When the eye ages, and cataract develops, an early and frequent problem is from straylight deterioration. Straylight causes problems not explained by visual acuity loss, such as with driving at night, facial recognition, hazy vision, etc. Straylight must be taken into account for proper objective indication for cataract surgery. Van der Meulen et al., 2012
It is well recognized that in traffic, on the road, in the air, or on water, glare can be a safety issue. Straylight has been accepted by international agreement (Vos&vdB1999) as the defining quantity for disability glare. Licensing regulations often include glare sensitivity demands, and straylight is the gold standard manner to test for glare sensitivity. Van Rijn et al. 2011, van Bree et al. 2011, review van den Berg et al. 2009
Several studies showed the cornea to be very sensitive with respect to straylight effects. E.g. in many cases of Fuchs dystrophy straylight is more of a problem than acuity, especially at younger age (van der Meulen et al. 2011). Other dystrophies studied included the crystalline form as very important (van den Berg 1986), as are cornea transplants (Cheng et al. 2011). Contact lenses were found to often show deleterious straylight effects. van der Meulen et al. 2010
Surprisingly, refractive surgery does NOT on average make straylight worse, whereas in a small percentage of cases straylight does deteriorate, corresponding clinical findings, such as haze, folds, interface debris, etc. Speculatively, the overall favorable effect has been attributed to the relief from ill-tolerated contact lenses. Rozema et al. 2010, Lapid et al. 2010a, Lapid et al. 2010b, Paarlberg et al. 2011
For a full listing of clinical straylight studies please see the 2013 survey.