A comparative study to determine the optimal intravitreal injection angle to the eye: A computational fluid-structure interaction model

This study was aimed at investigating the role of IVI angle on the induced stresses and deformations among the components of the eye. Thereafter, the most optimal angle of IVI to minimize the complications of post IVI at the injection site on a basis of the computed stresses via a Fluid-Structure Interaction (FSI) computational model was proposed. IntraVitreal Injection (IVI) is broadly employed as a principal treatment of vascular vitro-retinal diseases. So far, there have been reports regarding the complications of post IVI and determine them as severe uveitis, tractional retinal detachment, IntraOcular Pressure (IOP) elevation as well as ocular haemorrhage. However, there is a lack of knowledge on how to reduce the subsequent ocular tissue damage and patient symptoms in the injection site. Seven different IVI angles were simulated, including 0°, 15°, 30°, 45°, 60°, 75°, and 90°, through the Finite Element (FE) code; and the term, â € post IVI complication' or â 'injury', in the results was interpreted as the level of maximal principal stress in the eye components. The results revealed the lowest amount of stresses at the angle of 45° in respect to the horizontal line (acute to the surface of the sclera) for the lens, iris, vitreous body, aqueous body, ciliary body, sclera, retina, and choroid. The cornea illustrated the same amount of stress at the angles of 45°, 60°, 75°, and 90° with the highest one at the IVI angle of 30°. The lowest and the highest stresses among the eye components regardless of IVI angle were observed in the choroid and retina/sclera, respectively, which imply the importance of the IVI angle on the stresses of these eye components. The findings of the contemporary research revealed that the IVI angle of 45° would trigger less post IVI complications and, as a result, a more effective surgery outcome compared to the other angles, i.e., 0°, 15°, 30°, 60°, 75°, and 90°.