AOSLO-Based Precise Measurement of Retinal Hemodynamics: Development and Application Assessment

The retina is the initial site where the eye receives external light and forms vision, and it is also the site where various blinding eye diseases occur. Retinal diseases such as diabetic retinopathy (DR), high myopia-related retinal disease, and age-related macular degeneration (AMD) impose a significant visual burden worldwide. The retinal vascular system is involved in the nutrient supply and waste transport of retinal cells, and the integrity of its structure and function is the foundation for maintaining retinal function. Therefore, assessing changes in retinal blood flow can help understand the mechanisms underlying disease progression, thereby promoting early diagnosis and precise treatment of retinal diseases.

Retinal vessels are the only circulatory system in the human body that can be directly observed, allowing for direct visualization and assessment of changes in hemodynamic characteristics such as retinal vascular blood flow velocity. Traditional fluorescein fundus angiography (FFA) involves intravenous injection of fluorescein to indirectly assess retinal perfusion velocity by observing the distribution of fluorescein in the retinal vascular system over time. However, FFA is an invasive procedure and is not suitable for evaluating early hemodynamic changes.

With the development of ophthalmic imaging technology, new fundus imaging techniques can provide more objective, convenient, and non-invasive tools for measuring blood flow velocity. Currently, mainstream hemodynamic evaluation devices, such as laser Doppler, retinal function imaging (RFI), and laser speckle technology, can quantify parameters such as blood flow velocity, blood flow volume, and vascular resistance by extracting spatiotemporal imaging signals of red blood cell movement or analyzing the optical effects caused by movement. However, these devices are limited in clinical application due to issues such as low resolution, low measurement accuracy, and poor reproducibility.

Adaptive optics (AO) is a technology that corrects aberrations and improves the imaging resolution of optical systems. By combining high-definition fundus scanning with a scanning laser ophthalmoscope (SLO), it is possible to achieve cellular-level resolution imaging and quantitative analysis of retinal vascular structures. By using AO-SLO to collect high spatio-temporal resolution image sequences of retinal vessels, it is possible to establish a novel method for evaluating retinal hemodynamics, enabling precise and stable measurements of blood flow velocity and blood flow volume.

Myopia is a highly prevalent eye disease worldwide, with an estimated prevalence exceeding 50% by 2050. Compared to moderate and low myopia, high myopia significantly increases the incidence of macular degeneration and glaucoma. The exact mechanisms underlying the pathological changes in high myopia remain controversial, but increasing evidence suggests that blood flow alterations may be a key pathological mechanism in high myopia-related retinal diseases. Due to the lack of objective evaluation methods, the patterns of hemodynamic changes in high myopia remain unclear. In summary, there is currently a lack of objective, precise hemodynamic quantification assessment tools in ophthalmic clinical practice. Developing a novel retinal hemodynamic imaging assessment model based on AO-SLO, establishing precise hemodynamic measurement methods, and achieving real-time, non-invasive, high-resolution imaging and quantitative analysis of retinal blood flow in living human eyes will provide important imaging evidence for the early diagnosis of retinal diseases such as high myopia-related retinal lesions.

This project will Innovate the AO-SLO blood flow imaging scanning module and acquisition mode, develop algorithms for extracting spatio-temporal signal features from blood flow images, and achieve quantitative analysis of retinal hemodynamics based on AO-SLO; construct an in vitro retinal hemodynamic measurement simulation eye, conduct multi-dimensional AO-SLO hemodynamic measurements, and establish an intelligent model for precise calibration of retinal hemodynamic parameters; conduct AO-SLO-based retinal hemodynamic studies in high myopia, integrating multi-modal ophthalmic imaging to investigate the patterns of changes in retinal vascular structure and blood flow function in high myopia. Ultimately, a new precision measurement imaging technology platform for retinal hemodynamics will be established.

This study will analyze the following indicators: retinal blood flow velocity, flow velocity standard deviation, flow rate, vessel diameter, lumen diameter, wall thickness, wall-to-lumen ratio, vascular density, diameter, and tortuosity measurements in participants with high myopia and non-high myopia one week after enrollment. Quantitative data will be described using mean ± standard deviation (M±SD), and differences between the two groups will be analyzed, along with correlation analysis.

Inclusion criteria

• Participants must understand the clinical study and voluntarily participate, and sign an informed consent form;
• Age 18-30 years old, no gender restrictions;
• Equivalent spherical power≤0D cylindrical power -2.0D to +2.0D, best-corrected visual acuity ≥ 1.0

Exclusion criteria

• Participants with significant refractive media opacity-related conditions (severe cataracts, vitreous diseases, corneal diseases, etc.) at screening, or unable to complete or cooperate with routine ophthalmic examinations;
• History of or concurrent conditions such as ptosis, nystagmus, diabetic retinopathy, various macular degeneration, retinal vascular diseases, optic nerve inflammatory diseases, primary angle-closure glaucoma, various secondary glaucoma, amblyopia, or severe strabismus
• History of previous eye surgery
• Patients with severe hypertension, diabetes, or other systemic diseases that cause secondary changes in the retina
• Patients with posterior scleral staphyloma, lacquer cracks, choroidal neovascularization, or Fuchs' spots
• Pregnant women, breastfeeding women, monocular individuals, and individuals with disabilities.