Visual disability variables. II: The difficulty of tasks for a sample of low-vision patients.

Objectives: To test the validity and reliability of measures of visual ability and to evaluate the relation between measurements made at the task level and measurements made at the goal level of a hierarchical model for visual disability.

Design: Validation of a telephone-administered functional assessment instrument using Rasch analysis on self-assessment ratings.

Setting: Telephone interviews of respondents in their homes.

Visual disability variables. I: the importance and difficulty of activity goals for a sample of low-vision patients.

Objective: To test the validity and reliability of latent trait measures estimated from ratings by low-vision patients of the importance and difficulty of selected activity goals.

Design: Validation of a telephone-administered functional assessment instrument using Rasch analysis of self-assessment ratings.

Setting: Telephone interviews of respondents in their homes.

Oculomotor strategies for the direction of gaze tested with a real-world activity.

Laboratory-based models of oculomotor strategy that differ in the amount and type of top-down information were evaluated against a baseline case of random scanning for predicting the gaze patterns of subjects performing a real-world activity--walking to a target. Images of four subjects' eyes and field of view were simultaneously recorded as they performed the mobility task. Offline analyses generated movies of the eye on scene and a categorization scheme was used to classify the locations of the fixations.

Fixation behavior while walking: persons with central visual field loss.

The aim of this study was to determine the effect of central visual field loss (CFL) on fixation patterns of a person walking towards a target. Subjects were four visually normal persons and 10 persons with CFL. Eye position on scene was recorded and classified into 20 scene categories.

The sensation of angina can be evoked by stimulation of the human thalamus.

We have performed single-neuron recording and microstimulation in the region of the thalamic principal sensory nucleus (ventrocaudal nucleus, Vc) prior to implantation of a deep brain-stimulating electrode in a patient with pain secondary to arachnoiditis and with a past history of unstable angina. Cells located in the 16 mm lateral plane had cutaneous receptive fields on the chest wall. At and posterior to the location of these cells stimulation coincided precisely with the sensation of angina (stimulation-associated angina).