visual fields were per- formed only on those with clinical suspicion of optic disc damage. Secondary ACG was present in two participants. CONCLUSIONS: The prevalence of PACG in this urban population in southern India is close to that reported recently in a Mongolian population. A large proportion of the PACG in this population was undiagnosed and untreated. Because visual loss resulting from PACG is potentially preventable if peripheral iridotomy or iridectomy is performed in the early stage, strategies for early detection of PACG could reduce the high risk of blindness resulting from PACG seen in this urban population in India.

Adolescent↗

PubMed2000

Open-angle glaucoma in an urban population in southern India: the Andhra Pradesh eye disease study.

OBJECTIVE: To assess the prevalence and features of open-angle glaucoma in an urban population in southern India. DESIGN: A population-based cross-sectional study. PARTICIPANTS: A total of 2522 persons (85.4% of those eligible) of all ages, including 1399 persons 30 years of age or older, from 24 clusters representative of the population of Hyderabad city. TESTING: The participants underwent an interview and detailed eye examination that included logarithm of minimum angle of resolution visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, dilatation, cataract grading, and stereoscopic fundus evaluation. Automated Humphrey threshold 24-2 visual fields (Humphrey Instruments Inc., San Leandro, CA) and optic disc photography were performed when indicated by standardized criteria for disc damage or if intraocular pressure (IOP) was 22 mmHg or more. MAIN OUTCOME MEASURES: Definite primary open-angle glaucoma (POAG) was defined as obvious glaucomatous optic disc damage and visual field loss in the presence of an open-angle, and suspected POAG was defined as suspected glaucomatous optic disc damage without definite visual field loss. Ocular hypertension (OHT) was defined as IOP of 22 mmHg or more without glaucomatous optic disc damage or visual field loss in the presence of an open-angle. Glaucomatous optic disc damage or IOP of 22 mmHg or more secondary to an obvious cause and with an open-angle was defined as secondary open-angle glaucoma. RESULTS: Definite POAG, suspected POAG, and OHT were present in 27, 14, and 7 participants, respectively, with age- and gender-adjusted prevalence (95% confidence interval) of 1.62% (0.77%-2.48%), 0.79% (0.39%-1.41%), and 0.32% (0.10%-0.78%) in those 30 years of age or older, and 2.56% (1.22%-3.91%), 1.11% (0.43%-1.78%), and 0.42% (0.11%-1.12%) in those 40 years of age or older, respectively. The prevalence of POAG increased significantly with age using multivariate analysis (P < 0.001). Only two of 27 participants (7.4%) with definite POAG had been previously diagnosed and treated, and 66.7% of the previously undiagnosed had IOP less than 22 mmHg. Fourteen of 27 participants (51.9%) with definite POAG had severe glaucomatous damage based on optic disc and visual field criteria, of which five participants (18.5%) had at least one blind eye as a result of POAG (all with best-corrected distance visual acuity less than 20/400 or central visual field less than 10 degrees); the other 13 participants (48.1%) had moderate glaucomatous damage. Because visual fields and optic disc photography were not performed on all participants, the prevalence of POAG may have been underestimated. Secondary open-angle glaucoma was present in one participant as a result of angle recession. CONCLUSIONS: The prevalence of open-angle glaucoma in this urban population in southern India is at least as much as that reported recently from white populations in developed countries. However, the vast majority of persons with glaucoma were undiagnosed in this population, and a large proportion of those having definite POAG already had severe glaucomatous damage.

Adolescent↗

PubMed2000

Ocular trauma in an urban population in southern India: the Andhra Pradesh Eye Disease Study.

PURPOSE: To assess the cumulative prevalence of ocular trauma and presence of vision loss due to ocular trauma in an urban population in southern India. METHODS: As part of the population-based Andhra Pradesh Eye Disease Study, 2522 people of all ages from 24 clusters representative of the population of Hyderabad city in southern India, underwent a detailed interview and standardized dilated ocular evaluation. An eye was considered to be blind due to trauma if best corrected distance visual acuity was worse than 6/60 due to trauma. RESULTS: One hundred and thirteen subjects gave a history of ocular trauma and another two had evidence of ocular trauma by examination, a combined age sex-adjusted rate of 3.97% (95% CI 2.52-5.42%). Blindness in one eye due to trauma was present in 17 subjects, and in both eyes in one subject, a combined age-sex-adjusted prevalence of 0.60% (95% CI 0.23-1.04%). Visual acuity in all the blind eyes except one was worse than 3/60. With multiple logistic regression, the odds of blindness in at least one eye due to trauma were highest for current age range of 30-39 years (odds ratio 6.33, 95% CI 1.69-23.77 compared with a current age of less than 30 years), were significantly higher for lower socioeconomic status (3.74, 95% CI 1.18 -11.84), and were higher for males (2.48, 95% CI 0.91-6.82) though this did not reach statistical significance. Trauma resulting in blindness had occurred by the age of 15 years in 55% of subjects, and before the age of 40 years in 92.1% of subjects; this had occurred most commonly while playing (53.6% of the cases). With multiple logistic regression, the odds ratios for any ocular trauma were significantly higher for males (2.10, 95% CI 1.40-3.15), and for labourers than for other occupations (2.50, 95% CI 1.62-3.86). CONCLUSIONS: Ocular trauma affects one in 25 people in this urban population in India, and one in 167 people in this population are estimated to be blind in at least one eye due to trauma. The majority of the trauma resulting in blindness occurs during childhood and young adulthood, and slightly more than half occurs while playing. Targeting mothers and children of lower socioeconomic strata in eye health awareness strategies to reduce blindness due to trauma needs to be considered in urban India.

