New algorithm for post-radial keratotomy intraocular lens power calculations based on rotating Scheimpflug camera...

Area of Science:

• Ophthalmology
• Refractive Surgery
• Biomedical Optics

Background:

• Radial keratotomy (RK) alters corneal curvature, complicating intraocular lens (IOL) power calculations for subsequent cataract surgery.
• Accurate IOL power calculation is crucial for achieving desired refractive outcomes after cataract surgery in post-RK eyes.

Purpose of the Study:

• To develop and validate an algorithm for calculating IOL power in post-RK eyes using Pentacam Scheimpflug camera data.
• To compare the accuracy of this new algorithm against established methods using topography data.

Main Methods:

• A case series design was employed, analyzing data from 83 eyes of 57 patients with previous RK.
• IOL power was calculated using the Aramberri double-K-modified Holladay 1 formula with Scheimpflug measurements, including sagittal front-surface power and central corneal thickness (CCT).
• Results were compared to actual postoperative refractive outcomes and calculations derived from the Atlas topography system.

Main Results:

• The Pentacam Scheimpflug algorithm, utilizing mean pupil-centered sagittal front power adjusted for CCT, demonstrated effective IOL power calculation.
• Accuracy was comparable to the topography system, with 42% of eyes achieving a refractive outcome within ±0.50 diopters (D) and 76% within ±1.00 D of the target.

Conclusions:

• Pentacam Scheimpflug data, specifically sagittal front-surface power and CCT, provides a reliable method for IOL power calculation in post-RK eyes.
• This approach yields results equivalent to the multizone method using topography systems, offering a viable alternative for refractive surgery planning.