Ocular explosions from periocular anesthetic injections - A clinical, histopathologic, experimental, and biophysical study

Objectives: An increasing number of cases are being recognized in which a p eriocular anesthetic for cataract surgery has been inadvertently injected d irectly into the globe under high pressure until the globe ruptures or "exp lodes." The objectives of the current study were to (1) analyze this injury clinically and histopathologically through a series of seven case reports; (2) reproduce the injury experimentally in human eyebank eyes, live anesth etized rabbit eyes, and human cadaveric eyes; (3) investigate the biophysic al basis of the injury; and (4) outline recommendations to help decrease th e risk of ocular rupture with periocular injections. Designs/Participants: Clinical, histopathologic, experimental animal, autop sy eye, and theoretical biophysical study. Methods: The clinical and histopathologic findings of the patients' eyes we re documented. Human eyebank eyes, live anesthetized rabbit eyes, and human cadaveric eyes were exploded via direct intraocular saline injection. The laws of Bernoulli, LaPlace, Friedenwald, and Pascal were used to investigat e theoretically the biophysics of the injury, Results: The findings of anterior and posterior scleral rupture, retinal de tachment, vitreous hemorrhage, and lens extrusion were observed clinically and experimentally. In some clinical and experimental cases, the anterior s egment appeared entirely normal despite a posterior rupture, The surgeon pr oceeded with and completed the cataract surgery in two of the seven clinica l cases without knowledge of the rupture. The pressure required to produce such an injury is in the range of 2800 to 6400 mmHg, and this pressure is m ore easily attained with a 3-ml syringe than with a 12-ml syringe, Conclusions: Explosion of an eyeball during the injection of anesthesia for ocular surgery is a devastating injury that may go unrecognized, The proba bility of an ocular explosion can be minimized by (1) the use of a blunt ne edle and a 12-ml syringe, (2) aspirating the plunger and wiggling the syrin ge before injection, (3) discontinuing the injection ii corneal edema or re sistance to injection is noted, and (4) inspecting the globe for evidence o f intraocular injection before ocular massage or placement of a Honan ballo on. On recognition of an ocular explosion, immediate referral to and interv ention by a vitreoretinal surgeon is optimal.