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Re: Ang et al: Descemet's stripping automated endothelial keratoplasty with anterior chamber intraocular lenses: complications and 3-year outcomes
  1. Rashmi Mittal,
  2. Prashant Garg
  1. Cornea and Anterior Segment Services, LV Prasad Eye Institute, Hyderabad, Andhra Pradesh, India
  1. Correspondence to Dr Rashmi Mittal, Cornea and Anterior Segment Services, LV Prasad Eye Institute, Hyderabad, AP 500034, India; rashmimittal2002{at}gmail.com

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Dear editor,

We read with interest the article titled ‘Descemet's stripping automated endothelial keratoplasty with anterior chamber intraocular lenses: complications and 3-year outcomes’ by Ang et al. 1 Although the authors concluded that endothelial cell loss and graft survival in anterior chamber intraocular lens (ACIOL) group were significantly poorer compared with Descemet's stripping automated endothelial keratoplasty (DSAEK) controls at 3 years postoperatively, we would like to draw attention to following issues:

  1. Though the title of the article stated that it was a ‘3-year’ outcome study, visual outcome and complications were analysed only at the end of 1 year.

  2. Clinical data at 3 years were available for only eight of 18 eyes in ACIOL arm and 39 of 114 eyes in posterior chamber intraocular lens (PCIOL) arm. But the authors have calculated the graft failure rate taking 18 and 114 eyes as the denominator in ACIOL and PCIOL groups, respectively. This is the best case scenario assuming that all patients who were lost to follow-up had clear grafts. Even in this best case scenario, a careful analysis revealed that the 95% CI of the two groups overlap (16.38% to 61.42% for ACIOL group and 4.89% to 16.15% for PCIOL group), suggesting that no one procedure is superior to the other. The actual graft failure based on the data available at 3 years would be 87.5% (95% CI 64.58% to 110.42%) and 38.8% (95% CI 16.31% to 45.29%) in the ACIOL and PCIOL groups, respectively. Though clinically it might give an impression that DSAEK while retaining ACIOL may be associated with poor graft survival at 3 years, the available sample size is too small to derive any statistical relevance. Thus, it would be inappropriate to conclude that DSAEK in the setting of ACIOL is associated with poor graft survival at 3 years.

  3. The 95% CIs of the mean endothelial cell density at 3 years in the two groups also overlap (707.97 to 1764.03 cells/mm2 in the ACIOL group and 1721.77 to 2090.23 cells/mm2 in the PCIOL group), suggesting that statistically both the groups have a similar risk of endothelial cell loss at the end of 3 years.

  4. Moreover, the high rate of graft failure (87.5%) seen in the ACIOL group at 3 years does not clinically corroborate the mean endothelial cell density of 1236 cells.

  5. The 95% CIs of the rate of development of glaucoma in the two groups also overlap. While three out of 19 eyes (17.5%) developed de novo glaucoma in the control group, the true rate of glaucoma development is likely to be somewhere between 10.53% and 24.47% (95% CI). On the other hand, with 44.4% de novo glaucoma in the ACIOL group, the true rate of glaucoma development is likely to be somewhere between 21.45% and 67.35%. Therefore, statistically, there is no true difference in the rate of development of glaucoma between the two groups. Similarly, there was no definite evidence that glaucoma following DSAEK in the setting of ACIOL is associated with an increased need for glaucoma surgery. Thus, it would be again inappropriate to conclude that DSAEK with retained ACIOL has a higher risk for glaucoma.

While pointing out these concerns, we do not want to undermine the importance of the study question the authors tried to address in this manuscript but we really wonder if the study achieved its desired goals.

Reference

Footnotes

  • Contributors Both the corresponding author and the coauthor were actively involved in the analysis or interpretation of data, drafting the work and revising it critically for important intellectual content.

  • Competing interests None.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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