LAUSR

To the Editor: We read with great interest about “Clinical Outcomes of Descemet Stripping Endothelial Keratoplasty in Eyes with Glaucoma Drainage Devices” by Kang et al.1 We would like to commend the authors for analyzing the outcomes of descemet stripping endothelial keratoplasty (DSEK) in eyes with glaucoma drainage devices (GDD). As DSEK is emerging as an effective alternative to PK for endothelial disorders in general, this study shows the DSEK is feasible and has excellent outcomes in eyes with GDD. We would like to point out a few concerns about the article. First, the postoperative endothelial cell density (ECD)is not mentioned in this article. As the presence of the tube opening can have an adverse effect on the endothelial layer, it can reduce the cell count in the long term, especially after a DSEK.2 It would have been more informative if the authors have provided the ECD in the study and whether there was a tube cornea touch. It is not mentioned about the length of the tube and the distance between the internal opening of the tube and cornea. We feel that the distance between the tube tip and the endothelial graft has a bearing on the ECD count and subsequent graft failure. Also, there was no mention of the placement of the tube opening in the anterior chamber or the sulcus. It would have been better if the authors had mentioned where exactly the graft detachments occurred. Were they near to the tip of GDD or away from it? This is important as the changes in aqueous humor circulation patterns owing to a glaucoma shunt tube may influence the site of graft detachment. In the introduction section, the authors have mentioned that the DSEK procedure is more challenging in the eyes with abnormal anterior segments. How do they define “abnormal anterior segment” and “complex eyes”? DSEK was performed in 85 eyes of 83 patients, but table 1 (patient demographics) shows the sex of the study participants as 46 males and 39 females, that is, 85 patients. There was also an error in the number of post-DSEK graft dislocations as the total number given is 27, but the total number of post-vitrectomy and nonvitrectomized eyes is shown as 28 eyes. Also, the authors could have tried a repeat air or gas injection for post-DSEK graft re-detachments, instead of repeating the DSEK procedure itself. Table 1 shows that in the 22 eyes, GDD tube was removed and repositioned through the pars plana. We feel that repositioning GDD tube to the ciliary sulcus is technically less challenging, more so in pseudophakic eyes (80 study eyes had posterior chamber intraocular lens) than repositioning the tube in pars plana, with requires pars plana vitrectomy with its related complications and the need for assistance of a retinal surgeon, as mentioned. One of the study outcomes measures was intraocular pressure (IOP) after the DESK. It is not mentioned as to, how the preoperative and postoperative IOP was measured. Did any of the patients have pupillary block on first postoperative day, as a cause for the rise in IOP? Increase in IOP was seen in 21 (24.7%) eyes in the study. What was the mean time period at which an increase in IOP was noted? Two eyes underwent reneedling for IOP control. It is not clear whether the needling was done before the DSEK or in 2 sessions after the surgery. There were 2 cases each of choroidal detachments and retinal detachments in the postoperative period but there was no mention of hypotony. New GDDwas inserted in 11.8% of the patients and in those patients, who underwent GDD implantation/revision, increased IOP was observed in 6 patients. But there is no mention about the type of the new GDD whether it was valved or nonvalved which can have a bearing on the postoperative IOP. Standard deviation for themean value for preoperative and postoperative vision and IOP is not given. In the visual outcomes, full form of CDVA is not mentioned and table 2 shows best-corrected visual acuity. In the text, vision is given in Log MAR (Logarithm of the minimum angle of resolution) but in table 2, it is given as Snellen visual acuity. As visual acuity is one of the outcome measures, there should be uniformity in the presentation of visual acuity throughout the study. It would be informative if the authors had mentioned the number of eyes with synechial angle closure and preoperative and postoperative extent of the peripheral anterior synechiae. This is important as 3 eyes had ICE syndrome and progressive angle closure can cause anterior migration of the GDD tube.3