Longitudinal Biometric Changes and Intraocular Lens Calculation Formula Accuracy in Delayed Cataract Surgery Cases

Area of Science:

• Ophthalmology
• Refractive Surgery
• Biomedical Engineering

Background:

• Delayed cataract surgery, defined as postponement exceeding three months, presents unique challenges for accurate intraocular lens (IOL) power calculation.
• Changes in ocular parameters over time can affect the predictability of postoperative refractive error (PE).

Purpose of the Study:

• To compare postoperative refractive error (PE) calculated using various intraocular lens (IOL) calculation formulas based on initial versus remeasured ocular parameters in eyes undergoing delayed cataract surgery.
• To assess the impact of changes in axial length, keratometric power, anterior chamber depth (ACD), and lens thickness (LT) on IOL power calculations.

Main Methods:

• A cohort of 57 eyes undergoing delayed cataract surgery (average delay of 14 months) was analyzed.
• Initial and remeasured ocular parameters (axial length, keratometric power, ACD, LT) were obtained.
• Postoperative refractive errors were calculated using Sanders-Retzlaff-Kraff/Theoretical (SRK/T), Haigis, Barrett Universal II (BU II), Kane, and Emmetropia Verifying Optical (EVO) formulas, comparing results from initial and remeasured data.

Main Results:

• Significant changes in ocular parameters were observed: ACD deepened and LT thinned between initial and remeasured assessments.
• The Haigis and EVO formulas demonstrated a significant myopic shift in mean PE when using remeasured data compared to initial data.
• No significant differences in mean absolute error or median absolute error were found among the formulas, but LT emerged as a significant factor for the Haigis formula in regression analysis.

Conclusions:

• The choice of intraocular lens (IOL) calculation formula is critical for optimizing refractive outcomes in delayed cataract surgery.
• Formula-specific characteristics and potential changes in ocular parameters over time, particularly lens thickness, should be considered when selecting IOL power.