Experts endorse standard terminology for ocular surface procedures

A report issued by a Cornea Society committee defines types and sources of transplanted ocular surface tissue, authors say.

Edward J. Holland

Clinicians have devised an international nomenclature for ocular surface rehabilitation procedures that classifies transplant tissue sources and types, a report said.

A committee selected by the Cornea Society set broad classification guidelines based on existing terminology and innovations that have occurred in the last 15 years, the report said.

“There’s been a significant increase in the number of procedures for ocular surface transplantation that had been reported in the last several years. The problem is that there has been no agreement on a classification of how you describe these procedures,” Edward J. Holland, MD, the corresponding author and OSN Cornea/External Disease Board Member, said.

Dr. Holland is the committee’s United States chairman.

“We were getting multiple names for basically the same surgical procedure, or a name for a surgical procedure was used to describe very different procedures. So, we didn’t have any consensus,” Dr. Holland said. “If we want to read about these procedures in the literature and compare procedures and outcomes, we basically need to speak the same language.”

Proposed nomenclature

The proposed nomenclature is based on the anatomic source of the tissue being transplanted, such as the conjunctiva, limbus or mucosa. It defines tissue sources as autologous or allogenic (cadaveric or living-related). The report also addresses cell culture methods, the authors said.

“It will be pretty straightforward for the clinicians to follow,” Dr. Holland said. “We just urge clinicians in this field to stop inventing their own names for these procedures and start using the new proposed classifications. We are encouraging surgeons and cornea specialists around the world to use this terminology.”

The report was published in the journal Cornea.

Tissue types, sources

According to the report, the primary anatomic sources of tissue for ocular surface rehabilitation are the conjunctiva and limbus. A third source, other mucosal tissue, was added. Other mucosal tissue encompasses buccal, nasal, rectal and peritoneal mucosa.

Limbal tissue is defined as limbal conjunctiva and keratolimbal tissue, which encompass anterior corneal and scleral tissue.

Conjunctival limbal tissue is obtained from the patient’s fellow eye or the eye of a living relative.

The terminology also covers tissue-engineered grafts and ex vivo cell cultivation techniques.

Expanded cell culture of cadaveric limbal tissue is termed “ex vivo cultivated cadaveric limbal allograft,” the authors said.

The nomenclature does not include amniotic membrane, which is used as substrate or tissue filler for various indications.

“Amniotic membrane is not a stem cell transplant, so we did not include it,” Dr. Holland said. “That’s not transplanting living tissue. That’s stored amnion. So, even though it is used in ocular surface transplantation by certain surgeons, we were describing stem cell transplants or tissue transplantation. Amnion is an adjunct to these procedures but is not part of the nomenclature.”

The authors noted that while autologous tissue is the optimal source when available, its use is not feasible in treating bilateral disease; the best alternative is best-matched living-related tissue, the authors said.

The viability of nonrelated cadaveric tissue hinges on tissue preservation and surgical technique, they said.

The committee’s next plans include proposing definitions and classifications of ocular surface disease and limbal stem cell dysfunction, devising a grading system, defining outcomes, and proposing therapies, Dr. Holland said.

“We want to evaluate where we are today in ocular surface transplantation, assess outcomes of present therapies and come up with a grading system that we can all use,” he said. “Then, finally, we will propose potential clinical trials.” – by Matt Hasson

Reference:

• Daya SM, Chan CC, Holland EJ. Cornea Society nomenclature for ocular surface rehabilitative procedures. Cornea. 2011;30(10):1115-1119.

• Edward J. Holland, MD, can be reached at HolPro Vision, 10794 Saunders Lane, Union, KY 41091; 859-657-6108; email: eholland@holprovision.com.
• Disclosure: Dr. Holland is a consultant for Alcon.