Comparison of White-to-White Measurements Between Pentacam and MS-39 and Their Relationship with Visual and Refractive Status.

OBJECTIVES

To compare white-to-white (WTW) measurements obtained by Pentacam and MS-39 and to assess their relationship with visual and refractive status.

MATERIALS AND

METHODS

This prospective cross-sectional study included 126 participants (one eye per participant). Visual acuity was measured with and without correction using a Snellen chart and converted to logarithm of the minimum angle of resolution (logMAR). Refractive status was determined by manifest refraction, and the spherical equivalent was calculated. WTW measurements were determined using Pentacam and MS-39. For paired comparisons, Wilcoxon signed-rank test was used. Intraclass correlation coefficients (ICC) and Bland-Altman plots were used to assess agreement between the two devices. Spearman test was used to evaluate the correlation with visual and refractive variables.

RESULTS

The mean age of the participants was 27.21±5.64 years. Mean uncorrected distance and corrected visual acuities were 1.11±0.45 logMAR and 0.05±0.20 logMAR, respectively. The mean spherical equivalent was -4.02±2.03 diopters. The mean WTW distance was 11.82±0.41 mm with Pentacam and 11.83±0.43 mm with MS-39. No statistically significant paired difference was found between the devices (W=3839.5, p=0.584). A Bland-Altman mean bias of -0.009 mm suggested a small systematic difference between the two devices. Intraclass correlation showed good agreement (ICC=0.847, 95% confidence interval: 0.789-0.890; p<0.001). While there was no significant correlation with corrected distance visual acuity, both WTW measures had weak but significant correlations with uncorrected distance visual acuity and spherical equivalent.

CONCLUSION

Pentacam and MS-39 produce comparable results overall and show strong agreement for WTW measurements. While the inter-device difference was unaffected by visual and refractive state, WTW showed minor correlations with unaided visual acuity and refractive error.