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Pau Santos, Juan A. Martínez-Roda, Juan C. Ondategui, Jorge Cazal, Maria Ballesta, Fernando Díaz-Doutón, Jaume Pujol, Meritxell Vilaseca; Assessment of corneal scattering using Purkinje images. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5811.
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© ARVO (1962-2015); The Authors (2016-present)
To assess corneal scattering using a novel technique based on measuring the contrast of the third (P3) Purkinje image, which accounts for the scattering of the cornea and anterior chamber.
Corneal scattering was assessed measuring the contrast of P3, of a 2-fringes pattern aperture. Intraocular scattering was also measured using commercial systems: Objective Scatter Index (OSI) (HD Analyzer, Visiometrics SL, Spain), corneal densitometry (Pentacam, Oculus Optikgeräte GmbH, Germany) and Log(S) (CQuant, Oculus Optikgeräte GmbH, Germany).We carried out a preliminary study including 4 naked eyes of healthy patients (aged 21 to 28 years) as well as wearing contact lenses (CL) with several degrees of scattering (9mm SFX, Cataract, USA): low (L), medium (M), high (H) and very high (VH). Then, we conducted a study at the University Vision Center (CUV) of the Universitat Politecnica de Catalunya (UPC) (Terrassa, Spain) and at CIMA Sanitas Hospital (Barcelona, Spain), including 11 eyes of patients (aged 24 to 65 years) with corneal disorders (CD) such as keratitis, cornea Verticillata, Fuchs dystrophy and complications from laser (Femto-Lasik) refractive surgery. 17 eyes of healthy patients (aged 29 to 52 years) were used as control group (C).
In eyes with CLs of different degree of scattering the mean P3 contrast (±SD) was of 0.53±0.04 (naked), 0.49±0.05 (L), 0.40±0.09 (M), 0.35±0.07 (H) and 0.28±0.11 (VH). Log(S) (±SD) values were 0.82±0.1 (naked), 1.27±0.21 (L), 1.98±0.04 (M), 1.99±0.13 (H) and 2.10±0.17 (VH). OSI (±SD) values were0.43±0.16 (naked), 0.62±0.38 (L), 0.64±0.23 (M), 1.14±1.17 (H) and 1.22±1.36 (VH). Densitometry values couldn’t be assessed in eyes with CLs due to internal reflections.In the eyes of the control group and CD the P3 contrast (±SD) was 0.52±0.07 (C) and 0.44±0.11 (CD); Log(S) (±SD) values were 0.89±0.13 (C) and 1.29±0.23 (CD); OSI (±SD) values were 0.55±0.26 (C) and 2.47±1.69 (CD); and densitometry(±SD) values were 30.28±1.64 (C) and 34.37±3.78 (CD).We found significant differences in P3 contrast between eyes from the control group and CD (t-test p=0.005). Log(S), OSI and densitometry p-values were <0.001, 0.011 and 0.004, respectively.
The results show the usefulness of measuring the contrast of P3 image to assess corneal scattering. Future work will focus on the possibility of discriminating corneal and lens scattering comparing the contrast of P3 and P4 images.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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