JAN 13, 2015
This prospective, randomized study found that corneal sensation recovery was better with femtosecond-assisted LASIK using an inverted side cut compared with a conventional side cut, although no difference was found in subjective dry eye symptoms.
This interesting study follows human and animal data suggesting that inverted side cuts result in better wound apposition and healing. The authors suggest that greater wound apposition may result in better corneal nerve healing and faster return to normal corneal sensation.
They randomized the dominant eyes of 120 myopic subjects to receive femtosecond-assisted LASIK with a conventional 70-degree side cut made with the 60 kHz IntraLase FS or an inverted 130-degree side cut made with the 150 kHz IntraLase iFS. The fellow eye received the other treatment.
Both groups experienced a decrease in corneal sensation, which returned to normal levels at 12 months. However, corneal sensation was significantly greater in the inverted side cut group than in the conventional group at all time points; the difference, however, was small at the one and 12 month time points. Only one patient in the inverted side cut group didn’t recover full corneal sensation by one year, compared to six patients in the conventional side cut group. There were no statistically significant differences in any of the dry eye parameters between groups at any time point.
The strength of this study is its one-year duration. One limitation, however, is that the laser platform was different between groups. It would be interesting to see if these results could be reproduced by using the same 150 kHz IntraLase iFS femtosecond laser for both 130-degree inverted cuts and 70-degree conventional cuts. Finally, as has been suggested in the past, dry eye symptomatology is a difficult parameter to precisely measure, especially in patients with bilateral surgery whose symptom reporting in one eye may be influenced by their overall comfort and outcome in both eyes.