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Repeatability and validity of astigmatism measurements
J J Walline1, K A Kinney, K Zadnik
1Ohio State University College of Optometry, Columbus 43210-1240, USA. walline.1@osu.edu
Journal of Refractive Surgery (Thorofare, N.J. : 1995)
|February 13, 1999
Summary
Accurate astigmatism measurement is crucial for refractive surgery outcomes. Cycloplegic autorefraction offers the most reliable and repeatable method for assessing refractive astigmatism and cylinder axis.
Area of Science:
- Ophthalmology
- Optometry
- Refractive Surgery
Background:
- Accurate astigmatism measurement is vital for predicting refractive surgery outcomes.
- Understanding measurement repeatability helps differentiate true refractive changes from errors.
Purpose of the Study:
- To evaluate the repeatability of different astigmatic refractive error measurement techniques.
- To compare the agreement between various methods for measuring astigmatism.
Main Methods:
- Forty adults with refractive errors underwent noncycloplegic and cycloplegic measurements.
- Techniques included retinoscopy, subjective refraction, and autorefraction over two visits.
- Repeatability was assessed using difference versus mean plots and 95% limits of agreement.
Main Results:
- Cycloplegic autorefraction demonstrated the highest reliability for refractive astigmatism (+/- 0.28 D).
- Noncycloplegic retinoscopy showed the least reliability (+/- 1.02 D).
- Cycloplegic autorefraction was also the most repeatable for cylinder axis measurement.
Conclusions:
- Cycloplegic autorefraction is the preferred method for measuring astigmatism changes in studies.
- This technique provides the most accurate and repeatable refractive error assessment for refractive surgery planning.