Contrast sensitivity in relapsing-remitting multiple sclerosis assessed by sine-wave gratings and angular frequency stimuli.
Vis Neurosci
; 31(6): 381-6, 2014 Nov.
Article
in En
| MEDLINE
| ID: mdl-24834838
Previous studies have shown that multiple sclerosis (MS) affects the visual system, mainly by reducing contrast sensitivity (CS), a function that can be assessed by measuring contrast sensitivity function (CSF). To this end, we measured both the CSF for sine-wave gratings and angular frequency stimuli with 20 participants aged between 21 and 44 years, of both genders, with normal or corrected to normal visual acuity. Of these 20 participants, there were 10 volunteers with clinically defined MS of the relapsing-remitting clinical form, with no history of optic neuritis (ON), as well as 10 healthy volunteers who served as the control group (CG). We used a forced-choice detection paradigm. The results showed reduced CS to both classes of stimuli. Differences were found for sine-wave gratings at spatial frequencies of 0.5, 1.25, and 2.5 cycles per degree (cpd) (P < 0.002) and for angular frequency stimuli of 4, 24, and 48 cycles/360° (P < 0.05). On the one hand, comparing the maxima of the respective CSFs, the CS to angular frequency stimuli (24 cycles/360°) was 1.61-fold higher than that of the CS to vertical sine-wave gratings (4.0 cpd) in the CG; for the MS group, these values were 1.55-fold higher. On the other hand, CS in the MS group attained only 75% for 24 cycles/360° and 78% for 4.0 cpd of the 100% CS estimates found for the CG at the peak frequencies. These findings suggest that MS affects the visual system, mostly at its maximum contrast sensitivities. Also, since angular frequencies and sine-wave gratings operate at distinct levels of contrast in the visual system, MS seems to affect CS at both high and low levels of contrast.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Perceptual Disorders
/
Sensory Thresholds
/
Contrast Sensitivity
/
Multiple Sclerosis, Relapsing-Remitting
Type of study:
Diagnostic_studies
Limits:
Adult
/
Female
/
Humans
/
Male
Language:
En
Journal:
Vis Neurosci
Journal subject:
NEUROLOGIA
/
OFTALMOLOGIA
Year:
2014
Document type:
Article
Affiliation country:
Brazil
Country of publication:
United kingdom