Author reply

Abstract

We appreciate the interest of Prasanth et al.1Vajaranant T.S. Price M.O. Price F.W. et al.Visual acuity and intraocular pressure after Descemet's stripping endothelial keratoplasty in eyes with and without preexisting glaucoma.Ophthalmology. 2009; 116: 1644-1650Abstract Full Text Full Text PDF PubMed Scopus (125) Google Scholar in our article and agree intraocular pressure (IOP) elevation after Descemet's stripping endothelial keratoplasty (DSEK) can have several causes. These include chronic angle closure, inflammation, graft rejection, and steroid-related ocular hypertension as noted in the discussion section of our report. Our suggestion that steroid-related ocular hypertension was probably a major cause in this series should not imply it was the only cause.We agree that angle closure induced by an air bubble can lead to immediate postoperative IOP elevation after DSEK and potentially cause peripheral iridocorneal adhesion and chronic angle closure if left untreated, as reported by Lee et al,2Lee J.S. Desai N.R. Schmidt G.W. et al.Secondary angle closure caused by air migrating behind the pupil in descemet stripping endothelial keratoplasty.Cornea. 2009; 28: 652-656Crossref PubMed Scopus (45) Google Scholar but we had no occurrence of this in this series. In our experience, development or progression of peripheral anterior synechia (PAS) is common in eyes where anterior chamber lenses have been removed or in eyes with previous filtration surgery, but eyes with uncomplicated histories are unlikely to develop angle closure after DSEK. None of our cases with uncomplicated histories had graft edges de-centered to the extent that angle encroachment or graft-iris touch would have occurred without being visible by slit-lamp examination. Certainly, careful examination of angle structures can lead to improved understanding of chronic IOP elevation related to angle closure.Prasanth et al. noted that patients with preexisting glaucoma usually have a higher incidence of steroid-responsive IOP elevation than patients without preexisting glaucoma. Previous short-term studies showed glaucoma patients and glaucoma suspects develop higher incidence and higher degree of steroid-induced ocular hypertension.3Jones 3rd, R. Rhee D.J. Corticosteroid-induced ocular hypertension and glaucoma: a brief review and update of the literature.Curr Opin Ophthalmol. 2006; 17: 163-167PubMed Google Scholar However, with more frequent administration and increased duration of therapy, the difference in response between the groups decreases. In our study, we found higher incidence of IOP elevation in patients with preexisting glaucoma (43%–45%) compared with patients without preexisting glaucoma (35%). In addition, the percentage of cases needing glaucoma medications and less-potent steroid was higher in patients with preexisting glaucoma (38%–44% vs. 27%). We believe the incidence of steroid-response in the patients with preexisting glaucoma was likely underreported in our cohort for several reasons. First, with the concern of optic nerve damage in patients with preexisting glaucoma, treating physicians were likely promptly to intervene using glaucoma medications and/or less potent steroids before the IOP elevation reached our study criteria (an absolute increase of IOP ≥24 mmHg or relative IOP increase from baseline ≥10 mmHg). Second, glaucoma medications and functioning glaucoma surgeries in patients with preexisting glaucoma might also minimize the degree of IOP elevation due to steroids. In addition, medical and surgical interventions during the pre- and postoperative periods could alter IOP during follow up and therefore could lessen significant difference of IOP changes among 3 groups in our study.Although steroids could induce IOP elevation in some patients with prior filtering surgeries,4Wilensky J.T. Snyder D. Gieser D. Steroid-induced ocular hypertension in patients with filtering blebs.Ophthalmology. 1980; 87: 240-244Abstract Full Text PDF PubMed Scopus (22) Google Scholar we agree that steroid response was not the only reason for elevated IOP in this group and postoperative inflammation could play a role in post-DSEK failure of preexisting filtering glaucoma surgeries. Four eyes with prior glaucoma surgery required subsequent glaucoma procedures: trabeculectomies in 2 eyes failed after DSEK; in 1 eye, PAS present before DSEK progressed and covered the tube, requiring tube repositioning; and a tube in 1 eye was trimmed because it was too close to the DSEK graft.Little is known regarding survival of glaucoma surgery after DSEK. In our cohort of 21 eyes with prior glaucoma surgery, the Kaplan-Meier survival analysis using an IOP ≤18 mmHg criterion demonstrates a survival rate of 0.89 at 1 month, 0.57 at 3 months, and 0.48 at 12 months (Vajaranant and Price et al. American Glaucoma Society annual meeting, San Diego, CA 2009). At baseline, 90% of these patients had IOP control (≤18 mmHg). During a 1-year follow up, 33% required additional glaucoma medications and 19% needed subsequent glaucoma procedures. After medical and surgical interventions, 70% of these cases achieved IOP control (≤18 mmHg) at a 12-month endpoint (Vajaranant TS, Price MO, unpublished data, March 2009).DSEK is a relatively new procedure so the effect of glaucoma and glaucoma surgery on DSEK outcomes, as well as effect of DSEK on prior glaucoma surgeries has not been extensively investigated. We truly appreciate the interest and comments of Prasanth et al., and look forward to further investigations and reports in these important areas. We appreciate the interest of Prasanth et al.1Vajaranant T.S. Price M.O. Price F.W. et al.Visual acuity and intraocular pressure after Descemet's stripping endothelial keratoplasty in eyes with and without preexisting glaucoma.Ophthalmology. 