EyeWorld Asia-Pacific September 2017 Issue

LASIK patients benefit from plugs at the time of surgery Symptom questionnaire scores, corneal staining, and osmolarity improve with punctal occlusion W e know that LASIK causes transient, neurotrophic dry eye. This can result in su- perficial punctate keratitis and loss of visual quality during the first few months after surgery. This improves over time and by 3 to 6 months is generally completely resolved. Be- cause of the accompanying loss of corneal sensation while the corneal nerves regenerate, patients may not complain of dryness, but fluctuat- ing vision and symptoms like glare and halo that are related to the ocular surface problems may affect their satisfaction with the proce- dure and surgeon. Refractive surgeons should strive to improve the ocular surface before surgery to make sure the preoperative measurements are accurate and the eye will heal well. In addition, I think that placing a temporary punctal plug at the time of LASIK surgery could be an excellent solution to this transient, neurotrophic dry eye. I set out to objectively test in a prospective study whether temporary punctal occlusion could improve the ocular surface quality and reduce symp- toms following LASIK. Study design Forty patients undergoing bilateral simultaneous LASIK at my practice, Ophthalmic Consultants of Long Island, New York, were enrolled. Patients were not excluded for prior by Eric Donnenfeld, MD contact lens use or for prior history or treatment of dry eye or meibo- mian gland dysfunction (MGD). Exclusion criteria included those undergoing monocular LASIK and those with ocular surface irregu- larities such as pinguecula, current punctal occlusion, lacrimal drain- age dysfunction, and use of any topical medications other than artificial tears or cyclosporine A (Restasis, Allergan, Dublin, Ireland). Subjects were randomized to the treatment group or the control group, with 20 patients in each. All eyes underwent femtosecond laser flap creation and wavefront-guided LASIK, with the same flap param- eters in all eyes. In the treatment group, Extend punctal plugs (Bea- ver-Visitec International, Waltham, Massachusetts) were placed in the lower punctum of each eye at the conclusion of surgery. These synthetic plugs swell to comfortably fit the canalicular system without foreign body sensation or irritation. They are absorbable, fully dissolv- ing within about 3 months, around the time when we would expect corneal sensation and dry eye symptoms to improve in the post- LASIK eye. The same postoperative medications were prescribed in all eyes. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), fluorescein staining, tear production (Schirmer score), matrix metalloproteinase 9 (MMP-9) detec- tion, tear osmolarity, and Ocular Surface Disease Index (OSDI) scor- ing were evaluated at 1 week and 1 and 3 months and compared to the same measures preoperatively. Staining was used to grade the ocu- lar surface quality. In addition to standard pre- and post-LASIK visual acuity assess- ments, patients underwent slit lamp biomicroscopy with fluorescein staining, which was used to grade the ocular surface quality (0 to 4); Schirmer basic secretion test with topical anesthetic; and MMP-9 and osmolarity testing of the tear film. All subjects also completed OSDI questionnaires at each visit. Results are reported at baseline (preop), and at 1 week, 1 month, and 3 months. Data were analyzed for left and right eyes separately, using either parametric or non-parametric methods, depending on the nature of the response. Results for right and left eyes were very consistent; data for right eyes is presented here, except where noted below. Results Preoperative characteristics are shown in Table 1. There were no statistically significant differences between the treatment and control groups in age, sex, median OSDI scores, or visual acuity at baseline. Ocular surface testing also revealed that the two groups were quite simi- lar preoperatively. The only statisti- cally significant difference was in the presence of a positive test for the cytokine MMP-9. Three eyes in the control group were MMP-9 posi- tive versus none in the plug group. However, this did not correspond to any meaningful differences in staining or OSDI score. Overall, these were not patients with signifi- cant ocular surface problems prior to surgery; all were deemed to be good candidates for corneal refrac- tive surgery. Punctal occlusion had a modest effect on Schirmer scores. When both eyes were evaluated, patients who received plugs had higher Schirmer scores by 1.03 mm, on av- erage (P=0.29). Looking at left and right eyes separately, the increase was statistically significant in left eyes (2.73 mm, P=0.014) but not in right eyes. Although one might have expected to see a larger effect from plugs, we also know that the sensitivity of Schirmer testing is relatively poor in normal eyes. There were small improvements in visual acuity. For example, at the 1-week mark, UCVA was 20/18 in the plug group versus 20/21 in the control group. Overall, punctal Table 1. Preoperative characteristics were equivalent in both groups except for MMP-9 tear testing, which was more likely to be positive in the control group. continued on page 50 EWAP REFRACTIVE 47 September 2017