Jason Noble1, Navapol Kanchanaranya2, Robert G Devenyi3, Wai-Ching Lam3. 1. Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada. 2. Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada. 3. Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
Abstract
AIM: To evaluate the effect of scleral buckling on intraocular pressure (IOP) change during atmospheric decompression for eyes with small volumes of intravitreal gas. METHODS: 12 eyes of 12 patients, including 6 with and 6 without scleral buckles, were evaluated in a hypobaric chamber simulating air travel approximately 1 month post pars plana vitrectomy with 15% C3F8 gas fluid exchange. The chamber was decompressed with an ascent rate of 300 feet/min to a peak altitude of 8000 feet. After 15 min of cruising, descent was undertaken at 300 feet/min. IOP was measured at baseline and then every 5 min using slit-lamp mounted Goldmann applanation tonometry. The data were entered onto a spreadsheet and comparative statistics were done. RESULTS: During ascent, IOP steadily rose from an average of 13±3 mm Hg to a peak of 26±9 mm Hg at 8000 feet. Patients with scleral buckles had significantly lower peak IOPs compared with those without buckles (20±5 mm Hg vs 32±8 mm Hg, p=0.013, t test) representing lower absolute increases in IOP (7±1 mm Hg vs 19±7 mm Hg, p=0.001, t test) and lower percentage increases in IOP from baseline (62±25% vs 140±40%, respectively). CONCLUSIONS: Eyes with small volumes of intravitreal gas demonstrate significant IOP changes during atmospheric decompression in simulated flight. The presence of a scleral buckle significantly limits the magnitude of IOP change, suggesting that such patients can likely tolerate typical air travel without undue risk of dangerous IOP elevation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
AIM: To evaluate the effect of scleral buckling on intraocular pressure (IOP) change during atmospheric decompression for eyes with small volumes of intravitreal gas. METHODS: 12 eyes of 12 patients, including 6 with and 6 without scleral buckles, were evaluated in a hypobaric chamber simulating air travel approximately 1 month post pars plana vitrectomy with 15% C3F8 gas fluid exchange. The chamber was decompressed with an ascent rate of 300 feet/min to a peak altitude of 8000 feet. After 15 min of cruising, descent was undertaken at 300 feet/min. IOP was measured at baseline and then every 5 min using slit-lamp mounted Goldmann applanation tonometry. The data were entered onto a spreadsheet and comparative statistics were done. RESULTS: During ascent, IOP steadily rose from an average of 13±3 mm Hg to a peak of 26±9 mm Hg at 8000 feet. Patients with scleral buckles had significantly lower peak IOPs compared with those without buckles (20±5 mm Hg vs 32±8 mm Hg, p=0.013, t test) representing lower absolute increases in IOP (7±1 mm Hg vs 19±7 mm Hg, p=0.001, t test) and lower percentage increases in IOP from baseline (62±25% vs 140±40%, respectively). CONCLUSIONS: Eyes with small volumes of intravitreal gas demonstrate significant IOP changes during atmospheric decompression in simulated flight. The presence of a scleral buckle significantly limits the magnitude of IOP change, suggesting that such patients can likely tolerate typical air travel without undue risk of dangerous IOP elevation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.