Suspect limbal stem cell deficiency in all contact lens wearers
Contact lens-induced limbal stem cell deficiency can be caused by a number of factors and results in a significant loss of stem cells and corneal conjunctivalization. Treatment including spectacle wear and topical therapy can put soft contact lens wearers back into their lenses again.
Limbal stem cell deficiency (LSCD) is a pathological state secondary to limbal damage characterized by poor epithelialization, chronic stromal inflammation and corneal vascularization and conjunctivalization.
Contact lens-induced LSCD, which may represent 15% of known LSCD cases, can be caused by poorly fitting contact lenses, overwear or misuse of contact lenses or hypoxia.
Causes of LSCD
LSCD does not spontaneously occur; it takes an insult to the cornea to develop, PCON Editorial Board Member Paul M. Karpecki, OD, FAAO, told Primary Care Optometry News. Such an insult could be a result of misuse or neglect or it may be caused by the mechanics of the contact lens in certain patients.
[LSCD] is more prevalent in patients who chronically abuse their eyes, William Townsend, OD, FAAO, said in an interview. If they sleep in lenses that were never designed to be slept in or overwear their lenses, LSCD could develop.
Images: Karpecki PM
Another cause could be too much pressure on the limbus, or lenses that do not allow enough oxygen through. According to PCON Editorial Board Member Joseph P. Shovlin, OD, FAAO, certain patients using certain lenses are susceptible.
There is likely a mechanical component with lens edge chafing, sicca and even hypoxia playing at least some role in the pathogenesis of limbal stem cell deficiency in soft lens wearers, Dr. Shovlin told PCON. The role, if any, multipupose disinfecting solutions play is speculative.
Dr. Townsend agreed. In the older generation of lenses that had lower DK, patients with a very high myopic prescription would have a thicker lens in the periphery as compared to the center, he said. They might be getting adequate oxygen flow through the center because its thin, but as you get closer to the periphery that reduction in oxygen flow causes chronic hypoxia.
Signs to consider
LSCD starts as a sectoral haze in the cornea and most commonly presents as superior corneal vascularization that moves toward the center, Dr. Karpecki said. A telltale sign of LSCD is that one eye is typically more involved than the other.
It comes in from the limbus as a corneal haze the epithelium is very irregular; you can see neovascularization or just stromal clouding, he said.
Dr. Shovlin clarified the analysis, saying that many practitioners confuse what they are calling stem cell deficiency with other contact lens-related and medication toxicities.
The different wave-like advancing epitheliopathies are hallmarked by an irregular epithelium and subepithelial haze that originate from the upper aspect of the limbus and can be seen with anti-glaucoma medications, soft lens wear, past ocular surgery, acne rosacea and atopic dermatitis, Dr. Shovlin said. One way to differentiate between contact lens associated superior limbic keratitis (SLK) and LSCD is to use differential stains such as lissamine green and sodium fluorescein. LSCD is late-fluorescein positive, but lissamine green negative. The SLK lesion will be lissamine green and fluorescein positive.
According to Dr. Townsend, the first priority is to have an index of suspicion. Even if the patient is compliant and asymptomatic, check for signs of LSCD. Pull up the upper eyelid. Look for LSCD assume that contact lens wearers will have vascularization until proven otherwise, he said. LSCD may also occur as a result of chronic UV radiation.
How to treat LSCD
When treating contact lens-induced limbal stem cell deficiency, first remove the lenses, Loretta Szczotka-Flynn, OD, PhD, told PCON.
I try to take things away from the limbus, which gives it more oxygen, she said. By clearing it out totally and not putting any pressure on it considering the mechanical component youre better off. I try to put patients in GP lenses or spectacles instead.
In addition to demanding a hiatus from contact lens wear, Dr. Shovlin also recommends topical treatments.
Topical steroids even preservative free are beneficial, along with additional measures to manage the sicca component, such as punctal occlusion and topical cyclosporine. Dr. Shovlin said he occludes the lower puncta only, because that is where most of the therapeutic effect occurs.
If these measures do not improve the condition after about 6 months, Dr. Townsend recommends limbal stem cell transplantation. Once youve really lost limbal stem cells, it may be a serious issue patients may not get better on their own, he said.
Dr. Karpecki echoed his statement, suggesting autografts or preferably allografts and an amniotic membrane transplant. Though more typically used with chemical burns, aniridia or chronic bullous keratopathy, allografts (growing limbal stem cells from a patients existing stem cells) are an option for the most severe patients with both eyes involved.
If the patient does not improve [after first-line therapy], the second step would be to débride that area of irregular epithelium, and then add a ton of lubricating and anti-inflammatory drops such as loteprednol and cyclosporine and hope it grows back a lot healthier, Dr. Karpecki said. The third step, if it returns or involves more than just a sectoral region, would require either an amniotic membrane transplant or an allograft.
The future of stem cells
Limited studies are available on LSCD, which makes it difficult for general practitioners to recognize it, Dr. Szczotka-Flynn said.
Diagnosis is poor, she said. We need to get something in the literature or the average practitioner will never officially diagnose it [using impression cytology]. Most of us are unsure of what were dealing with and just diagnose it clinically by how the patient looks behind the slit lamp.
Regardless, the treatments for LSCD are very effective if caught early enough in the disease process, Dr. Karpecki said. As more information becomes available about the possibilities of stem cells, researchers are looking toward the potential benefits they could yield to treat other conditions.
Stem cells differentiate into anything depending on where theyre from, and the future [of stem cell research] is huge, Dr. Karpecki said. The way were going to solve dry macular degeneration is likely going to involve RPA stem cells, which are being grown in labs. Its an exciting area for the future that has the potential to solve a lot of problems.
For more information:
- Paul M. Karpecki, OD, FAAO, is clinical director of Corneal Services and Ocular Surface Research for Koffler Vision Group in Lexington, Ky. He can be reached at (859) 227-7781; email@example.com.
- William Townsend, OD, FAAO, practices at Advanced Eye Care in Canyon, Texas, and is an adjunct professor at the University of Houston College of Optometry. He can be reached at (806) 655-7748; firstname.lastname@example.org.
- Joseph P. Shovlin, OD, FAAO, practices at Northeastern Eye Institute in Scranton, Pa. He can be reached at (570) 342-3145; email@example.com.
- Loretta Szczotka-Flynn OD, PhD, can be reached at University Hospitals Eye Institute, Case Western Reserve University; (216) 844-3609; Loretta.Szczotka@UHhospitals.org.