First Author: G.Bamonte THE NETHERLANDS
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To describe a technique of vitreous base visualisation through trans-scleral illumination using a standard 25-gauge light probe.
Description of a surgical technique.
All vitrectomies are done with the Alcon (Fort Worth, Texas, USA) Constellation vitrectomy system, with an integrated xenon light source, using 25-gauge+ instruments and valved trocars. The Eibos system (Möller-Wedel, Wedel, Germany) is used to provide wide-angle viewing of the retina. After core vitrectomy and the necessary procedures triamcinolone acetonide (Kenacort), is injected in the vitreous cavity. Then, a sleeve obtained by cutting approximately 30 mm from the 20-gauge Venflon tm Pro cannula (BD, Helsinborg, Sweden) is used to cover the standard 25-gauge light pipe. This device reduces abrasion of conjunctiva and sclera and increases the rigidity of the light pipe. Light brightness is increased to 100%, and intraocular pressure is set at 20 mm Hg. The light probe, modified by the sleeve, is used to indent the sclera and trans-illuminate the vitreous cavity. The residual vitreous then becomes visible as a relatively optically free space between the crystals of triamcinolone, dispersed in balanced salt solution, and the light transmitted through the retinal periphery. Vitreous base shaving is carried out for 360°. At the end of the procedure, careful inspection of the peripheral retina is performed and laser retinopexy carried out when needed.
The sleeve, obtained from the 20-gauge Venflon tm Pro cannula is cheap and readily available in virtually any operation room. It fits any 25-gauge light probe, also from fabricants other than Alcon. Potential concerns may arise. 1) The sleeve, as described here, is flexible. Excessive tension might therefore bend the light probe at the junction with the hand piece and potentially break it, especially with 25-gauge systems. Activating the cutter in the mid-vitreous cavity before indenting the sclera facilitates this step and minimises damages. 2) Iatrogenic retinal tears may result from aggressive vitreous base shaving with trans-illumination. The charts of patients operated for macular pucker and vitreous floaters by means of this technique, between March 2012 and September 2013, have been evaluated. An iatrogenic peripheral retinal tear, as a result of vitreous shaving, was reported in six out of 143 eyes (4.1%), which is consistent with most literature reports. 3) Relatively lower transmission of light through the eye wall is achieved in patients with a dark skin. This might be an issue only during the learning curve of this technique.
This technique can represent a valid and low-cost option to achieve accurate vitreous base shaving.