Ophthalmology referrals from optometry: a comparative study (the R.O.C.S study).

Objective: To characterize emergency optometrist referrals triaged at a tertiary ophthalmology care centre by physical examination findings and provisional diagnosis accuracy.

Design: Prospective case review.

Participants: Consecutive patients referred to a tertiary eye care clinic for an after-hours ocular consult.

Patient satisfaction with wait times at an emergency ophthalmology on-call service.

Objective: To assess patient satisfaction with emergency ophthalmology care and determine the effect provision of anticipated appointment wait time has on scores.

Design: Single-centre, randomized control trial.

Participants: Fifty patients triaged at the Hamilton Regional Eye Institute (HREI) from November 2015 to July 2016.

Regeneration of functional nerves within full thickness collagen-phosphorylcholine corneal substitute implants in guinea pigs.

Our objective was to evaluate promotion of tissue and nerve regeneration by extracellular matrix (ECM) mimics, using corneal implantation as a model system. Porcine type I collagen and 2-methacryloyloxyethyl phosphorylcholine (MPC) were crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) and moulded into appropriate corneal dimensions to serve as substitutes for natural corneal ECM. These were implanted as full thickness grafts by penetrating keratoplasty into the corneas of guinea pigs after removal of the host tissue, and tracked over eight months, by clinical examination, slit-lamp biomicroscopy, and esthesiometry.

Synthetic neoglycopolymer-recombinant human collagen hybrids as biomimetic crosslinking agents in corneal tissue engineering.

Saturated neoglycopolymers, prepared via tandem ROMP-hydrogenation (ROMP=ring-opening metathesis polymerization) of carbohydrate-functionalized norbornenes, are investigated as novel collagen crosslinking agents in corneal tissue engineering. The neoglycopolymers were incorporated into recombinant human collagen type III (RHC III) as collagen crosslinking agents and glycosaminoglycan (GAG) mimics. The purely synthetic nature of these composites is designed to reduce susceptibility to immunological and allergic reactions, and to circumvent the transmission of animal infectious diseases.

Bioengineered corneas for transplantation and in vitro toxicology.

Bioengineered corneas have been designed to replace partial or the full-thickness of defective corneas, as an alternative to using donor tissues. They range from prosthetic devices that solely address replacement of the cornea's function, to tissue engineered hydrogels that permit regeneration of host tissues. In cases where corneal stem cells have been depleted by injury or disease, most frequently involving the superficial epithelium, tissue engineered lamellar implants reconstructed with stem cells have been transplanted.

Collagen-phosphorylcholine interpenetrating network hydrogels as corneal substitutes.

A biointeractive collagen-phospholipid corneal substitute was fabricated from interpenetrating polymeric networks comprising 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide and N-hydroxysuccinimide crosslinked porcine atelocollagen, and poly(ethylene glycol) diacrylate crosslinked 2-methacryloyloxyethyl phosphorylcholine (MPC). The resulting hydrogels showed an overall increase in mechanical strength beyond that of either original component and enhanced stability against enzymatic digestion (by collagenase) or UV degradation. More strikingly, these hydrogels retained the full biointeractive, cell friendly properties of collagen in promoting corneal cell and nerve in-growth and regeneration (despite MPC's known anti-adhesive properties).

Regeneration of corneal cells and nerves in an implanted collagen corneal substitute.

Purpose: Our objective was to evaluate promotion of tissue regeneration by extracellular matrix (ECM) mimics, by using corneal implantation as a model system.

Methods: Carbodiimide cross-linked porcine type I collagen was molded into appropriate corneal dimensions to serve as substitutes for natural corneal ECM. These were implanted into corneas of mini-pigs after removal of the host tissue, and tracked over 12 months, by clinical examination, slit-lamp biomicroscopy, in vivo confocal microscopy, topography, and esthesiometry.

Tissue-engineered recombinant human collagen-based corneal substitutes for implantation: performance of type I versus type III collagen.

Purpose: To compare the efficacies of recombinant human collagens types I and III as corneal substitutes for implantation.

Methods: Recombinant human collagen (13.7%) type I or III was thoroughly mixed with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide.

Immunological responses in mice to full-thickness corneal grafts engineered from porcine collagen.

Tissue-engineered (TE) corneas were fabricated from porcine collagen cross-linked with 1-ethyl-3-(3-dimethyl aminoproplyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS), and were transplanted into BALB/c mice orthotopically using a full-thickness penetrating keratoplasty (PKP) procedure. The biocompatibility was evaluated by assessing both local and systemic immune responses. Myeloid cells including granulocytes and macrophages were the main infiltrating cells in recipient cornea and in retro-TE corneal membrane which developed 7-10 days post surgery.

Building in vitro models of organs.

Tissue-engineering techniques are being used to build in vitro models of organs as substitutes for human donor organs for transplantation as well as in vitro toxicology testing (as alternatives to use of animals). Tissue engineering involves the fabrication of scaffolds from materials that are biologically compatible to serve as cellular supports and microhabitats in order to reconstitute a desired tissue or organ. Three organ systems that are currently the foci of tissue engineering efforts for both transplantation and in vitro toxicology testing purposes are discussed.

Functional innervation in tissue engineered models for in vitro study and testing purposes.

The biotechnology industry is rapidly expanding and the emerging field of tissue engineering is projected to have a high impact in the near future. Recently the field of cellular, drug, and prosthetic delivery has melded with the field of tissue engineering to make simulated tissues. In addition to their roles as tissue substitutes for transplantation, these simulated tissues may provide more accurate models and environments for toxicology testing and the study of peripheral nerves.