Subject(s)
Alzheimer Disease/complications , Color Vision Defects/etiology , Aged , Alzheimer Disease/physiopathology , Cognition Disorders/complications , Cognition Disorders/physiopathology , Color Vision Defects/diagnosis , Color Vision Defects/physiopathology , Contrast Sensitivity/physiology , Female , Humans , Tomography, Optical Coherence , Visual Field Tests , Visual Fields/physiology , Visual Pathways/physiopathologyABSTRACT
BACKGROUND: Some diseases that affect the visual system may show loss of chromatic-achromatic sensitivity before obvious physical signs appear in the usual examination of the eye's posterior segment. A perimetric study has been conducted with four typical patients with glaucoma and diabetes, at different stages of the disease. MATERIALS AND METHODS: In addition to the standard white-on-white (standard automated perimetry [SAP]), a test battery has been used to study patient's contrast sensitivity, using stimuli with different chromatic, spatial, and temporal content (multichannel perimetry). The choice of stimuli tries to maximize the response of different visual mechanisms: Achromatic (parvocellular and magnocellular origin); chromatic red-green (parvocellular origin); and chromatic blue-yellow (koniocellular origin). RESULTS: The results seem to indicate losses in the achromatic-parvocellular perimetry and both chromatic perimetry tests, undetected by conventional SAP. CONCLUSIONS: Our results illustrate that our patients without visible retinal alterations show signs of suspicion in multichannel perimetry.
Subject(s)
Diabetes Mellitus, Type 2/complications , Glaucoma/complications , Visual Field Tests/methods , Visual Fields , Adult , Contrast Sensitivity , Diabetes Mellitus, Type 2/physiopathology , Female , Glaucoma/diagnosis , Glaucoma/physiopathology , Humans , Male , Middle Aged , Reproducibility of ResultsABSTRACT
BACKGROUND: In this study, the reliability of perimetric contrast sensitivity measurements favouring the achromatic, the red-green and the blue-yellow post-receptorial mechanisms was analysed. METHODS: A new technique, multichannel ATD perimetry, provides spatial and temporal stimuli favouring the detection by an achromatic mechanism (A), from a magno or parvocellular origin or by a red-green (RG) chromatic mechanism, with a parvocellular origin or a blue-yellow (BY) mechanism, with a koniocellular origin. The repeatability and reproducibility of contrast sensitivity measurements with these stimuli were studied in a group of 40 healthy subjects. The analysis was carried out on 21 testing points within a 60° by 40° fovea-centred region of the visual field. RESULTS: The within-observer repeatability for the four mechanisms studied is either good or excellent when the intra-class correlation coefficient (ICC) can be calculated. For the remaining points, the Friedman's test finds that the measurements are repeatable. The between-observer reproducibility was either excellent or good in cases where the ICC was applied and according to the Friedman's test all results were reproducible. CONCLUSIONS: The results obtained showed good repeatability and reproducibility with A, RG and BY stimuli, although with BY stimuli repeatability is slightly worse. Future studies on the diagnostic validity of this device are based on the fact that changes of sensitivity can be compared by means of a visual single task, contrast sensitivity measurement and using a common metric.
