Posters

The change and correlations of corneal nerve density, sensitivity and tear parameters after LASIK

Poster Details

First Author: S.Chen CHINA

Co Author(s):    C. Chao   F. Stapleton   X. Zhou   S. Zhou   B. Golebiowski  

Abstract Details

Purpose:

（1）To evaluate the change of corneal subbasal nerve density and sensitivity post Femtosecond LASIK and their relations with dry eye symptoms.(2)To investigate the effect of Femtosecond LASIK on tear film osmolarity and its relationship with non-invasive tear breakup time and lower tear meniscus height.

Setting:

The School of ophthalmology and optometry, Wenzhou Medical Univerisity, China. The school of optometry and vision sience, the university of new south wales, Sydney.

Methods:

20 Femtosecond-LASIK refractive surgery candidates (12 men and 8 women) were recruited from the Refractive Surgery Centre of our hospital. Examinations were performed preoperatively and at 1day, 1week, 1month, 3months and 6months after the surgery. Using a special questionnaire (Ocular Comfort Index of Chinese version), subjective dry eye complaints was evaluated. And then, the tear film osmolarity was measured with the TearLabTM Osmolarity System. Lower tear meniscus was taken by the Ultrahigh-scan depth OCT and non-invasive tear breakup time was measured with the Tearscope. Cochet-Bonnet esthesiometer was used to evaluate the corneal sensitivity and confocal images of subbasal nerves were obtained centrally and 2.5mm temporally and superiorly with the Laser in vivo confocal microscopy.

Results:

(1) The total score of dry eye subjective symptoms, the lower tear meniscus height and the non-invasive tear breakup time showed no statistically significant change after LASIK. (2) Subbasal corneal nerve density at all regions were at their lowest at 1 week after the surgery(P＜0.0001) and did not return to the preoperative level at 6 months after LASIK. The recovery of nerve density was faster at the superior area than the other. (3)Central and temporal corneal sensitivity decreased significantly after the procedure(P＜0.01) and returned to preoperative level by 6 months(Central P=0.242,Temporal P=0.149).The superior corneal sensitivity reduced with no statistical significant. (4) Tear film osmolarity was increased significantly at 1 day(P=0.013) and 1 week (P=0.007)after LASIK and returned to preoperative level at 1 month and 3 months after the surgery(P＞0.05).After 6 months, tear film osmolarity decreased significantly(P＜0.01). (5) The total score of dry eye symptoms negatively correlated with the corneal sensitivity (1 week post LASIK) and corneal subbasal nerve density(1,3,6 months post LASIK)(P＜0.05) while the tear film osmolarity showed strong correlation with non-invasive tear breakup time at preoperative and 1 day and 3 months post-operative time.

Conclusions:

(1) Both subbasal corneal nerve density and corneal sensitivity decreased immediately after LASIK. Corneal sensitivity returned to preoperative values within the first 6 months post-LASIK while corneal nerve density did not return to a third of preoperative level. (2) Subbasal corneal nerve density and corneal sensitivity decrease after LASIK, with l east change in the superior area, highlighting the preservation of nerves in the hinge position. (3) Tear film osmolarity increased significantly during the first 1 week after the procedure and at the same time, corneal sensitivity and subbasal nerve density reached their lowest, showing that the postoperative inflammation was active during this time. (4) Tear film osmolarity showed a good relationship with non-invasive tear breakup time both preoperatively and postoperatively, indicating that non-invasive tear breakup time is of important clinical value. FINANCIAL INTEREST: NONE