Lu LW, Rocha-de-Lossada C, Rachwani-Anil R, Flikier S, Flikier D. The role of posterior corneal power in 21st century biometry: A review.
J Fr Ophtalmol 2021;
44:1052-1058. [PMID:
34148699 DOI:
10.1016/j.jfo.2020.11.031]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 10/31/2020] [Accepted: 11/05/2020] [Indexed: 10/21/2022]
Abstract
PURPOSE
Intraocular lens (IOL) calculation and biometry have evolved significantly in recent decades. However, present outcomes are still suboptimal. Our objective is to summarize the results reported in the literature with regard to a new variable, the value of the relationship between anterior and posterior corneal curvature in the biometric calculation of IOL power.
METHODS
We have created a narrative revision of the existing evidence regarding the posterior to anterior corneal curvature ratio in IOL calculation.
RESULTS
The corneal posterior/anterior ratio (P/A ratio), also called Gullstrand ratio, has a standard deviation of 2.4% in normal people, hence causing a possible IOL power miscalculation error of up to 0.75 diopters (D). This error is magnified in pathological corneas or in those with previous refractive surgery. Including the P/A ratio in the IOL formula reduces errors in the calculation of IOL power.
CONCLUSIONS
Measurement of the posterior corneal surface should be recommended prior to IOL calculation, given the demonstrated results regarding the P/A ratio for IOL power calculation. Regarding toric IOL calculation, we suggest incorporation of all internal astigmatic vectors, for instance, posterior corneal surface, IOL tilt induced toricity, and retinal astigmatism. All of these factors may improve surgical outcomes.
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