The impact of intraocular pressure on optical coherence tomography angiography: A review of current evidence

Author: Williams PJ, Gregory A, Komro J, You Q, Ross B, Colon C, Juzych MS, Hughes BA, Ridha F.

Geographical coverage: Not reported

Sector: Treatment

Sub-sector: imaging technique

Equity focus: Not explicitly stated

Study population: Manuscripts involving intraocular pressure (IOP) change and concurrent optical coherence tomography angiography (OCTA).

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background

Optical coherence tomography angiography (OCTA) is a noninvasive technique visualising retinal and optic nerve vasculature by tracking red blood cell movement. Introduced commercially in 2014, OCTA has improved diagnostic accuracy for retinal diseases and glaucoma, providing an alternative to fluorescein angiography. OCTA offers quantifiable capillary density metrics essential for assessing vascular changes in ocular pathologies. However, intraocular pressure (IOP) fluctuations can affect OCTA readings and its diagnostic reliability, potentially causing misinterpretations of disease progression. While clinically adopted, there is limited consensus on IOP variability’s precise impact on OCTA metrics.

Objectives

To present current evidence relating to the effect of IOP on OCTA metrics to aggregate information and guide future studies.

Main findings

Authors found that intraocular pressure (IOP) changes can affect superficial vascular plexus vessel density (VD) measurements on OCTA, particularly when IOP rises above the physiological norm. The review encompassed 45 studies categorized into six groups based on primary intervention:

1. IOP reduction and glaucoma surgery (13 studies): Most studies reported significant IOP reductions post-surgery, but improvements in superficial vessel density (VD) were inconsistent due to small sample sizes and variable image quality.
2. IOP reduction and specific ophthalmic drops (9 studies): Beta-blockers were associated with reduced VD in normal-tension glaucoma patients, whereas drops like latanoprost showed improvements in macular VD.
3. Diurnal IOP variability (9 studies): No significant impact on superficial retinal capillary measurements was detected, suggesting autoregulatory mechanisms in individuals with normal IOP (10–21 mmHg).
4. Laser interventions (4 studies): Acute IOP elevation after laser peripheral iridotomy led to reduced superficial VD, while selective laser trabeculoplasty showed temporary VD improvements.
5. Cataract surgery (3 studies): Improved OCTA image quality and VD metrics were noted, likely due to enhanced signal strength from intraocular lens implantation.
6. Other interventions (7 studies): Various IOP-related changes were explored, with some showing VD improvements after IOP reduction.

Overall, IOP changes exceeding the physiological range significantly affected superficial VD measurements, while diurnal variations did not. Cataract surgery primarily improved OCTA metrics through enhanced image quality. The review underscores the necessity for standardized OCTA data acquisition and reporting to advance future research.

Methodology

The studies published from January 1, 2015 to August 27, 2022, and reporting OCTA scans of either the optic disc or macula and a change in IOP with corresponding OCTA scans before and after the IOP change were included on the review. All languages were included and translated. Authors searched in PubMed/Medline, Cochrane, Web of Science, and Google Scholar databases. Reference lists of the identified studies were scanned to find additional relevant publications. Two reviewers independently screened the potentially relevant articles against the eligibility criteria. Data collected included sample size, IOP changes, OCTA metrics (e.g., vessel density), and image quality metrics (e.g., signal strength). Statistical analysis was deferred due to inconsistencies in data reporting.

Applicability/external validity

The review did not discuss the applicability or external validity of its findings. Although it summarized the impact of IOP changes on OCTA metrics across various interventions, it lacked an evaluation of how generalisable these findings are to broader populations or clinical settings. The review noted limitations such as variability in imaging techniques, small sample sizes, and inconsistent reporting, but did not assess their impact on real-world clinical practice.

Geographic focus

Geographic location of included studies was not reported by the authors.

Summary of quality assessment

Overall, there is low confidence in the conclusions about the effects of this study due to important methodological concerns. The review authors did not contact experts during their search. They also didn’t specify their data extraction method or assess study quality.