EVALUATING TEAR FILM QUALITY WITH A DOUBLE-PASS BASED SCATTERING INDEX Pablo Artal, Guillermo M. Pérez, María Fernández, Sandra Mirabet*, José M. Marín* L ABORATORIO DE O PTICA, U NIVERSIDAD DE M URCIA, SPAIN * Hospital Virgen de la Arrixaca, Murcia, SPAIN Supported by:

The quality of the tear film affects the retinal image and visual performance Double-pass retinal image...the dynamic analysis of the double- pass retinal images may provide objective information on tear film quality

Methods (I) OQAS Instrument (Visiometrics SL) Dynamic recording & analysis of Double-Pass (DP) retinal images 1 Entrance Pupil Exit Pupil Input Beam DP Image Beam Splitter Scheme of the DP method 1. Santamaría, Artal & Bescós., J.Opt. Soc. Am. A., 1987 An Objective Scatter Index (OSI), estimated from the double pass images, quantifies scattering. Changes in scattering over time are related to tear film. Double-pass (DP) retinal image OSI

Patients 6 Healthy Eyes Age = 28 ± 5 8 Dry Eyes Age = 48 ± 11 Methods (II) Series of DP images recorded with an OQAS Instrument (Visiometrics SL) - Series of DP images were registered during 30 seconds - Defocus and astigmatism were previously corrected - The OSI parameter was computed for every DP image of the series - Every series was characterized by an average value of OSI and its corresponding standard deviation Processing the DP images - Different break-up cycles were recorded in every series DP Image

Results (I) Temporal evolution of the DP images for normal and dry eyes Healthy Eye Normal break-up cycles Healthy Eye Accelerated break-up cycles Dry Eye

Healthy Eyes Normal break-up cycles OSI time (s) Results (II) Objective scatter index (OSI) as a function of time

Healthy Eyes Normal break-up cycles OSI time (s) Healthy Eyes Accelerated break-up cycles Results (II) Objective scatter index (OSI) as a function of time

Healthy Eyes Normal break-up cycles OSI time (s) Dry Eyes Healthy Eyes Accelerated break-up cycles Results (II) Objective scatter index (OSI) as a function of time

Average objective scatter index (OSI) for every eye tested Results (III) Healthy Eyes Normal break-up cycles OSI = 0.5 ± 0.1 Healthy Eyes Accelerated break-up cycles OSI = 0.9 ± 0.3 Dry Eyes OSI = 3 ± 2

Healthy Eyes Accelerated break-up cycles SD_OSI = 0.3 ± 0.1 Healthy Eyes Normal break-up cycles SD_OSI = 0.08 ± 0.03 Dry Eyes SD_OSI = 0.6 ± 0.4 Standard deviation of the objective scatter index (OSI) for every eye tested Results (III)

Average objective scatter index (OSI) for every eye tested Results (III) Healthy Eyes Normal break-up cycles OSI = 0.5 ± 0.1 Healthy Eyes Accelerated break-up cycles OSI = 0.9 ± 0.3 Dry Eyes OSI = 3 ± 2 OSI is larger and more variable in dry eye’s patients!

i) A novel robust and objective method to measure the optical quality of tear film has been developed based on measuring the induced changes of ocular scatter estimated from double-pass images. ii) This technique may be useful to detect and follow- up tear-film related patient’s complaints more accurately than with current approaches. Conclusions