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$Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter$

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Objective and subjective refractive error measurements in monkeys.

Li-Fang Hung¹, Ramkumar Ramamirtham, Janice M Wensveen

¹College of Optometry, University of Houston, Houston, Texas 77204-2020, USA.

Optometry and Vision Science : Official Publication of the American Academy of Optometry

|December 27, 2011

Summary

Objective methods like retinoscopy and autorefraction overestimate hyperopia in rhesus monkeys compared to subjective refraction. This overestimation is significant, potentially impacting animal model research.

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Area of Science:

Ophthalmology
Animal Models
Vision Science

Background:

Accurate refractive error assessment is crucial for understanding visual development and function in laboratory animals.
Objective methods are commonly used but their functional significance requires validation against subjective measures.
Adolescent rhesus monkeys serve as a relevant model for human eye research.

Purpose of the Study:

To compare objective and subjective refractive error measurements in adolescent rhesus monkeys.
To evaluate the functional significance of objective refractive error measures in a non-human primate model.
To identify potential biases in objective refractive error assessment methods.

Main Methods:

Refractive error was measured using retinoscopy and autorefraction under cycloplegia and anesthesia.
Subjective refraction was determined using psychophysical methods measuring contrast sensitivity.
Axial eye dimensions were assessed via A-Scan ultrasonography.

Main Results:

Objective methods (retinoscopy, autorefraction) consistently overestimated hyperopia compared to subjective refraction.
Subjective refractions were not influenced by cycloplegia.
The difference in hyperopic measurements between objective and subjective methods was approximately 1.2-1.4 diopters.

Conclusions:

Commonly used objective methods significantly overestimate hyperopia in rhesus monkeys.
This hyperopic bias in objective measurements may be attributed to factors like the 'small-eye artifact'.
Findings highlight the need for careful interpretation of objective refractive data in animal studies.