Orbital Magnetic Resonance Imaging Demonstrates Better Contact between the Gas and Anterior Inferior Retina in Side versus Face-Down Position

Purpose: To demonstrate the relationship between an intraocular gas bubble, the retina, and the residual intraocular fluid in different head positions using orbital magnetic resonance imaging (MRI) in 3 patients who underwent pars plana vitrectomy (PPV) with gas tamponade.

Design: Novel study.

Participants: Patients undergoing PPV with gas-fluid exchange (sulfurhexafluoride [SF₆] or perfluoropropane [C₃F₈]).

Methods: Magnetic resonance imaging scans were obtained in 3 patients undergoing PPV with gas-fluid exchange (SF₆ or C₃F₈). All surgeries were performed by a single surgeon (E.D.M.). On the first postoperative day, the volume of intraocular gas fill was estimated separately by 2 surgeons (A.H. and E.D.M). Four orbital MRI scans were obtained from different head positions, including face up (supine), face down (prone on a massage pillow), flat on the right side, and flat on the left side.

Main outcome measure: Relationship between the gas bubble and residual vitreous fluid.

Results: The MRI images demonstrated, with excellent contrast, the gas and fluid locations in the vitreous cavity in all scans. The relationship between the gas bubble and residual vitreous fluid showed a rapid shift when the patient's head position changed. The MRI images demonstrated that with both 70% gas fill and 95% gas fill, lying on the side can give better support to the inferior retina than face-down positioning. The images demonstrated the importance of accurate head positioning, because a slight change in head position resulted in inadequate contact between the anterior inferior retina and the gas bubble.

Conclusions: To our knowledge, this is the first time that the relationship between an intraocular gas bubble and contact with the retina has been evaluated in different head positions in vivo using MRI imaging. The MRI images demonstrated that side positioning gives better contact between the gas bubble and the inferior and anterior retina than prone positioning even when the gas fill is only 70% of the vitreous cavity.