Eyeworld

NOV 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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60 EW CORNEA November 2012 Cornea editor's corner of the world Limbal stem cell deficiency associated with contact lens wear by Ellen Stodola EyeWorld Staff Writer L L imbal 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 unrecog- nized: 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 discontinu- ation 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 man- agement of contact lens-induced LSCD. Edward J. Holland, M.D., cornea editor imbal 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 epithe- lium 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 Cali- fornia, 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 peo- ple 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 ophthal- mologists 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 rang- ing from sub-total to total corneal involvement," Dr. Chan said. She said it is important to recog- nize the developing LSCD in order 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 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 charac- teristic 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 be- comes 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" appear- ance might become noticeable, Dr. Jeng said.

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