Restrictive posturing after vitrectomy and gas tamponade may be unnecessary

This experimental study evaluated the fluid dynamics and fluid shear stresses on the retina after vitrectomy and gas tamponade in response to saccadic eye and normal head movements. Results of the computer modeling suggest that restrictive posturing after vitrectomy and gas tamponade may be unnecessary.

The authors used high-resolution computational fluid dynamic software in which the fluid volume within the eye was discretized using 6 × 10⁵ elements and solved with a volume-of-fluid method. The eye was abstracted to a sphere. Vertical and horizontal saccades and sudden rectilinear displacement of the head were examined. Gas fill fraction was varied from 20 percent to 80 percent of the eye height filled with gas.

This study predicts that saccadic eye movements and normal head movements generate only small fluid shear stresses on the retina that are below published norms for retinal adhesion strength. Sudden, jerking head movements generate fluid shear forces similar to retinal adhesion strength that localize to the area of gas-fluid interface. Fluid sloshing occurs after movement but rapidly decays on cessation of movement.

Although restrictive posturing after vitrectomy and gas tamponade may be unnecessary, patients should avoid sudden head movements.