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Ophthalmology. 2014 Dec;121(12):2311-6. doi: 10.1016/j.ophtha.2014.07.015. Epub 2014 Aug 30.

Corneal sensation and dry eye symptoms after conventional versus inverted side-cut femtosecond LASIK: a prospective randomized study.

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Byers Eye Institute, Stanford University School of Medicine, Stanford, California.
Byers Eye Institute, Stanford University School of Medicine, Stanford, California. Electronic address:



To compare corneal sensation and self-reported dry eye symptoms after femtosecond-assisted LASIK with conventional versus inverted side cuts.


Prospective, randomized, eye-to-eye study.


A total of 120 eyes in 60 participants with myopia.


Fellow eyes were randomized to receive femtosecond-assisted LASIK with a conventional 70-degree side cut made with the 60 kHz IntraLase FS (Abbott Medical Optics, Santa Ana, CA) or an inverted 130-degree side cut made with the 150 kHz IntraLase iFS (Abbott Medical Optics). Cochet-Bonnet aesthesiometry (Luneau Ophthalmologia, Chartes, France) measured corneal sensation (60 mm = normal sensation; <60 mm = depressed sensation) preoperatively and at postoperative months 1, 3, 6, and 12. Participants also completed serial dry eye surveys using the same subscales (frequency, severity, bothersome) as the validated, Rasch-tested, linear-scaled Quality of Vision questionnaire.


Objective corneal sensation and self-reported light sensitivity, dryness, foreign body sensation, and pain/discomfort.


Preoperative corneal sensation as measured by mean Cochet-Bonnet aethesiometry was equal between the inverted and conventional side cut groups but was better in eyes with an inverted side cut compared with a conventional side cut at all postoperative months (inverted vs. conventional: 1 month, 14.5 vs. 13.2 mm; 3 months, 24.9 vs. 18.4 mm; 6 months, 51.2 vs. 42.6 mm; 12 months, 59.8 vs. 58.3 mm; all P ≤ 0.02). None of the subjective dry eye parameters demonstrated statistically significant differences between the groups at any time point.


The LASIK flaps with an inverted side cut are associated with superior recovery of corneal sensation compared with flaps with a conventional side cut during the first postoperative year; however, this may not translate to significant improvements in subjective dry eye symptoms.

[Indexed for MEDLINE]

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