Vasilios S. Liarakos

Near complete visual recovery and refractive stability in modern corneal transplantation: Descemet membrane endothelial keratoplasty (DMEK)

OBJECTIVE To report the 6 months results of a large prospective study on Descemet membrane endothelial keratoplasty (DMEK) for management of corneal endothelial disorders. METHODS DMEK was performed in 300 consecutive eyes with Fuchs endothelial dystrophy, bullous keratopathy or previous corneal transplant failure. Best spectacle corrected visual acuity (BSCVA), refractive outcome and endothelial cell density (ECD) were evaluated before and at 1, 3, and 6 months after surgery. Intra- and postoperative complications were documented. RESULTS At 6 months, 98% of eyes reached a BCVA of ≥20/40 (≥0.5), 79% ≥20/25 (≥0.8), 46% ≥20/20 (≥1.0), and 14% ≥20/18 (≥1.2) (n=221). The pre- to 6 months postoperative spherical equivalent (SE) showed a +0.33D (±1.08D) hyperopic shift (P=0.0000). Refractive stability was shown at 3 months after DMEK, i.e. no significant change in SE (P=0.0822) or refractive cylinder (P=0.6182) at 3 versus 6 months follow-up. Donor ECD showed a decrease from 2561 (±198)cells/mm(2) before, to 1674 (±518)cells/mm(2) at 6 months after surgery (n=251) (P=0.0000). The main complication was (partial) graft detachment occurring in 31 eyes (10%). Secondary ocular hypertension was seen in 13 eyes (6%): 6 induced by air-bubble dislocation posterior to the iris and 4 induced by steroids. Secondary cataract requiring phaco-emulsification developed in 3 out of 63 (5%) phakic eyes. CONCLUSIONS DMEK may provide a refractively neutral near complete, rapid visual rehabilitation with ECDs similar to earlier endothelial keratoplasty techniques. This combined with a relatively low complication rate, would indicate that DMEK is a safe and effective treatment for corneal endothelial disorders.

Intraocular Graft Unfolding Techniques in Descemet Membrane Endothelial Keratoplasty

OBJECTIVE To define various Descemet graft unfolding techniques in Descemet membrane endothelial keratoplasty. METHODS In a retrospective analysis, the surgical videos of 100 consecutive Descemet membrane endothelial keratoplasty cases with at least 6 months of follow-up were evaluated and categorized. The Descemet graft unfolding methods were categorized into 4 basic techniques and 3 auxiliary techniques. RESULTS All Descemet membrane endothelial keratoplasty surgical procedures could be completed using (a combination of) 4 Descemet graft unfolding techniques: (1) standardized no-touch graft unfolding using a double roll, (2) carpet unrolling while fixating 1 graft edge (Dirisamer technique), (3) small air bubble-assisted unrolling (Dapena maneuver), (4) the single sliding cannula maneuver. Additional maneuvers included turning over the graft when oriented upside down (flushing); manual graft centration with a cannula; and bubble bumping to unfold peripheral inward folds. In 73% of surgical procedures, technique 1 was used, while a combination of techniques was used in 44% and auxiliary techniques in 62%. None of the techniques showed a correlation with the best-corrected visual acuity, endothelial cell density, or postoperative complication rate (P > .10). CONCLUSIONS Descemet membrane endothelial keratoplasty may be further facilitated by using controlled techniques for unfolding the Descemet graft inside the recipient anterior chamber, either as stand-alone techniques or used in various combinations.

Identifying causes for poor visual outcome after DSEK/DSAEK following secondary DMEK in the same eye

Purpose:  To identify causes of reduced visual acuity after Descemet stripping (automated) endothelial keratoplasty (DSEK/DSAEK) and to determine whether such eyes can be successfully ‘repaired’ with a secondary Descemet membrane endothelial keratoplasty (DMEK).

Bowman Layer Transplantation to Reduce and Stabilize Progressive, Advanced Keratoconus

OBJECTIVE To evaluate the clinical outcome of mid-stromal isolated Bowman layer transplantation, a new surgical technique to reduce and stabilize ectasia in eyes with advanced keratoconus, to postpone penetrating keratoplasty or deep anterior lamellar keratoplasty, and to enable continued daily contact lens wear. DESIGN Prospective, nonrandomized cohort study at a tertiary referral center. PARTICIPANTS Twenty-two eyes of 19 patients with progressive, advanced keratoconus not eligible for ultraviolet cross-linking. INTERVENTIONS The mid-stroma was manually dissected and an isolated donor Bowman layer was positioned within the stromal pocket. MAIN OUTCOME MEASURES Before and up to 36 months after surgery (mean follow-up, 21±7 months), best spectacle-corrected visual acuity (BSCVA), best contact lens-corrected visual acuity (BCLVA), Scheimpflug-based corneal tomography measurements, endothelial cell density, biomicroscopy, refraction, and intraoperative and postoperative complications were recorded. RESULTS Two surgeries were complicated by an intraoperative perforation of Descemet membrane; no other intraoperative or postoperative complications were observed. Maximum keratometry decreased on average from 77.2±6.2 diopters (D) to 69.2±3.7 D (P < 0.001) at 1 month after surgery and remained stable thereafter (P ≥ 0.072). Mean BSCVA improved from 1.27±0.44 logarithm of the minimum angle of resolution units before surgery to 0.90±0.30 logarithm of the minimum angle of resolution units 12 months after surgery (P < 0.001), whereas BCLVA remained stable (P = 0.105). Mean thinnest-point pachymetry increased from 332±59 μm before surgery to 360±50 μm at the latest follow-up (P = 0.012), and no change in endothelial cell density was found (P = 0.355). CONCLUSIONS With isolated Bowman layer transplantation, reduction and stabilization of corneal ectasia was achieved in eyes with progressive, advanced keratoconus. Given the low risk for complications, the procedure may be performed to postpone penetrating or deep anterior lamellar keratoplasty.

