DMEK visual rehabilitation

A new decision tree for the management of eyes with incomplete visual rehabilitation after DMEK offers a systematic approach for determining the underlying cause and guidance on targeted intervention for improving clinical outcomes. Developed by investigators at the Netherlands Institute for Innovative Ocular Surgery (NIIOS), the decision tree is based on findings from a retrospective study analysing data from 178 DMEK eyes. The information was recently published [AJO, 2013;156:780-8], and presented by Isabel Dapena MD, PhD at the 4th EuCornea Congress in Amsterdam. Dr Dapena reported that 69 (39 per cent) of the 178 eyes had incomplete visual rehabilitation at six months after surgery. The cause could be determined in nearly all cases. “The presence of undefined imperfections in corneal optical quality can limit visual recovery after other endothelial keratoplasty procedures, but is not an issue with DMEK. Therefore, we undertook this study to test the hypothesis that incomplete visual rehabilitation after DMEK should be explained by identifiable and potentially treatable causes,” said Dr Dapena. Eyes included in the study were identified from a consecutive series of 200 DMEK cases after excluding those with incomplete follow-up or ocular pathology recognised prior to DMEK. Incomplete visual rehabilitation was defined as either BCVA ≤0.7, which was present in 57 eyes, or BCVA ≥0.8 with subjective visual complaints, which affected 12 eyes.   Common patient-related causes Categorisation of the causes for incomplete visual rehabilitation showed that the problem was primarily patient-related in 40 of the 69 eyes, primarily related to a graft issue in 21 eyes, and involved a combination of patient and graft factors in eight eyes. The most common patient-related causes were noncorneal ocular pathology, mainly maculopathy that was frequently suspected but not recognised prior to surgery, followed by corneal irregularities and/or scarring, which could often be attributed to longstanding corneal oedema. Graft detachment was the leading graft-related cause, but a smaller subgroup of eyes had “delayed graft function” with delayed time to clearing of an attached graft. The management decision tree divides patients as to whether they have reduced visual acuity or visual discomfort. Examination of eyes with reduced visual acuity begins with evaluation for corneal oedema. If absent, the surgeon can assume that a patient-related cause explains the decreased vision and should conduct further examinations to identify if there is anterior corneal scarring or irregularities, which may be correctable with a contact lens; or any posterior pole pathology, cataract or posterior capsule opacification (PCO) requiring treatment.   Incomplete visual rehabilitation The presence of corneal oedema indicates a graft-related cause for incomplete visual rehabilitation and is an indication for anterior segment OCT to determine if the graft is detached or has delayed function. “If there are signs of corneal clearance, the graft is functional and the eye can be followed for up to two to three months to see if the cornea clears by itself. If there are no signs of clearance, then rebubbling should be performed within the first postoperative weeks. Only if these measures do not help will the patient need to undergo retransplantation,” Dr Dapena said. Patients with visual discomfort and BCVA ≥0.8 should be evaluated to rule out cataract and/or PCO. Unexplained visual symptoms may be managed successfully with a soft contact lens or may resolve spontaneously with time.