dry eye
Treatment for Patients with Dry Eye Pre- & Postop
BY WILLIAM TRATTLER, M.D.

Over the past few years, the volume of surface ablation procedures has steadily grown in the United States, reaching 16.7% of all laser vision correction procedures in the spring of 2006.1 Surgeons have switched to surface ablation in patients who have any risk factors for post-LASIK ectasia, as well as for patients with previous RK, PRK and even previous LASIK. An additional reason that doctors may recommend surface ablation over LASIK is for patients with moderate to severe dry eye.

However, patients undergoing surface ablation are still at risk for dry eye, and steps to minimize or avoid the development of dry eye are critical for better refractive outcomes. This article will discuss the basic science and clinical studies that explain why dry eye increases after refractive surgery and also suggest some excellent treatment options for patients with moderate to severe dry eye before or after surgery.

Figure. Loss of goblet cell density following LASIK in patients with and without dry eye.

Post-LASIK Dry Eye

Post-LASIK dry eye can be a highly frustrating situation for both the patient and the surgeon. The hallmark symptoms of post-LASIK dry eye are poor quality of vision and fluctuating vision over the first 6 to 12 months, rather than ocular irritation.

The reason that ocular irritation is not a prominent symptom during the first year has to do with the loss of corneal sensitivity that occurs following LASIK. Recovery of corneal sensitivity can take 6 months to a year.2,3 Interestingly, the time required for corneal sensitivity to return to normal will vary based on the depth of the LASIK flap and the depth of the ablation. In comparison, the time to corneal sensitivity recovery after surface ablation is significantly shorter, ranging from 3 to 9 months, with the time course also related to the depth of ablation.4,5 The loss of corneal sensation is a critical factor in the development of postoperative dry eye, as this leads to a reduced blink rate and decreased tear production.6,7

Other Important Factors in Postoperative Dry Eye

Examination of patients following LASIK has revealed other important factors that can potentially lead to chronic dry eye, including loss of goblet cells and reduction in tear production. Conjunctival goblet cells play an important role in tear film quality, by secreting mucins which have gel-like properties that increase tear viscosity. Many surgeons feel that goblet cell density initially drops following LASIK due to damage from the microkeratome suction ring. However, Julie Albietz, M.D., has reported that there is a significant, progressive loss of goblet cells following LASIK (Figure).8 In one study, Dr. Albietz found that patients without pre-existing dry eye who underwent LASIK had a 27% reduction in goblet cell density at 1 year, while patients with pre-existing dry eye had a 71% reduction in goblet cells. Not surprisingly, the time course for goblet cell density loss and recovery more or less matches the time course of loss of corneal sensitivity, suggesting there is a feedback loop.

Loss of tear production following LASIK has also been found to match the curves of corneal sensitivity and loss of goblet cells. Jose Benitez-del-Castillo, M.D., determined the tear function index, which is a measurement of tear secretion based on Schirmer's scores divided by tear clearance rates.9 He determined that there is a reduction in tear secretion following LASIK and that tear secretion returns to baseline after 9 months.

Treatment Options

Odyssey's Parasol punctal plug.

Patients undergoing surface ablation may have a lower risk of postoperative dry eye compared to LASIK due to a quicker recovery of corneal sensation. However, postoperative dry eye still occurs. Even more important, in my experience dry eye during the first few postoperative days can lead to delayed epithelial healing and increased pain. 

Therefore, I have found that the placement of punctal plugs (Parasol, Odyssey Medical, Memphis, Tenn.) and pretreatment with cyclosporine ophthalmic emulsion 0.05% (Restasis, Allergan) prior to surface ablation can make a very positive impact in reducing dry eye during the postoperative period. The goal of these two interventions is to raise the quantity of the tear film (punctal plugs) and improve tear quantity and quality (cyclosporine 0.05%). These interventions help reduce early postop dry eye and therefore help with epithelial healing. The continuation of cyclosporine 0.05% and plugs during the first 3 to
9 months helps the dry eye that develops due to loss of corneal sensitivity.

