Microstriae after LASIK are common

March 15, 2007

Las Vegas-Microstriae following LASIK are common, although clinically significant microstriae are much less frequent. The decision to treat the microstriae or leave them alone depends primarily on whether the patient has any visual complaints attributable to the striae, said Michael A. Lawless, MD.

"If there are objective signs of microstriae, no visual complaints, and acceptable uncorrected and best-corrected acuity [UCVA and BCVA], then leave them alone," Dr. Lawless said. "If microstriae are present and the patient has visual complaints, a decision needs to be made as to the cause of the complaints and/or whether the microstriae are truly responsible."

Speaking during a refractive surgery subspecialty day program at the American Academy of Ophthalmology annual meeting, Dr. Lawless noted that microstriae are extremely common, reported in one study to oc-cur in 94% of post-LASIK eyes when examined with confocal microscopy. However, clinically significant microstriae are rare, estimated to occur in 0.6% or less of cases.

In addition, a disparity in chord length exists between the flap and the newly contoured stromal bed.

Most microstriae are seen in eyes with high myopia, and surgical techniques may also contribute to the incidence of these wrinkles. For example, localized microtrauma, flap dehydration or excessive hydration, poor flap adherence due to epithelial breakdown or epithelial loss, and excessive flap manipulation can all have an impact on the development of microstriae, Dr. Lawless said.

Diagnostic tests

Diagnostic tests for microstriae have varying degrees of utility. Corneal topography color maps are not helpful, Dr. Lawless said. Wavefront analysis may be somewhat useful in determining whether visual complaints are due to spherical aberration or to some form of irregular astigmatism, which is the cause of problems in microstriae, he continued.

Tests that help a little include retroillumination after dilatation, when it reveals a cracked mud appearance, and negative staining fluorescein pattern. It can be difficult, however, to quantify the results of these tests, Dr. Lawless said. For example, while the fluorescein test may reveal microstriae, it does not help determine whether they require treatment.

"Once you've excluded other causes of visual complaints, it is most helpful to look for placido mires-subtle irregular astigmatism, putting a soft contact lens on to neutralize some of the irregular astigmatism, and a gas-permeable contact lens for more advanced cases," Dr. Lawless said.

If either type of contact lens eliminates symptoms and improves BCVA, this suggests that the microstriae are clinically significant and should be treated, Dr. Lawless added.

"If you're going to treat, remember that almost all microstriae-related visual complaints will disappear with time and that time is measured in months, not weeks," Dr. Lawless continued. "The problem is irregular astigmatism, and it is solved by epithelial remodeling."

Some patients, surgeons, and co-managing optometrists want a faster solution, but early intervention is not necessarily effective, Dr. Lawless said.