Agreements’profile of Scheimpflug-based optical biometer with gold standard partial coherence interferometry

AIM:To determine the agreement of ocular biometric indices including axial length,keratometric readings,anterior chamber depth,and horizontal corneal diameter between the Pentacam AXL and IOL Master 500.METHODS:The study was a large cross-sectional population-based study(Tehran Geriatric Eye Study)conducted from Jan 2019 to Jan 2020.A total of 160 clusters were randomly selected proportional to size(each cluster contained 20 individuals)from 22 strata of Tehran city.All people aged 60y and above were invited to participate in the study.For all participants,preliminary ocular examinations were performed including the measurement of uncorrected and best-corrected visual acuity,objective and subjective refraction,anterior and posterior segment examinations.All participants underwent an ocular biometry using the Pentacam AXL and IOL Master 500.RESULTS:The 95%limits of agreement(LoA)between the two devices were-0.13 to 0.19,-0.15 to 0.17,and-0.13 to 0.19 in normal,pseudophakic,and cataractous eyes,respectively.With increasing the axial length,the difference between the two devices significantly increased in all three groups of normal,pseudophakic,and cataractous eyes(P<0.001).The 95% LoAs between the two devices regarding the mean keratometry shows that the best LoAs were seen in cataractous(-0.33 to 0.81)and followed by normal eyes(-0.36 to 0.86)and the pseudophakic eyes(-0.48 to 0.90)had the widest LoA.The 95% LoAs for horizontal corneal diameter measurements were-0.08 to 0.86,-0.03 to 0.83,and-0.07 to 0.87 in normal,pseudophakic,and cataractous eyes,respectively.The 95% LoAs of anterior chamber depth measurements between the two devices was-0.39 to 0.19 and-0.37 to 0.13 in normal eyes and cataractous,respectively.CONCLUSION:The Pentacam AXL has excellent agreement with the gold standard,IOL Master 500 in measuring axial length.In eyes with cataracts,the difference between the two devices is more scattered.With the increasing of axial length,the difference between the two devices increased,which should be considered when using Pentacam AXL.

Comparison of a new optical biometer and a standard biometer in cataract patients

Background:Cataract surgery is the most common surgical procedure in ophthalmology.Biometry data and accurate intraocular lens(IOL)calculations are very important in achieving the desired refractive outcomes.The aim of this study was to compare measurements using a new optical low coherence reflectometry(OLCR)biometer(OA-2000)and the gold standard partial coherence interferometry(PCI)optical biometer(IOLMaster 500).Methods:Ocular biometry of cataract patients were measured by the OA-2000 and IOLMaster 500 to compare keratometry(K),axial length(AL),anterior chamber depth(ACD),white-to-white(WTW)diameter,and IOL power using the SRK/T formula.Results:One hundred and two eyes of 68 cataract patients were evaluated with the two optical biometers.The mean values of the AL,K,ACD,and WTW differed very little(OCLR biometer,23.12 mm,44.50 diopters(D),3.06,and 11.64 mm,respectively;PCI biometer,23.18 mm,44.6 D,3.15,and 11.86 mm,respectively),but the differences were significant(all,p≤0.05).The AL,K,and ACD showed excellent correlations(r=0.999,0.980,and 0.824,respectively;all p<0.001);however,there was a weak correlation of the WTW diameter between the two devices(r=0.256).The IOL powers using the SRK-T formula derived from both instruments were very similar,with an excellent correlation(r=0.989).The mean difference between the two instruments was 0.32 D.Conclusions:The OLCR biometer showed very a strong agreement with the standard PCI optical biometer for almost all ocular biometry measurements,except for the WTW diameter.Trial registration:TCTR20160614003;date 06/09/2016;‘retrospectively registered’.