Longitudinal Assessment of Optical Quality and Intraocular Scattering Using the Double-Pass Instrument in Normal Eyes and Eyes with Short Tear Breakup Time

Abstract

PurposeTo assess the longitudinal changes in optical quality including intraocular scattering in normal eyes and eyes with short tear breakup time (TBUT).MethodsWe prospectively examined twenty eyes of 20 healthy subjects, and age-matched twenty eyes of 20 short TBUT subjects. The modulation transfer function (MTF) cutoff frequency, the Strehl ratio, and the objective scattering index (OSI) were quantitatively assessed using an Optical Quality Analysis System. We investigated the changes in these variables measured consecutively at the initial examination, 5, and 10 seconds without blinking. We also compared these variables in eyes with short TBUT with those in normal eyes.ResultsNo significant differences in the MTF cutoff frequency, Strehl ratio, or OSI were detected over a 10-second period in normal eyes. These variables also became significantly degraded even over a 5-second period in eyes with short TBUT (p<0.01). We found significant differences in these variables at 5 and 10 seconds (p<0.05), but none immediately after the blink between normal and short TBUT eyes.ConclusionsOptical quality including intraocular scattering deteriorated significantly with time in eyes with short TBUT, whereas we found significant differences over a 10-second period in normal eyes. Eyes with short TBUT showed greater deterioration in optical quality after the blink than normal eyes. The longitudinal assessment of optical quality may be effective in distinguishing eyes with short TBUT from normal eyes.

TFOS DEWS II Tear Film Report

“…Thus, analysis of double-pass retinal images on the time scale of the blink cycle may provide an indirect measure of tear film stability. Deteriorations in image quality metrics such as intensity distribution index [107], Strehl ratio, modulation transfer function cut-off frequency and objective scattering index [108] are observed in dry eye. More data are needed to establish the diagnostic ability of this approach for discriminating dry eye.…”

Overview of Objective Methods for Assessing Dynamic Changes in Optical Quality

“…[31][32][33][34][35][36][37][38][39][40][41][42] Moreover, the double-pass system is capable of monitoring postblink dynamic changes in optical quality associated with changes in the tear film. [43][44][45][46][47] Previous investigations using sequential HOA measurements showed that postblink dynamic changes in optical quality occur even in clinically normal subjects and revealed that such postblink changes in dry eyes can be classified into two patterns. 33,38,39 In dry eyes with a decreased tear film break-up time and dry eye symptoms without ocular surface damage and tear deficiency, the HOA pattern exhibited an upward curve after blinking that continued to increase.…”

Binocular summation and visual function with induced anisocoria and monovision

“…Tarrasa, Spain), an optical instrument based on the double-pass technique widely validated [27][28][29]. This device provides information on higher-order aberrations, diffraction, and scattered light, using an infrared laser diode (λ = 780nm) as light source.…”

“…However, due to the noise introduced by the CCD camera, which collect the double-pass image, the MTF cutoff is the frequency (cpd) at 1% of maximum MTF. That is, the double-pass device uses a MTF threshold value of 0.01 for reporting the MTF cutoff [27,29]. The definition used here for this parameter is not equal to the classical definition, which is calculated based on wavelength and pupil diameter [30].…”