Evaluation of intraocular gas using magnetic resonance imaging after pars plana vitrectomy with gas tamponade for rhegmatogenous retinal detachment

Abstract

We used magnetic resonance imaging (MRI) to assess how a patient's posture affects intraocular gas changes and whether the postoperative prone position is required after pars plana vitrectomy (ppV) with gas tamponade for rhegmatogenous retinal detachments (RRDs). eight patients with RRDs who underwent ppV combined with cataract surgery with gas tamponade were prospectively included. they underwent MRi examination both in the prone and supine positions. We separated the retina into four parts: superior-posterior, superior-anterior, inferior-posterior, and inferior-anterior. We then calculated the gas contact rate as (the length of the retina contacting the gas in each retinal part) divided by (the length of each retinal part) × 100% in both the prone and supine positions. The mean gas contact rate of the superior-anterior part of the retina was significantly higher (P = 0.006) in the supine position than in the prone position. the mean gas contact rate of the inferior-anterior part of the retina was also significantly higher (P = 0.0004) in the supine position than in the prone position. We believe that if all retinal breaks were located anterior to the equator, the supine position may provide better tamponade gas coverage for the breaks than the prone position. Although potential postoperative complications caused by the supine position require careful attention, our result may shorten the duration of postoperative prone position and may decrease the patients' discomfort after ppV with gas tamponade for RRDs.

Application of moving particle semi-implicit (MPS) method on retro-oil fluid using three-dimensional vitreous cavity models from magnetic resonance imaging

“…Next, we separated the 3-D vitreous cavity at 1:30, 4:30, 7:30, and 10:30 into four quadrants and then defined the position of the ora serrata of the inferior retina as the anatomical differences as 6.7 mm posterior to the limbus. Then, we defined the equator as 6.5 mm posterior to the ora serrata in the inferior retinal area, according to the vortex vein ampullae 15 , 16 . Therefore, the inferior quadrant of the retina was separated into two parts, inferior-anterior and inferior-posterior (Fig.…”

Computational fluid dynamics (CFD) simulation analysis on retinal gas cover rates using computational eye models

“…In the current study, all gas cover rates in each quadrant in prone position were < 100% when the gas volume was 80%. Furthermore, we have previously reported that if patients were superficially maintained in a strict prone position, the supraduction angle (°) of the eyeball to the perpendicular line was positive (16.1°; range, 6.3-29.9) 16 . In the current study, in the prone with closed eyes position, the gas cover rates of the nasal and temporal retinas were < 100%, despite the intraocular gas volume being 90%.…”

“…Figure 1 A–F shows resting positions of the 24 mm eye model, which represents the postoperative body positions. We have previously reported that even if patients superficially maintain a strict prone position with eyes closed, the mean supraduction angle (°) of the eyeball to the perpendicular line is positive (16.1°) 16 . Therefore, six resting positions of the eyeball examined were as follows: Supine: The direction of the eyeball is 90° upward from the horizontal line Sitting: The direction of the eyeball is parallel to the horizontal line Prone with closed eyes: The supraduction angle of the eyeball to the perpendicular line is 16.1° Prone: The direction of the eyeball is 90° downward from the horizontal line Lower temporal: The eyeball was rotated 90° from the sitting position, such that the temporal retina was on the horizon side Lower nasal: The eyeball was rotated 90° from the sitting position, such that the nasal retina was on the horizon side …”

“…In addition, Martinez-Castillo et al reported that PPV alone, with no prone position in the postoperative period, achieves a high reattachment rate without severe postoperative complications in the management of pseudophakic RRDs due to inferior retinal breaks 15 . We have previously demonstrated using magnetic resonance imaging that intraocular gas may cover the peripheral retina better in the supine position than in the prone position 16 . However, sitting and lateral positions are also used postoperatively.…”

“…Figure 1A-F shows resting positions of the 24 mm eye model, which represents the postoperative body positions. We have previously reported that even if patients superficially maintain a strict prone position with eyes closed, the mean supraduction angle (°) of the eyeball to the perpendicular line is positive (16.1°) 16 . Therefore, six resting positions of the eyeball examined were as follows:…”