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We read the article published by Chaudhary, et al (1) with great interest and laud them on the quality and design of their study. Primary congenital blindness (PCG) poses a challenge to clinicians, both in terms of diagnosis, and treatment. (2)
We would like to bring to the authors’ notice a similar study conducted in 2017 (3) of 230 eyes of 121 PCG patients having undergone a primary CTT. This study differed from the present study in the fact that it had a longer average follow-up period of 28.87 years with a more concentrated follow-up range of 21.5-38 years. There were also two main differences in the findings of the two studies.
Contrary to the results in the present study where the infants with PCG fared better than the neonates (48.9% >6/60), the previous study found that 76.3% newborns with PCG had a vision better than 6/60. Additionally, the previous study, found visual acuity to be better than 6/60 in a greater proportion of patients (76.1%) at the last follow-up, as compared to the proportion in the study by Chaudhary et al (55.3%). Applying the WHO recommendation of measuring vision in the better eye, (4) the results improved to 89.3% in the study by Sood et al. (3)
A possible reason for these disparities between the studies could be the difference in presentation times of the patients and the study inclusion criteria. While the present study reports late presentation, over half of the patients (53%) in the earlier pub...
A possible reason for these disparities between the studies could be the difference in presentation times of the patients and the study inclusion criteria. While the present study reports late presentation, over half of the patients (53%) in the earlier publication were operated before they reached 28 days of age. Further, the present study only includes patients with enlarged corneal diameter (>12mm) and pre-surgery IOP of 22mmHg, whereas our study had 31.74% patients with corneal diameter between 10-12mm and 0.87% patients with IOP less than 20mmHg. The former constituted 42.1% of the patients with visual acuity better than 6/60, while the latter constituted 0% of the same.
The authors of the present study also conducted an in-depth analysis of causes behind poor visual outcomes, whereas the previous study focused only on three pre-determined factors, with only one in common with the present study. Needless to say, both studies add considerably to existing literature, bolstered in their endeavour by their large sample size, a rarity by itself in studies reporting long-term outcomes in PCG patients.
1. Chaudhary RS, Gupta A, Sharma A, et al Long-term functional outcomes of different subtypes of primary congenital glaucoma British Journal of Ophthalmology Published Online First: 23 December 2019. doi: 10.1136/bjophthalmol-2019-315131
2. Mandal AK, Chakrabarti D. Update on congenital glaucoma. Indian J Ophthalmol 2011;59, Suppl S1:148-57
3. Sood D, Rathore A, Sood I, Singh G, Sood NN. Long-term outcome of combined trabeculotomy-trabeculectomy by a single surgeon in patients with primary congenital glaucoma. Eye (Lond). 2018;32(2):426–432. doi:10.1038/eye.2017.207
4. World Health Organization. Change the Definition of Blindness; 2020. Available at: http://www.who.int/blindness/Change%20the %20Definition%20of%20Blindness.pdf. [Accessed on 04 May 2020].
ACKNOWLEDGEMENT: The authors would like to thank Dr Shalinder Sabherwal for his review of the manuscript for this Letter in Response.