Timeless Tips to remember - Consider sources of bias when using OCT angiography
June 24, 2026

Timeless Tips to remember - Consider sources of bias when using OCT angiography

OCT angiography (OCTA) has gained great interest in glaucoma diagnosis (1, 2) and follow up(3). However, several conditions and diseases can impact its results and should be considered, especially when performing longitudinal analyses(4). The following systemic diseases have been identified as potential sources of bias (even when no visible fundus changes exist): arterial hypertension, Diabetes Mellitus, coronary artery disease, carotid artery stenosis, chronic kidney disease (as well as being under haemodialysis), obstructive sleep apnea syndrome, and several neurodegenerative diseases, such as Alzheimer’s Disease, multiple sclerosis and Parkinson’s Disease(5). Overall, these diseases led to reduced vessel density (VD) and an increased foveal avascular zone (FAZ) area and perimeter. Other conditions, such as performing regular high-intensity interval exercise (VD decrease) or being pregnant (VD increase) can also impact the results. Many of the published studies on this topic did not perform adjustment for relevant confounders and this should be improved in future studies.


References

  1. Van Melkebeke L, Barbosa-Breda J, Huygens M, Stalmans I. Optical Coherence Tomography Angiography in Glaucoma: A Review. Ophthalmic Res. 2018: 1-13.
  2. Miguel AIM, Silva AB, Azevedo LF. Diagnostic performance of optical coherence tomography aniography in glaucoma: a systematic review and meta-analysis. The British journal of ophthalmology. 2019; 103(11):1677-84.
  3. Miguel A, Silva A, Barbosa-Breda J, Azevedo L, Abdulrahman A, Hereth E, et al. OCT-angiography detects longitudinal microvascular changes in glaucoma: a systematic review. The British journal of ophthalmology 2022; 106(5): 667-75.
  4. Monteiro-Henriques I, Rocha-Sousa A, Barbosa-Breda J. Optical coherrence tomography angiography changes in cardiovascular systemic diseases and risk factors: A Review. Acta ophtahlmologica 2022; 100(1):e1-e15.
  5. Tsokolas G, Tsaousis KT, DiakonisVF, Matsou A, Tyradellis S. Optical Coherence Tomography Angiography in Neurodegenerative Diseases: A Review. Eye Brain. 2020; 12: 73-87.


Contributor: João Barbosa Breda MD PhD FEBOS, Porto, Portugal
Tip originally published: October 2023


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