Effect of Increasing Povidone-Iodine Exposure on Corneal Epithelium and Impact on Donor Rim Cultures

Suitability and Early Clinical Outcomes of Corneal Donor Tissue in the 76-80-Year-Old Age Group

PURPOSE

There is a significant global shortage of corneal donor tissue suitable for keratoplasty. One simple strategy for addressing this shortage is to increase the upper age limit for acceptable tissue over the current customary upper limit of age 75. We describe a pilot study completed at one eye bank procuring, processing, and distributing keratoplasty tissue from donors aged 76 to 80 years.

METHODS

This is a retrospective case series of donor tissues aged 76 to 80 years in comparison with donor tissues aged 71 to 75 years. Standard tissue parameters were evaluated for all tissues, including tissue suitability, mean endothelial cell density (ECD), death-to-procurement time, and cause of death. For the older tissues, clinical outcomes through 3 months were obtained from each surgeon, including intraoperative and postoperative complications.

RESULTS

Corneal tissues from donors aged 76 to 80 years had a similar suitability rate (57%) when compared with donors aged 71 to 75 years (59%) (P = 0.635). Both groups had comparable ECDs (P = 0.097). Early clinical outcomes of corneal grafts from donors older than 76 years were favorable, with no early graft failure or significant concerns for clinical safety or efficacy.

CONCLUSIONS

Our findings suggest that corneal tissues aged 76 to 80 years can be safely and efficiently transplanted in the United States. While additional study is needed, our results strengthen the case that expanding the upper age limit for donor age has the potential to help meet the global shortage for suitable keratoplasty tissue.

Corneal Endothelium Viability Assay Using Trypan Blue Dye After Preloaded Descemet Membrane Endothelial Keratoplasty Graft Preparation

PURPOSE

The purpose of this study was to establish a validated method, consistent with Eye Bank Association of America medical standards, for evaluating endothelial cell loss (ECL) from an entire Descemet membrane endothelial keratoplasty (DMEK) graft using trypan blue dye as an alternative to specular microscopy.

METHOD

Twenty-nine corneas were prepared for preloaded DMEK by a single technician, and the endothelium was stained with trypan blue dye for 30 seconds. The technician estimated total cell loss as a percentage of the graft and captured an image. Images were evaluated by a blinded technician using ImageJ software to determine ECL and compared with endothelial cell density from specular microscopy. Tissue processing intervals were analyzed for 4 months before and after implementation of this method.

RESULTS

For the 29 grafts, there was no statistically significant difference ( t test, P = 0.285) between ECL estimated by a processor (mean = 5.8%) and ECL calculated using an ImageJ software (mean = 5.1%). The processor tended to estimate greater ECL than the actual ECL determined by ImageJ (paired t test, P = 0.022). Comparatively, postprocessing endothelial cell density measured by specular microscopy were higher compared with the preprocessing endothelial cell density (mean = 4.5% P = 0.0006). After implementation of this evaluation method, DMEK graft processing time intervals were reduced by 47.9% compared with specular microscopy evaluation ( P < 0.001).

CONCLUSIONS

Our results show that visual ECL estimation using trypan blue staining by a DMEK graft processor is a reliable and efficient method for endothelial assessment. Unlike specular microscopy, this method achieves comprehensive visualization of the entire endothelium, reduces total time out of cold storage, and decreases total time required to prepare and evaluate DMEK grafts.

In praise of povidone-iodine application in ophthalmology

Polyvinyl pyrrolidone or povidone-iodine (PVP-I) is a water-soluble complex formed by the combination of iodine and a water-soluble polymer, polyvinyl pyrrolidone. This complex exerts bactericidal, fungicidal, and virucidal action by gradually releasing free iodine at the site of application to react with pathogens. In ophthalmology, PVP-I is used as a disinfectant and antiseptic agent for preoperative preparation of the skin and mucous membranes and for treating contaminated wounds. PVP-I has been shown to reduce effectively the risk of endophthalmitis in various ocular procedures, including cataract surgery and intravitreal injections; however, it has also been used in the treatment of conjunctivitis, keratitis, and endophthalmitis, with promising results especially in low-resource situations. PVP-I has been associated with complications such as postoperative eye pain, persistent corneal epithelial defects, ocular inflammation, and an attendant risk of keratitis. In cases of poor PVP-I tolerance, applying PVP-I at lower concentrations or using alternative antiseptics such as chlorhexidine should be considered. We provide an update on the efficacy of PVP-I in the prophylaxis and treatment of conjunctivitis, keratitis, and endophthalmitis and a comprehensive analysis of the current literature regarding the use of PVP-I in the management of these ocular conditions. Also, PVP-I-related adverse effects and toxicities and its alternatives are discussed. The goal is to present a thorough evaluation of the available evidence and to offer practical recommendations for clinicians regarding the therapeutic usage of PVP-I in ophthalmology.