Can Cryotherapy Increase Intraocular Pressure?
Yes, cryotherapy can significantly increase intraocular pressure, particularly during cyclocryotherapy procedures for glaucoma, with pressure spikes reaching up to 32 mmHg in humans during the freezing stage. 1
Mechanism of IOP Elevation During Cryotherapy
The pressure rise during cryotherapy occurs through a specific physical mechanism:
- Ice ball formation inside the eye causes volumetric expansion of intraocular contents, which directly increases IOP. 1
- During cyclocryotherapy, mean IOP increases from 53 mmHg immediately before freezing to 68 mmHg during the cryo freezing stage in human patients. 1
- This pressure spike is unavoidable because it results from the fundamental physics of water expanding when it freezes within the confined space of the eye. 1
- The pressure returns to baseline only after the ice thaws, with thaw times correlating with the duration of elevated IOP. 1
Clinical Significance and Risk
The IOP spikes during cyclocryotherapy pose particular danger to patients with advanced glaucoma:
- These pressure elevations can cause further injury to already damaged glaucomatous optic nerves. 1
- The acute pressure rise may be responsible for visual impairment that occurs after cryotherapy treatment. 1
- In neovascular glaucoma treated with combined transscleral panretinal cryocoagulation and cyclocryocoagulation, 27% of eyes developed extreme hypotension and subsequent bulbar atrophy with amaurosis, attributed to overly extensive cyclocryocoagulation. 2
Post-Procedure IOP Management
After pneumatic retinopexy with cryotherapy, specific precautions are mandatory:
- IOP measurement must be performed at 1-2 days postoperatively and again at 1-2 weeks as routine follow-up. 3
- Patients must avoid air travel and ascending to altitudes >1000 feet above the surgical site until complete gas absorption (SF6 lasts 2-3 weeks; C3F8 persists 6-8 weeks). 3
- Failure to warn patients about altitude restrictions can result in catastrophic vision loss from central retinal artery occlusion due to gas expansion and further IOP elevation. 3
- Nitrous oxide anesthesia is absolutely contraindicated in patients with intraocular gas, as it causes dangerous IOP rises; patients should wear warning wristbands. 3
Alternative Considerations
Given the unavoidable nature of IOP spikes during cyclocryotherapy, other cyclodestructive methods may be more prudent, particularly in patients with advanced glaucoma where the optic nerve cannot tolerate additional pressure-related injury. 1