Local steepening in peripheral corneal curvature after corneal refractive therapy and LASIK.
OBJECTIVE
The purpose of this study was to assess the changes in curvature along the horizontal meridian of the anterior cornea occurring after refractive surgery and corneal refractive therapy (CRT).


METHODS
One hundred twenty-two eyes of 122 patients (70 female) with a mean (SD) age of 30.6 +/- 7.5 years were retrospectively analyzed in this study. Forty-three of those underwent standard laser in situ keratomileusis (LASIK) ablation, 40 had customized LASIK and 39 had CRT with orthokeratology lenses. Patients in different groups were matched to be comparable in terms of pretreatment refractive error and corneal topographic profiles. Topographical data along the horizontal meridian were collected over a 10 mm corneal diameter in 1 mm steps using the tangential power map from the computer display.


RESULTS
A statistically significant increase in corneal power (p < 0.05) was observed at the nasal and temporal locations between 2 and 3 mm for CRT and 3 and 4 mm for LASIK procedures, from corneal keratometric center. This steepening was more pronounced after CRT treatment (p < 0.05 for all comparisons against LASIK groups) but not significantly different between LASIK groups (p > 0.124, Mann-Whitney Test).


CONCLUSIONS
Both, surgical and non-surgical interventions show a mid-peripheral local corneal steepening. However, the narrower optic zone and higher midperipheral steepening with CRT seems to provide the potential to create a more relative peripheralmyopic increase in corneal power than LASIK, which may have implications in slowing down myopia progression.
Queirós
António
A
School of Sciences, University of Minho, Braga, Portugal. aqp@fisica.uminho.pt
González-Méijome
José Manuel
JM
Villa-Collar
César
C
Gutiérrez
Angel Ramón
AR
Jorge
Jorge
J
D000328:Adult; D001251:Astigmatism / Q000601:surgery*; D003261:Contact Lenses; D003315:Cornea / Q000033:anatomy & histology* / Q000601:surgery; D003710:Demography; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008297:Male; D009216:Myopia / Q000601:surgery*; D012030:Refractive Errors / Q000628:therapy*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity; D055815:Young Adult