Adolescent↗

PubMed2000

Population based assessment of uveitis in an urban population in southern India.

AIM: To assess the prevalence of active and inactive uveitis unrelated to previous surgery or trauma in an urban population in southern India. METHODS: As part of the Andhra Pradesh Eye Disease Study, 2522 subjects (85.4% of those eligible), a sample representative of the population of Hyderabad city in southern India, underwent interview and detailed dilated eye examination. Presence of sequelae of uveitis without current active inflammation was defined as inactive uveitis. RESULTS: Unequivocal evidence of active or inactive uveitis unrelated to previous surgery or trauma was present in 21 subjects, an age-sex adjusted prevalence of 0.73% (95% confidence interval (CI) 0.44-1.14%). Active uveitis was present in eight subjects, an age-sex adjusted prevalence of 0.37% (95% CI 0. 19-0.70), of which 0.06% was anterior, 0.25% intermediate, and 0.06% posterior. The 0.36% (95% CI 0.17-0.68%) prevalence of inactive uveitis included macular chorioretinitis scars (0.26%), anterior (0. 07%) and previous vasculitis involving the whole eye (0.03%). The prevalence of visual impairment due to uveitis of less than 6/18 in at least one eye was 0.27%, less than 6/60 in at least one eye was 0. 16%, and less than 6/60 in both eyes was 0.03%. CONCLUSION: These population based cross sectional data give an estimate of the prevalence of various types of uveitis in this urban population in India. Active or past uveitis that might need treatment at some stage was present in one of every 140 people in this population.

Acute Disease↗

PubMed2000

Sample size for ophthalmology studies.

Knowledge and the usage of actual sample size formulae are a necessity as validity of the inferences from research studies is often dependent on this. This paper explains how sample sizes are calculated. The concept of sampling variation is explained to emphasize the need for its proper calculation. Sample size formulae are explained with examples to provide researchers with a means of calculating the sample sizes for the commonly used study designs. Ophthalmic data are used as examples. It is perceived that this will improve the quality of inferences drawn from ophthalmic research studies.

Humans↗

PubMedDate not supplied

Estimation of blindness in India from 2000 through 2020: implications for the blindness control policy.

BACKGROUND: To eliminate avoidable blindness in India, appropriate national planning is necessary, which should be based on current and reliable data. A national survey done in 1986-89 reported that 1.5% of the Indian population (12 million people) was blind with a presenting visual acuity of < 6/60 in the better eye. The original goal of the National Programme for Control of Blindness was to reduce this prevalence to 0.3% by 2000. We have recently reported the prevalence of blindness in the population of Andhra Pradesh to be 1.66% with a presenting visual acuity of < 6/60 in the better eye as the sole criterion and 1.84% with a presenting visual acuity of < 6/60 orcentral visual field < 20 degrees in the better eye. We used these population-based data to estimate blindness in India in 2000 and project the possible scenarios of blindness through 2020 with different emphases of the blindness control policy in India. METHODS: Recent population-based data on the age-, sex- and cause-specific blindness rates from the Andhra Pradesh Eye Disease Study for the entire age range were applied to the population distribution of India to estimate the number of blind persons in 2000. The age-, sex- and cause-specific rates of blindness were then applied to the estimated age, sex and urban-rural population distribution of India in 2010 and 2020 to project the number of persons blind (from various causes) and the blind person-years that would be suffered under varying degrees of emphasis in the policy to control blindness due to particular diseases. For these projections, blindness was defined as a presenting distance visual acuity of < 6/60 or central visual field < 200 in the better eye. RESULTS: The number of blind persons in India in 2000 was estimated to be 18.7 million (95% confidence interval [CI]: 15.2-22.3), of which 9.5 million were cataract-related and 3 million refractive error-related. If there is no change in the current trend of blindness, the number of blind persons in India would increase to 24.1 million (95% CI: 19.7-28.4) in 2010, and to 31.6 million (95% Cl: 26.4-36.9) in 2020. If effective strategies are put in place to eliminate 95% of blindness due to cataract by 2020, blindness in 15.6 million persons would be prevented who would otherwise be blind in 2020 if the current trend continues, and 78 million blind person-years would be prevented in these persons. Similarly, if effective strategies are also implemented to eliminate 95% of the refractive error blindness by 2020, another 4.2 million persons would be prevented from being blind in 2020, and 82 million blind person-years would be prevented. In addition, if strategies to prevent 90% of the preventable blindness due to corneal disease and glaucoma are successful by 2020, blindness in an additional 3.6 million persons in 2020 and 29 million blind person-years would be prevented. CONCLUSION: The planning of blindness control in India should take into account recent population-based data for the entire age range, which suggest that the number of blind persons in India is currently over 18 million. This estimate is 50% more than the figure of 12 million from a decade ago that is still quoted widely in the blindness control policy documents. If avoidable blindness is to be substantially reduced in India by 2020, effective strategies against blindness due to cataract and refractive error are needed urgently as both these conditions are relatively easy to treat. Also, strategies against preventable corneal and glaucoma blindness need to be strengthened soon for them to show an impact over the next two decades.

Adolescent↗