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Tal Rubinstein, Natta Sakolsatayadorn, Bryan Costin, Stephen McNutt, George Trichonas, Jennifer McBride, Julian Perry; The Effect of Sub-Tenon Injections on Increasing Optic Nerve Length Excision during Enucleation: Case Control Trial in Fresh Frozen Human Cadavers. Invest. Ophthalmol. Vis. Sci. 2013;54(15):749.
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In cases of malignancies of the eye involving the optic nerve, removing longer nerve segments could theoretically reduce the risk of leaving malignant tissue within the orbit. This study examines the utility of sub-Tenon injections prior to enucleation in order to anteriorly displace the globe and obtain a longer segment of the optic nerve in the specimen.
This is a comparative case control laboratory study of human cadavers. Twelve orbits from six unpreserved, fresh frozen adult cadavers were examined. A conventional enucleation technique using mildly curved scissors from a nasal approach was performed on one hemi-face as a control. On the contralateral hemi-face, an otherwise identical enucleation technique was performed, except that 10 ml (2.5 ml in each oblique quadrant) of normal saline was injected into the sub-Tenon space prior to optic nerve resection. Hertel exophthalmometry measurements were obtained prior to intervention and after the sub-Tenon injections. Optic nerve length after enucleation was measured with a metric ruler. Student T-tests were used for data analysis.
The mean difference in Hertel measurements in eyes after sub-Tenon injections was 5.8 mm (16.5 mm pre-sub-Tenon vs. 22.3 mm post-sub-Tenon, p = 0.007). The mean optic nerve length was 11 mm in the sub-Tenon injection group and 8.67 mm in the control group (p = 0.078).
Our study evaluates the utility of sub-Tenon injections during enucleation to advance the globe anteriorly and increase optic nerve length excision. Our data indicate a significant anterior displacement in eyes treated with sub-Tenon injections. In addition, we demonstrate a trend toward significance in that enucleated eyes treated with sub-Tenon injections contain longer optic nerves compared to untreated eyes. The examination of more eyes may be needed for further statistical analysis.
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