Clinicians stress preop evaluation, treatment to avoid dry eye after LASIK

Take preventive measures preoperatively

Elizabeth Muckley

Elizabeth Muckley, OD, FAAO: The first step in managing LASIK-induced dry eye is to identify those patients at risk preoperatively and take preventive measures prior to surgery. The incidence of dry eye is higher among women, long-term contact lens wearers, patients on certain systemic medications and older patients. Those with meibomian gland dysfunction are also at risk.

If I suspect someone may be at risk for postoperative dry eye, I insert extended-duration collagen punctal plugs inferiorly, prior to surgery. Some collagen plugs last approximately 90 days, which can increase the tear meniscus to help heal the surface or flap.

Managing lid gland dysfunction is also critical to improving the quality of tears. This is typically done through oral doxycycline, lid hygiene and warm compresses. Any keratopathy should be resolved if the patient is to undergo successful surgery.

For some patients, I may counsel toward surface ablation, which may be less associated with protracted dry eye. In at-risk patients, the thinner, planar, laser-created flap is preferable to one created by a microkeratome, as it is associated with more rapid healing, presumably faster regeneration of the corneal nerves and more rapid return of normal tear function.

If a patient develops postoperative dryness despite preventive measures, the initial approach includes preservative-free tears, gels and nighttime ointments. Oral omega-3 supplements can also be helpful.

If additional treatment is needed, I progress to a regimen of Lotemax (loteprednol etabonate suspension, Bausch & Lomb) twice daily for 4 weeks while at the same time starting Restasis (cyclosporine, Allergan). I like the steroid at first because it quiets inflammation associated with dry eye discomfort. Restasis typically burns upon instillation, especially if there is punctate keratopathy. The steroid initially helps to minimize this.

I also remind patients not to use an overhead fan while sleeping and to turn the car air vents away from the eyes when driving. The benefits of a cool mist humidifier in the rooms a patient most often occupies can help, especially in the dry winter months.

Fortunately, in most patients, the cornea begins to return to normal by 6 months postoperatively, although one study showed that it can take up to 9 months. Sometimes just encouragement and patience is needed to get through those initial months.

Screen, treat preoperatively

Jim Owen

Jim Owen, OD, MBA, FAAO: Some consider dry eye the most common side effect of LASIK.

Identifying those patients at risk prior to surgery is important. Based on history, female patients, patients older than 50 years, hyperopic patients, Asians and those who are on medicines that may dry the eyes are at an increased risk of postoperative dry eye, according to Schaumberg and colleagues. Also, clinical findings of decreased tear break-up time, decreased tear lake and superficial staining with fluorescein or lissamine green are signs that the cornea is dry.

Our preoperative protocol for treating dry eye includes discontinuing contact lens use, artificial tears and Restasis. Prior to surgery all patients should have a healthy stable tear layer or they may be unsatisfied with their results.

At TLC Laser Centers, we have noticed several factors that contribute to postoperative dry eye. One such factor is the corneal nerves being severed when creating the flap and ablated in the treatment. This leads to a decrease in corneal sensation that can last for up to 18 months. Also, goblet cells are often damaged during the procedure, leading to a less stable tear layer. Last, the corneal shape is changed during surgery, which can affect the distribution of tears over the cornea.

Treating dry eye postoperatively allows patients to achieve their best vision and be as satisfied as possible with our work, as dry eye affects the visual outcome. All of our patients take artificial tears and Restasis for at least 1 month after surgery.

Studies have shown Restasis improves refractive outcomes and can decrease enhancement rates of LASIK patients. Restasis also may increase corneal sensation. According to Ursea and colleagues, many patients stay on Restasis for up to 3 months. Artificial tears are also an important component of the postop regimen. We prefer Blink Tears (AMO, Irvine, Calif.) because it provides long-lasting relief from dry eye symptoms and is reported by patients to provide a good quality of vision immediately after instillation.

Treat presurgically

Brett G. Bence

Brett G. Bence, OD, FAAO: At our surgical centers, we begin treating this aggravating, latent condition during the preoperative management. The use of prophylactic Restasis and continued use for 1 to 3 months or longer after the procedure along with nonpreserved artificial tears (Refresh Plus, Allergan) and lubricating ointment at bedtime (Refresh PM, Allergan) is beneficial. If presurgical dry eye or eyelid disease is manifest, treatment prior to surgery will reduce post-LASIK complications.

