Related Experiment Videos
A-Scan axial length measurement in the tonometer prism holder
Annals of Ophthalmology
|September 1, 1983
Summary
This study investigated how applanating pressure affects axial length measurements in normal eyes using A-Scan. Varying pressure altered axial length readings and intraocular lens calculations, highlighting the need for standardized applanation in ophthalmic biometry.
Area of Science:
- Ophthalmology
- Biometry
- Ophthalmic Instrumentation
Background:
- Accurate axial length measurement is crucial for intraocular lens (IOL) power calculations.
- Applanation tonometry is often used in conjunction with biometry, but its effect on axial length is not fully understood.
Purpose of the Study:
- To evaluate the impact of varying applanating pressure on axial length measurements obtained by A-Scan.
- To compare these measurements with traditional hand-held A-Scan readings.
Main Methods:
- Axial length was measured in ten normal eyes using a JED-MED Axisonic II A-Scan device.
- The A-Scan probe was integrated into a Haag-Streit R 900 applanation tonometer prism holder.
- Applanating pressure was systematically varied, and measurements were recorded at different tensions.
Main Results:
- Variations in applanating pressure resulted in changes to the measured axial length.
- Intraocular lens (IOL) emmetropia calculations also showed variability based on the applied applanation pressure.
- The study compared these findings to standard hand-held A-Scan measurements.
Conclusions:
- Applanating pressure significantly influences axial length measurements.
- Standardized applanation techniques are essential for reliable biometry and accurate IOL calculations.
- This highlights a potential source of error in ophthalmic biometry that requires careful consideration.