Differential cataract blindness by sex in India: Evidence from two large national surveys

Evaluation and model to achieve sex parity in cataract surgical coverage in Theni district, India

BACKGROUND/AIMS

To propose an approach to determine the target ratio of cataract surgical rates (CSRs) of female to male subpopulations to increase sex parity in cataract surgical coverage (CSC), based on the sex gap in cataract burden and incidence, and demonstrate its application to Theni district, India.

METHODS

A population-based longitudinal study between January 2016 and April 2018. We recruited 24 327 participants using random cluster sampling. We conducted detailed eye examinations of 7087 participants aged ≥40 years (4098 females, 2989 males). We fit exponential models to the age-specific and sex-specific cataract burden and estimated annual incidence rates. We developed a spreadsheet-based planning tool to compute the target CSR ratio of female to male subpopulations.

RESULTS

Among those aged ≥40 years, cataract burden was 21.4% for females and 17.5% for males (p<0.05). CSC was 73.9% for females versus 78.6% for males (p<0.05), with an effective CSC of 52.6% for females versus 57.6% for males (p<0.05). Treating only incident cataracts each year requires a target CSR ratio of female to male subpopulations of 1.30, while addressing in addition 10% of the coverage backlog for females and 5% for males requires a target CSR ratio of 1.48.

CONCLUSIONS

The female population in Theni district, as in many low-income and middle-income countries, bears a higher cataract burden and lower CSC. To enhance sex parity in coverage, both the higher number of annual incident cataracts and the larger backlog in females will need to be addressed.

Rapid survey for assessing effective cataract surgical coverage (eCSC) and effective refractive error coverage (eREC)-Novel indicators of universal eye health

PURPOSE

As per the recent World Health Organization estimates, approximately 2.2 billion people have near and distance vision impairment (VI) globally, and out of this almost 50% is avoidable.

METHODS

The Rapid Assessment of Avoidable Visual Impairment survey was a cross-sectional study conducted in September 2021, using cluster random sampling in 42 clusters with a cluster size of 140, giving a total of 6000 participants. Two teams comprising of trained optometrists and social workers conducted the ocular examination which included unaided, pinhole, and aided visual acuity assessments followed by examination of the anterior segment and lens. Distance visual acuity was measured using simplified tumbling "E" charts of different sizes for VA of 6/12, 6/18, and 6/60. The lens assessment was done in an un-dilated pupil with torch light by the optometrist.

RESULTS

Overall, 6520 individuals aged 6 years and above were enumerated, of whom 5440 (83.4%) were examined. The response rate for examination was better among females (93.1%) than males (73.9%), and it decreased from 93.8% in the age group 6-15 years to 77.1% in the 45+ age group. The prevalence of blindness and VI were 0.18% (95% CI: 0.06-0.29) and 4.19% (95%CI: 3.65-4.72), respectively. The major causes of VI in all age groups were uncorrected refractive error (65.4%), cataract (23.7%), cataract surgical complications (2.6%), corneal opacity (0.4%), and other posterior segment diseases (7.5%). The effective cataract surgical coverage (eCSC) was 61.8%, effective refractive error coverage (eREC) for distance vision was 59.8%, and eREC for near vision was 47.0%.

CONCLUSION

The RAAVI methodology is suitable to measure effective coverage in the general population, both for baseline measurement and periodic monitoring. The 2030 targets for the surveyed district are 90% eCSC and 100% eREC. Such exercises need to be conducted in each district of the country to determine the baseline and target values of effective coverage.

[Prevalence of ophthalmic diseases in the population older than 50 years]

The ageing of population is accompanied by an increase in the frequency of chronic diseases, including ophthalmic. The progression of ophthalmologic disturbances has population specificity and its analysis in Russian population is relevant.

PURPOSE

To study the prevalence and age- and gender-related gradient of ophthalmic diseases (cataract, glaucoma, age-related macular degeneration, diabetic and hypertensive retinopathy) in the Russian population older than 50 years.

MATERIAL AND METHODS

A random population cohort (9360, aged 45-69 years) was examined in Novosibirsk in 2003/05 and re-examined in 2015/17 (the HAPIEE project). Ophthalmological parameters were studied in a random subsample (324 m/f, aged 55-84, 2015/17). Clinical and instrumental methods were applied to assess eye diseases: cataract, glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), hypertensive retinopathy (HR) and other ophthalmic diseases.

