Viscoelastic purity

Quality assurance in corneal transplants: Donor cornea assessment and oversight

The cornea is the most frequently transplanted human tissue, and corneal transplantation represents the most successful allogeneic transplant worldwide. In order to obtain good surgical outcome and visual rehabilitation and to ensure the safety of the recipient, accurate screening of donors and donor tissues is necessary throughout the process. This mitigates the risks of transmission to the recipient, including infectious diseases and environmental contaminants, and ensures high optical and functional quality of the tissues. The process can be divided into 3 stages: (1) donor evaluation and selection before tissue harvest performed by the retrieval team, (2) tissue analysis during the storage phase conducted by the eye bank technicians after the retrieval, and, (3) tissue quality checks undertaken by the surgeons in the operating room before transplantation. Although process improvements over the years have greatly enhanced safety, quality, and outcome of the corneal transplants, a lack of standardization between centers during certain phases of the process still remains, and may impact on the quality and number of transplanted corneas. Here we detail the donor screening process for the retrieval teams, eye bank operators. and ophthalmic surgeons and examine the limitations associated with each of these stages.

Endotoxins in ophthalmic viscosurgical devices

PURPOSE

To measure the endotoxin concentration (EC) of 25 commercially available, hyaluronic acid- and hydroxypropylmethylcellulose-based (HPMC) ophthalmic viscosurgical devices (OVDs).

METHODS

The in vitro Limulus amebocyte lysate (LAL) assay, which indicates the presence of endotoxins originating from gram-negative bacteria, was used to determine the EC. The procedure was performed according to the European Pharmacopoeia/USP. EC including duplicate determinations, negative controls, dilution series with control standard endotoxin, dilution series with sample extract and positive sample control.

RESULTS

16 OVDs (Amvisc, Amvisc Plus, Biolon, Coatel, Healon, Healon GV, Healon, HPMC Ophtal L, Microvisc, Microvisc Plus, Ocucoat, Provisc, Rayvisc, Viscoat, Visco Shield 2%, Visko 1.4%) had an EC under 1.2 endotoxin units/mL, five (Adatocel, HPMC Ophtal H, LA Gel, Viscorneal, Viscorneal Plus) had an EC > or = 1.2 and < or = 24 EU/ml, and four (Biocorneal, Dispasan also named Ophthalin, Dispasan Plus, Visko 1%) had an EC of > 24 EU/ml.

DISCUSSION

To avoid viscoelastic-related inflammatory or immunological reactions, the use of pure OVDs is recommended, especially for surgical procedures with an inherent possibility of leaving viscoelastic remnants in the eye (e.g., cataract surgery, visco-canalostomy or penetrating keratoplasty).