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 periocular anesthetic for cataract surgery has been inadvertently injected directly into the globe under high pressure until the globe ruptures or "explodes." 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 anesthetized rabbit eyes, and human cadaveric eyes; (3) investigate the biophysical basis of the injury; and (4) outline recommendations to help decrease the risk of ocular rupture with periocular injections. DESIGNS/PARTICIPANTS: Clinical, histopathologic, experimental animal, autopsy eye, and theoretical biophysical study.
METHODS: The clinical and histopathologic findings of the patients' eyes were 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 investigate theoretically the biophysics of the injury.
RESULTS: The findings of anterior and posterior scleral rupture, retinal detachment, vitreous hemorrhage, and lens extrusion were observed clinically and experimentally. In some clinical and experimental cases, the anterior segment appeared entirely normal despite a posterior rupture. The surgeon proceeded with and completed the cataract surgery in two of the seven clinical 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 more 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 probability of an ocular explosion can be minimized by (1) the use of a blunt needle and a 12-ml syringe, (2) aspirating the plunger and wiggling the syringe before injection, (3) discontinuing the injection if corneal edema or resistance to injection is noted, and (4) inspecting the globe for evidence of intraocular injection before ocular massage or placement of a Honan balloon. On recognition of an ocular explosion, immediate referral to and intervention by a vitreoretinal surgeon is optimal.