Which ocular tissue produces A scan spikes?

The lens is responsible for producing A-scan spikes in ultrasound imaging of the eye. When an A-scan is performed, sound waves are transmitted into the eye, and different ocular structures reflect these sound waves at varying intensities. The lens is highly refractive and has a significant acoustic interface due to the difference in density between the lens and the surrounding aqueous humor, which leads to a strong return echo. This causes a distinct spike on the A-scan, indicating the precise location of the lens within the ocular structure.

The other tissues mentioned do not provide the same level of distinct reflectivity. The choroid, while it does have reflective properties, typically does not produce sharp spikes on an A-scan due to its vascular nature and is located deeper within the eye. The anterior chamber consists mostly of aqueous humor, which offers much less reflectivity compared to the lens. Lastly, the vitreous body is a gel-like substance that does not create the acute spikes seen with the lens, as it does not reflect sound waves in the same concentrated manner. Thus, the lens stands out as the primary contributor to A-scan spikes in ocular ultrasound assessments.