TY - JOUR
T1 - The effect of corneal irregularity on astigmatism measurement by automated versus ray tracing keratometry
AU - Roh, Hyun Cheol
AU - Chuck, Roy S.
AU - Lee, Jimmy K.
AU - Park, Choul Yong
N1 - Publisher Copyright:
© 2015 Wolters Kluwer Health, Inc.
PY - 2015/4/6
Y1 - 2015/4/6
N2 - The aim of this study was to compare the effect of corneal irregularity on astigmatism assessment using automated keratometry (AK) (IOLMaster) versus ray tracing keratometry (Pentacam). This is an observational case series approved by the institutional review board of Dongguk University Hospital, Goyang, South Korea. A total of 207 eyes of 207 cataract patients were included. Preoperative corneal astigmatism was measured by both IOLMaster and Pentacam. Corneal irregularity index (IR) was calculated in Fourier analysis map of Pentacam. AK by IOLMaster and total corneal refractive power (TCRP, 3mm and 4mm zone analysis with pupil centered) by Pentacam were selected and the difference between the 2 measurements (delta Δ) was calculated using vector analysis. Ocular residual astigmatism (ORA) after cataract surgery was calculated by subtracting 6-month postoperative refractive astigmatism (RA) measurements from corresponding preoperative values (AK, TCRP3, and TCRP4). The mean irregularity index measured was 0.042±0.019mm (mean±standard deviation) and was positively correlated with age and magnitude of corneal astigmatism (P<0.001 and P<0.05). The difference (Δ) between TCRPs and AK (ΔTCRPs-AK) was 0.43±0.37 (TCRP3) and 0.39±0.35 (TCRP4) diopters. Linear regression analysis revealed that age (P<0.001), IR (P<0.001), and AK (P<0.001) were positively correlated with ΔTCRPs-AK. In highly irregular corneas (IR over 0.77 diopters: mean+2 standard deviation), postoperative ORAs calculated using TCRPs were significantly lower than ORAs calculated using AK. Corneal irregularities significantly impact astigmatism assessment by IOLMaster (AK) and Pentacam (TCRPs). Compared with AK, TCRPs were more accurate in predicting postoperative residual astigmatism in highly irregular corneas.
AB - The aim of this study was to compare the effect of corneal irregularity on astigmatism assessment using automated keratometry (AK) (IOLMaster) versus ray tracing keratometry (Pentacam). This is an observational case series approved by the institutional review board of Dongguk University Hospital, Goyang, South Korea. A total of 207 eyes of 207 cataract patients were included. Preoperative corneal astigmatism was measured by both IOLMaster and Pentacam. Corneal irregularity index (IR) was calculated in Fourier analysis map of Pentacam. AK by IOLMaster and total corneal refractive power (TCRP, 3mm and 4mm zone analysis with pupil centered) by Pentacam were selected and the difference between the 2 measurements (delta Δ) was calculated using vector analysis. Ocular residual astigmatism (ORA) after cataract surgery was calculated by subtracting 6-month postoperative refractive astigmatism (RA) measurements from corresponding preoperative values (AK, TCRP3, and TCRP4). The mean irregularity index measured was 0.042±0.019mm (mean±standard deviation) and was positively correlated with age and magnitude of corneal astigmatism (P<0.001 and P<0.05). The difference (Δ) between TCRPs and AK (ΔTCRPs-AK) was 0.43±0.37 (TCRP3) and 0.39±0.35 (TCRP4) diopters. Linear regression analysis revealed that age (P<0.001), IR (P<0.001), and AK (P<0.001) were positively correlated with ΔTCRPs-AK. In highly irregular corneas (IR over 0.77 diopters: mean+2 standard deviation), postoperative ORAs calculated using TCRPs were significantly lower than ORAs calculated using AK. Corneal irregularities significantly impact astigmatism assessment by IOLMaster (AK) and Pentacam (TCRPs). Compared with AK, TCRPs were more accurate in predicting postoperative residual astigmatism in highly irregular corneas.
UR - http://www.scopus.com/inward/record.url?scp=84929501055&partnerID=8YFLogxK
U2 - 10.1097/MD.0000000000000677
DO - 10.1097/MD.0000000000000677
M3 - Article
C2 - 25837759
AN - SCOPUS:84929501055
SN - 0025-7974
VL - 94
JO - Medicine (United States)
JF - Medicine (United States)
IS - 13
M1 - e677
ER -