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Nina Rosa Konichi da Silva, Diego Tapias, Robert B Bhisitkul; Evaluation of self-sealing scleral incision integrity in a fluorescein-perfused human cadaver eye model.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2833.
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© ARVO (1962-2015); The Authors (2016-present)
Determining the ideal parameters for self-sealing trans-scleral incisions will facilitate future developments in intravitreal devices, including those for ocular drug delivery. In a human cadaver eye model of intraocular fluorescein egress, with India Ink histologic study, we studied a range of wound sizes and constructions to define the limits of office-based, sutureless scleral incisions.
A standard 25-gauge BSS-infusion port (Alcon) was placed in fresh human cadaver eyes harvested for this study. Fluorescein sodium (25%, 0.1 ml) was injected into the vitreous cavity on a 25G needle. With the conjunctiva excised, beveled transcleral incisions were performed at the pars plana in each quadrant, using a range of standard ophthalmic surgical blades (3.0mm, 2.4mm, 2.2mm, 2.0mm, 1.3mm, 1.0mm). The resulting wounds were not manipulated with any instruments, and were not sutured. Under the operating microscope, with both standard and cobalt blue illumination, fluorescein leakage at each incision site was assessed with and without provocation (scleral manipulation) at a set range of low (2-8mmHg), normal (10-18mmHg), and high (>35mmHg) IOPs by varying the BSS infusion pressure, as measured by Tono-Pen. Finally, India ink was placed over the transcleral incisions, then eyes were fixed for histology to examine for ingress.
In 2 eyes, scleral incisions of 1.0mm (ClearCut, Alcon), 1.3 mm (V-Lance, Alcon) and 2.0mm (Laseredge, Baush & Lomb) in size were consistently self-sealing, allowing no egress of vitreous fluid at a range of IOPs and under provocation. Larger incisions of 2.2mm (ClearCut, Alcon) and 2.4mm (ClearCut, Alcon) displayed vitreous fluorescein leakage under provocation, and the 3.0mm (ClearCut, Alcon) incision showed spontaneous leakage at normal IOP (Table 1 below). The histologic analysis corresponds with fluorescein leakage results.
The fluorescein-infused human cadaver eye offers a simple model for preliminary assessments of wound integrity. Using commercially available ophthalmic blades, and absent wound manipulation, self-sealing scleral incisions were possible up to 2.0mm, expanding the potential size of office-based injections for future intraocular technologies while avoiding wound complications such as hypotony and endophthalmitis risk.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Table 1 - Self-sealing transcleral incisions tests
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