Optical Quality of the Cornea After Descemet Membrane Endothelial Keratoplasty

PURPOSE To evaluate corneal higher-order aberrations (HOAs) and backscattered light before and after Descemet membrane endothelial keratoplasty (DMEK) and their correlation with visual outcome. DESIGN Retrospective study. METHODS In a total of 118 consecutive eyes of 118 patients who underwent uneventful DMEK for Fuchs endothelial dystrophy at a tertiary referral center, best spectacle-corrected visual acuity (BSCVA), corneal HOAs, and backscattered light were evaluated preoperatively and at 6 months postoperatively. Outcome data were compared to an age-matched control group with uncomplicated eyes (n = 27). RESULTS Compared to the control group, Fuchs endothelial dystrophy eyes, before as well as 6 months after DMEK, showed higher values of anterior and posterior HOAs and backscattered light (P < .033). Postoperative anterior HOAs and backscattered light (0-2 mm) were associated with lower 6-month BSCVA (positively related with logMAR BSCVA) (P ≤ .020). Anterior corneal HOAs did not change from preoperative to 6 months after DMEK (P = .649), while total posterior HOAs (RMS third to sixth Zernike order) and haze decreased (P < .001). CONCLUSIONS Anterior and posterior corneal HOAs, as well as backscattered light from the cornea, were elevated in eyes suffering from Fuchs endothelial dystrophy and remained higher throughout 6 months after DMEK. If present, anterior surface irregularities and anterior corneal haze may be the most important limiting factors in visual rehabilitation after DMEK.

The effect of subconjunctival ranibizumab on corneal and anterior segment neovascularization: study on an animal model.

Purpose To evaluate the effect of subconjunctival anti—vascular endothelial growth factor (VEGF) ranibizumab on corneal and anterior segment neovascularization. Methods In this experimental study and laboratory investigation, chemical cauterization was utilized to induce corneal neovascularization in 16 rabbits randomly divided in 2 equal groups. Cauterized eyes were either treated with 0.1 mL (1 mg) of subconjunctival ranibizumab or administered a sham injection. A third group of 4 rabbits served as control for side effects after ranibizumab administration. All animals were monitored daily for 14 days and the extent of corneal scarring and neovascularization was measured on days 1, 7, and 14. After enucleation, ocular tissues were separated under a surgical microscope and VEGF levels were measured with ELISA. Statistical analysis was performed to compare the extent of corneal neovascularization and VEGF levels between treated and untreated eyes. Results Subconjunctival ranibizumab inhibited corneal neovascularization significantly both in the first and the second week compared to untreated controls (p = 0.006 and p = 0.001, respectively). The VEGF levels were significantly lower in all anterior segment tissues like the cornea, iris, aqueous humor, and conjunctiva of the treated eyes (p<0.01). The reduction of VEGF levels ranged from 19% to 73% in different ocular tissues. Corneal scarring was not significantly affected by anti-VEGF treatment (p = 0.7). No side effects were noticed. Conclusions Early subconjunctival administration of ranibizumab may successfully inhibit alkali-induced corneal neovascularization in an animal model. Subconjunctival ranibizumab reduces VEGF levels significantly not only in the cornea and the bulbar conjunctiva but also in the aqueous humor and the iris.

Preliminary outcome of hemi-Descemet membrane endothelial keratoplasty for Fuchs endothelial dystrophy

Background/aims To evaluate the clinical outcome of a full-diameter, untrephined, semicircular Descemet graft in a consecutive series of Descemet membrane endothelial keratoplasty (hemi-DMEK), potentially allowing the harvesting of two grafts from a single donor corneoscleral rim. Methods Interventional case series of 10 eyes of 10 patients with Fuchs endothelial dystrophy. Best corrected visual acuity (BCVA), endothelial cell density (ECD) and central corneal thickness (CCT) were evaluated up to 6 months postoperatively, and intraoperative and postoperative complications were recorded. Results Hemi-DMEK was successful in 9 out of 10 eyes; one eye showed persistent graft detachment despite rebubbling and underwent a secondary DMEK. BCVA improved in all successful hemi-DMEK eyes: at 6 months 100% of eyes (n=7) reached ≥20/40 (≥0.5), 86% (n=6) ≥20/25 (≥0.8), 29% (n=2) ≥20/20 (≥1.0) and 14% (n=1) reached 20/17 (≥1.2). Two eyes were excluded from visual analysis due to low visual potential. Preoperative donor ECD declined from 2744 (±181) cells/mm2 to 940 (±380) cells/mm2 centrally at 6 months postoperatively (n=9), with (donor and/or host) endothelial cell redistribution over bare stromal areas adjacent to the graft. Average CCT decreased from 745 (±153) µm preoperatively to 520 (±37) µm at 6 months. Four eyes required rebubbling for visually significant graft detachment. No other complications occurred throughout the study period. Conclusions Hemi-DMEK may give visual outcomes similar to those in conventional DMEK. If ECD decrease and graft detachment rate would prove acceptable in larger series, hemi-DMEK could have the potential to double the availability of donor tissue for endothelial keratoplasty.

Unfolding Techniques for the DMEK Graft

In Descemet membrane endothelial keratoplasty (DMEK), graft unfolding is often perceived as the most difficult step and the most challenging to learn [1–3]. Of course, the best way to learn anything is by practice, and for DMEK surgery, there exist both an animal eye model [4] and a method for simulating the operation using an artificial anterior chamber (which is how we teach graft unfolding at our wet-lab courses). Beginning surgeons may also be comforted to know that most clinical outcomes during the “learning curve” of the operation approximate those obtained by more experienced hands [5–7].