Utilization rate and usage patterns of phakic and pseudophakic donor corneas recovered by the Singapore Eye Bank

Purpose To compare the utilization rate and usage patterns of pseudophakic and phakic donor corneas recovered by the Singapore Eye Bank. Methods Records of local donor corneas recovered by the Singapore Eye Bank from 2012 to 2017 were examined. Corneas that were deemed suitable for clinical use were stratified into phakic and pseudophakic groups. We examined the basic demographic pattern of both groups and the initial type of surgery/ies that the corneas were suitable for based on tissue parameters such as time from harvesting, stromal clarity, the clear central corneal area, the presence of Descemet’s membrane tears or defects, and endothelial cell density and quality. We also identified the types of corneal grafts that the corneas were eventually used for; Penetrating Keratoplasty (PK), Anterior Lamellar Keratoplasty (ALK), Endothelial Keratoplasty (EK). Finally, the overall utilization rates for each group were determined. Results A total of 986 corneas deemed suitable for transplant were analyzed, 908 (92%) were phakic and 78 were pseudophakic (8%). The average age of pseudophakic donor corneas was (65 ± 8 yrs. old) and there was a slight male preponderance for both groups (55%). Age adjusted analysis of pseudophakic corneas showed the endothelial cell density (ECD) (mean: 2327 ± 47.1 cells/mm2) and clear area (mean: 7.0 ± 0.7 mm) were lesser than phakic corneas. The percentage of pseudophakic corneas that were of EK standard (ECD >2500 cells/mm2) were lower compared to phakic corneas (37% and 77% respectively, p < 0.001). There was significant correlation between previous cataract surgery and the endothelial cell count of the donor corneas (p < 0.001), and regression analysis also showed a strong association of ECD with cataract surgery in reference to non-cataract surgery (-478.8 (95% CI-576.9 to -380.7). The overall utilization rate for pseudophakic corneas was 58% compared to that of phakic corneas at 83%. The most common reason for pseudophakic corneas not to be utilized was due to the presence of Descemet’s membrane (DM) tears or defects under the main or side port incision created during phacoemulsification (30%). Phakic corneas were used primarily for optical grafts 84% (mainly EK) while pseudophakic corneas were used mostly for therapeutic/tectonic grafts 47% (mainly ALK or patch grafts). Conclusion Compared to phakic donor corneas, pseudophakic corneas generally have lower overall tissue quality leading to lower uptake by surgeons and lower utilization rates. Eye banks must continuously refine their donor acceptance criteria and engage surgeons to optimize utilization of each recovered tissue.

Terrien’s Marginal Degeneration with Hydrops

We report a case of bilateral Terrien’s Marginal Degeneration with Hydrops. A 59 year old man presented with dimunition of vision in both eyes since 3 years. On examination both eyes had superior ectatic changes with right eye having scarred Descemet’s membrane indicating a healed hydrops and left eye showing superior corneal edema indicating resolving hydrops.

Microstructure characteristics of cornea of some birds: a comparative study

Background Light is the critical factor that affects the eye's morphology and auxiliary plans. The ecomorphological engineering of the cornea aids the physiological activities of the cornea during connections between photoreceptor neurons and light photons. Cornea was dissected free from the orbit from three avian species as ibis (Eudocium albus), duck (Anas platyrhynchus domesticus) and hawk (Buteo Buteo) and prepared for light and scanning electron microscopy and special stain for structural comparison related to function. Results The three investigated avian species are composed of three identical layers; epithelium, stroma, and endothelium, and two basement membranes; bowman's and Descemet’s membrane, separating two cellular layers, except for B. buteo which only has a Descemet’s membrane. The corneal layers in the investigated species display different affinity to stain with Periodic Acid Schiff stain. The external corneal surface secured by different normal epithelial cells ran from hexagonal to regular polygonal cells. Those epithelial cells are punctured by different diameter microholes and microplicae and microvilli of various length. Blebs are scarcely distributed over their surface. The present investigation utilized histological, histochemical and SEM examination. Conclusions The study presents a brief image/account of certain structures of cornea for three of Avian’s species. Data distinguish the anatomic structures of the owl's eye. The discussion explains the role of some functional anatomical structures all through the vision.

On the Dangers of Tropical Spiders as a Pet: A Review of Ocular Symptoms Caused by Tarantula Hairs

Tarantulas are large spiders that can defend themselves by shedding urticating hairs (setae). In this paper, we aim to discuss the ocular conditions caused by these setae through a literature review. In total, 25 cases were identified in the PubMed database. Tarantula setae have a barbed structure that enables migration through the globe. They give rise to a spectrum of complaints, causing a granulomatous inflammatory reaction in the compartment they settle. Superficial corneal hairs cause a mild keratitis, while hairs that penetrate Descemet’s membrane can induce an anterior uveitis. Both can be treated with local steroids; when possible, hairs should be debrided. Setae that migrate into the posterior segment can cause a focal vitritis that can be more difficult to treat, sometimes requiring vitrectomy.

Aqueous humour cytokine profiles after Descemet’s membrane endothelial keratoplasty

The aim of this study was to compare aqueous humour (AqH) cytokine profiles before and after Descemet’s membrane endothelial keratoplasty (DMEK) in eyes with bullous keratopathy (BK) and age-matched normal eyes. A total of 49 participants (mean age 75.0 ± 13.5 years) were divided into three groups: (1) BK patients scheduled for DMEK (BK group); (2) patients after DMEK (DMEK group; average postoperative time 1,018 ± 460 days); and (3) control participants without corneal endothelial disease scheduled for cataract surgery (control group). AqH (0.2 mL) was collected from all participants, and the levels of various AqH cytokines were simultaneously measured using a multiplex bead immunoassay. The DMEK group exhibited significantly lower concentrations of several pro-inflammatory cytokines, such as IL-1β, IL-5, IL-6, IL-10, and IL-8, and granulocyte colony stimulating factor than the BK group. In addition, the levels of IL-1β and IL-5 were significantly lower in the DMEK group than in the control group. The AqH levels of several pro-inflammatory cytokines were significantly reduced after DMEK, indicating that regeneration of the endothelial pump owing to the transplantation of a healthy endothelium might have a positive effect on anterior chamber inflammation.