*2.3.3 A-scan ultrasound biometry*

Although A-scan biometry is less accurate and requires more operator skills to ensure consistent accuracy in comparison with optical biometry, it can be used in presence of dense cataract or corneal edema when the optical biometry cannot take measurements [23]. However, for the optimization of a-scan results, the immersion instead of the applanation (contact) technique could be chosen, since the former has better repeatability and higher accuracy than the latter [24, 25].
