Topographic predicted corneal acuity with intrastromal corneal ring segments.
OBJECTIVE
To evaluate predicted optical quality of the central anterior corneal surface before and after the intrastromal corneal ring segment (ICRS) refractive procedure using a clinical videokeratoscope and software index developed for that purpose.


METHODS
Predicted corneal acuity, a topographically derived index provided with the EyeSys System 2000 videokeratscope, representing potential optical quality of the cornea, was assessed preoperatively and at postoperative month 3 in 94 eyes that received an ICRS to treat -1.00 to -6.00 D of myopia. Predicted corneal acuity was calculated by determining the difference between a measured cornea and its best-fit ellipses for reflected ring circumferences within the central 3 mm diameter zone.


RESULTS
Preoperative predicted corneal acuity was 20/10 in 92 of 94 eyes (98%). At month 3 after the ICRS procedure, 48 (51%) of moderately myopic eyes were corrected to 20/20 or better, 96% (90 eyes) were corrected to 20/40 or better, and 98% of eyes (92 eyes) had a predicted corneal acuity of 20/10. For the eyes with a predicted corneal acuity of 20/10, spectacle-corrected visual acuity was normally distributed between 20/10 and 20/25.


CONCLUSIONS
Predicted corneal acuity did not change significantly from baseline in eyes with an ICRS. This suggests that topographic irregularities in the central 3 mm of the cornea detectable by predicted corneal acuity software were not induced in the central cornea with the ICRS.
Holmes-Higgin
D K
DK
Northwest Corneal Services and the Corneal Topography Reading Center, Portland, OR 97223, USA.
Burris
T E
TE
Asbell
P A
PA
Durrie
D S
DS
Schanzlin
D J
DJ
D003319:Corneal Stroma / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D005500:Follow-Up Studies; D006801:Humans; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D014792:Visual Acuity