2009; 116: 1644-1650Abstract Full Text Full Text PDF PubMed Scopus (125) Google Scholar in our article and agree intraocular pressure (IOP) elevation after Descemet's stripping endothelial keratoplasty (DSEK) can have several causes. These include chronic angle closure, inflammation, graft rejection, and steroid-related ocular hypertension as noted in the discussion section of our report. Our suggestion that steroid-related ocular hypertension was probably a major cause in this series should not imply it was the only cause. We agree that angle closure induced by an air bubble can lead to immediate postoperative IOP elevation after DSEK and potentially cause peripheral iridocorneal adhesion and chronic angle closure if left untreated, as reported by Lee et al,2Lee J.S. Desai N.R. Schmidt G.W. et al.Secondary angle closure caused by air migrating behind the pupil in descemet stripping endothelial keratoplasty.Cornea. 2009; 28: 652-656Crossref PubMed Scopus (45) Google Scholar but we had no occurrence of this in this series. In our experience, development or progression of peripheral anterior synechia (PAS) is common in eyes where anterior chamber lenses have been removed or in eyes with previous filtration surgery, but eyes with uncomplicated histories are unlikely to develop angle closure after DSEK. None of our cases with uncomplicated histories had graft edges de-centered to the extent that angle encroachment or graft-iris touch would have occurred without being visible by slit-lamp examination. Certainly, careful examination of angle structures can lead to improved understanding of chronic IOP elevation related to angle closure. Prasanth et al. noted that patients with preexisting glaucoma usually have a higher incidence of steroid-responsive IOP elevation than patients without preexisting glaucoma. Previous short-term studies showed glaucoma patients and glaucoma suspects develop higher incidence and higher degree of steroid-induced ocular hypertension.3Jones 3rd, R. Rhee D.J. Corticosteroid-induced ocular hypertension and glaucoma: a brief review and update of the literature.Curr Opin Ophthalmol. 2006; 17: 163-167PubMed Google Scholar However, with more frequent administration and increased duration of therapy, the difference in response between the groups decreases. In our study, we found higher incidence of IOP elevation in patients with preexisting glaucoma (43%–45%) compared with patients without preexisting glaucoma (35%). In addition, the percentage of cases needing glaucoma medications and less-potent steroid was higher in patients with preexisting glaucoma (38%–44% vs. 27%). We believe the incidence of steroid-response in the patients with preexisting glaucoma was likely underreported in our cohort for several reasons. First, with the concern of optic nerve damage in patients with preexisting glaucoma, treating physicians were likely promptly to intervene using glaucoma medications and/or less potent steroids before the IOP elevation reached our study criteria (an absolute increase of IOP ≥24 mmHg or relative IOP increase from baseline ≥10 mmHg). Second, glaucoma medications and functioning glaucoma surgeries in patients with preexisting glaucoma might also minimize the degree of IOP elevation due to steroids. In addition, medical and surgical interventions during the pre- and postoperative periods could alter IOP during follow up and therefore could lessen significant difference of IOP changes among 3 groups in our study. Although steroids could induce IOP elevation in some patients with prior filtering surgeries,4Wilensky J.T. Snyder D. Gieser D. Steroid-induced ocular hypertension in patients with filtering blebs.Ophthalmology. 1980; 87: 240-244Abstract Full Text PDF PubMed Scopus (22) Google Scholar we agree that steroid response was not the only reason for elevated IOP in this group and postoperative inflammation could play a role in post-DSEK failure of preexisting filtering glaucoma surgeries. Four eyes with prior glaucoma surgery required subsequent glaucoma procedures: trabeculectomies in 2 eyes failed after DSEK; in 1 eye, PAS present before DSEK progressed and covered the tube, requiring tube repositioning; and a tube in 1 eye was trimmed because it was too close to the DSEK graft. Little is known regarding survival of glaucoma surgery after DSEK. In our cohort of 21 eyes with prior glaucoma surgery, the Kaplan-Meier survival analysis using an IOP ≤18 mmHg criterion demonstrates a survival rate of 0.89 at 1 month, 0.57 at 3 months, and 0.48 at 12 months (Vajaranant and Price et al. American Glaucoma Society annual meeting, San Diego, CA 2009). At baseline, 90% of these patients had IOP control (≤18 mmHg). During a 1-year follow up, 33% required additional glaucoma medications and 19% needed subsequent glaucoma procedures. After medical and surgical interventions, 70% of these cases achieved IOP control (≤18 mmHg) at a 12-month endpoint (Vajaranant TS, Price MO, unpublished data, March 2009). DSEK is a relatively new procedure so the effect of glaucoma and glaucoma surgery on DSEK outcomes, as well as effect of DSEK on prior glaucoma surgeries has not been extensively investigated. We truly appreciate the interest and comments of Prasanth et al., and look forward to further investigations and reports in these important areas. IOP Changes after DSEKOphthalmologyVol. 117Issue 7PreviewWe read with great interest the recently published article by Vajaranant et al.1 regarding the pattern of intraocular pressure (IOP) changes after Descemet's stripping endothelial keratoplasty (DSEK) in patients without preexisting glaucoma and in those with preexisting glaucoma, with and without prior glaucoma surgery (GS). The authors concluded that there was a substantial incidence of IOP elevation after DSEK in all the 3 groups and have attributed it entirely to the use of corticosteroids. Although a well-designed study, we would like to highlight certain issues. Full-Text PDF