Ultrasonography and optical low-coherence interferometry compared in the chicken eye

Area of Science:

• Ophthalmology
• Comparative Biometry
• Animal Models

Background:

• Accurate ocular biometry is crucial for understanding eye development and disease.
• A-scan ultrasonography and optical low-coherence interferometry (OLCI) are common methods for measuring ocular parameters.

Purpose of the Study:

• To compare the accuracy and consistency of A-scan ultrasonography and OLCI for measuring ocular biometry in chicken eyes.
• Specifically compare anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), and axial length (AL).

Main Methods:

• Ocular biometry was performed on 42 two-week-old chicks using both A-scan ultrasonography and OLCI.
• Statistical analyses included Bland-Altman plots, repeatability, and correlation analyses.

Main Results:

• High correlations were observed between the two methods for ACD (r=0.6144), VCD (r=0.9595), and AL (r=0.9290), but not for LT (r=0.1604).
• OLCI demonstrated greater consistency with smaller coefficients of variation and higher intraclass correlation.
• Bland-Altman analysis revealed systematic differences in measurements between the two techniques for LT, VCD, and AL.

Conclusions:

• While A-scan ultrasonography and OLCI show high correlation for most ocular parameters in chickens, they are not interchangeable due to differing measurement principles and potential for corneal indentation with ultrasound.
• OLCI offers better consistency and repeatability but requires anesthesia in chicks, unlike in human measurements.
• These findings highlight the importance of method selection in avian ocular research.