Abstract
Purpose: :
To study the effect of LASIK surgery on the conjunctival goblet cell and epithelial cell populations, as one of the proposed mechanisms for dry eye occurring after Lasik, when the flap is created with IntraLase Femtosecond Laser (IL) and with mechanical microkeratome (M2 Moria).
Methods: :
Prospective study with analysis of 50 eyes, 25 with M2 LASIK and 25 with IntraLase/LASIK procedures by one surgeon for the correction of myopia. Patients between 22 and 48 years old with a normal ocular surface before the surgery were evaluated before applying the suction ring and after the surgery (1 week, 1 month, 3 months and 6 months) by conjunctival impression cytology in two places (upper at 12 and lower temporal inferior) of the perilimbal conjunctiva to determine goblet cell density and epithelial cell morphology. The time that the suction ring was applied on the eye was also registered.
Results: :
The mean goblet cell count (GCC) pre–surgery was 359 ± 97 SD/mm2 with M2 and 340 ± 63 SD/mm2 with IL. All the patients, in both groups, showed a decrease in the goblet cell count after LASIK surgery. At one week and one month the GCC decreased significatively (p<0,001) in the M2 group, and from the third month the GCC began to increase. In the IL group the GCC at 3 months was still very low (p<0,033) and recovery of the goblet cells was observed after 6 months. At one week, one month and 3 months GCC was lower with IL than with M2, p<0,019, p<0,001 and p<0,024 respectively. The mean period that the suction ring was applied was 22 ± 8 seconds for M2 and 108 ± 34 seconds for IntraLase.
Conclusions: :
Analysis by impression cytology of the ocular surface before and after LASIK surgery showed a great reduction in the goblet cell populations in both groups, although this decrease was greater with IntraLase than M2, possibly due to the long period the suction ring is putting pressure on the conjunctiva to create the flap before the surgery. We can conclude that this change is due to mechanical stress applied on the ocular surface during surgery and this could be the main cause for the dry eye syndrome post Lasik.
Keywords: refractive surgery: LASIK • cornea: tears/tear film/dry eye