Assessment of Visual Performance in Patients With Low Levels of Astigmatism
Overview
- Phase
- Not Applicable
- Intervention
- Not specified
- Conditions
- Cataract Extraction
- Sponsor
- Alcon Research
- Enrollment
- 40
- Locations
- 1
- Primary Endpoint
- High and Low Contrast Acuity
- Status
- Completed
- Last Updated
- 15 years ago
Overview
Brief Summary
To assess visual performance in patients with low levels (0.5-0.75 Diopters) of corneal astigmatism.
Investigators
Eligibility Criteria
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
Outcomes
Primary Outcomes
High and Low Contrast Acuity
Time Frame: Day of study visit
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).
Contrast Sensitivity
Time Frame: Day of Study Visit
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.
Reading Acuity and Speed
Time Frame: Day of Study Visit
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).