Assessment of Visual Performance in Patients With Low Levels of Astigmatism

N/ACompletedNCT00842231

Alcon Research40 enrolled

Overview

To assess visual performance in patients with low levels (0.5-0.75 Diopters) of corneal astigmatism.

Study Type

OBSERVATIONAL

Enrollment

Conditions

Cataract Extraction Corneal Astigmatism

Interventions

Visual performance measuresOTHER

Collection of visual performance measures in subjects with low levels of astigmatism.

Eligibility

Sex: ALLMin age: 50 YearsMax age: 75 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * 50-75 years of age * Proof of eye exam within the last 12 months * Operated for uncomplicated, age-related cataracts \>3 months * Corneal astigmatism of 0.5-0.75 diopter Exclusion Criteria: * Previous ocular or refractive surgery/trauma * Clinically severe corneal dystrophy * Amblyopia * Degenerative visual disorders

Locations (1)

Contact Alcon Call Center For Trial Locations

Fort Worth, Texas, United States

Outcomes

Primary Outcomes

High and Low Contrast Acuity

Visual acuity differences between subjects tested with full correction and spherical equivalent (SE) correction at contrast levels of 9% and 25% (low contrast acuity) and 100% (high contrast acuity). LogMAR is the "logarithm of the minimum angle of resolution". A lower logMAR value indicates better VA. These measurements were performed under photopic conditions by means of 9%, 25%, and 100% contrast ETDRS (Early Treatment Diabetic Retinopathy Study) charts (Vector Vision).

Time frame: Day of study visit

Contrast Sensitivity

Contrast Sensitivity (CS) differences between subjects tested with full correction \& spherical equivalent (SE) correction. CS is the measurement of one's ability to detect slight changes in luminance before it becomes indistinguishable. CS is measured in logarithmic units by means of an illuminated box, the CSV 1000 by Vector Vision. Testing was performed under photopic conditions (no glare) \& mesopic conditions (with \& without glare), and was measured at four spatial frequencies of 3, 6, 9, and 12 cycles per degree (cpd). A higher value for the logarithmic units translates to better CS.

Time frame: Day of Study Visit

Reading Acuity and Speed

Reading Acuity and Speed differences between subjects tested with full correction and spherical equivalent (SE) correction. Reading Acuity was measured using the Radner reading charts, which are logarithmically scaled at different acuity levels (print sizes), and expressed in terms of logRAD (logrithmic Reading Acuity Determination). Reading speed was measured in words per minute (wpm). The results were presented as Average Reading Speed by Print Size (logRAD).

Time frame: Day of Study Visit

Data from ClinicalTrials.gov

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