Refractive Accuracy of a Novel Swept-Source OCT in Patients With Short and Long Eyes

Purpose: To analyze the refractive accuracy of a novel swept-source optical coherence biometer (SS-OCT), that uses individual refractive indices to measure axial length, in short and long eyes implanted with monofocal intraocular lenses (IOLs). Methods: This retrospective comparative study considered eyes with short axial length (AL) (< 22.5 mm) or long AL (> 26 mm) bilaterally implanted with the Acrysof IQ monofocal IOL. All eyes were preoperatively analyzed with the Argos biometer and IOL calculations were made using the Barrett Universal II (BUII). One month after the surgery, refractive and visual outcomes and refractive prediction errors were calculated. Furthermore, a back calculation of the prediction errors based on the Barrett True Axial Length (BTAL) formula was also performed and the results of both formulas were compared. Results: Sixty eyes of 60 patients (30 with AL < 22.5 mm (short) and 30 with AL > 26 mm (long)) were included. After surgery, monocular UDVA was 0.03 ± 0.10 and 0.10 ± 0.15 logMAR for short-eye and long-eye groups, respectively. For short eyes, mean prediction error (MPE) with BUII and BTAL were 0.19 ± 0.34 D and 0.00 ± 0.35 D, respectively (p  <  0.001). Mean absolute error (MAE) was 0.32 ± 0.22 D with the BUII and 0.29 ± 0.20 D with the BTAL formula (p=0.21). For long eyes, MPE with BUII was -0.15 ± 0.35 D and -0.13 ± 0.36 D with BTAL (p=0.08), while MAE was 0.31 ± 0.21 D and 0.32 ± 0.20 D with BUII and BTAL, respectively (p=0.33). The percentage of eyes with a prediction error within ±0.5 D predicted postop spherical equivalent was > 75% for both groups and both formulas (p > 0.05 for all situations). Conclusions: The novel SS-OCT biometer using individual refractive indices to measure AL showed an overall good refractive accuracy using the BUII. The results were similar or better with the optimized BTAL formula, suggesting that formulas purposely designed for biometric measurements with this novel technology are a promising tool for eyes with extreme AL.