CORNEA

Cornea editor's corner of the world

Limbal stem cell deficiency associated with contact lens wear

Limbal stem cell deficiency (LSCD) can be one of the most devastating corneal diseases, with severe visual loss, and it is a challenge to treat. Most clinicians are aware of the more common causes of LSCD: chemical and thermal injuries, autoimmune conjunctivitis (Stevens-Johnsons syndrome and mucous membrane pemphigoid), genetic diseases such as congenital aniridia, and post- surgical stem cell loss with mitomycin-C. However, the most common cause of LSCD may be the one that is the most unrecognized: contact lens-induced LSCD. The majority of these cases result in partial stem cell loss in the superior cornea. Total limbal deficiency requiring a limbal stem cell transplant has been seen by many corneal specialists. Typically these patients had symptoms and corneal findings of LSCD for months and even years, but the diagnosis was not made. The key to this condition is understanding that LSCD can result from contact lenses, and discontinuation of the lenses at the appropriate time can resolve the problem. In this month's "Cornea corner of the world," Bennie Jeng, M.D., Ali Djalilian, M.D., and Clara Chan, M.D., discuss the clinical findings and management of contact lens-induced LSCD.

Edward J. Holland, M.D., cornea editor

Whorl-like epitheliopathy, along with fluorescein staining of the epithelium, can be an early sign of LSCD

Total limbal stem cell deficiency with late fluorescein staining of the abnormal epithelium over the complete corneal surface

An opaque epithelium indicates the progression of LSCD as the epithelium loses its luster and begins to have a different appearance

Superficial neovascularization is one of the noticeable signs that a patient is developing LSCD

Late fluorescein staining of the epithelium Source (all): Clara Chan, M.D.

Limbal stem cell deficiency (LSCD) may not be a widely recognized health risk, but a number of people are affected by it, and this number is especially notable among contact lens wearers.

Limbal stem cells are needed to help renew and repopulate the corneal epithelium, and LSCD can damage and put the corneal epithelium at risk. A particular risk is that some symptoms are hard to detect at first, and contact lens wearers are often hesitant to stop their usage.

"It is more common than we think, is the bottom line," said Bennie Jeng, M.D., professor of ophthalmology, University of California, San Francisco (UCSF), and co-director, UCSF Cornea Service.

Dr. Jeng said one of the few estimations is that about 2.4% of all contact lens wearers experience LSCD, which can be a significant number.

"If we estimate that there are 30 million people wearing contact lenses, then upward of 700,000 people could have some degree of stem cell deficiency, if you take the 2.4%, so that's actually a lot of people," he said.

Ali Djalilian, M.D., associate professor of ophthalmology, Illinois Eye and Ear Infirmary, University of Illinois, Chicago, agreed that it is hard to pinpoint an exact number of contact lens wearers who are affected by LSCD.

"It happens enough that, given the millions of soft contact lens wearers, comprehensive ophthalmologists will definitely come across such patients," he said.

Signs and symptoms

Clara Chan, M.D., clinical lecturer, Department of Ophthalmology, University of Toronto, said there are various patient symptoms that can be associated with LSCD, as well as various signs that can be seen on the eye. Some of these symptoms could include foreign body sensation, contact lens intolerance, or photophobia, she said.

"Limbal stem cell deficiency related to contact lens wear may be mild and focal, or severe and ranging from sub-total to total corneal involvement," Dr. Chan said.

She said it is important to recognize the developing LSCD in order to take early treatment measures. "It is likely that many patients who wear contact lenses have limbal stem cells that have been stressed by years of soft CL wear," Dr. Chan said.

She said it is possible that LSCD can escalate as stem cells become exhausted from a variety of factors.

"[The] earliest and most characteristic sign is punctate fluorescein staining of the epithelium in the superior cornea near the limbus," Dr. Djalilian said. "The staining pattern often follows a whorl-like pattern." Dr. Djalilian said this can often be confusing because it may look similar to dry eye symptoms. "Sometimes, the very first signs are some neovascularization coming onto the cornea, and then what we'll see is that the epithelium becomes kind of irregular, and it loses its luster," Dr. Jeng said. He said this might cause "somewhat of a funny light reflex" or cause the epithelium to appear dull or opaque.

Later on, a "streaming" appearance might become noticeable, Dr. Jeng said.

"Those can be early and late signs because the streaming can be extensive, or it can be localized in the periphery," he said.

However, Dr. Jeng said it is possible for patients to feel no different at all with LSCD or to have mild symptoms such as irritation, redness, light sensitivity, or some decreased vision.

Complications and treatment

LSCD can heal on its own; however, sometimes a more rigorous treatment plan, like surgery, is necessary. "The treatment for this can be as simple as taking [patients] out of the contact lenses and lubricating," Dr. Jeng said. "Sometimes we'll throw in topical steroids."

He said in more advanced cases, surgery might be the answer, but this requires a certain degree of caution because LSCD in one eye usually indicates a higher possibility of a patient having it in the other eye as well, so taking cells to transplant from one eye to the other could lead to stem cell failure in the "good" eye.

"If you knock out enough of your stem cells, then you can have chronic, non-healing epithelial defects, end up with scarring and ultimately vision loss," Dr. Jeng said.

Dr. Djalilian said some of the other complications that can arise from LSCD include "secondary stromal scarring, loss of vision, and permanent loss of the limbal stem cells."

Dr. Djalilian said in addition to recommending patients stop wearing contact lenses, it is important to "optimize the tear film with the use of artificial tears, anti-inflammatory therapy, punctal occlusion, as well as treatment of associated meibomian gland disease."

He said this treatment aids in reversing LSCD and its symptoms. Dr. Djalilian indicated that patients with LSCD could be candidates for refractive surgery, but may "require extra vigilance in pre- and post-op care."

Similarly, Dr. Chan stressed that surgery is an option for those with LSCD, but a degree of caution is required.

"Carefully selected patients with mild limbal stem cell deficiency that is stable and with an ocular surface that has been optimized may be candidates for laser vision correction," she said.

However, patients also need to be aware of the difficulties that may come with the healing process and that some surgeries may further aggravate the LSCD.

Editors' note: The physicians have no financial interests related to this article.

Contact information:

Chan: 416-960-5007, clarachanmd@gmail.com
Djalilian: 312-996-8937, ali.djalilian@gmail.com
Jeng: 415-206-8304, JengB@vision.ucsf.edu