Intuitively, the decision to use an anti-inflammatory drug makes little sense due to the primary cause of postsurgical dry eye being neurogenic, not inflammatory. However, my observations and the clinical evidence in our surgical practice guide us to support this approach.

In refractory post-LASIK dry eye cases, removable (not permanent intracanalicular) punctal plugs are a viable option. In cases of moderate (not severe) exposure keratopathy, an interesting option that seems to work well is the medium-term Dissolvable Opaque Herrick Intracanalicular Plug (Lacrimedics, Eastsound, Wash.). These seem reasonably effective for 3 to 6 months, generally the duration of time we administer therapy for these patients.

Dry eye due to LASIK tends to resolve within 3 months, seldom lasting up to 6 months. The corneal nerves should regenerate by that time. For dry eye signs and symptoms lasting more than 6 months, there should be identifiable concomitant factors that will necessitate continuing management.

Prepare the ocular surface preoperatively

Katherine M. Mastrota

Katherine M. Mastrota, OD, MS, FAAO: Intuitively, the management of post-LASIK dry eye would parallel cataract surgery-induced dry eye, a common issue in every cataract surgery practice.

Often, preexisting asymptomatic dry eye is tipped into patient-aware dry eye after surgical procedures by mechanisms including mechanical manipulation, trauma-induced inflammation and postoperative medications.

Minor speculum-induced postoperative lagophthalmos can allow for exposure-driven dry eye; severed corneal nerves from either procedure (less so in cataract surgery) position the ocular surface for neurotrophic dry eye; intraoperative surface desiccation challenges the ocular surface in the postoperative period; necessary multiple postoperative medications, in the long term, can become surface-toxic; and inflammatory mediators from surgical trauma can exacerbate surface disruption.

To limit postoperative dry eye I prepare the ocular surface before surgery, optimizing it by reducing the bacterial load on the eyelid and eyelashes with commercially prepared solutions such as OcuSoft Lid Scrub Pre-Moistened Pads (Cynacon-OcuSoft, Richmond, Texas), initiating cyclosporine therapy (Restasis) as indicated, bolstering meibomian gland secretion with omega-3 supplementation and addressing meibomian gland dysfunction with warm compresses and therapeutic management if necessary.

Zylet (tobramycin-loteprednol, Bausch & Lomb) is a good choice in managing preoperative blepharoconjunctivitis, and AzaSite (1% azithromycin, Inspire) has shown promise in reducing the inflammation of the lid margin associated with meibomian gland dysfunction (an off-label use). Additionally, I suggest patients take 2 g of vitamin C per day for quicker corneal rehabilitation.

Postoperatively I am careful to assess lid apposition and check for surface staining, adding a lubricating gel or mask at night to limit exposure. I slowly taper steroid and nonsteroidal anti-inflammatory drug administration, in effect, weaning the eye from the anti-inflammatory effects and simultaneously reducing preservative impact on the surface.

Cyclosporine therapy is continued or initiated on the basis of dry eye signs and symptoms. Nonpreserved tears such as Blink Tears or Optive Sensitive (Allergan) can be prescribed. Vitamin C and omega-3 supplementation is continued. Adequate hydration is important, and patients are encouraged to increase their fluid intake as a general rule.

Underlying postoperative corneal inflammation and desiccation stress is activation of matrix metalloproteinases (MMPs) by the corneal and conjunctival epithelia. MMPs play an important role in corneal wound healing and in disease states. MMP-9 is found under pathologic conditions, such as dry eye, and after corneal wounding.

Interestingly, in vitro azithromycin ophthalmic solution 1% has been demonstrated to suppress human corneal cell MMP-9 and may be beneficial in conditions where MMPs are elevated, as in the postsurgical and dry eye. Future studies for this off-label use of AzaSite are in order.

Limit risk preoperatively

Joseph Stamm

Joseph Stamm, OD, FAAO(Dipl): Although it may sound obvious, the best way to manage post-LASIK dry eye is to minimize its risk before surgery. Virtually every eye that undergoes LASIK will experience a degree of dryness afterwards.

