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Age dependence of ocular biometric measurements under cycloplegia with tropicamide and cyclopentolate
Helen Owens1, Leon F Garner, Marice KH Yap
1Department of Optometry and Vision Science, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Insights
Cyclopentolate more effectively relaxes accommodation in young children than tropicamide. However, using tropicamide with a local anesthetic yields similar refractive results, making it suitable for ocular biometry in children.
Area of Science:
- Ophthalmology
- Pediatric Optometry
Background:
- Cyclopentolate is frequently used for pediatric refraction.
- Tropicamide is often recommended for ocular biometry studies.
- A comparison of these cycloplegic agents is needed for pediatric eye exams.
Purpose of the Study:
- To compare the efficacy of cyclopentolate and tropicamide in inducing cycloplegia for biometric measurements in children.
- To evaluate the influence of age on the effectiveness of these cycloplegic agents.
Main Methods:
- Two groups of Tibetan children in Nepal were administered cyclopentolate and tropicamide on separate occasions.
- Refraction, phakometry, and A-scan ultrasonography were performed after cycloplegia induction.
- Measurements were analyzed for differences based on drug type and age group.
Main Results:
- Cyclopentolate demonstrated superior cycloplegia in younger children, confirmed by phakometry.
- Clinical refractive measurements showed no significant differences between the two drugs.
- Biometric measurements, particularly phakometry with near fixation targets, may introduce errors.
Conclusions:
- While cyclopentolate offers stronger accommodation relaxation in young children, tropicamide combined with a local anesthetic provides comparable refractive data.
- This combination is suitable for pediatric ocular biometry, irrespective of age.
- Careful consideration of fixation targets is necessary during phakometry to minimize measurement errors.
Abstract:
BACKGROUND: Cyclopentolate continues to be the cycloplegic of choice for refracting young children, although many studies of ocular biometry promote the use of tropicamide. METHODS: To clarify the role of drug type in biometric measurements, cycloplegia was induced in two disparate age groups using cyclopentolate and tropicamide on two separate occasions. Refraction, phakometry and A-scan ultrasonography measurements were made on two groups of Tibetan children resident in Nepal. RESULTS: Cyclopentolate produced significantly more cycloplegia in the younger group, which was supported by phakometry measurements. However, in clinical terms, the difference between the measurements was not significant. CONCLUSION: We conclude that although cyclopentolate is more effective than tropicamide in relaxing accommodation in young children, the use of a local anaesthetic prior to instillation of tropicamide produces refractive data virtually equivalent to that of cyclopentolate, regardless of the age group measured. However, biometric measurements may be susceptible to greater error when near fixation targets are used during phakometry procedures.