Abstract
Abstract: :
Background: Gas tamponade, following vitrectomy for retinal detachment is an effective surgical tool, with appropriate head posturing. Adequate posturing for inferior retinal breaks is difficult to achieve and common practice involves a compromise between ideal tamponade, probably obtained in a supine head posture, and avoidance of gas cataract and angle closure glaucoma. The latter may be consequent to an anterior translation of the 'lens-iris diaphragm'due to the flotational force of the intraocular gas. Both complications of supine posturing may be irrelevant in pseudophakic eyes, in which inferior retinal breaks are often present. Purpose: 1) To determine whether the conformation of intraocular gas following vitrectomy, with prone, supine or alternating lateral head posturing, is consistent with adequate tamponade of inferior retinal breaks. 2) To determine the effect of supine posturing on intraocular pressure (IOP) and anterior segment anatomy of pseudophakic eyes. Methods: CT scans were obtained of 5 eyes containing gas following vitrectomy for pseudophakic retinal detachment. Scans were acquired in prone, supine and lateral positions with monitoring of the direction of gaze; scans were also taken with the eyes in "upgaze" of 45 degrees and straight down with the prone head posture. Three of the above patients were maintained in a supine head posture for 8 hours. The intraocular pressure (IOP), anterior chamber depth (ACD) and 'drainage angle' were measured at regular intervals, using a tonometer and 20kHz A and B-mode ultrasound scans of anterior segment, respectively. Results: The gas bubble within the vitreous cavity was consistent with tamponade of inferior breaks in all positions tested when the gas fill was greater than two-thirds and if gaze was held in the primary position. However, even with a gas fill greater than two thirds, changes in direction of gaze resulted in a bubble position not consistent with tamponade of the inferior retina. This was not the case in supine-postured eyes even with a significantly lesser gas fill. Supine posturing of gas-filled eyes at least three months after cataract surgery resulted in no clinically significant changes in IOP, ACD or 'drainage angle'. Conclusion: Gas tamponade with supine head posturing following vitrectomy is consistent with better tamponade of inferior retinal breaks and appears safe in the short term.
Keywords: 628 vitreoretinal surgery • 563 retinal detachment