Dry Eyes After Laser in situKeratomileusis (LASIK)
Original article contributed by:
Brandon Rodriguez, MD
Brandon Rodriguez, MD
· 1 Introduction
· 2 Pathophysiology
· 3 Symptoms
· 4 Therapeutic Options
· 5 Conclusion
· 6 References
Dry Eye Syndromeafter Laser in situ keratomileusis (LASIK) is the most common side effectencountered by cornea-refractive surgeons since femtosecond technology hasnearly eliminated flap related complications. Unfortunately, despite thecontinuing advances in LASIK technology and visual results, the cure forLASIK-associated dry eye has yet to be elucidated.
Approximately 4%of LASIK patients develop dry eye syndrome (1), however this has been reportedto be as high as 60-70% (2). Varying degrees of dryness usually last from 3-6months; however it can persist for months to years. This is especially true forthose that had dry eye symptoms before surgery and were inadequately treated.Dryness after LASIK has been linked to numerous possible etiologies to includebut not limited to, dryness before surgery, female gender (3) and meanspherical equivalent treatment. The most common etiology described is secondaryto the transection of corneal nerves and loss of superficial cornealinnervation (4-7). These sensory nerves originate from the ophthalmic divisionof cranial nerve 5, the trigeminal nerve. Classically during flap creation, asuperior hinge is created resulting in the greatest transection of cornealnerves since a large proportion of nerves enter from the radial aspects of thecornea. These radial fibers run radially in the middle third of the stroma,divide to form a dense subepithelial plexus and then run perpendicularly topenetrate Bowmans layer and supply the epithelium (2). Alternating the hinge tothe nasal or temporal aspect has been shown to reduce the amount of dryness andlost corneal sensation up to 6 months postoperatively (p < 0.0001) (4).However, beyond that time point there are no differences. The relative risk fordryness per diopter of myopia was found to be 0.88 which correlatedapproximately with the laser-calculated depth of ablation and combined ablationdepth and flap creation (RR 1.01/µm)(6). In order to possibly decrease drynesscaused by flap creation, reducing the flap thickness has been shown to haveless of an effect on corneal sensation and tear function tests (8). Thealternative is to perform surface ablation, as these patients typicallyexperience less dry eye symptoms because only superficial nerves are ablatedversus the deeper stromal nerve plexus (2, 9).
Despitecontrolling the above etiologies/risk factors, dryness continues to occur.Given the advent of femtosecond technology, the microkeratome versus thefemtosecond laser was evaluated for differences in the mechanism of flapcreation. In a randomized clinical trial of 51 patients, one eye was performedwith a mechanical keratome and the fellow eye with a femtosecond laserkeratome. There was no statistically significant difference in self-reporteddry eye symptoms between the 2 eyes. These findings were irrespective of thecentral ablation depth, flap thickness and age (9). However, another studypresented the opposite results and postulated that the femtosecond laser maytransect peripheral corneal nerve fibers after they have undergone morebranching or lost their nerve sheath. This was thought to be related to theability of the femtosecond laser to create a more uniform flap (11).
One specialconsideration is the hyperopic population. This group was evaluatedretrospectively and dryness was found to occur mainly in females. Interestinglyenough, the same group was also found to undergo regression in 32% ofindividuals 12 months after surgery (10). Whether or not the regression issecondary to the dryness or the inherent effects of the hyperopic ablation hasyet to be elucidated.
For the vastmajority of patients, dry eye poses little concern, especially since symptomstypically abate within 3 to 6 months. The most common symptom associated withdry eye after LASIK is fluctuation in vision, especially within the first 6weeks. Other symptoms can vary dramatically and include but are not limited to,irritation, pain, redness, foreign body sensation, slow healing, regression,and worsening astigmatism (1, 12).
Dry eyesymptoms, although mild for some, can be the number one reason fordissatisfaction with LASIK, despite having excellent visual acuity results(13). Therefore, in order to maximize surgical outcomes, it is imperative tooptimize the ocular surface before performing any refractive surgicalprocedure.
