Strength of Human LASIK Wounds With Histologic, Ultrastructural, and Clinical Correlations Ingo Schmack, MD; Daniel G. Dawson, MD; Bernard E. McCarey, PhD; George O. Waring III, MD, FACS, FRCOphth; Hans E. Grossniklaus, MD; Henry F. Edelhauser, PhD Northeastern State University 04/17/13
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Cohesive Tensile Strength of Human LASIK Wounds With
Histologic, Ultrastructural, and Clinical Correlations
Ingo Schmack, MD; Daniel G. Dawson, MD; Bernard E. McCarey, PhD;
George O. Waring III, MD, FACS, FRCOphth; Hans E. Grossniklaus, MD; Henry F. Edelhauser, PhD
Northeastern State University04/17/13
The purpose of the current study was to QUANTIFY the strength of the LASIK interface.
25 corneoscleral
SPECIMENS from 13 donors with a history of LASIK (23 mechanical microkeratome, 2 laser microkeratome) were obtained from various eye banks in North America.
Avg Age: 44 years
Avg Time after LASIK: 3 years
Five age-matched and time-in-preservation-matched
normal corneoscleral SPECIMENS from 5 patients served as controls
Diagram shows how the LASIK corneoscleral specimenswere sectioned to obtain 4-mm-wide
STRIPS and then subsequently processed.
Cross-sectional diagram of THE MIDDLE STRIP in (A) showing how the manual lamellar dissection was connected to the LASIK interface wound at the hinge. C = central wound, P = paracentral wound, M = peripheral flap wound margin.
Diagram demonstrates HOW THE FLAP AND RESIDUAL STROMAL BED WERE SEPARATED using the motorized pulling device. Blue lines = LASIK wound, red lines = manual lamellar dissection, red dots = point where blunt tipped cannula was inserted.
THE MOTORIZED PULLING ARM with a central 4-mm LASIK corneal strip (white asterisk) in
place. THE FORCE REQUIRED FOR SEPARATION IS RECORDED
5 years after surgery
TIME
Symbol Key: 1. Square (at arrow) = mean of 5 control corneas; 2. LASIK wound margin hypercellular scar (black solid circles); 3. Central/paracentral hypocellular LASIK scar (open circles)
The cohesive tensile strength of these three groups were found to be different from each other in a statistically significant way.
3. LASIK paracentral & central regions
2. LASIK wound margin, which plateaus in strength after 3.5 yrs