Agreement between IOLMaster® 500 and Pentacam® HR for keratometry assessment in type 2 diabetic and nondiabetic patients

Abstract

AIM: To evaluate inter-device agreement of anterior keratometry obtained by the IOLMaster® 500 and Pentacam® HR in type 2 diabetic and non-diabetic patients. METHODS: Corneal measurements were sequentially performed in 60 diabetes mellitus (DM) and 48 age and sex-matched controls undergoing cataract surgery. Variables recorded included flat and steep keratometry, mean keratometry (Km), astigmatism magnitude, axis location, J0 and J45 components. Bland-Altman plots and intraclass correlation coefficients were used for examination of agreement. Subgroup analyses were performed for astigmatism magnitude, diabetes duration, hemoglobin A1c (HbA1c) levels and diabetic retinopathy (DR) stage. RESULTS: Agreement for Km and astigmatism magnitude were considered good and moderate, with 95% limits of agreement (LoA) of -1.09 to 1.23 diopters (D) and -0.83 to 0.86 D in DM group, respectively; and -0.59 to 0.72 D and -0.98 to 0.75 D in non-DM group, respectively. In contrast, the 95% LoA for corneal axis exceeded the clinically relevant margins in both groups. In the total sample, only 41 eyes (38%) had a smaller than 5-degree difference. Diabetes duration, HbA1c levels and DR stage were not found to significantly affect agreement. Logistic regression showed that higher corneal power (P=0.021) and astigmatism magnitude (P=0.011) were associated with a decreased risk of having a difference in axis location greater than 10-degrees. CONCLUSION: In both groups, IOLMaster and Pentacam agree well for corneal power and moderately for astigmatism. However, axis location disagreement is frequent in eyes with flatter corneas and small amounts of astigmatism.