Ocular Tissue - Irish Blood Transfusion Service

Ocular Tissue

The Irish Eye Bank provides ocular tissue (corneas and sclera) for ophthalmic surgery. Corneal transplants have been carried out for more than 100 years. Each year in Ireland many people suffering from blindness through scarred or damaged corneas receive the gift of sight by a simple surgical procedure known as a Corneal Transplant. The damaged cornea is removed and replaced with a clear healthy donor cornea.  Some of the conditions that may lead to a corneal transplant include bullous keratopathy, keratoconus, corneal degeneration, corneal trauma or perforation, scarring, ulcers, and chemical burns.

Eye tissue is offered for transplant up to 24hours after death through a fully consented donation process.  The Eye Bank screens donations in accordance with policies and procedures that guide and determine eligibility for cornea and sclera transplantation. The screening process includes review of the donors’ medical-social history, blood screening for viral and bacterial infection and full body examination.  Unlike organ donation, in which retrieval is restricted by time and the immediate availability of a potential recipient, corneo-scleral tissue can be stored and used up to 14 days after procurement before it expires, and can be grafted into any recipient, regardless of recipient age, race, or blood type.

The Irish Eye Bank ceased accepting ocular donations in January 2004 due to the concerns surrounding variant Creutzfeldt-Jakob Disease (vCJD).  Corneas are considered to have a higher theoretical risk of transmission of vCJD than blood, so the decision was taken to import all ocular tissue from Rocky Mountain Lions Eye Bank (RMLEB) in Denver, Colorado; a vCJD-free  zone. Corneas are still imported for Irish patients from RMLEB today in what continues to be a trusted and cooperative international collaboration.

 

What is a Cornea?

The cornea is the transparent dome on the front of the eye, which acts like a window, protecting the inner light-detecting components of the eye and allowing clear vision. It is organised into 5 distinct functional layers. If the cornea is damaged either through injury or disease, it becomes cloudy and can eventually leading to blindness.  Depending on the surgical requirement or disease, a corneal transplant may involve a full cornea (all 5 intact layers, e.g. “PK” surgery) being transplanted at one time, or specific layers of the cornea being separated and transplanted in place of the patients damaged layers (e.g. “DSAEK” surgery).

 

What is a Sclera?

The sclera is the white spherical shell which, together with the cornea, makes up the outer structural wall of the eyeball. Scleral tissue can be used to surgically secure artificial drainage tubes and valves which help regulate intra-ocular pressure, and can also be used in reconstructive surgery for example in the event of enucleation.