IOL calculation for humanitarian missions

Biometric data are not necessarily available in the developing world during humanitarian missions. A US Navy humanitarian team looked at the possibility that the correlation between corneal power and axial length might be used for intraocular lens (IOL) power calculation when biometric data are incomplete. They collected measurements of K and AL from all adult cataract surgery charts and used these to calculate emmetropic IOL powers. A formula for estimating K or AL was derived by Deming regression analysis. The emmetropic IOL powers were calculated by hypothetical scenarios as follows: (1) K estimated from the formula and measured AL, (2) mean population K and measured AL, (3) measured K and estimated AL, and (4) measured K and mean population AL. The mean absolute refractive error (MAE) was calculated for each hypothetical scenario and an additional scenario (scenario 5) using single IOL power for all eyes. An analysis indicated that the correlation between K and AL could be used to improve accuracy of IOL calculation when K is unavailable. When the AL is unavailable, the mean population IOL power was the most accurate.

 JW Schmitz, JCRS, “Intraocular lens power calculation for humanitarian missions based on partial biometryâ€, Volume 38, Issue 7, 1187- 1191.