Session Title: Vitreoretinal Surgery IV
Session Date/Time: Friday 27/09/2013 | 16:30-18:00
Paper Time: 17:26
Venue: Hall 3 (Level 0)
First Author: M.Dogramaci UK
Co Author(s): T. Williamson
Saccadic movements can result in vitreous oscillations and tractions at vitreo-retinal adhesions points, such tractions can result in retinal breaks and retinal detachments
Lister Surgicentre, Coreys Mill Lane, Stevenage, UK, SG1 4AB and St. Thomas' Hospital, Westminister Bridge Road, London, SE17EH.UK
We constructed a computer generated model eye using Ansys 14.0 Finite Element Analysis (FEA) software to study vitreous dynamics during saccadic eye movements. The retinal shell was 400 µm in thickness posteriorly, the ora serrata was 20mm in diameter, the axial length of the model ranged between 18-32 mm, the vitreous volume ranged between 0.5-5ml, the vitreo-retinal adhesions were located at a distance ranged between 1-17mm from the ora serrata and with a circumferential length ranged between 5-110°, the vitreous base was designed to be 4mm wide, saccadic angular peak velocity was 500◦ /s.
The study showed that the shear stress at the viteroretinal adhesion points was positively correlated with the axial length and the circumferential length of the vitreo-retinal adhesion points, and it was negatively correlated with the distance of the vitreo-retinal adhesion point from the ora serrata and the thickness of the adjacent retina. The shear stress also peaked with half filled vitreous cavity. No relation were found between the amplitude of saccadic movement and the shear stress
FEA findings were in line with the clinical and the anatomical findings in eyes with vitreo-retinal adhesions. Furthermore the findings suggested that partly removed vitreous, vitreoretinal adhesions of > 2 clock hours and vitreo-retinal adhesions associated with retinal thinning could increase the risk of retinal breaks. It also suggests that microsaccadic eye movements can generate dynamic stresses.