Implementation of the Frequency Scatter Index in Clinical Commercially Available Double-pass Systems

Abstract

Implementation of the Frequency Scatter Index in clinical commercially available double-pass systemsPurpose: A previous work has reported a methodology to quantify intraocular scattering using a high sensitivity double-pass instrument with a robust index, the frequency scatter index (FSI). The purpose of our study was to evaluate an adaptation of the FSI for use in clinical double-pass systems.Methods: A prospective observational study was carried out in a group of patients with nuclear cataracts (n=52) and in a control group (n=11) using conventional double-pass systems. The FSI and the objective scatter index (OSI) were used to assess the scattering. The Spearman coefficient was calculated to assess the correlation between OSI and FSI, obtained from the double-pass images.Simultaneous measurements were performed with a double-pass and with a Hartmann-Shack wavefront sensor in the control group. The root mean square wavefront error (RMS) and the full width at half maximum of the double-pass image (FWHM) were used to quantify the residual aberrations introduced by the variations in pupil size and retinal eccentricity.Results: Measurement in eyes with different grades of cataracts shows a strong correlation (ρ=0.929, p<0.0001) between the FSI and the OSI. A certain degree of correlation was observed between the OSI and the RMS and between the OSI and the FWHM, both for measurements with a different pupillary diameter and with a different retinal eccentricity (p<0.05). No relationship was observed between the FSI and the RMS or between the FSI and the FWHM (p>0.05). Conclusion:We have introduced and evaluated an adaptation of a methodology proposed recently for the measurement of intraocular scattering using the doublepass technique with a robust index, which is less affected by ocular aberrations.The FSI can be applied to conventional double-pass instruments available in clinical environments.