Intraocular lens power calculation after myopic and hyperopic laser vision correction using optical coherence...

Area of Science:

• Ophthalmology
• Biomedical Optics
• Refractive Surgery

Background:

• Accurate intraocular lens (IOL) power calculation is crucial for successful cataract surgery outcomes.
• Previous laser vision correction (LVC) significantly alters corneal power, complicating standard IOL calculations.
• Existing formulas may not adequately address refractive changes after LVC.

Purpose of the Study:

• To evaluate the precision of optical coherence tomography (OCT) for measuring corneal power in eyes with a history of myopic and hyperopic LVC.
• To develop and assess an OCT-based formula for intraocular lens (IOL) power calculation in post-LVC cataract patients.
• To compare the refractive prediction accuracy of the OCT-based IOL formula against the established Haigis-L formula.

Main Methods:

• Prospective study enrolling patients with prior LVC undergoing cataract surgery at two specialized eye centers.
• Corneal power measurement using a Fourier-domain OCT system, with intravisit repeatability assessed.
• Axial length, anterior chamber depth, and keratometry measured using the IOLMaster.
• Development of an OCT-based IOL formula and calculation of its mean absolute error (MAE).

Main Results:

• The intravisit repeatability of OCT corneal power measurement was found to be 0.24 D.
• In the myopic LVC group, the OCT formula achieved a MAE of 0.57 D, compared to 0.73 D for the Haigis-L formula.
• In the hyperopic LVC group, the OCT formula yielded a MAE of 0.26 D, outperforming the Haigis-L formula's MAE of 0.54 D.

Conclusions:

• Optical coherence tomography (OCT) provides precise measurements of corneal power.
• An OCT-based IOL power calculation formula demonstrates predictive accuracy equivalent to current standards for eyes with prior LVC.
• OCT technology offers a reliable solution for optimizing IOL power calculations in complex post-refractive surgery eyes.