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Topography, pachymetry better assess ocular stability before surgery in contact lens users
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Corneal topography and optical pachymetry may be better methods for determining ocular stability in soft contact lens-wearing photorefractive surgery candidates, a prospective study found.
"In light of this finding, the current protocol in practice of determining the readiness of contact lens candidates for photorefractive surgery may be inadequate," the study authors said, referring to manifest refraction and keratometry.
Loretta T. Ng, OD, FAAO, of the Southern California School of Optometry, and colleagues compared manifest refraction and keratometry with corneal topography and optical pachymetry for assessing corneal and refractive stabilization after soft contact lens wear in photorefractive candidates.
During each study visit, patients removed their contact lenses 30 minutes before undergoing the four tests in the same order. The study included 15 soft contact lens wearers and five non-contact lens-wearing control patients.
"The timing of the last visit was determined when the four procedures resulted in stable findings when compared with the previous visit," the authors said.
In the study group, stability was identified after 10.7 days using manifest refraction, 16.2 days using keratometry, 28.1 days using topography and 35.1 days using pachymetry, according to the study.
The researchers found a statistically significant difference between the newer vs. older technologies (P < .001). The control group, however, showed little variability between the tests, the authors noted.
"Analysis of variance of the various soft contact lenses modalities suggested extended hydrogel wearers taking the longest time to reach stability after discontinuing full-time contact lens use," they added.
The study is published in the May issue of Optometry and Vision Science.