Kyros Moutsouris

Refractive change and stability after Descemet membrane endothelial keratoplasty Effect of corneal dehydration-induced hyperopic shift on intraocular lens power calculation

PURPOSE: To determine the refractive change and stability of the transplanted cornea after Descemet membrane endothelial keratoplasty (DMEK) through a 3.0 mm clear corneal incision. SETTING: Tertiary referral center. DESIGN: Cohort study. METHODS: Subjective and objective refractive data from pseudophakic eyes were obtained before and 3 and 6 months after DMEK. RESULTS: The study comprised 50 eyes, 7 were phakic and 43 pseudophakic. Six months postoperatively, the corrected distance visual acuity was 20/25 (0.8) or better in 38 eyes (74%). The mean increase in spherical equivalent at 6 months (N = 50) was +0.32 diopter (D) ± 1.01 D (SD) (P=.0304) and in refractive cylinder, −0.48 ± 1.02 D (P=.001). Although Scheimpflug imaging showed a stable anterior corneal curvature, the posterior curvature increased from 5.50 ± 0.5 D preoperatively to 6.40 ± 0.4 D at 6 months and pachymetry decreased from 672 ± 82 μm to 540 ± 59 μm, respectively (both N = 32) (both P=.000). CONCLUSIONS: After DMEK, a slight preoperative to postoperative refractive change and stabilization at 3 months occurred that may induce a hyperopic shift that was not the result of the negative lenticule effect of DSEK/DSAEK. Thus, in DMEK, the hyperopic shift may result from a reversal of a preceding myopic shift induced by stromal swelling in endothelial disease. If so, normal intraocular power nomograms apply for cataract surgery before or during DMEK. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Optical coherence tomography, Scheimpflug imaging, and slit-lamp biomicroscopy in the early detection of graft detachment after Descemet membrane endothelial keratoplasty.

Purpose: To evaluate the efficacy of anterior segment optical coherence tomography (OCT), Scheimpflug imaging, and slit-lamp biomicroscopy in the early detection of a (partial) graft detachment after Descemet membrane endothelial keratoplasty (DMEK). Methods: Anterior segment OCT, Scheimpflug imaging, and slit-lamp biomicroscopy were performed in 120 eyes of 110 patients after DMEK. Results: Seventy-eight eyes showed a normal corneal clearance, and the attached Descemet grafts could not be identified with any of the imaging techniques. Forty-two eyes showed persistent stromal edema in the first postoperative month. In transplanted corneas that (partially) did not clear in the early postoperative period, OCT had an added diagnostic value in 36% of cases (15 of 42 eyes) in visualizing whether the graft was detached and, in particular, to discriminate between a “flat” graft detachment and delayed corneal clearance. In contrast, in the presence of corneal edema, Scheimpflug imaging did not provide more information than slit-lamp biomicroscopy in the detection of a graft detachment. Conclusions: Anterior segment OCT may be an effective tool in the detection of an early graft detachment after DMEK, to determine if secondary surgical intervention is indicated or is to be avoided.

Incidence of recipient Descemet membrane remnants at the donor-to-stromal interface after descemetorhexis in endothelial keratoplasty

In 2004, our group described a descemetorhexis to enable Descemet stripping (automated) endothelial keratoplasty (DSEK/DSAEK) and Descemet membrane endothelial keratoplasty (DMEK).1 Removal of the recipient Descemet membrane (DM) may be an important step in endothelial keratoplasty, because the procedures are predominantly performed for Fuchs endothelial dystrophy, a corneal disorder characterised by guttatae, that is, collagenous Hassall–Henle warts in DM. Since these guttatae themselves may cause reduced visual acuity, incomplete removal of the pathological DM may compromise the optical performance of the cornea after transplantation.1 Recently, we observed two eyes that showed guttata-like abnormalities after DMEK (figure 1), suggesting that large areas of recipient DM remained in situ despite the performance of a ‘complete’ descemetorhexis during surgery. This finding could relate to the anatomy of DM (ie, a separation of the posterior (postnatal) DM from the anterior (prenatal) DM) or to observations in pathology specimens, in which diseased DM in Fuchs endothelial dystrophy showed a multiple layered structure.2 Figure 1 Images displaying a large central island of recipient Descemet membrane after Descemet membrane endothelial keratoplasty (DMEK), despite its supposedly ‘complete’ …

Biomechanical and optical behavior of human corneas before and after photorefractive keratectomy

Purpose To evaluate numerically the biomechanical and optical behavior of human corneas and quantitatively estimate the changes in refractive power and stress caused by photorefractive keratectomy (PRK). Setting Athineum Refractive Center, Athens, Greece, and Politecnico di Milano, Milan, Italy. Design Retrospective comparative interventional cohort study. Methods Corneal topographies of 10 human eyes were taken with a scanning‐slit corneal topographer (Orbscan II) before and after PRK. Ten patient‐specific finite element models were created to estimate the strain and stress fields in the cornea in preoperative and postoperative configurations. The biomechanical response in postoperative eyes was computed by directly modeling the postoperative geometry from the topographer and by reproducing the corneal ablation planned for the PRK with a numerical reprofiling procedure. Results Postoperative corneas were more compliant than preoperative corneas. In the optical zone, corneal thinning decreased the mechanical stiffness, causing local resteepening and making the central refractive power more sensitive to variations in intraocular pressure (IOP). At physiologic IOP, the postoperative corneas had a mean 7% forward increase in apical displacement and a mean 20% increase in the stress components at the center of the anterior surface over the preoperative condition. Conclusion Patient‐specific numerical models of the cornea can provide quantitative information on the changes in refractive power and in the stress field caused by refractive surgery. Financial Disclosures No author has a financial or proprietary interest in any material or method mentioned.

