Survivability of locally prepared versus imported Descemet membrane endothelial keratoplasty grafts in Edmonton.

OBJECTIVE: This study aimed to evaluate the long-term graft survivability of locally prestripped versus imported prestripped Descemet membrane endothelial keratoplasty (DMEK) grafts in Edmonton. DESIGN: Prospective cohort study of patients who underwent DMEK surgery between January 1, 2020, and December 31, 2020. PARTICIPANTS: All patients receiving a DMEK transplant during the study period in Edmonton. METHODS: Two local technicians were trained to prestrip DMEK grafts in Edmonton. When available, local tissue was prestripped for DMEK surgery; otherwise, prestripped DMEK grafts were imported from an accredited American eye bank. Patient characteristics and DMEK graft characteristics and DMEK survivability were evaluated and compared between the 2 groups. RESULTS: Thirty-two locally prestripped DMEK grafts and 35 imported prestripped DMEK grafts were used during the study period. Donor cornea characteristics and patient characteristics were similar between the 2 groups. Best-corrected visual acuity improved up to 6 months postoperatively and was 0.2 logMAR in the locally prestripped DMEK group and 0.2 logMAR in the imported DMEK group (p = 0.56). Rebubble rates were 25% in the locally prestripped DMEK group and 19% in the imported DMEK group (p = 0.43). There was 1 primary graft failure in each group (p = 0.93). Endothelial cell density decreased by 37% in the locally prestripped DMEK group and by 33% in the imported DMEK group 2 years after transplantation. CONCLUSIONS: The long-term survivability of locally prepared DMEK grafts is comparable with that of DMEK grafts imported from American eye banks.

Porcine cataract creation using formalin or microwave treatment for an ophthalmology wet lab.

OBJECTIVE: Wet labs are an important part of ophthalmology residency training in order to develop intraocular surgical proficiency. The purpose of this study was to compare the effectiveness of formalin versus microwave treatment to produce porcine cadaveric cataracts. DESIGN: This study was a comparative observational study at a single centre. METHODS: Cataracts were created through the injection of 0.1 mL of 100% ethanol into the anterior chamber followed by the infiltration of 0.1 mL of 37% formalin using a short 30-gauge needle into the lens by introduction through the pars plana. The comparison group investigated porcine eyes treated with a microwave for 5-13 seconds using a 700 W power setting. Two observers used a validated nuclear opalescence and corneal clarity scale to independently grade the treated eyes. RESULTS: In total, 70 eyes were treated with either formalin or by microwave. The formalin eyes had an average lens opacity score of 0.04 ± 0.03 and 1.91 ± 01.10 pre- and post-treatment (p < 0.001). Microwaved eyes had an average pretreatment lens opacity of score 0.10 ± 0.31, which increased to 2.86 ± 0.1.08 post-treatment (p < 0.001). Post-treatment lens opacity was significantly greater in microwave eyes than in formalin-treated eyes (p = 0.003). Pretreatment corneal clarity was 3.65 ± 0.73 in the formalin group, and 3.70 ± 0.93 in the microwave group. After treatment, there was a significant reduction in corneal clarity within the formalin (3.01 ± 1.04, p = 0.0012) and microwave groups (3.03 ± 1.07, p < 0.001). CONCLUSIONS: Porcine eye models provide a realistic way to simulate cataracts and so residents can practice the basics of cataract surgery. Both microwave and formalin-based treatments are able to opacify the porcine lens with acceptable reductions in corneal clarity.