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T. J. T. P. Van Den Berg, I. J. van der Meulen, L. A. Engelbrecht; Sources of Straylight in Pseudophakia. Invest. Ophthalmol. Vis. Sci. 2008;49(13):387. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Despite good visual acuity, patients with cataract may be dissatisfied with their quality of vision due to increased intraocular light scattering. Cataract extraction and placement of a clear intraocular lens (IOL) is presumed to decrease these complaints by diminishing the amount of intraocular opacities. However, subjective complaints of intraocular light scattering do not disappear in all pseudophakic patients. The C-Quant straylight meter (Oculus GmbH) is a diagnostic tool which measures in a functional sense the effect of forward scatter. By using this instrument, we evaluated quality of vision in pseudophakic patients to obtain mean and range of the amount of straylight in these patients. The amount of straylight was correlated with diverse intraocular structures, in particular the size of the capsular rhexis in relation to pupil size, and the amount of anterior and posterior capsular opacification.
We performed a retrospective review of straylight measurements (straylight parameter "s") in 261 pseudophakic eyes. To correlate the straylight measurements with the diverse intraocular factors and systemic disorders, 100 pseudophakic patients were followed prospectively by straylight measurements and dilated anterior segment examination to assess the potential contribution of the rhexis, and a numerical (0-5) slitlamp grading of the opacification of both capsules. To obtain insight in the isolated influence of the IOL, the rhexis size and the capsular opacifications on the amount of straylight, in vitro light scattering measurements expressed in s units on explanted IOLs including the capsules were performed.
A large variation in straylight values is present among pseudophakic patients. In most patients the amount of straylight does not return to the level of young healthy eyes (average log(s) elevation = 0.38 ± 0.03 s.e.). As might be expected, a small sized capsulorhexis gave strong straylight contributions: s elevation = 21 x grade x (fraction of pupillary surface occupied by the anterior capsule). From the in vitro results it was estimated that: log s elevation = 3 x grade for the posterior capsule. However, these relations explained only part of the elevated straylight levels measured in the whole population.
Straylight elevations in pseudophakic patients could only partly be explained on the basis of the posterior (and anterior) capsule. Apart from potential contributions from the IOLs themselves (van der Mooren et al. ARVO 2007), more research is needed into other potential effects.
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