Table 1.
Different types of artifact in optical coherence tomography
| Type of artifacts | Definition | Frequency (%) | Time-domain OCT | Fourier- domain OCT | Patient- related | Operator- related | Software- and hardware-related | What to do? |
|---|---|---|---|---|---|---|---|---|
| Software | ||||||||
| Misidentification of retinal layers3,4 | Incorrect detection of borders of the retinal layers | ? | + | + | +* | + | Manual correction | |
| Incomplete segmentation error5 | Stop or missing segmentation lines before reaching the lateral sides of scan | 33.2 | + | + | +* | + | Repeat the scan in the area of interest | |
| Complete segmentation failure9 | No segmentation lines placed along retina boundaries | 2-4.5 | + | + | +* | +** | + | Repeat the scan in the area of interest |
| Mirror artifact (inverted artifact) 10 | Image folds on itself around the zero line, in entire length or at the end (s) of the image | 9.3 | - | + | +* | +** | + | Repeat the scan in the area of interest |
| Degraded image scan11,12 | Apparently look-like broken retina (a type of misidentification) | 6.7-11.7 | + | + | +& | + | Repeat scan after proper positioning | |
| Static or fixed image artifact5 | In multiple adjacent B-scans, a fixed part of image with no changes is observed | Rare | - | + | + | Repeat the scan | ||
| Linear artifact13 | Three hyper-reflective lines with the stable location that could be beyond, beneath, or at the identical level of the sclera-choroidal interface in the enhanced depth imaging OCT | 81.88 | - | + | + | Consider it when the choroidal thickness is more than 485 Repeat the scan Capture images as clearly as possible Evaluate images under the primary mode, that is, a white line on a black background | ||
| PFCL-producing artifact14 | Distortion of structures below bubble of PFCL with | + | + | +* | + | + | ||
| Operator-related | ||||||||
| Cut edge artifact11,15,16 | Edge of the scan is inappropriately illustrated | 0.17-6.3 | + | + | +! | + | Ignore the first scan | |
| Out-of-register artifact7,11,12 | Vertically displaced image as much as a part of the inner or outer retina is located out of the range of scan | 2.4-13 | ++ | + | + | Repeat the scan after realigning the area of interest | ||
| Patient-related | ||||||||
| Blink artifact12 | A part of data are lost due to patient’s blinking | 0.09 | ++ | + | + | Repeat the scan | ||
| Off-center artifact7,17–19 | Displacement of fovea over 0.25 mm from its real location | 3.7-16.7 | + | + | +* | Repeat the scan/manually plot the fovea | ||
| Motion artifact4,17,20,21 | Structural distortion in image due to eye movement | ++ | + | + | + | Repeat the scan and devices with eye tracking | ||
| Patient-related | ||||||||
| Foveal duplication22,23 | Double fovea in OCT image of the same eye (a type of motion artifact) | Rare | ++ | + | + | Repeat the scan | ||
| Segmentation shift5 | Vertical shift in segmentation lines (with stable distance from each other) is observed in retinal image | 27.6 | + | +? | + | +? | Repeat the scan | |
*Ocular pathology related, **Poor positioning, !Iris blockage, &Media opacity. OCT: Optical coherence tomography, PFCL: Perfluorocarbon liquid