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Direct measurement of microkeratome gap width by electron microscopy
1Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Kowloon, Hong Kong, China. liukingyu@hotmail.com
Journal of Cataract and Refractive Surgery
|June 16, 2001
Summary
Scanning electron microscopy revealed significant microkeratome gap width variations, exceeding acceptable tolerances for laser in situ keratomileusis (LASIK). These manufacturing inconsistencies may contribute to unexpected LASIK complications, necessitating pre-use validation of all microkeratome devices.
Area of Science:
- Ophthalmology
- Surgical Technology
- Medical Device Manufacturing
Background:
- Accurate microkeratome function is critical for safe and effective laser in situ keratomileusis (LASIK) surgery.
- Microkeratome gap width directly influences flap thickness and surgical outcomes.
- Previous assessments of microkeratome precision have relied on indirect methods.
Purpose of the Study:
- To directly and accurately measure the microkeratome gap width using scanning electron microscopy (SEM).
- To assess the precision and consistency of microkeratome manufacturing.
- To identify potential sources of error in LASIK flap creation.
Main Methods:
- Utilized a Cambridge Stereoscan S440 scanning electron microscope for high-accuracy measurements (+/-1.5 microm).
- Measured the gap width of four SCMD microkeratomes.
- Compared SEM measurements against manufacturer specifications.
Main Results:
- Manufacturer's specification for the microkeratome gap was 150.0 microm.
- SEM measurements revealed significant variability: 164.7, 190.0, 200.6, and 145.9 microm.
- Two microkeratomes exhibited errors exceeding 25% from the specified gap width (errors of 9.8%, 26.7%, 33.7%, and 2.7%).
Conclusions:
- Substantial variations in microkeratome gap width were observed, exceeding LASIK tolerance standards.
- Inconsistent microkeratome manufacturing and calibration may be linked to LASIK complications like keratectasia and corneal perforations.
- Validation of new microkeratomes and blades before clinical use is crucial to prevent flap-related issues in LASIK.