Patients and Examinations
The surgical maneuvers and evaluation protocols used in this retrospective study were approved by the Institutional Review Board of Yokohama Minami Kyosai Hospital (Approval no. YKH_30_02_08). We carefully followed all ethical principles within the Declaration of Helsinki. Patients exhibiting endothelial dysfunction derived from PEX or FECD and cataract were enrolled after giving written informed consent. The diagnosis of PEX keratopathy was confirmed clinically as well as electron microscopy. A total of 37 surgeries were performed at the department of ophthalmology of Yokohama Minami Kyosai Hospital in Kanagawa, Japan, between April 1, 2016, and December 31, 2017. Fourteen eyes of 14 patients (five males and eight females) were considered eligible for the study. Six eyes revealed PEX syndrome (PEX group), and the other 8 eyes revealed FECD (FECD group).
We performed a standard ophthalmic examination and took the following measurements preoperatively and up to 6 months after the operation: best spectacle-corrected visual acuity (BSCVA), corneal endothelial cell density (ECD), central corneal thickness (CCT), and graft adaptation. Graft adaptation was assessed via slit-lamp microscopy and anterior segment optical coherence tomography (AS-OCT, SS1000, Tomey, Aichi, Japan). Corneal thickness was also measured using AS-OCT. Preoperative ECDs were retrieved from donor eye bank records, and postoperative ECDs were measured with the aid of a specular microscope (FA3509, Konan Medical, Hyogo, Japan). To detect clinical/subclinical cystoid macular edema (CME), spectral-domain OCT (RS 3000, Nidek, Aichi, Japan) was performed at 1 month, 3 months, and 6 months after DMEK. CME was defined by the presence of intraretinal fluid spaces, which are seen in the fovea region using spectral-domain OCT.
Cataract surgery was scheduled about four weeks before DMEK. It was performed under sub-Tenon anesthesia. The pupil was preoperatively treated with mydriatic agents. Tropicamide and phenylephrine were used the same morning to achieve mydriasis. Maximum pre-operative pupil dilation was noted. Phacoemulsification was performed, and the foldable intraocular lens (IOL) was placed in the bag. Five PEX-syndrome patients who needed transscleral-sutured IOL implantation due to zonular dialysis were excluded from this study.
Surgical Procedure of DMEK
The graft edges were stained using 0.1% Brilliant Blue G (BBG) 250 (BBG; Sigma-Aldrich, St. Louis, MO, USA) (1.0 mg/mL) during peeling. A punch was gently placed on the endothelial surface to indent a circle 7.75, 8.0, or 8.25 mm in diameter. Next, 1.0- and 1.5-mm-diameter dermatological biopsy punches (Kai Industries, Seki, Japan) were used to place asymmetric marks on the edges of the identified circles . Donor grafts were cut using the donor punch, stained with 0.1% BBG for 1 minute, and stored in a balanced salt solution (BSS) (BSS-plus; Alcon, Osaka, Japan) for about 30 min prior to insertion .
All surgeries were performed under local anesthesia. After establishing a retrobulbar block and a Nadbath facial nerve block, two paracenteses and a 2.8-mm upper corneal or corneoscleral incision were made for the recipient cornea. Peripheral iridotomy was performed at the 6-o’clock position using a 25-gauge vitreous cutter to prevent the development of a postoperative pupillary block. The donor membrane graft was placed into an IOL injector (model WJ-60M; Santen Pharmaceuticals, Osaka, Japan) and inserted into the anterior chamber .
The inserted graft was unfolded using a no-touch technique with shallowing of the anterior chamber . After the correct orientation was confirmed, the anterior chamber was filled with air to adhere the graft to the host cornea. Fifteen minutes later, the air was partially replaced with BSS. Finally, 0.4 mg of betamethasone (Rinderon; Shionogi, Osaka, Japan) was subconjunctivally administered in 1.5% (w/v) levofloxacin eye drops (Cravit; Santen Pharmaceuticals).
Postoperative medications were given four times daily for 3 months and tapered thereafter. They included 1.5% (w/v) levofloxacin (Cravit), 0.1% (w/v) betamethasone sodium phosphate (Sanbetasone; Santen Pharmaceuticals), and 2% (w/v) rebamipide ophthalmic solution (Mucosta; Otsuka, Tokyo, Japan).
Male/female and right/left ratios were compared using the χ2 test. The paired t-test was used to compare preoperative and postoperative values and the unpaired t-test was used to compare the PEX group and the FECD group. Moreover, multiple regression analysis was performed after the age adjustment. All analyses were performed using JMP 13.2.0 (SAS institute inc., Cary NC, USA). A P-value of<0.05 was considered to be statistically significant.