Thin flaps studied for risks

Surgical pearls may help physicians manage them better

Buttonhole flap with cannula
through the center of button hole.


Grade 4 DLK.
Source: Louis Probst, M.D.

Thin flaps have several risks associated with them, but if they are well constructed, the benefits outweigh the risks, said Jose Gabriel Matos, M.D.
Dr. Matos, Eyevision International, San Juan, Puerto Rico, said when creating a flap during surgery, thin flaps are safe and effective and preserve cornea tissue and biomechanical integrity.
“Generally, thin flaps are deemed by most of us as inadequate; they are associated with flap displacement, striae, irregular astigmatism, and precursors of buttonholes,” Dr. Matos said.

Thin flap results

Dr. Matos said he reviewed 171 eyes of the 89 patients for which he used Becton, Dickinson & Co. (BD, Franklin Lakes, N.J.) microkeratomes but with specially chosen heads for the process. He also used a LADARVision (Alcon Laboratories, Fort Worth, Texas) CustomCornea platform.
All of the eyes were treated for lower and higher aberrations without enhancements. The mean flap thickness was 89.3 microns with a 13-micron standard deviation, he said. There was a thickness range from 80 to 105 microns.
Dr. Matos treated from -0.50 –7.00 D of sphere and up to –1.75D of astigmatism. All of these patients obtained UCVA of 20/25 or better. At the one- and three-month post-op mark, all patients were corrected to 20/20 best-corrected spectacle acuity and 26% to 20/15.
More than one-quarter of the patients (28%) gained one line and the manifest sphere was within 1 D for 99% of the patients.
“So in general, we got good visual results with an uncorrected visual acuity of 20/20 in 95% of the patients,” Dr. Matos said. As far as contrast, the post-op uncorrected compared with the pre-op best-corrected showed a slight gain in photopic contrast sensitivity; however, there was a slight loss in the post-op mesopic contrast sensitivity.

Advice and benefits

Dr. Matos said it is very important for physicians in these cases to lay back the flap very carefully. Because he already has the patients dilated to do the surgery, Dr. Matos said he uses transillumination to make sure he does not have any micro- or macro-striae. Transillumination helps to ensure there are no flap-related complications despite using these thin flaps.
Among the benefits of cutting thinner flaps is preserving the cornea.
“We must remember the superficial stroma layers are the ones that are associated with the biomechanical integrity of the cornea, and procedures that preserve these upper layers of the stroma are beneficial,” Dr. Matos said.
He said it is important to maintain the corneal stability and spare tissue, especially now that there are new custom treatments.
Well-constructed thin flaps are safe and effective, and they preserve cornea tissue and biomechanical integrity, he said. The stromal beds were smooth because these layers are more compact layers of the cornea.
And because they are possibly less damaging to cornea nerves, Dr. Matos suggested that perhaps surgeons should study the effect on producing less dry eye with thinner flaps.

Editors’ note: Dr. Matos has no financial interests related to his comments.

Contact Information
Matos: 787-281-0030, jgmatos@eyevisioninternational.com