Impact Of Measured Posterior Corneal Power In Iol Power Calculation After Laser Vision Correction
Published 2024 - 42nd Congress of the ESCRS
Reference: PP05.16 | Type: Free paper | DOI: 10.82333/3hdc-5z32
Authors: Inês Gonçalves Figueiredo* 1 , Raquel Félix 1 , João Bernardes 2 , Miguel Raimundo 2 , Conceição Lobo 2 , Joaquim Murta 3
1Ophthalmology,Unidade Local de Saúde de Coimbra,Coimbra,Portugal, 2Ophthalmology,Unidade Local de Saúde de Coimbra,Coimbra,Portugal;Faculty of Medicine, University of Coimbra,Coimbra,Portugal;Clinical Academic Center of Coimbra,Coimbra,Portugal, 3Ophthalmology,Unidade Local de Saúde de Coimbra,Coimbra,Portugal;Clinical Academic Center of Coimbra,Coimbra,Portugal;Faculty of Medicine, University of Coimbra,Coimbra,Portugal
Purpose
IOL power calculations in eyes previously submitted to corneal refractive surgery are typically less accurate than unoperated eyes. Modern formulas for this purpose include the Barrett, EVO and Hoffer QST which all have post laser vision correction (LVC) variants. The option to manually input measured posterior corneal data has the potential to further refine and improve these predictions.
Setting
Academic University Hospital
Methods
Retrospective study of eyes with history of myopic laser vision correction (LVC) that underwent cataract surgery. Pre-operative evaluation included an optical biometer (Argos or IOL Master) and corneal tomography (Pentacam) for SimK values and measured posterior corneal curvature data (PK). Post-operative spherical equivalent (SE) for the IOL was estimated with Barrett True K, EVO and Hoffer QST formulas for myopic LVC, with and without the option of inputting PK. No pre-LVC historical data was used. Outcomes included: unoptimized mean prediction error (ME), standard deviation (SD), proportion of eyes within 0.25, 0.50 and 1.00 diopters (D) of predictions and percentage of eyes with hyperopic prediction errors (PE), namely exceeding +0.50D.
Results
We included 48 eyes with a mean axial length (AL) of 23.9 ± 2.08 mm (range 23.19 to 32.68 mm). With measured PK data in IOL estimation, lower ME (SD) values were achieved irrespective of the formula used. The ME/SD values for each formula pair with and without PK, respectively, were: Barrett True K 0.039 (0.498) versus 0.048 (0.491), EVO 0.119 (0.462) vs 0.160 (0.457), and Hoffer QST 0.194 (0.684) vs 0.260 (0.608). The percentages of eyes with hyperopic PE and those exceeding +0.50D of hyperopic PE were lower when PK data was included: Barret True K 47.9/20.8% vs 56.3/22.9%, EVO 56.3/22.9% vs 64.6/25.0% and Hoffer QST 62.5/29.2% vs 77.1/35.4%.
Conclusions
The addition of measured posterior corneal data significantly improved predictions for all evaluated “no history” post-LVC IOL formula pairs and decreased the incidence of hyperopic prediction errors. Our results support routinely using this option in IOL power calculation after myopic LVC.