Peripheral Iridotomy-Less Approach in Descemet’s Membrane Endothelial Keratoplasty Using Pupil-Dilating Eye Drops, a Retrospective Case–Control Study

Tarek Bayyoud,1 Karl Ulrich Bartz-Schmidt,1 Martin Rohrbach,1 Faik Gelisken,1 David Goldblum,2 Peter Martus,3 Sebastian Thaler1 1Department of Ophthalmology, University Hospital of Tübingen, Tübingen, 72076, Germany; 2Ophthalmology, Pallas Kliniken (Olten-Bern-Zürich-Aargau), Olten, 4600, Switzerland; 3Institute for Clinical Epidemiology and Applied Biometry, University of Tübingen, Tübingen, 72076, GermanyCorrespondence: Tarek Bayyoud, Department of Ophthalmology, University Hospital of Tübingen, Elfriede-Aulhorn-Str. 7, 72076, Tübingen, Germany, Tel +49 07071-29-88188, Fax +49 07071-29-5018, Email [email protected]: To assess clinical outcomes after Descemet’s Membrane Endothelial Keratoplasty (DMEK) with mydriatic eye drops without peripheral iridotomy (PI-less). We performed a retrospective, observational clinical study to determine the postoperative intraocular pressure (IOP) changes and graft viability in a cohort of patients with Fuchs’ endothelial corneal dystrophy (FECD) and bullous keratopathy (BK).Patients and Methods: Included in this study were 41 PI-less DMEK patients with 44 eyes (median age: 77 years; range: 53– 88 years). Patients received either PI-less DMEK (group-1) or PI-less triple DMEK (group-2). The mean follow-up duration was 16 months. Eyes after standard DMEK or triple DMEK served as controls (n = 20). Included in the study were patients admitted to the hospital (securing IOP control), patients in which the tamponading agent was air or gas (SF6) and only patients with physiological air resorption, ie without routine, postoperative air/gas release (90% air/gas fill of the anterior chamber at end of surgery). Phakic eyes were not included. Postoperatively, mydriatic eye drops were administered for three days 4x/d (phenylephrine 25 mg/mL, tropicamide 5 mg/mL). The best-corrected visual acuity (BCVA), endothelial cell density (ECD), and IOP were assessed. Intra- and postoperative complications and management were recorded.Results: BCVA improved significantly in both groups (group-1:0.90 ± 0.57 to 0.20 ± 0.23logMAR (p = 0.000); group-2:0.47 ± 0.23 to 0.17 ± 0.42logMAR (p = 0.0067). ECD decreased significantly: Group-1 2428± 225 cells/mm2 to 1810± 236 cells/mm2 (p = 0.005); group-2 2447 ± 178 cells/mm2 to 1866 ± 229 cells/mm2 (p = 0.012). After postoperative day-1 IOP decreased significantly: Group-1 p = 0.004 (10.0 ± 2.8 mmHg) and p = 0.002 (11.3 ± 3.1 mmHg); group-2 p = 0.002 (10.7 ± 3.6 mmHg) and p = 0.002 (11.4 ± 2.2 mmHg); for postoperative days 2 and 3, respectively. Postoperative adverse events included pupillary block necessitating emergency air release. Intergroup analysis did not show a significant difference in ECD, IOP (after postoperative day-1) and logMAR (after 6 months).Conclusion: Patients may benefit from the promising results of the study regarding postoperative IOP developments and graft viability after DMEK using mydriatic eye drops (phenylephrine 25 mg/mL, tropicamide 5 mg/mL). PI-less triple DMEK in particular might improve accessibility, reduce surgical complexity, or lower costs, making it attractive in resource-limited settings. Close postoperative IOP monitoring is advised in PI-less DMEKs.Plain Language Summary: What is already known on this topicThe standard procedure for a lamellar corneal transplant (DMEK) involves the placement of a peripheral iridotomy (PI) or iris hole;If corneal transplant surgery without PI (PI-less DMEK) is performed, then partial evacuation of air/gas from the anterior chamber of the eye 1-2 h after surgery besides postoperative pupil-dilating medication (mydriatics, phenylephrine 25 mg/mL, tropicamide 5 mg/mL) is necessary to avoid potentially sight-threatening increase in eye pressure (so-called pupillary block).What this study addsPatients benefit from a DMEK without an iris hole, from having no routine postoperative air/ gas release and having no significantly increased risk of pupillary block;For the first time we have shown that the results of a PI-less triple DMEK (including cataract surgery) and a PI-less DMEK are comparable.How this study might affect research, practice or policy● The investigated PI-less triple DMEK procedure incorporating cataract surgery might offer unique benefits for the patients: This approach might improve accessibility, reduce surgical complexity, or lower costs, making it attractive in resource-limited settings.Keywords: descemet membrane endothelial keratoplasty, DMEK, pupil-dilating eye drops, no peripheral iridotomy, PI-less