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Huawei Zhao; In Situ Measurement of Dysphotopsia of IOLs. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3757.
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To explore and measure in situ the positive and negative dysphotopsia of an intraocular lens (IOL), including its angular location, appearance and relative intensity using a Laboratory setup.
An experimental setup that mimics the major components of a pseudophakic eye was established including a wide angle light source similar to a typical clinic room lighting (with or without Lambersian Dispersion), an aperture, an IOL, and an image recording system. The potential angular positive (bright unwanted) and negative (dim or dark unwanted) dysphotopsia together with the expected image was observed, recorded, and analyzed from recorded sequential images that contained information of the spatial location and the energy distribution of rays forming the dysphotopsia. The aperture diameter was adjustable from 2.0 mm up to 7.0 mm, covering a typical pupil size of 3.0 mm and 5.0 mm of a pseudophakic eye in photopic and mesopic light respectively. The setup was used in air and in water and allowed angulated light rays from 0 to 100 degrees into the system to form images.
Angular positive and negative dysphotopsia was produced by typical IOLs including square-edge and rounded edge IOLs. Observations of the rays forming the dysphotopsia proved that the positive dysphotopsia was caused primarily by the internal reflection from the IOL edge. The missing light primarily due to the IOL edge appeared as a dark line or arc or shadow on the periphery of the recorded images that caused discontinuous angular field, a common negative dysphotopsia phenomena Both the positive dysphotopsia and the negative dysphotopsia varied with pupil size, IOL design (refractive index, surface and edge profile), and the incident light angles.
We have built an in situ laboratory use setup to objectively observe, measure, and analyze the dysphotopsia of IOLs either in air or water. By correlating the measured dysphotopsia to theoretically simulated and clinically reported dysphotopsia, the measurement system and measured results can be helpful to understand, duplicate, and potentially predict the light disturbance commonly interacted by the pseudophakics in clinic.
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