Abstract
Purpose::
To study straylight values among the population and in cataract surgery patients in order to evaluate possible gains and losses with the intent to consider straylight as an added tool for clinical decision making on cataract extraction.
Methods::
In a multicenter European study active drivers were tested for prevalence of different ocular conditions relevant to driver licensing. A subset of the data on both eyes of all 2422 included subjects, in particular visual acuity, straylight (at 10 degrees) and LOCS III, was analysed. The eyes were divided into 4 groups according to slitlamp finding and LOCS classification as follows: 220 pseudophakic eyes, 3182 non-cataractous eyes (average LOCS score <1.5), 134 cataractous eyes (average LOCS score >3.0), and a rest group. Visual acuity was determined using logMar according to the modified ETDRS system in steps of 0.02 log units. Straylight was determined using the Compensation Comparison method and specified as the logarithm of the straylight parameter s (log(s)). In the cataract surgery patients the C-Quant instrument of Oculus was used, employing this same method, but at 7 degrees straylight angle.
Results::
The age dependence of straylight in the non-cataractous group compared well to earlier data. An age norm for straylight was defined as follows: log(s) = constant + log(1+(age/65)4), with the value of the constant = 0.90 for 10 degrees straylight angle and 0.87 for 7 degrees. So, on average, straylight doubles in non-cataractous eyes by the age of 65, and triples by the age of 77. Population standard deviation around this age norm was about 0.10 log units. Most interesting was the finding that in pseudophakia, straylight values can be much improved not only compared to the cataract group, but also compared to the non-cataract group. Visual acuity and straylight were found to vary quite independently.
Conclusions::
Lens extraction holds promise not only to improve upon the condition of the eye in case of cataract, but also to improve upon the "normal" (but strong) increase in straylight value, quite independently from visual acuity.
Keywords: cataract • optical properties • clinical (human) or epidemiologic studies: systems/equipment/techniques