Modeling Microdebrider-Mediated Ophthalmic Damage: A Word of Caution in Endoscopic Sinus Surgery.

Background The microdebrider has become nearly universal in the treatment of sinonasal pathology; however, recent case reports have demonstrated the potential for major ophthalmic complications. The goal of this study was twofold: 1) determine the anatomical proximity of ophthalmic structures to the paranasal sinuses, and 2) assess the timeframe at which ophthalmic injury may occur with the use of a microdebrider during FESS utilizing a cadaveric model. Methodology/Principal Computed tomography scans from 50 patients were accessed retrospectively. The distances between the lamina papyracea (LP) and orbital structures were determined at varying depths. Seven cadavers (14 sides) were studied using three microdebrider systems operated by otolaryngology residents. Following removal of a window of LP, the time from activation of the microdebrider on the periorbita until transection of the medial rectus (MR), optic nerve (ON), and to aspiration of the globe were measured. Results The mean distance between the LP and MR at the level of the anterior aspect of the anterior ethmoid and basal lamella were 3.59 ±1.2mm and 1.5 ±0.8mm, respectively. The mean distance between the LP and ON at the level of the basal lamella was 8.1 ±2.1mm. Mean transection times for the MR and ON were 13.4 ± 7.3 seconds and 37.3 ± 9.2 seconds, respectively, with minimum times of 4 seconds and 26 seconds. Conclusions The proximity of orbital structures to the paranasal sinuses and the rapidity of ophthalmic damage following violation of the periorbita reaffirms the need for cautious use of the microdebrider during FESS.