Study of Macular vessel density changes using OCTA in children undergoing Strabismus surgery.

My Postgraduate Thesis  is on Study of Macular vessel density changes using OCTA in children undergoing Strabismus surgery. Surgeries done to correct strabismus range from Recession/Resection procedures to Muscle Transpostions. The Extraocular muscles are supplied by Medial and Lateral Muscular Arteries which are branches of Ophthalmic Artery. The Medial muscular branch supplies the Medial rectus, Inferior rectus and Inferior oblique ; Lateral muscular branch supplies the Lateral rectus, Superior rectus and Superior oblique. The anterior segment is supplied predominantly by 7 anterior ciliary arteries arising from the muscular arteries supplying the Recti. Two each from Superior, Inferior, Medial recti and one from Lateral rectus muscle. Burden on Anteriror ciliary arteries of Medial recti to supply nasal half of anterior segment is reduced by the presence of medically placed long posterior ciliary artery. Damage to ciliary arteries are invariable during these procedures. Consequently there is compensatory collateral connections made between anterior and posterior segment circulation. The dreaded complication of Anterior segment ischemia can be avoided by refraining simultaneous surgery of 2 vertical recti and lateral rectus. Inferior oblique muscle originates from the anterior orbit medially and inserts onto the inferotemporal part of posterior sclera. The posterior end of the linear insertion lies in close proximity with the point corresponding with fovea. In Inferior oblique muscle recession there is a risk of compromising foveal vascularity leading to compensatory vascular changes post operatively. Optical coherence tomography angiography (OCTA) is a comparatively novel technique for imaging the posterior segment vasculature within a short period of time, without the use of contrast dyes (non invasive). The machine takes consecutive OCT-B scans of precise retinal cross section to produce a map of blood flow by analysing the consecutive OCT-B scans for movement of erythrocytes within retinal blood vessels. In this study we will record the vessel density in 3 segmentations of the retina, ie. Superficial Capillary Plexus (SCP), Deep Capillary Plexus (DCP), Choriocapillaris (CCP) layers both preoperatively and postoperatively among Paediatric subjects.

We also intend to correlate more parameters obtained through OCTA as the study progresses.