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LASIK surgeons may start to take on more controversial, contraindicated cases
Better diagnostic testing, topical medications and literature review allow LASIK treatment of cases with dry eye, glaucoma and large pupils.
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Results from the U.S. National Health and Nutrition Study indicate that the rate and degree of myopia are increasing.
The correction of myopia accounts for almost 85% of U.S. refractive surgery. More than 65 million Americans (130 million eyes) are LASIK candidates, and approximately 1.4 million myopes (2.8 million eyes) reach 21 years of age each year in this country. Depending on consumer confidence and the economy as a whole, these numbers suggest a potential of up to 2 million LASIK procedures per year. Unfortunately, these numbers are not quite what we once saw with the original LASIK boom in the early 2000s.
The 2013 International Society of Refractive Surgery Survey, overseen by Richard Duffey, showed that the percentage of surgeons performing at least 75 LASIK cases per month dropped from 27% in 2001 to 9% in 2012 and 2013. These declining numbers may push LASIK surgeons to start expanding their procedure volume to more “controversial” or “contraindicated” cases to grow their overall volumes. Many articles and papers have been written on laser vision correction of keratoconus, forme fruste keratoconus and suspicious corneal topographies, but what about autoimmune diseases, dry eye, glaucoma and large pupils?
My review on the U.S. Food and Drug Administration language for these controversial categories is based on the website www.fda.gov/MedicalDevices/default.htm. In autoimmune/collagen vascular diseases such as rheumatoid arthritis and lupus, the FDA site states that a patient is probably not a good candidate if he or she has been or is being treated for diseases that affect wound healing. As for dry eye, the FDA site states that LASIK surgery aggravates this condition and that dry eye should be screened for indicators of risk. With glaucoma/glaucoma suspect/ocular hypertension patients, the FDA site lists these as precautions in which the safety and effectiveness in these situations has not been determined. Lastly, in large pupils, the FDA site states that evaluation is to be done in a dark room and that younger patients and patients on certain medications who are prone to large pupils should be screened for indicators of risk.
LASIK in dry eye patients
So why is dry eye in LASIK so important? LASIK-induced neurotrophic epitheliopathy (LINE), as first described by Steve Wilson in 2001, is considered the most common complication of LASIK and can affect greater than 50% of LASIK patients in the first 6 months postoperatively. Tsubota even reported as far back as 2002 that pre-existing dry eye is a critical risk factor for severe dry eye postoperatively up to 1 year after LASIK. Due to a disruption in the normal neural feedback loop between the ocular surface and lacrimal glands, LINE can cause regression of effect and bothersome visual fluctuations. Common systemic medications such as antihistamines, blood pressure medications (particularly diuretics and beta blockers) and tricyclic antidepressants are notorious dry eye-exacerbating agents.
A comprehensive literature review of all publications dated to 2012 concluded that LASIK may be safe if collagen vascular disease, which included rheumatoid arthritis, lupus and seronegative spondyloarthropathies in this group, is well-controlled with minimal ocular manifestations and no clinical signs and/or history of dry eye symptoms. Sjögren’s syndrome patients in this review were considered not suitable LASIK candidates. The good news is a new proprietary blood test to detect three early antibodies (SP-1, CA-6, PSP) is available, as the Sjo diagnostic test (Nicox) detects Sjögren’s syndrome in patients with dry eye syndrome. Sjögren’s affects up to 4 million people in the U.S. and is seen in one out of 10 dry eye patients. Other useful tests to diagnose dry eye preoperatively include tear osmolarity (TearLab) and the recently approved InflammaDry (Rapid Pathogen Screening), which detects elevated levels of matrix metalloproteinase-9 (MMP-9) in the tears of dry eye patients.
I will typically use tear osmolarity measurements to follow my patient’s response to therapy for LINE if there are problems in the postoperative period. My therapy of choice for at least 6 months postoperatively in problematic patients with LINE is topical cyclosporine (Restasis, Allergan) due to its specific anti-inflammatory activity against cytokines typically seen with neurogenic LINE.
LASIK in glaucoma patients
Some helpful suggestions in patients with primary open-angle glaucoma, primary open-angle glaucoma suspect or ocular hypertension who want LASIK include: baseline optic nerve head/retinal nerve fiber analysis and visual fields should be assessed before LASIK; avoid LASIK in patients with blebs; beware of inducing an IOP spike with steroid therapy postoperatively; and ester steroids such as Lotemax gel (loteprednol etabonate ophthalmic gel 0.5%, Bausch + Lomb) may be safer in these patients.
Many topical glaucoma agents can increase expression of MMP on the ocular surface and contain higher levels of benzalkonium chloride (BAK) preservative, which can aggravate LINE in the postoperative period. Lotemax gel as an anti-inflammatory topically contains only 0.003% BAK, and in use with preservative-free topical IOP-lowering medications such as Zioptan (tafluprost ophthalmic solution 0.0015%, Merck), it may be a good combination in this category of patients who are LASIK candidates. Again, tear osmolarity is an excellent gauge to manage the response to ocular surface LINE therapy in the LASIK patient on glaucoma medications.
LASIK in large pupils
Since the early 2000s, better diagnostic methods have evolved to measure scotopic and mesopic pupil size — Colvard (Oasis Medical), Neur-Optics (NeurOptics), OPD-Scan III (Marco) and iTrace (Tracey Technologies), as examples. Many publications have concluded recently that large pupil size does not correlate with positive postoperative visual symptomatology. The most recent review by Myung et al in the November 2013 issue of Journal of Refractive Surgery concluded that modern LASIK has negated the role of the low-light pupil in predicting adverse visual outcomes after LASIK outside of the early postoperative period. My only advice is to take notice of younger patients who desire LASIK and are on systemic medications such as tricyclic antidepressants and/or anticholinergics (bladder/bowel reasons) that can alter pupil size significantly.
In summary, LASIK can be suitable for patients in somewhat historically controversial situations such as dry eye, glaucoma and large pupils. Better diagnostic testing, better topical medications and better review of the literature have facilitated our decision as premium surgeons to better select these patients for LASIK.
Stay tuned for my next column on the diagnostic challenge for today’s premium eye surgeon.