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Session Title: Quality of vision evaluation techniques
Session Date/Time: Tuesday 08/10/2013 | 14:00-16:00
Paper Time: 14:38
Venue: Elicium 2 (First Floor)
First Author: : S.Peixoto-De-Matos PORTUGAL
Co Author(s): : J. Salgado-Borges L. Dias J. Costa M. Ribeiro P. Fernandes J.
To evaluate Light Distortion surrounding an intense source of light measured with an experimental device in a population of pseudophakic patients implanted with monofocal intraocular lens (IOL).
CEORLab - Center of Physics - University of Minho Braga - Portugal Clinica Oftalmológica Salgado-Borges - Porto - Portugal
Sixty-five patients (age 69±7 years, range: 53 to 86 years; 65% females) undergone facoemulsification followed by pseudophakic IOL implantation with monofocal IOL by the same experienced surgeon. Examinations were performance between 5 to 8 months after surgery and an ophthalmological and optometric examination confirmed good ocular health status and media transparency while an optometric examination showed that all patients achieved at least 0.8 decimal unaided monocular VA and at least 1.0 for best corrected visual acuity. Patients worn their distance prescription while the exam was performed. The testing screen is formed by small light emitting diodes (LED) surrounding a central intense source of light. The patient was asked to identify the peripheral LEDs from a distance of 2.5 meters in a totally darkened room except for the sources of light used for testing. Evaluations were conducted with the natural pupil of the patients, without pharmacological dilation. Three measures of light distortion were conducted in the tested eye (always monocularly) and then the result was automatically averaged by the software system attached to the hardware displaying the LEDs. System calculates average area covered by the Light Distortion sensation, decentration respect to the (0,0) Cartesian origin and irregularity of the Light Distortion.
Average power of the lenses was 21.4±2.4diopters (14 to 26 diopters) with a post-operative spherical equivalent refractive error of M=0.11±0.53D and cylinder components of astigmatism J0=-0.08±0.28 diopters and J45=0.029±0.16 diopters. Mean distortion area was 25.17±16.6% (range: 7.94 to 90 %) with a best fit circle of 39.29±12.1 mm (range: 22 to 78 mm) around the central source of light in the testing panel. The distortion surrounding the stimulus was slightly decentered to the second quadrant (x-coordinate=-0.18, y-coordinate=0.18) with an index of irregulartity (±SD) of 0.91±7.32 mm (range: 0.0 to 12.7 mm).
Even in patients achieving satisfactory unaided and best corrected visual acuity, some degree of light distortion might be present when evaluated under challenging conditions as the visualization of a bright source of light against a dark background in pseudophakic eyes with IOL implantation. The experimental device used in this study allows to obtain a graphical and numerical representation of the approximate form of the light distortion seen by patients. It might be useful in cases of pseudophakic patients with alterations of the transparency of the ocular media or implanted IOL.
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