Comparison of cataract surgery outcomes between a secondary and a tertiary eye hospital in Tamil Nadu, India.

PURPOSE: To examine the difference in post-operative visual outcomes of cataract surgeries between a tertiary and secondary centre at Aravind Eye Hospitals in Tamil Nadu, India. METHODS: Our retrospective cross-sectional study analysed cataract surgeries at a secondary centre and its associated tertiary centre in 2021. Our main outcome measures were postoperative best corrected visual acuity (BCVA), spherical equivalent, and intraoperative and postoperative complications. Two-sample proportion tests and logistic regression analyses were performed. RESULTS: The analysis of 32,302 cataract surgeries in 2021 of which 4357 were performed at the secondary centre and 27,945 were performed at the tertiary centre showed that the tertiary centre operated on more advanced cataract condition (p < 0.001). Intraoperative (p < 0.001) and post-operative complication rates (p < 0.001) were higher in the tertiary centre. The odds of effective outcomes (BCVA > = 6/12) controlling for all covariates are poorer (p < 0.0001) in the tertiary centre for both phacoemulsification (phaco) and manual small incision cataract surgeries (MSICS). CONCLUSION: World Health Organization recommendations for the effective outcome of cataract surgery are met by both the tertiary and secondary centres, but the odds of effective outcomes in the tertiary centre was lower after adjusting for all known factors. Further investigations of the causes of poor vision in both phaco and MSICS in the tertiary centre are needed to improve the situation.

Water depth effect on energy, exergy losses, and exergy efficiency of solar still with wick materials: an experimental research.

This study analyzes the energy and exergy destruction of a solar still with black painted wick materials (SS with BPWM) at different salt water depths (Wd) of 1, 2, and 3 cm. The coefficients of heat transfer for evaporative, convective, and radiant heat transfer have been calculated for a basin, water, and glass. The thermal efficiency and exergy losses caused by basin material, basin water, and glass material were also determined. An SS with BPWM at Wd of 1, 2, and 3 cm has produced a maximum yield of 0.4, 0.55, and 0.38 kg per hour, respectively. An SS with BPWM at Wd of 1, 2, and 3 cm has produced a daily yield of 1.95, 2.34, and 1.81 kg, respectively. From the SS with BPWM at Wd of 1, 2, and 3 cm, respectively, daily yields of 1.95, 2.34, and 1.81 kg were obtained. The highest exergy loss of the glass material, basin material, and basin water for the SS with BPWM at 1 cm Wd was 728.7, 133.4, and 123.8 W/m2, respectively. The SS with BPWM's thermal and exergy efficiency are 41.1 and 3.1% at 1 cm Wd, 43.3 and 3.9% at 2 cm Wd, and 38.2 and 2.9% at 3 cm Wd, respectively. The results show that compared to the exergy loss of basin water in SS with BPWM at 1 and 3 cm Wd, the basin water exergy loss of SS with BPWM at 2 cm Wd is minimal.