A New Study Shows Flap Size Does Not Affect LASIK Results or LASIK Dry Eye. A patient from Santa Maria recently asked me if the LASIK flap edge causes night vision problems so that larger diameter flaps would be preferred over smaller diameter flaps. Another patient from Santa Barbara asked me if larger flaps cause more dry eye than smaller flaps after LASIK.
These are questions I get quite a bit. A newly published study of different flap diameters gives us good answers to theses questions.
Dr. Daniel Durrie of Overland Park, Kansas just published a study of 30 LASIK patients in which one eye had wavefront LASIK with a large diameter flap (9mm) and the other eye had wavefront LASIK with a small diameter flap (8mm). This was an excellent study design since the same patient had both types of flaps — one on each eye, which takes out genetic variables. Flap thickness was set at 110 microns, which is defined as a “thin flap” LASIK or SBK technique. This is the same wavefront laser technique and same flap thickness goals I use in my own patients as well. Patient ages in the study ranged from 21 to 38 years of age.
The study results were equally excellent for both the 9 mm flap eyes and the 8 mm flap eyes. There was no difference in final objectively measured vision between the two groups nor was there a difference in the subjective perception of vision between the large flap LASIK eyes and the small flap LASIK eyes. Night vision was the same in both the large flap LASIK group and the small flap LASIK group. By one month, both groups had temporary dry eye of equal degree, but both flap size groups showed objectively demonstrated resolution of their dry eyes in the same time period.
The author of the study concluded that “thin flap LASIK performed with modern lasers can produce excellent visual acuity results, irrespective of flap size.” The authors further concluded that thin flap LASIK “does not cause dry eye in patients with no history of dry eye. Furthermore, subjective halos, glare and night vision problems were not worsened and in many cases improved after wavefront-guided laser vision correction.”
I think this was an excellent study and the results are typical of what we see on a daily basis in our practice. I too have found that flap size does not influence visual outcome, night vision, or dry eye. The most important factor in determining the best possible visual outcome and night vision is the use of wavefront guided lasers, not flap diameter, in my experience.
See Also
Flap Size Does Not Affect Dry Eye After LASIK
Flap Size Does Not Affect Dry Eye After LASIK
Refractive Changes Induced by the LASIK Flap in a Biomechanical Finite Element Model
A model using finite element analysis looks at the biomechanical effects of the LASIK flap on the cornea.
Retrospective Analysis of Actual Flap Diameter Compared with Microkeratome Ring Size Performed by Different Surgeons
A study looking a intended versus achieved LASIK flap diameters with a mechanical microkeratome.
Corneal Flap Dimensions in Laser In Situ Keratomileusis (LASIK) using the Innovatome Automatic Microkeratome
www.ekjo.org
Femtosecond Laser-Assisted Corneal Flap Cuts: Morphology, Accuracy, and Histopathology
A study looking a flap parameters in LASIK flaps made with the femtosecond laser.
One Thousand Consecutive IntraLase Laser In Situ Keratomileusis (LASIK) Flaps
A study looking at the results of one thousand LASIK flaps using the IntraLase femtosecond laser
Flap Dimensions Created With The IntraLase FS Laser
Measurements of LASIK flaps created with the Intralase FS femtosecond laser.
Precision of Flap Measurements for Laser In Situ Keratomileusis
Measurement of LASIK flap parameters.
Dry Eye After LASIK for Myopia: Incidence and Risk Factors
A look at factors associated with dry eye after LASIK, including any potential role of the LASIK flap in causing post-LASIK dry eye.
The Effect of Hinge Position on Corneal Sensation and Dry Eye after LASIK
Some doctors have postulated that different hinge positions might affect dry eye after LASIK. This study looks at the effect of various LASIK flap hinge positions on post-operative dry eye.
LASIK-Associated Dry Eye and Neurotrophic Epitheliopathy: Pathophysiology Strategies for Prevention and Treatment
This article looks at possible causes of dry eye after LASIK, including the effect of corneal nerve regeneration after LASIK flap creation and healing.
SBK LASIK flaps
This is an article I authored looking at SBK LASIK flaps created with the XP keratome.