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Accommodation causes with-the-rule astigmatism in emmetropes
M Tsukamoto1, K Nakajima, J Nishino
1Department of Ophthalmology, Nara Medical University, Kashihara, Japan.
Summary
Bilateral emmetropes exhibit with-the-rule astigmatism and accommodative lag in the horizontal meridian during accommodation. This study measured accommodative responses using an advanced photorefractometer.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Astigmatism changes during accommodation are crucial for understanding visual function.
- Emmetropia, a state of normal vision, serves as a baseline for studying refractive error development.
Purpose of the Study:
- To quantify astigmatism alterations in bilateral emmetropes during accommodation.
- Investigate the relationship between accommodative stimulus and response across different meridians.
Main Methods:
- Utilized an improved photorefractometer (PR-1100) for simultaneous binocular refraction measurement.
- Employed natural space fixation targets to assess accommodative responses.
- Measured responses in all meridians during accommodation.
Main Results:
- Accommodative responses were greater in the vertical meridian compared to the horizontal meridian.
- A lag of accommodation was observed in the horizontal meridian, where responses were less than the stimulus.
- The majority of subjects developed with-the-rule astigmatism upon accommodation.
Conclusions:
- Bilateral emmetropes typically develop with-the-rule astigmatism when accommodating.
- Accommodative lag in the horizontal meridian is a common finding in emmetropes.
- The study highlights meridian-specific differences in accommodative behavior.