Case Report

An understanding of the reasons for dry eye development following PRK and LASIK allows for the development of an effective treatment plan. For example, a 54–year-old male underwent PRK in March of 2006 with a local surgeon. Following the removal of the contact lens on postoperative day 5, the patient was prescribed a 1-month taper of topical steroids along with artificial tears as needed. Unfortunately, this patient ended up undercorrected in his left eye and underwent an enhancement in July of 2006. The patient was prescribed a similar treatment regimen, but never recovered 20/20 and was unhappy with his quality of vision. He noted fluctuation in his quality of vision, but did not experience ocular irritation. After 2 months of reduced quality of vision, the patient was sent in for a second opinion.

On my exam, the patient had BCVA of 20/30 in the left eye. Fluorescein staining revealed punctuate staining centrally, along with a reduced tear film. The goal of treatment in this postop patient was to raise the tear film and improve tear film quality. Parasol punctal plugs were placed inferiorly, and the patient was started on prednisolone acetate ophthalmic suspension (Pred Forte, Allergan) q.i.d. for
4 days and cyclosporine 0.05% OU b.i.d. At the next visit 3 weeks later, the tear lake was higher and the central corneal punctuate staining was reduced. The patient continued on cyclosporine 0.05% b.i.d. along with Refresh liquigel (Allergan) t.i.d, and on his next visit that was 3 weeks later, he reached 20/20 with refraction.

Summary

Postoperative dry eye is common following laser refractive surgery. Although LASIK has a longer period of loss of corneal sensitivity and reduced tear quantity, surface ablation can also lead to similar postoperative problems. Increasing the tear volume and improving the tear film quality are important steps in treating the reduced quality of vision that occurs with postoperative dry eye. Prophylactic treatment of surface ablation patients with punctal plugs and cyclosporine 0.05% can potentially improve visual outcomes and reduce rates of enhancements, leading to more satisfied patients.

William Trattler, M.D., is the director of cornea at The Center For Excellence In Eye Care, in Miami, FL. Dr. Trattler completed his Ophthalmology residency at the University of Pennsylvania's Scheie Eye Institute, and performed a cornea and refractive surgery fellowship at Southwestern Medical Center in Dallas. Dr. Trattler has been involved in a number of phase 3 and phase 4 dry eye treatment studies.

References

1. Market Scope, LLC. Available at: http://www.market-scope.com. Accessed November 10, 2006.

2. Donnenfeld ED, Solomon K, Perry HD, et al. The effect of hinge position on corneal sensation and dry eye after LASIK. Ophthalmology. 2003; 110:1023–1029; discussion by CJ Rapuano, 1029-1030.

3. Nassaralla BA, McLeod SD, Nassaralla JJ, Jr. Effect of myopic LASIK on human corneal sensitivity. Ophthalmology. 2003;110:497-502

4. Campos M, Hertzog L, Garbus JJ, et al .Corneal sensitivity after photorefractivekeratectomy. Am J Ophthalmol. 1992;114:51-54.

5. Wu Y, Chu RY, Zhou XT, et al. Recovery of corneal sensitivity after laser-assisted subepithelial keratectomy. J Cataract Refract Surg. 2006;32:785-788.

6. Beuerman RW, Schimmelpfennig B. Sensory denervation of the rabbit cornea affects epithelial properties. Exp Neurol. 1980;69:196-201

7. Martin XY, Safran AB. Corneal hypoesthesia. Surv Ophthalmol. 1988;33:28-40.

8. Albietz JM, Lenton LM, McLennan SG. Effect of laser in situ keratomileusis for hyperopia on tear film and ocular surface. J Refract Surg. 2002;18:113-123.

9. Benitez-del-Castillo J, del Rio T, Iradier T, Hernandez JL, Castillo A, Garcia-Sanchez J. Decrease in tear secretion and corneal sensitivity after laser in situ keratomileusis. Cornea. 2001;20:30-32.