Evaluation of Optimised Implantable Collamer Lens Sizing using an Optical Low-Coherence Reflectometry Biometry Device...

Area of Science:

• Ophthalmology
• Refractive Surgery
• Biometry

Background:

• Implantable Collamer Lens (ICL) surgery is a viable treatment for ametropia when laser vision correction is unsuitable.
• Precise lens sizing is critical to avoid suboptimal vault heights, which can lead to complications.
• The Online Calculator and Ordering System (OCOS) uses white-to-white (WTW) measurements for ICL sizing, often with a standard subtraction value.

Purpose of the Study:

• To evaluate if a more specific WTW subtraction value for the LENSTAR 900 (LS900) biometry device can enhance ICL sizing accuracy.
• To assess the impact of different WTW subtraction values on ICL vault height outcomes.

Main Methods:

• A retrospective observational cohort study involving 199 eyes from 102 patients undergoing ICL surgery.
• Pre-operative biometry was performed using the LS900, with ICLs sized via the OCOS calculator using a 0.4mm WTW subtraction.
• Vault height was measured at multiple post-operative time points, and simulations were conducted using a 0.25mm WTW subtraction for the LS900.

Main Results:

• 'Ideal' ICL sizing was achieved in 70% of cases at 3 months, decreasing to 67% at 12 months.
• The majority of incorrectly sized lenses were oversized at 3 months but became undersized by 12 months.
• Simulations indicated that a 0.25mm WTW subtraction for LS900 biometry could shift vault heights away from undersizing at 12 months.

Conclusions:

• Current OCOS calculator sizing with a 0.4mm WTW subtraction may lead to oversizing, potentially due to measurement discrepancies.
• An adjusted WTW subtraction of 0.25mm for LS900 biometry shows potential to reduce the incidence of low vaults, a risk factor for cataract development.
• Further real-world studies are necessary to validate the improved accuracy of the 0.25mm WTW subtraction for ICL sizing.