Radial graft contraction may relate to subnormal visual acuity in Descemet stripping (automated) endothelial keratoplasty

Since 1998, we have introduced various concepts for endothelial keratoplasty, popularised as ‘deep lamellar endothelial keratoplasty’ (DLEK), ‘Descemet stripping (automated) endothelial keratoplasty’ (DSEK/DSAEK) and ‘Descemet membrane endothelial keratoplasty’ (DMEK).1 Large clinical studies on DSEK/DSAEK reported a best-corrected visual acuity (BCVA) averaging 20/40 (0.5) at 6 months after surgery, with only few cases reaching ≥20/25 (≥0.8).2 3 In a first series of DMEK surgeries for Fuchs endothelial dystrophy, a majority of cases reached ≥20/25 (≥0.8).4 Apparently, a cornea may obtain a better optical performance after transplantation of an isolated donor Descemet membrane and its endothelium in DMEK, than with a thicker graft also containing donor posterior stroma as used in DSEK/DSAEK.1 If so, compromised optical quality of the transplanted cornea may relate to the presence of donor stroma in DSEK grafts. In this letter, we describe a potential mechanism of how donor posterior stroma may limit final BCVA in endothelial keratoplasty, by progressive graft contraction. A …

First DLEK series: 10-year follow-up.

Dear Editor: Since 1998, we have introduced various techniques for endothelial keratoplasty. A first technique, deep lamellar endothelial keratoplasty (DLEK) was performed in a series of 22 eyes, before we switched to Descemet’s stripping endothelial keratoplasty (DSEK) in 2001. Although the short-term clinical results compared favorably to penetrating keratoplasty (PK), there is limited information on longterm outcome and endothelial graft survival. Concern has been raised about an early postoperative drop in endothelial cell density (ECD), due to intraoperative manipulation of the donor tissue during preparation and implantation. To determine long-term endothelial transplant performance, we re-examined the first cohort of DLEK patients worldwide, one decade after surgery. Clinical evaluation included best spectacle corrected visual acuity (BSCVA), biomicroscopy, ECD measurements, and Pentacam analysis. Of the 22 eyes, 3 were lost to follow up (Cases 3, 8, 13); and 3 had a secondary PK within the first year after DLEK (intraoperative microperforation, graft detachment, and interface scarring; Cases 5, 9, 12) and 3 had a graft (endothelial) failure after 1 and 6 years (Cases 20, 2 and 22) (Table 1; available at http://aaojournal.org). Hence, 13 patients were available for examination with on average 9.9 ( 1.2) years of follow-up. With biomicroscopy (n 13), optical coherence tomography (n 6) and confocal microscopy (n 3), no long-term changes in stromal anatomy, inflammation, or wound-healing abnormalities were detected. All transplanted corneas showed a well-integrated graft, with some reflectivity at the donor-tohost stromal interface (Figure 1; available at http://aaojournal. org). Of the 15 eyes (Cases 2–4, 6, 7, 10, 11, 13–18, 21, and 22) with normal visual potential, all but 3 (Cases 10, 13, and 16) had a BSCVA 20/40 at 3–5 years after surgery (12/15 80%). At 7–12 years, 9 eyes had normal visual potential (Cases 4, 6, 7, 10, 11, 14, 16, 17, and 21), all but 2 (Cases 10 and 11) had a BSCVA 20/40 (7/9 78%). One eye (Case 10) had a BSCVA of 20/200, due to stromal scarring after herpes keratitis 18 months after surgery. At 10 years, spherical equivalent averaged –0.1 D ( 1.6 D) (preoperative: –0.3 D [ 1.5 D]) (n 1 2) (Table 1). Refractive astigmatism averaged 2.1 D ( 1.4 D) (preoperative: 0.9 D [ 1.0 D]) (n 12). With topography, all transplanted corneas showed against-the-rule astigmatism, and mild corneal surface irregularities, correctable with spectacles (Figure 1; available at http://aaojournal.org). Central corneal pachymetry averaged 578 m ( 71.8 m) (n 7) and ECD averaged 591 cells/mm ( 160 cells/mm) (n 6) (Table 1 and Figure 2; available at http://aaojournal.org), reflecting a decrease in ECD of 79% at one decade. Kaplan-Meier analysis showed an 84% graft survival estimate at an overall follow-up time of 7.1 ( 4.1)