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FLORENCE CABOT, Alain SAAD, Nour Maya HADDAD, Alice GRISE-DULAC, Jean-Luc FEBBRARO, Damien GATINEL; Subjective Evaluation Of Crystalline Opacities Level By Measuring Ocular Light Scattering: Correlation With Visual Acuity, Lens Opacity Classification And Patient’S Discomfort. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3057.
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The OQAS (Optical Quality Analyzing System,Visiometrics) provides an objective measurement of ocular light diffusion . Our study’s primary goal was to study possible correlations between visual acuity, OQAS scores, patient’s discomfort and the level of lens opacification.
Propective monocentric study performed between January 2010 and January 2011. Included patients were referred for cataract evaluation. Patients having other pathologies impairing ocular transparency (corneal dystrophies and retinal anomalies) were excluded. Participants completed a questionnaire (to evaluate their discomfort based on cataract induced symptoms) and a comprehensive eye examination that included assessment of lens opacification, using the slit lamp-based Lens Opacities Classification System III (LOCS III), maximal contrast best-corrected visual acuity (BCVA), intraocular pressure and fundus examination. OQAS measurement of optical quality is based on the double-pass technique and provides us with ocular MTF (Module Transfer Function) and OSI (Ocular Scatter Index).
235 eyes of 127 patients were included. Mean OSI was 4,15 +/-0,24. Mean MTF cut off was 16,20 +/-0,82 cycles/degree. We found a positive correlation between OSI and cataract severity (r= 0,5 for posterior subcapsular cataracts p=0,0001 and r=0,4 for cortico-nuclear cataracts p=0,0001). In the posterior subcapsular group, OSI was correlated to symptoms like: diplopia (r=0,5 ; p= 0,05) visual acuity fluctuations (r=0,5 ; p=0,05) and difficulty focalizing (r=0,5 ; p=0,02). In patients presenting with severe discomfort but with BCVA greater than 20/30 the mean OSI was 2,37 +/-0,3.
Patients presenting with incipient cataract might complain of visual discomfort despite minor lens opacity at slit lamp examination and/or minor loss of BCVA. OQAS scores associated to a quality of vision assessment through a questionnaire might justify earlier surgery than regular guidelines. The measurement of ocular scattering might be a useful tool in the preoperative evaluation of cataract patients through objective quantification of the optical effects of the crystalline loss of transparency.
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