To determine the corneal power by topography, Orbscan, manual keratometry, as well as AdjEFFRP and AdjACCP formulae, compared with Galilei TCP and CHM as reference standards, also to assess the agreement of different keratometric methods and devices in detecting the corneal power after photorefractive keratectomy.

Keratometry was measured in 66 eyes of 33 refractive surgery candidates using manual keratometry (kr), Tomey (ACCP), Galilei (TCP), Orbscan II, and Eye sys (EffRP). Corneal power was also calculated with CHM and two corneal power formulae (adjusted ACCP and adjusted EFFRP).

CHM correlates with all keratometric methods and both formulae (adjusted ACCP and adjusted EFFRP); however, values obtained by manual keratometry, Tomey, Orbscan, Eye Sys are significantly greater than those of CHM (-0.55±0.66, -0.58±0.63, -0.36±0.62,-0.51±0.62, respectively) (p<0.001). CHM had the least mean differences with TCP, AdjACCP and AdjEffRP. CHM had the narrowest range of agreement with AdjEFFRP and AdjACCP

Manual keratometry, Tomey, Orbscan II and Eye Sys overestimate the corneal power, leading to hyperopic changes in estimating IOL. Using clinical history method as standard, CHM had the least differences with TCP, Adjusted ACCP and adjusted EFFRP but the narrowest range of agreement were found between CHM with Adjusted EffRP and Adjusted ACCP.