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Computer model determines ideal IOL powers for humanitarian cataract missions
J Cataract Refract Surg. 2009;35(10):1734-1738.
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An IOL power prediction model calculated the ideal distribution of IOLs for use on humanitarian missions by cataract surgeons in developing nations, a study showed.
Investigators aimed to reduce the likelihood that a patient would be rejected for treatment because of the unavailability of a suitable IOL power, and to limit the number of excess IOLs.
"In the past, some researchers advocated using a single IOL power or a small range of IOL powers to decrease mission costs," the study authors said. "However, with this strategy, many patients would likely achieve less than optimum visual outcomes."
The retrospective study included 103 patients in 12 countries. Investigators used biometric data to calculate the ideal emmetropic IOL power for each eye and statistical modeling to calculate the number of extra IOLs required at each power to account for variations in random population samples.
The model predicted that with this strategy, fewer than 2% of patients would be rejected because of a lack of IOLs with the suitable power. In simulated cataract surgery missions, between 80% and 97% of patients had access to precisely calculated emmetropic IOLs, the authors said.
"It is generalizable to missions of any size and should help planners minimize costs while ensuring excellent refractive outcomes," they said.
This paper describes a clever method of predicting the IOL power requirements for a charitable cataract population. The goal is to minimize the size of the IOL inventory to bring, while at the same time achieving close to emmetropia for 98% of patients. This methodology might also serve to guide organizations willing to donate IOLs as to the optimal distribution of powers that should be provided. The supply and delivery of IOLs is one of the largest expenses for cataract camps, and it is important to make this process as cost effective as possible. At the same time, near-emmetropic results are particularly important for a population which may be without access to spectacles. It will be interesting to see how accurate these predictions are after being implemented in actual humanitarian cataract surgery missions.
– David F. Chang, MD
OSN Cataract Surgery
Board Member