Abstract
PURPOSE: The purpose of this study was to examine the effect of intra-operative live refraction stability as a surrogate marker of ocular surface hydration on intra-operative aberrometry (IA) results and to quantify the minimum duration of stable refraction needed to achieve accurate intraocular lens (IOL) selection. METHODS: In this nonrandomized consecutive retrospective chart review, 18,000 data points from 45 live refraction runs of 15 patients were digitized and analyzed. An objective automated moving average method of frames lengths of 88 ms, 110 ms, and 132 ms with less than 0.5 diopters (D) of fluctuation was compared to raw IA capture data. The difference-vector (DV) of the predicted toric powers was compared among these groups. Subjectively, traces were classified as stable or unstable if the live refraction fluctuated less than 0.5 D for 5 seconds. The DV based on the stable period was compared with the IA capture data. RESULTS: The DVs for all frame intervals showed no significant difference when compared with IA readings. In 15 of 45 (33.3%) cases, IA active refraction traces were stable and the DV (0.27 D ± 0.15 D) was significantly less than unstable traces (0.49 D ± 0.28 D). IOL recommendations from 14 (93.3%) of stable runs led to a <0.5 D of postoperative cylinder compared to 14 (47.7%) in unstable runs. CONCLUSIONS: Intra-operative live refraction stability is affected by ocular hydration. Surgeons should look for periods of refractive stability for at least 5 seconds to better assess measurement quality. This can be facilitated by capturing and including the active refraction trace, which is currently unavailable for review. TRANSLATIONAL RELEVANCE: Graphing live refractive IA readings and determining refractive stability translates to more accurate IOL selection.