OCT-based IOL selection performs well in challenging eyes

Scranton, PA-A new optical coherence tomography (OCT)-based method for IOL power selection has been found to be a promising method for achieving good refractive outcomes when performing cataract surgery in eyes with a history of laser vision correction, according to analyses of data from a retrospective comparative case series.

The study-which was undertaken by researchers at the Commonwealth Medical College, Scranton, PA-included data from 34 eyes that had undergone LASIK or photorefractive keratectomy for myopic correction and had no vision-limiting disease other than cataract.

The OCT-based method-developed by Maolong Tang, PhD, and David Huang, MD, PhD-was used to calculate IOL power to achieve emmetropia in all eyes. Other methods used included:

·      The American Society of Cataract and Refractive Surgery online IOL calculator (34 eyes).

·      Clinical history method (25 eyes).

·      Haigis-L formula (32 eyes).

·      Use of corneal power measurements from slit-scanning topography (Orbscan II, Bausch + Lomb; 31 eyes).

Mean absolute error (MAE) was calculated using a stable MRSE measurement. The results showed that the OCT-based method was associated with the best numerical result (0.56 ± 0.46 D), and the difference was statistically significant when it was compared with the clinical history method, which had the highest MAE (1.03 D ± 0.88 D).

Secondary analyses calculated error distribution ranges. Whether considering the proportion of eyes within 0.5  or 1 D of target, the OCT-based method was again associated with the best numerical results.

“A study to establish benchmark standards for refractive outcomes after cataract surgery in the National Health Service suggested that at least 55% of eyes should be within 0.5 D of target and at least 85% should be within 1.0 D,” said Alex Harris, a fourth year medical student who presented the data. “The OCT-based method hit those marks with 59% of eyes being ±0.5 D and 88% falling within 1.0 D.

“Our study is limited by its small size,” Harris added. “However, the OCT-based method demonstrated comparable clinical utility relative to leading alternative methods, and it is widely available, which makes it an attractive solution for these challenging patients.”

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