Abstract
Purpose: :
Psychophysical evaluation of patients which had intracranial aneurysm of the carotid artery (IACA) and were submitted to vascular microsurgery. Achromatic and chromatic spatial vision tests were used.
Methods: :
Patients submitted to vascular microsurgery because of IACA (n=13, 50.2±7.2 yd) were evaluated using psychophysical tests. The luminance spatial contrast sensitivity (SC) and color discrimination capabilities were evaluated. The CS was measured at 11 spatial frequencies by presenting stationary sine-wave gratings. Contrast thresholds were determined via the adjustment method. The color discrimination ability was measured by using a computer version of the Farnsworth-Munsell 100 hue test (FM100). Each target comprised a 1º square patch. The patient’s error score was measured for stimuli with 30% of purity. We used the Mollon-Reffin protocol (MR) (Mollon and Reffin, 1989) to determine patient’s color discrimination thresholds. Five reference chromaticities were used for the surround. Discrimination thresholds were evaluated along 8 chromaticity axes irradiating from the reference points and the results were plotted as MacAdam ellipses.
Results: :
Patient’s results were compared with those of controls (39-60 yd) (CS, n=28, 50.9±5.5 yd; MR, n=19, 48.3±5.7 yd; FM100, n=35, 48.7±5.6 yd). The t-Student test (p<=0.05) was used for comparison. In general, patients had lower performance than controls in all psychophysical tests. Although there were no statistics differences between patients and controls (p>0.05), the former had a decrease in luminance contrast sensitivity at all spatial frequencies. For the MR test, the patients had color discrimination ellipses with larger area than controls (p<0.05). They had a poorer performance in the FM100 test than controls, making a number of non-oriented errors in the color space and showing higher scores than controls (p<0.05).
Conclusions: :
Post-surgery patients with IACA display a variable degree of chromatic and achromatic spatial vision deficit. However, the chromatic deficit is much more pronounced. These results support the necessity of performing a follow-up study of these patients, to look for recovery of their visual functions. Additionally, pre-surgery clinical variables as well as post-surgery complications and sequels may have some influence on visual dysfunctions and must be investigated.
Keywords: color vision • contrast sensitivity • neuro-ophthalmology: cortical function/rehabilitation