Acute Effects of Cervical Manual Therapy on Eye Blood Flow

This study evaluates the acute effects of cervical manual therapy on retinal and choroidal microvascular perfusion using optical coherence tomography angiography (OCTA). In this prospective randomized sham-controlled trial, 100 patients with chronic mechanical neck pain were randomly assigned to receive either cervical high-velocity low-amplitude manipulation combined with Maitland mobilization (manual therapy group) or sham treatment. Bilateral OCTA examinations were performed at baseline and at 15, 30, 60, and 120 minutes after intervention. The primary outcome is whole-image density Secondary outcomes include whole-image and parafoveal vessel density, radial peripapillary capillary (RPC) density, subfoveal choroidal thickness, foveal avascular zone parameters, retinal nerve fiber layer thickness, ganglion cell complex thickness, and macular thickness. The study aims to determine whether cervical manual therapy produces a significant augmentation of retinal and choroidal perfusion compared with sham treatment, with peak effects expected at 60 minutes post-intervention.

Inclusion Criteria: * Age 18-70 years * Chronic mechanical neck pain lasting ≥3 months according to IASP criteria * Baseline VAS pain score ≥3 * Absence of cervical radiculopathy or myelopathy * Ability to provide informed consent and comply with study procedures * Adequate ocular image quality for OCTA assessment Exclusion Criteria: * Previous cervical spine surgery or major cervical trauma * Vertebrobasilar insufficiency or other contraindications to cervical manual therapy * Active inflammatory rheumatic disease or systemic connective tissue disorder * Known retinal or optic nerve disease that may affect OCTA measurements (glaucoma, diabetic retinopathy, age-related macular degeneration, optic neuritis, etc.) * Diabetes mellitus with end-organ complications or uncontrolled systemic hypertension (\>160/100 mmHg) * Refractive error \> ±6.0 D spherical equivalent or astigmatism \>3.0 D * Intraocular pressure \>21 mmHg * Previous ocular surgery, ocular trauma, or retinal laser treatment * Media opacity preventing adequate OCTA image acquisition * Pregnancy or lactation * Participation in another interventional clinical study within the previous 30 days