Changes of the Subfoveal Hyporeflective Zone After Membrane Peeling With Air Tamponade and Balanced Salt Solution - a Pilot Study

During the last decade optical coherence tomography (OCT) extended the possibilities for in vivo macula diagnostic and was increasingly used for pre- and post-operative imaging of retinal diseases. Spectral-domain optical coherence tomography (SD-OCT) with its increased scanning speed and image-resolution provides more detailed information of microstructures in the macula. Epiretinal membrane (ERM) is a disorder involving the posterior pole of the eyeball. It can be idiopathic or caused secondarily in various ocular conditions, such as uveitis, trauma, retinal detachment or retinal vascular diseases. In patients who suffer from loss of vision and metamorphopsia, vitrectomy and membrane peeling is usually performed to remove the ERM.

Different study groups showed that intraoperative use of SD-OCT is possible. Two groups already achieved to work operation microscope integrated SD-OCT setup. Due to the high axial resolution of the SD-OCT some groups reported about an increased hyporeflective zone in the subfoveal region appearing directly after the membrane peeling procedure. It was hypothesized that this phenomenon could be an expression of surgical trauma, as this hyporeflective zone disappears in follow up OCT 10 days after surgery .

The aim of the study is to use a microscope integrated SD-OCT in order to measure the surgically induced hyporeflective zone in the subfoveal region during membrane peeling and to evaluate whether the hyporeflective zone, that is believed to be an expression of tissue trauma, disappears faster with air tamponade compared to eyes with balanced saline solution (BSS).

Both, intraocular air tamponade and BSS are commonly used after vitrectomy with membrane peeling and pose the standard of care for this operation and no information concerning the superiority of one method is available. The non-contact microscope integrated SD-OCT, does not require any relevant additional time during the operation procedure (max. 2 minutes per operation for the OCT scans). During the OCT measurement time the light of the microscope will be reduced to a minimum to avoid additional light exposure. The OCT scans will be performed only at different time points (as mentioned below) to keep the OCT light exposure low and far below the acceptable exposure time as mentioned in the OCT safety guidelines.

SD-OCT is a safe and commonly used diagnostic tool in ophthalmology and its application does not bear any additional risk for the patients included in the study. Furthermore, all devices used in this study are CE-marked (Communauté Européenne).