Therapeutic Options[edit source]
The mostimportant step in the prevention or reduction of dry eyes after LASIK is adetailed pre-operative screening. However, for those that do develop dry eyesafter LASIK, the Preferred Practice Patterns from the American Academy ofOphthalmology provides a great outline for treatment. Patients with mild dryeye symptoms should be treated with conservative measures. These includeartificial tears/ointments, warm compresses and environmental modification. Apreserved or non-preserved tear can significantly reduce, if not eliminate, allsymptoms. Evening ointments should not be used during the initial postoperativeperiod, in order to avoid possible migration under the flap (2). In extremeweather (hot or cold), air conditioning and heating systems, dry out the airwithin a home or office. Simply humidifying the environment can helpdramatically. Another conservative measure that should always be performed uponinitial presentation is a thorough check into medications that may exacerbatedry eye. Common medications include antihistamines, allergy medications,hormone replacement therapy, and over the counter “common cold” remedies (14).
For moderatesymptoms that are unresponsive to the above therapeutic measures, cyclosporineA 0.05%, punctual plugs and omega-3 fatty acid supplements should be used.Previous studies have reported that the use of cyclosporine A 0.05% not onlyimproves dryness and neurotrophic epitheliopathy, but also reduces the timeneeded for faster visual recovery after LASIK (7, 15). Per the Food and DrugAdministration (FDA) this is the only medication approved for the treatment ofchronic dry eye (there are other medications currently undergoing FDA trials,in various phases). Omega-3 fatty acids are a nutritional supplement that hasbeen shown to reduce the viscosity of meibomian oils and the inflammationwithin (14). (Note: A complete listing of therapeutic options, can be found withinthe Perferred Practice Patterns for Dry Eye Syndrome).
Dry eye syndromeis the most common side effect encountered after LASIK. All of the abovetherapeutic options and more have been shown to help control symptoms. Evenwithout treatment, dry eye will usually resolve without sequela in 3-6 months.However, in order to improve patient outcomes and satisfaction, it isimperative to optimize the ocular surface before performing any refractivesurgical procedures.
1. Foster CS,Azar DT, Dohlman CH. Smolin and Thoft’s The Cornea. 4th Edition. Philadelphia,PA. Lippincott Williams & Wilkins; 2005.
2. AAO.Refractive Surgery. 2011-2012.
3. Shoja MR,Besharati MR. Dry eye after LASIK for myopia: Incidence and risk factors.European J f Ophthamol 2007; 17:1-6.
4. DonnenfeldED, Solomon K, Perry HD, Doshi SJ, Ehrenhaus M, Solomon R, Biser S. The Effectof hinge position on corneal sensation and dry eye after LASIK. Ophthalmol2003; 110: 1023-1029.
5. Toda I,Asano-Kato N, Komai-Hori Y, Tsubota K. Dry Eye after laser in situkeratomileusis. Am J Ophthamol 2001; 132:1-7.
6. Dr Paiva CS,Chen Z, Koch DD, Hamill MB, Manual FK, Hassan SS, Wihelmus R, Pflugfelder SC.The incidence and risk factors for developing dry eye after myopic LASIK. Am JOphthalmol 2006; 141: 438-445.
7. Ambrosio RJr, Tervo T, Wilson SE. LASIK-associated dry eye and neurotrophicepitheliopathy: pathophysiology and strategies for prevention and treatment. JRefract Surg 2008; 4:396-407.
8. Barequet IS,Hirsh A, Levinger S. Effect of thin femtosecond LASIK flaps on cornealsensitivity and tear function. J Refract Surg 2008; 24:897-902.
9. Golas L,Manche EE. Dry Eye after laser in situ keratomileusis with femtosecond laserand mechanical keratome. J Cataract Refract Surg 2011; 37:1476-80.
10. Albietz JM,Lenton LM, McLennan SG. Effect of laser in situ keratomileusis for hyperopia ontear film and ocular surface. J Refract Surgery 2002; 18:113-23.
11.Christenbury. Clinical results of IntraLASIK versus Hansatome created flaps.AAO Annual Meeting 2002.
12. Azar DT,Gatinel D, Hoang-Xuan T. Refractive Surgery. 2nd Edition. China. Elsever, Inc.;2007.
13. Levinson BA,Rapuano CJ, Cohen EJ, Hammersmith KM, Ayres BC, Laibson PR. Referrals to theWills Eye Institute Cornea Service after laser in situ keratomileusis: reasonsfor patient dissatisfaction. J Cataract Refract Surg 2008; 34:32-39.
14. AAO.Preferred Practice Patterns. Dry Eye. 2011.
15. Ursea R,Purcell TL, Tan BU, Nalgirkar A, Lovaton, Ehrenhaus MR, Schanzln DJ. The effectof cyclosporine A (Restasis) on recovery of visual acuity following LASIK. JRefract Surg 2008; (24) 473-6.