RESULTS

In the studied sample of men and women aged 55-84 years, the prevalence of cataract was 72.8%, AMD - 25.7%, glaucoma - 6.2%, DR - 2.1%, HR - 79.6%. The prevalence of other ophthalmic diseases (myopia, hyperopia, astigmatism, pterygium, pinguecula, dystrophy of cornea and retina, tumors and inflammatory diseases) was 13.5%. The frequency of cataract (p<0.001) and AMD (p=0.003) significantly increased with age. The frequency of glaucoma did not change substantially in the studied age range with insignificant increase in those older than 80 years (14.3%). The frequency of DR and HR were not consistently related to age.

CONCLUSIONS

In the studied population sample of men and women aged 55-84 years (Novosibirsk), the prevalence of cataract and HR is high; the prevalence of AMD is similar to populations with moderate frequency of diseases; the frequency of glaucoma is close to populations with high prevalence of this disease. The frequency of cataract and AMD increased with age. There was no consistent age gradient of the frequency of glaucoma, DR and HR in the age range of 55-84 years.

Gender differences in blindness, cataract blindness and cataract surgical coverage in India: a systematic review and meta-analysis

BACKGROUND

The magnitude of blindness is unevenly distributed worldwide. This systematic review aimed to study gender differences in the prevalence of blindness, cataract blindness and cataract surgical coverage in India among persons aged 50 years and above.

METHODS

Literature search was carried out in the Medline, Web of Science, Google Scholar, EMBASE and Trip databases. Data were abstracted and risk of bias was assessed for the selected full-text articles. Pooled prevalence, ORs and risk differences were synthesised by meta-analyses.

RESULTS

22 studies were included in the systematic review. The pooled prevalence of blindness obtained for men was 4.17% and that for women was 5.68%. Women had 35% higher odds of being blind (OR 1.35, 95% CI 1.08 to 1.62) and 69% higher odds of being cataract blind (OR 1.69, 95% CI 1.44 to 1.95). Women had a 27% lower odds of getting cataract surgery (OR 0.73, 95% CI 0.45 to 1.01). In women, around 35% of the prevalence of blindness and 33% of the prevalence of cataract blindness are attributable to their gender.

CONCLUSION

Marked gender differences in blindness, cataract blindness and cataract surgical coverage were seen in India, with the odds being unfavourable for women. Interventions implemented for reduction of blindness, including cataract blindness, need to consider these gender differentials in the Indian context. Further research is needed to ascertain the reasons for these differences and devise interventions to reduce these differences in order to tackle the magnitude of avoidable blindness in India.

Comparative study of interhemispheric functional connectivity in left eye monocular blindness versus right eye monocular blindness: a resting-state functional MRI study

Objective

In the present study, we investigated the brain interhemispheric functional connectivity changes in left eye MB versus right eye MB patients by voxel-mirrored homotopic connectivity (VMHC) methods.

Methods

A total of 31 patients with MB (15 with left eye MB and 16 with right eye MB), and 31 healthy controls (HCs) closely matched for age were recruited. All subjects underwent functional magnetic resonance imaging (fMRI) examinations. The VMHC method was used to evaluate directly functional interactions between the hemispheres. A one-way ANOVA was performed to determine the regions in which the VMHC differs between the three groups. Patients with MB were distinguished from HCs by a receiver operating characteristic (ROC) curve. The relationships between the mean VMHC signal values in many brain regions and clinical features in MB patients were calculated by pearson correlation analysis.

Results

Compared with HCs, MB patients had significantly decreased VMHC values in the cuneus/calcarine/lingual gyrus. Furthermore, left eye MB showed decreased VMHC values in the cuneus/calcarine/lingual gyrus and showed increased VMHC values in the insula and middle frontal gyrus compared with HC. In addition, right eye MB showed decreased VMHC values in the cuneus/calcarine/lingual gyrus, primary motor cortex (M1)/primary somatosensory cortex (S1) and superior parietal lobule.

Conclusion

MB subjects showed abnormal brain interhemispheric functional connectivity in visual pathways. Furthermore, different patterns of brain interhemispheric functional connectivity occurred in the left eye and right eye MB. These VMHC values provide much useful information to explain the neural mechanism changes in MB.