IOP Changes after DSEK

Abstract

We read with great interest the recently published article by Vajaranant 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 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.Undoubtedly, steroid-induced ocular hypertension forms a major chunk of glaucoma following DSEK. However, the role of angle closure due to crowding of the angle and peripheral anterior synechiae cannot be ruled out. Gonioscopy thus forms an integral part of the postoperative follow-up. It provides clues to determine the exact mechanism of glaucoma following DSEK. The authors believe that since DSEK is performed with a small incision and often without suturing, the possibility of postoperative angle distortion is minimal. However, some amount of encroachment into the angle cannot be ruled out especially if the graft is decentred or in cases of patients with a history of narrow angles or have undergone laser iridotomy. Also, none of the patients developed a pupillary block glaucoma induced from the air bubble, which is a common cause reported in literature and is more common in eyes with preexisting narrow angles. This might also contribute to the formation of peripheral anterior synechiae, if left untreated resulting in chronic angle closure.2Lee W.B. Jacobs D.S. Musch D.C. et al.Descemet's stripping endothelial keratoplasty: safety and outcomes: a report by the American Academy of Ophthalmology.Ophthalmology. 2009; 116: 1818-1830Abstract Full Text Full Text PDF PubMed Scopus (475) Google ScholarIf we believe that steroid response is likely the major cause of postoperative IOP elevation after DSEK, all 3 groups had a comparable IOP rise of 35%, 45%, and 43% and IOP difference between the groups was not statistically significant. This is contrary to the published data that patients with glaucoma are much more likely to exhibit the steroid response than unaffected individuals, due to the expression of myocilin gene in the trabecular meshwork of 3%–5% patients of primary open-angle glaucoma.3Fingert J.H. Clark A.F. Craig J.E. et al.Evaluation of the myocilin (MYOC) glaucoma gene in monkey and human steroid-induced ocular hypertension.Invest Ophthalmol Vis Sci. 2001; 42: 145-152PubMed Google Scholar Moreover, 19% of patients in the GS group required additional filtering surgeries or reinforcement of the previous surgeries, factors contributing to the failure of the previous surgery has not been explained by the authors. If steroid usage was the only contributing factor to the rise of IOP, one would expect it to be controlled medically or with the tapering of steroids. This probably hints at other factors that were responsible for the failure of filtering surgeries like inflammation. This would guide us to have knowledge on the impact of DSEK on filtering blebs owing to the current evidence of about 50% failure of trabeculectomies following penetrating keratoplasty.4Gilvarry A.M. Kirkness C.M. Steele A.D. et al.The management of post-keratoplasty glaucoma by trabeculectomy.Eye (Lond). 1989; 3: 713-718Crossref PubMed Scopus (48) Google Scholar, 5WuDunn D. Alfonso E. Palmberg P.F. Combined penetrating keratoplasty and trabeculectomy with mitomycin C.Ophthalmology. 1999; 106: 396-400Abstract Full Text Full Text PDF PubMed Scopus (29) Google ScholarWe would like to congratulate the authors again for a well-constructed study with such a large number of patients highlighting the visual gain and IOP outcomes after DSEK, which have not been well investigated in the past. A systematic and planned evaluation of the anterior chamber angle either gonioscopically or with the use of anterior segment optical coherence tomography/ultrasound biomicroscopy would probably provide us with more valuable information of the anatomical alterations that occur following DSEK. We read with great interest the recently published article by Vajaranant 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 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. Undoubtedly, steroid-induced ocular hypertension forms a major chunk of glaucoma following DSEK. However, the role of angle closure due to crowding of the angle and peripheral anterior synechiae cannot be ruled out. Gonioscopy thus forms an integral part of the postoperative follow-up. It provides clues to determine the exact mechanism of glaucoma following DSEK. The authors believe that since DSEK is performed with a small incision and often without suturing, the possibility of postoperative angle distortion is minimal. However, some amount of encroachment into the angle cannot be ruled out especially if the graft is decentred or in cases of patients with a history of narrow angles or have undergone laser iridotomy. Also, none of the patients developed a pupillary block glaucoma induced from the air bubble, which is a common cause reported in literature and is more common in eyes with preexisting narrow angles. This might also contribute to the formation of peripheral anterior synechiae, if left untreated resulting in chronic angle closure.2Lee W.B. Jacobs D.S. Musch D.C. et al.Descemet's stripping endothelial keratoplasty: safety and outcomes: a report by the American Academy of Ophthalmology.Ophthalmology. 2009; 116: 1818-1830Abstract Full Text Full Text PDF PubMed Scopus (475) Google Scholar If we believe that steroid response is likely the major cause of postoperative IOP elevation after DSEK, all 3 groups had a comparable IOP rise of 35%, 45%, and 43% and IOP difference between the groups was not statistically significant. This is contrary to the published data that patients with glaucoma are much more likely to exhibit the steroid response than unaffected individuals, due to the expression of myocilin gene in the trabecular meshwork of 3%–5% patients of primary open-angle glaucoma.3Fingert J.H. Clark A.F. Craig J.E. et al.Evaluation of the myocilin (MYOC) glaucoma gene in monkey and human steroid-induced ocular hypertension.Invest Ophthalmol Vis Sci. 2001; 42: 145-152PubMed Google Scholar Moreover, 19% of patients in the GS group required additional filtering surgeries or reinforcement of the previous surgeries, factors contributing to the failure of the previous surgery has not been explained by the authors. If steroid usage was the only contributing factor to the rise of IOP, one would expect it to be controlled medically or with the tapering of steroids. This probably hints at other factors that were responsible for the failure of filtering surgeries like inflammation. This would guide us to have knowledge on the impact of DSEK on filtering blebs owing to the current evidence of about 50% failure of trabeculectomies following penetrating keratoplasty.4Gilvarry A.M. Kirkness C.M. Steele A.D. et al.The management of post-keratoplasty glaucoma by trabeculectomy.Eye (Lond). 1989; 3: 713-718Crossref PubMed Scopus (48) Google Scholar, 5WuDunn D. Alfonso E. Palmberg P.F. Combined penetrating keratoplasty and trabeculectomy with mitomycin C.Ophthalmology. 1999; 106: 396-400Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar We would like to congratulate the authors again for a well-constructed study with such a large number of patients highlighting the visual gain and IOP outcomes after DSEK, which have not been well investigated in the past. A systematic and planned evaluation of the anterior chamber angle either gonioscopically or with the use of anterior segment optical coherence tomography/ultrasound biomicroscopy would probably provide us with more valuable information of the anatomical alterations that occur following DSEK. Visual Acuity and Intraocular Pressure after Descemet's Stripping Endothelial Keratoplasty in Eyes with and without Preexisting GlaucomaOphthalmologyVol. 116Issue 9Preview(1) To characterize 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. (2) To compare vision and IOP outcomes among the 3 groups. Full-Text PDF Author replyOphthalmologyVol. 117Issue 7PreviewWe appreciate the interest of Prasanth et al.1 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. Full-Text PDF