Corneal Power Estimation Using Orbscan II Videokeratography in Eyes With Previous Corneal Refractive Surgeries

ABSTRACT

PURPOSE: To report three cases of corneal power estimation for intraocular lens power calculation using Orbscan II videokeratography in eyes with previous corneal refractive surgeries. CASE SUMMARY: In three eyes of three patients with previous corneal refractive surgeries, corneal power values were respectively measured at three, four, five, six mm-diameter zones of total mean, axial, tangential, and optical maps using Orbscan II videokeratography. Then, intraocular lens power values were calculated via the SRK/T formula. After cataract surgeries, back-calculated corneal power (BCK) values were estimated from post-phacoemulsification refraction data, and compared with those measured at three, four, five, six mm-diameter zones of each map in Orbscan II videokeratography. The postoperative refractive values after cataract surgeries were achieved within 1.5D of the target refraction in all eyes by using five mm total axial power and four mm total optical power for intraocular lens power calculation. Orbscan II parameters including three mm, four mm total axial power, and three mm total optical power were the least different from the BCK (0.69+/-0.49D, 1.08+/-0.54D, and 1.10+/-0.44D, respectively). CONCLUSIONS: If historical data are not available, Orbscan II videokeratography can be useful for estimating corneal power for intraocular lens power calculations in patients with previous corneal refractive surgeries.