Participant Inclusion Criteria:  Age range 30- < 91 years with minimum life expectancy of at least 1 year Willingness to return to study site for follow up at 1 month and 1 year Fluent in English or Spanish Willingness to have fingerstick blood sample collected to determine HbA1c level at entry and at 1 year. The participant must agree to have their primary care provider contacted (or an appropriate referral provided) if they were not known to have diabetes and the HbA1c suggests they may have diabetes. Similarly, if already known to have diabetes and the HbA1c is high, the participant must agree to have their primary care provider contacted or an appropriate referral provided. Has at least one eye clinically recommended for DMEK that is able to be scheduled for DMEK between 5 to 90 days after enrollment. If second eye is enrolled, it must be scheduled for DMEK between 7 days and 6 months after DMEK on the first eye.  Has a condition related to endothelial dysfunction which will be treated by DMEK. Eligible indications for DMEK include:  Presence of Fuchs endothelial corneal dystrophy (FECD) meeting at least one of the following: phakic FECD with or without cataract (triple procedure including DMEK for FECD, cataract extraction and posterior chamber intraocular lens implantation (IOL) is allowed) pseudophakic FECD with posterior capsule supported, sulcus supported, or scleral-fixated posterior chamber IOL pseudophakic corneal edema with posterior capsule supported, sulcus supported, or scleral-fixated posterior chamber IOL without FECD failed Descemet stripping automated endothelial keratoplasty (DSAEK) or DMEK originally performed for the same indications above without current exclusionary criteria, as described below  Exclusion Criteria:  Pregnant or planning to become pregnant prior to the DMEK study surgery, based on verbal report. Lack cognitive capacity such that consent could not be provided. Presence of a condition that has a high probability for failure (e.g., failed penetrating keratoplasty, uncontrolled uveitis) Stromal vascularization that will impede assessment of recipient stroma clarity Other primary endothelial dysfunction conditions including posterior polymorphous corneal dystrophy and congenital hereditary corneal dystrophy. Indication for surgery that is not suitable for DMEK (e.g, keratoconus, stromal dystrophies and scars) Aphakic corneal edema with or without FECD Anterior chamber IOL in study eye prior to DMEK or planned placement of anterior chamber IOL during DMEK Presence of vitreous in the anterior chamber Planned IOL exchange of an anterior chamber IOL with a posterior chamber IOL in study eye at time of study DMEK Pre-operative central sub-epithelial or stromal scarring that could impact post-operative recipient stromal clarity assessment Presence of anterior synechiae Peripheral anterior synechiae in the angle greater than a total of three clock hours Uncontrolled glaucoma with or without prior filtering surgery, tube shunt placement, or MIGS. Uncontrolled glaucoma is defined as intraocular pressure > 25mm Hg. Controlled glaucoma with prior tube shunt placement for glaucoma (controlled glaucoma with minimally invasive glaucoma surgery (MIGS) or trabeculectomy is allowed) Fellow eye visual acuity < 20/200 due to an ocular condition other than a cornea disease that would be a candidate for DMEK Intraocular pressure <8 mmHg Topical Rho kinase inhibitor, including netarsudil, used within 1 month prior to study entry and anticipated during the course of the study Fellow eye enrolled in the DEKS that has met study-criteria for graft failure.