Dear Editor,
We read with great interest the article by Ramyashri et al.,[1] Comparison of longterm outcomes of trabeculectomy and risk factors for failure in eyes post penetrating keratoplasty (PK) or Descemet’s stripping endothelial keratoplasty (DSEK). We congratulate the authors for their commendable work on reporting the survival rate of grafts and outcomes of trabeculectomy in the post-PK and post-DSEK eyes. Nonetheless, we put forward certain methodological limitations of the study. First, it would have been preferable to mention the type of PK (optical versus therapeutic) as it bears significance on graft survival rates. Second, the authors may consider presenting data on corneal endothelial cell count/density with time from graft surgery (at each follow-up visit) as it appears to be a reliable indicator for outcomes of corneal graft in previous studies.[2] Third, details on graft clarity grading were not mentioned. Trabeculectomy failure can result in intra-ocular pressure (IOP) elevation, which in turn can affect graft clarity and cause irreversible vision loss by optic nerve damage. However, post-operative IOP was not included in the univariate model.[3] Fourth, the authors could consider reporting on outcomes of trabeculectomy and trabeculectomy with mitomycin C (MMC) separately as the previous literature showed that trabeculectomy with MMC had higher graft survival rates.[4] Fifth, although the authors have clearly defined success, data on complete and qualified success and failures do not add up to 100% in Table 3. Finally, it is unclear from the analysis time presented in the Kaplan–Meier curve if patients in the post-PK group were followed up for over 2 decades and if so no data on graft failures after first few years have not been presented. Nevertheless, the excellent work by the authors is an important addition to the existing literature.
All authors have critically reviewed the research paper and have equally contributed to the manuscript.
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Conflicts of interest
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References
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