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A z-axis focus sweep is an automated scan that moves focus up and down through depth. The goal is to find the sharpest plane or to capture a range of sharp planes. It is used in imaging systems when a single focus point is not enough.
read more about z-axis focus sweep ...Depending on the device, either the lens optics move or the imaging plane shifts inside the system. The eye itself does not need to move, but steady fixation helps. The sweep samples multiple focus positions in a short run. Software then selects the best focus or combines slices.
A sweep can reduce missed detail when structures sit at different depths. It can also speed up image capture when manual refocusing would be slow. Some systems use sweeps to support autofocus before taking the final image. The benefit depends on what the clinician is trying to view.
Some reports show the single sharpest slice chosen from the sweep. Others show a stack or a combined image that looks sharp across more depth. If the system flags low quality, it may request a repeat scan. Your clinician reads the result with symptoms and other test data.
Blinking can break the tear film and add blur to part of the sweep. Eye motion can create doubled edges or misaligned slices. Makeup flakes or contact lens deposits can also add haze. If a scan looks off, a repeat after blinking and resting often helps.
They are related. A sweep is the action of scanning through focus, and a z-stack is the set of depth slices that can be created from that scan. Some devices use a sweep only to pick the best focus frame.
Yes. A rough tear film can create fluctuating blur during the sweep. Blinking fully and using recommended dry eye care can make imaging more repeatable.
Most people feel only bright lights and the need to hold still. The scan does not touch the eye in many systems. Tell the staff if you need a short break.
Imaging can support evaluation, but a retinal tear is often diagnosed with a dilated exam. If you have flashes, new floaters, or a curtain-like shadow, seek urgent care. Do not wait for a routine scan.
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High speed, long range, deep penetration swept source OCT for structural and angiographic imaging of the anterior eye. Scientific Reports. https://www.nature.com/articles/s41598-022-04784-0. Date Accessed March 11, 2026.
Retinal optical coherence tomography at 1 μm with dynamic focus control and axial motion tracking. PubMed. https://pubmed.ncbi.nlm.nih.gov/26882449/. Date Accessed March 11, 2026.
Accessible Digital Ophthalmoscopy Based on Liquid-Lens Autofocusing. UCL Discovery. https://discovery.ucl.ac.uk/id/eprint/1474285/1/bergeles2015accessible.pdf. Date Accessed March 11, 2026.