The lack of consensus regarding limbal stem cell deficiency has been resolved by a panel of experts that provided uniform guidelines for disease diagnosis and staging.
When goblet cells are present on the corneal surface, changes of the epithelial phenotype provide indirect evidence for the diagnosis of limbal stem cell deficiency: irregularity and haziness, vascularization, absence of the limbal palisades, persistent and recurrent epithelial defects, and subepithelial fibrosis, according to Dr. Kruse.
The symptoms include pain, foreign-body sensation, photophobia, resulting in decreased vision and quality of life.
The most important diagnostic test is surface late staining with fluorescein; the dye diffuses into the paracellular space of the conjunctivalized surface, and the abnormal delayed staining is seen 10 minutes or longer after fluorescein is instilled on the ocular surface, Dr. Kruse explained.
Other histologic and immunohistochemistry tests, that is, impression cytology and biopsy, also can be performed to diagnosis the presence of limbal stem cell disease.
In vivo imaging also has emerged as a noninvasive diagnostic tool that is equivalent to cytology, he noted.
An alternative imaging method is anterior-segment optical coherence tomography, which is also noninvasive and provides a larger field of view.
The expert panel also established a new staging system to guide therapy and surgery.
“Stage I is characterized by healthy corneal epithelium in the center and various degrees of conjunctivalization in the periphery,” Dr. Kruse expxlained. “In stage II, the corneal center shows signs of disease with various changes in the periphery. Stage III shows complete vascularization of the corneal surface.”
Limbal stem cell deficiency
Acquired limbal stem cell deficiency can result primarily from nonimmune causes: chemical, thermal, or radiation injury; contact lens-induced changes; surgery; trachoma and lid disease; and drugs. The immune causes include Stevens-Johnson syndrome, mucous membrane pemphigoid, allergic ocular surface disease, vernal and atopic keratoconjunctivitis, graft-versus-host disease, severe dry eye, and idiopathic problems.
Hereditary limbal stem cell deficiency results from congenital aniridia, dyskeratosis congenita, autoimmune polyglandular syndrome, ectodermal dysplasia, multiple endocrine deficiency, and xeroderma pigmentosum.
Dr. Kruse noted that the panel has established a new definition of limbal stem cell disease.
“We think it is important to look for signs of conjunctivalization on the ocular surface and to prove the existence of goblet cells when invasive therapy is performed,” he concluded. “We have provided a list of diseases causing limbal stem cell deficiency that is based on the current literature.”
Friedrich E. Kruse, MD
E: [email protected]
Dr. Kruse has no financial interest in any aspect of this report.