Purpose:
To compare Optical Stiles-Crawford effect (OSC) measurements with common ophthalmological diagnostic tests.
Methods:
In a two year period (august 2004 - august 2006) we performed fundus reflectometry with the Foveal Reflection Analyzer1 in 35 patients with visual complaints of unknown origin referred to us by the ophthalmology department of our Medical Center. Four patients were excluded from the analysis because of insufficient quality of the reflectional data. A model fit provided information on the total directional reflectance of the foveal cones (OSC) in 58 eyes of 31 patients; the left eye was not measured in 4 patients. Individual directional reflectance values were compared to those of a healthy control group (53 right eyes of 53 persons) and graded as normal or abnormal. Test results of other diagnostic tests were graded in the same way with respect to central retinal findings.
Results:
The agreement between OSC and results of other tests is shown in Fig. 1.ERG: electro-retinography, EOG: electro-oculography, FA: fluoro-angiography, OCT: optical coherence tomography, VEP: visual evoked potentials, BM: biomicroscopy, VF: visual field, CV: color vision, VA: visual acuity. Best agreement was found with cone photoreceptor specific electro-retinogram (ERG, 82.6 % agreement). Lowest agreement was found with visual acuity (VA, 55.2 % agreement). Of all techniques used to visualize the retina (FA, OCT, BM), OSC results corresponded best with FA.
Conclusions:
ERG and EOG are demanding and time consuming tests. Given the high correspondence with OSC as obtained with the Foveal Reflection Analyzer, this latter test which only takes a few minutes might be considered as an alternative for the detection of central photoreceptor defects.1. Zagers NPA, van de Kraats J, Berendschot TTJM, van Norren D. Simultaneous measurement of foveal spectral reflectance and cone- photoreceptor directionality. Appl Opt. 2002;41:4686-4696.
Keywords: optical properties • photoreceptors • visual acuity