High intraocular pressure in four vitrectomized eyes with intravitreal C3F8 without high altitude travel

Abstract

Importance It is well known that altitude ascent with intravitreal gas can cause expansion of gas and intraocular pressure (IOP) elevation. According to Boyle's law, the gas bubble will not expand unless a higher altitude than the gas insertion site has been reached. We report four cases in which intravitreal gas was injected at an altitude of 790 m (Jerusalem). All four cases developed high IOP even though they did not reach a higher altitude in their post-operative period. Observations A report of four patients following vitrectomy with 12% mixture of perfluoropropane and air are presented. All four patients arrived with ocular pain following the ascent by car of 765-1100 m to Jerusalem where the vitrectomy and gas insertion was conducted. Upon examination, all four patients had high IOP (30-55 mm Hg). IOP was well controlled with IOP-lowering medications. None of the patients suffered from long-term complications. Conclusions and Relevance Caution should be taken with altitude changes in patients with intravitreal gas even if there was no ascent from the altitude in which the vitrectomy was performed.

Patients With Intravitreal Gas Bubbles at Risk of High Intraocular Pressure Without Exceeding Elevation of Surgery: Theoretical Analysis

“…Our model 6 was adapted to approximate the four published clinical cases reported from Shaare Zedek Medical Center, Jerusalem, Israel. 11 The model was designed to use the input of a time-elevation vector that corresponded to the travel of each patient. The path of each patient began at the patients' homes and was idealized into three linear sections: a descent from home elevation (790 m, 790 m, 325 m, 240 m) to a low elevation (20 m, 0 m, 25 m, À310 m) at a constant rate (40 m/min, 40 m/min, 40 m/min, 35 m/min), a period of time spent at the low elevation (60 min), and a return ascent to high elevation (Jerusalem 790 m) at a constant rate (40 m/min, 40 m/ min, 40 m/min, 35 m/min).…”

“…The values for home elevation, low elevation, high elevation, and maximum ascent rate were taken directly from the clinical data. 11 Initial bubble size (70%, 55%) was taken directly from the published data for patients 1 and 2 who lived in Jerusalem. 11 Patients 3 and 4 lived at a lower elevation than where the initial surgery took place, so it was reasonable to assume that the bubble size had changed during the trip from surgery in Jerusalem to their home elevation.…”

“…11 Initial bubble size (70%, 55%) was taken directly from the published data for patients 1 and 2 who lived in Jerusalem. 11 Patients 3 and 4 lived at a lower elevation than where the initial surgery took place, so it was reasonable to assume that the bubble size had changed during the trip from surgery in Jerusalem to their home elevation. Therefore, the trip from Jerusalem to home was first modeled to determine the initial bubble size for the follow-up visit.…”

“…Recent observations in four cases from a clinic in Jerusalem, Israel, initiated concerns that postsurgical travel without exceeding the surgical elevation may put patients at risk. 11 Each of the four patients underwent surgery in Jerusalem to insert the gas bubble. Then they went home to heal.…”

“…It was hypothesized that an accumulation of aqueous humor caused the increase in gauge IOP. 11 The purpose of this study was to show the mechanism responsible for high peak IOP in patients with intravitreal gas bubbles resulting from a descent to low elevation and a return ascent, without exceeding the surgical elevation.…”