Corneal Endothelial Cell Protection With Viscoat and Healon or Healon Alone During Penetrating Keratoplasty

Optimization of Cultured Human Corneal Endothelial Cell Sheet Transplantation and Post-Operative Sheet Evaluation in a Rabbit Model

PURPOSE

To optimize cultured human corneal endothelial cell (cHCEC) sheet transplantation technique for maintenance of cHCEC viability.

MATERIALS AND METHODS

cHCEC sheets cultured on a collagen scaffold were covered with or without Viscoat® and exposed to humidified air in the incubator. cHCEC sheets with or without Viscoat® were transplanted into cadaveric porcine eyes by the DSAEK technique with full air tamponade and incubated for various time periods. Then cell viability was determined by using the live/dead assay kit. cHCEC sheets with Viscoat® were transplanted into rabbit eyes and the sheets were histologically evaluated before and 14 days after transplantation.

RESULTS

A collagen scaffold and Viscoat® were effective for protecting cHCEC from damage due to air exposure in vitro. All cells died after 18 hours of air exposure in porcine eyes in Viscoat® untreated control. In contrast, Viscoat® treatment sustained full cell viability following 2 hours and could maintain approximately 80% viability after 18 hours. In a rabbit model, transplanted cHCEC sheet with Viscoat® maintained cell density at 2803 ± 229 mm(2) (18% cell loss) and expression of N-cadherin, zonula occludens-1, and actin-filament localized to cell boundary as similar as donor HCEC.

CONCLUSION

Viscoat® can contribute to cHCEC protection from damage caused by exposure to air.

Comparison of cytotoxicity and wound healing effect of carboxymethylcellulose and hyaluronic acid on human corneal epithelial cells

AIM

To investigate the cytotoxic effect on human corneal epithelial cells (HCECs) and the ability to faciliate corneal epithelial wound healing of carboxymethylcellulose (CMC) and hyaluronic acid (HA).

METHODS

HCECs were exposed to 0.5% CMC (Refresh plus(®), Allergan, Irvine, California, USA) and 0.1% and 0.3% HA (Kynex(®), Alcon, Seoul, Korea, and Hyalein mini(®), Santen, Osaka, Japan) for the period of 30min, and 4, 12, and 24h. Methyl thiazolyl tetrazolium (MTT)-based calorimetric assay was performed to assess the metabolic activity of cellular proliferation and lactate dehydrogenase (LDH) leakage assay to assess the cytotoxicity. Apoptotic response was evaluated with flow cytometric analysis and fluorescence staining with Annexin V and propiodium iodide. Cellular morphology was evaluated by inverted phase-contrast light microscopy and electron microscopy. The wound widths were measured 24h after confluent HCECs were scratch wounded.

RESULTS

The inhibitory effect of human corneal epithelial proliferation and cytotoxicity showed the time-dependent response but no significant effect. Apoptosis developed in flow cytometry and apoptotic cells were demonstrated in fluorescent micrograph. The damaged HCECs were detached from the bottom of the dish and showed the well-developed vacuole formations. Both CMC and HA stimulated reepithehlialization of HCECs scratched, which were more observed in CMC.

CONCLUSION

CMC and HA, used in artificial tear formulation, could be utilized without any significant toxic effect on HCECs. Both significantly stimulated HCEC reepithelialization of corneal wounds.

Safety and efficacy of two ocular anesthetic methods for phacoemulsification: topical anesthesia and viscoanesthesia (VisThesia)

PURPOSE

VisThesia is a new ophthalmic viscosurgical device (OVD) which has 1% lidocaine combined with 1.5% sodium hyaluronate. This is a prospective evaluation of the safety and efficacy of VisThesia used in association with phacoemulsification.

METHODS

A total of 114 eyes were divided into two groups. Fifty-nine eyes were treated with tetracaine + oxybuprocaine topical anesthesia and DuoVisc OVD and 55 eyes were treated with VisThesia, for use as both topical anesthetic and OVD. Endothelial cell counts were measured at 30 days postoperatively and compared to preoperative baseline values. Pain and discomfort was subjectively evaluated by patients using a visual analog pain scale (0-10).

RESULTS

All surgeries were uneventful with no intraoperative or immediate postoperative complications. Patients receiving topical anesthesia had a mean pain score of 1.1+/-6.8 compared to a mean score of 1.3+/-4.6 for patients receiving VisThesia (p=0.59). Postoperatively, endothelial cell loss at 1 month was greater for patients receiving VisThesia (20.32%+/-43.75) than for those receiving the topical anesthetic (8.8%+/-59.6; p<0.0001).

CONCLUSIONS

The results from the visual analog pain scale were comparable between groups, showing that VisThesia provides similar pain relief to topical anesthesia. Specular microscopy performed at 30 days postoperatively showed a significantly greater loss of endothelial cells with the use of VisThesia, suggesting that the 1% lidocaine concentration used in VisThesia may be toxic to corneal endothelial cells.