The creation of the corneal lamellar flap severs a high percentage of the superficial sensory nerves leading to a mildly neurotrophic cornea. This lack of afferent sensory data suppresses the blink reflex, allowing for evaporation of the precorneal tear film. Location of the flap does not seem to influence this effect.

Damage to the limbal and conjunctival goblet cells by the suction ring of a mechanical microkeratome or a femtosecond laser decreases production of mucin, which further destabilizes the tear film.

The stability of the tear film begins to recover between 6 and 8 weeks after surgery. By 3 months postoperatively, the vast majority of otherwise normal eyes will have recovered sufficient tear film stability to be considered subjectively normal. A compromised tear film prior to surgery will make recovery from these stresses more difficult.

Preoperative testing with fluorescein will reveal tear stability and quality issues. Lissamine green or rose bengal staining of the conjunctiva will highlight mucin-related issues. For me, phenol red thread or Schirmer’s testing is not as vital, as it simply confirms the presence of a dry eye.

Aggressive treatment for meibomian gland dysfunction or aqueous-deficient dry eye must be complete before any surgery. Photorefractive keratectomy should be considered an option in the persistent, low-grade dry eye, as there is no damage to the goblet cells and no loss of blink reflex due to flap creation.

All LASIK patients must be counseled on the importance of aggressive artificial tear usage postoperatively. In the first week after surgery, use of nonpreserved tears of varying viscosities at least every hour should be emphasized. Avoidance of any tear product with benzalkonium chloride (BAK) is essential due to BAK’s documented cytotoxic capacity. Transiently preserved drops may be introduced at 1 week after surgery.

Many patients will begin to reduce the frequency of tear use prematurely due to the lack of physical symptoms. Continued, frequent use of tears must be stressed. I find that punctal occlusion with long-acting dissolvable plugs can bridge a patient over the time necessary for recovery of the tear film.

If a cycle of dryness is allowed to develop, topical loteprednol or cyclosporine can be started along with the tears to manage the inflammatory component. I have been able to discontinue these medications without need for a taper once the tear film has been re-established.

For more information:

• Elizabeth Muckley, OD, FAAO, is director of Optometric Services at Northeast Ohio Eye Surgeons, 2013 State Rt. 59, Kent, OH 44240; (330) 678-0201; e-mail: DrEDM1@aol.com.
• Jim Owen, OD, MBA, FAAO, can be reached at TLC Laser Eye Centers – La Jolla, 3655 Nobel Drive, La Jolla, CA 92122; (858) 558-6000; fax: (858) 558-6555; e-mail: encinitasod@cox.net.
• Brett G. Bence, OD, FAAO, is director of optometry at Northwest Eye Surgeons. He can be reached at 10330 Meridian Avenue North, Suite 370, Seattle, WA 98133; (206) 528-6000; fax: (206) 522-1479; e-mail: bbence@nweyes.com.
• Katherine M. Mastrota, OD, MS, FAAO is center director at Omni Eye Surgery, 36 East 36^th Street, New York, NY 10016; (212) 353-0030; fax: (212) 353-0083; e-mail: KatherineMastrota@msn.com. She is a member of the advisory boards for Allergan, AMO, Bausch & Lomb, Inspire and Cynacon-OcuSoft.
• Joseph Stamm, OD, FAAO(Dipl), is an assistant professor of ophthalmology at the University of Rochester Eye Institute, StrongVision Refractive Surgical Center. He can be reached at 100 Meridian Centre, Suite 125, Rochester, NY 14618; (585) 341-7815; fax: (585) 756-1975; e-mail: jstamm@rochester.rr.com. Drs. Muckley, Owen, Bence and Stamm have no direct financial interest in the products they mention, nor are they paid consultants for any companies they mention.

References:

• Schaumberg DA, Sullivan DA, Buring JE, Dana MR. Prevalence of dry eye syndrome among US women. Am J Ophthalmol. 2003;136:2318-2326.
• Ursea R, Purcell T, Tan B, Scanzlin D. The effect of cyclosporine A (Restasis) on recovery of visual acuity following LASIK. J Refract Surg. 2008;24(5):473-476.