ESCRS - PP05.12 - Impact Of Production Tolerance And Lens Thickness Formula Type On The Prediction Error Power Calculation

Impact Of Production Tolerance And Lens Thickness Formula Type On The Prediction Error Power Calculation

Published 2024 - 42nd Congress of the ESCRS

Reference: PP05.12 | Type: Free paper | DOI: 10.82333/g762-sd54

Authors: Joaquín Fernández* ¹ , Filomena Ribeiro ² , Noemí Burguera ¹ , Marina Rodríguez-Calvo-de-Mora ³ , Manuel Rodríguez-Vallejo ¹

¹Ophthalmology Department (VITHAS Hospital),Qvision,Almería,Spain, ²Departamento de Oftalmologia,Hospital da Luz,Lisbon,Portugal;Universidade de Lisboa,Faculdade de Medicina,Lisbon,Portugal, ³Ophthalmology Department,VITHAS Málaga,Málaga,Spain;Departamento de Oftalmologia,Hospital Regional Universitario de Málaga,Málaga,Spain;Ophthalmology Department (VITHAS Hospital),Qvision,Almería,Spain

Purpose

To evaluate the variations in the accuracy of intraocular lens (IOL) power calculation, specifically looking at the prediction error (PE) when comparing exact power (EP) to the power indicated on the label (LP), and to examine the precision of the Barrett formula with optimized constant against a Thick-lens formula.

Setting

Qvision, Ophthalmology Department, VITHAS Almería Hospital

Methods

The PE and its absolute value (APE) were determined for a randomly selected eye from patients who received the multifocal Liberty Q-Flex 640PM IOL (Medicontur Ltd.), taking into account both the LP and the EP as specified by the manufacturer. The results utilizing the Barrett formula with an optimized constant were then compared to those obtained with a Thick-lens formula customized for the surgeon, biometer, and IOL.

Results

The study analyzed 155 eyes in total. The average manufacturing tolerance was found to be 0.12 D for powers ranging from 15 to 25 D, and 0.19 D for powers between 25 to 30 D. When adjusted to the corneal plane, these averages were 0.07 D and 0.11 D, respectively, with a statistically significant difference (p = 0.002). The difference in mean PE when comparing LP to EP was ≤ 0.05 D for both formulas, not statistically significant (p>0.05). Similarly, no significant differences were observed for the APE, which was ≤ 0.01 D (p<0.05). The proportion of eyes achieving a prediction accuracy within ±0.375 D was between 74.2% and 75.5% (p>0.05).

Conclusions

Using EP instead of LP does not enhance the proportion of eyes achieving a deviation within ±0.375 D for patients who have received a multifocal IOL with diopter powers between 18 and 27 D. Moreover, when the constant is accurately adjusted, employing a thick-lens formula does not present any significant clinical differences in outcomes compared to using the Barrett formula.