Intraocular lens power calculation with ray tracing based on AS-OCT and adjusted axial length after myopic excimer laser surgery.

J Cataract Refract Surg

From the I.R.C.C.S. G.B. Bietti Foundation, Rome, Italy (Savini, Schiano-Lomoriello); Stein Eye Institute, University of California, Los Angeles, California (Hoffer); St. Mary's Eye Center, Santa Monica, California (Hoffer); Hospital da Luz Lisboa, Lisbon, Portugal (Ribeiro); Lisbon University, Lisbon, Portugal (Ribeiro); Visual Science Research Centre, Lisbon, Portugal (Ribeiro); GoLP/IPFN, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal (Dias, Coutinho); San Raffaele Hospital, Milan, Italy (Barboni); Studio Oculistico d'Azeglio, Bologna, Italy (Barboni).

Published: August 2022

Purpose: To report the results of intraocular lens (IOL) power calculation by ray tracing in eyes with previous myopic excimer laser surgery.

Setting: G.B. Bietti Foundation I.R.C.C.S., Rome, Italy.

Design: Retrospective interventional case series.

Methods: A series of consecutive patients undergoing phacoemulsification and IOL implantation after myopic excimer laser was investigated. IOL power was calculated using ray-tracing software available on the anterior segment optical coherence tomographer MS-39. Axial length (AL) was measured by optical biometry, and 4 values were investigated: (1) that from the printout, (2) the modified Wang/Koch formula, and (3) the polynomial equation for the Holladay 1 and (4) for the Holladay 2 formulas. The mean prediction error (PE), median absolute error (MedAE), and percentage of eyes with a PE within ±0.50 diopters (D) were reported.

Results: The study enrolled 39 eyes. Entering the original AL into ray tracing led to a mean hyperopic PE (+0.56 ±0.54 D), whereas with the Wang/Koch formula, a mean myopic PE (-0.41 ±0.53 D) was obtained. The Holladay 1 and 2 polynomial equations lead to the lowest PEs (-0.10 ±0.49 D and +0.08 ±0.49 D, respectively), lowest MedAE (0.37 D and 0.25 D), and highest percentages of eyes with a PE within ±0.50 D (71.79% and 76.92%). Calculations based on the Holladay 2 polynomial equation showed a statistically significant difference compared with other methods used (including Barrett-True K formula), with the only exception of the Holladay 1 polynomial equation.

Conclusions: IOL power was accurately calculated by ray tracing with adjusted AL according to the Holladay 2 polynomial equation.

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Source
http://dx.doi.org/10.1097/j.jcrs.0000000000000902DOI Listing

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