Which factor can negatively affect the accuracy of ultrasound biometry?

Corneal edema significantly impacts the accuracy of ultrasound biometry because it alters the optical properties of the cornea and increases its thickness. This swelling can lead to miscalculations when measuring the axial length of the eye. In ultrasound biometry, precise measurements of eye structures are critical for successful outcomes, especially when calculating intraocular lens power for cataract surgery. When the cornea is edematous, the ultrasound waves may not travel correctly through the altered tissue, resulting in inaccurate readings.

In contrast, while pupil dilation, blood vessel proximity, and corrective lens wear have their own effects on ocular measurements, they do not directly distort the measurements of eye tissue structures like corneal edema does. Pupil dilation primarily affects the visualization and assessment of the retina and anterior segment but doesn't significantly alter ultrasound measurements. Blood vessel proximity may introduce some interference but is less impactful than the physical changes seen in corneal edema. Lastly, while corrective lenses can affect visual acuity and might introduce some variability in refraction tests, they typically do not influence the direct measurement of eye anatomy through ultrasound.