First Author: S.Sosnovskii RUSSIA
Co Author(s): A. Kulikov D. Shamrey A. Remigin R. Berezin J. Oskanov D. Maltsev
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Suprachoroidal space (SCS) is a normally absent space enclosed between the sclera and the choroid. SCS is highly susceptible to various pathological disorders, including intraoperative or postoperative complications related to intraocular surgery. Nevertheless, safety and efficacy of surgical manipulations and delivery of pharmacologic agents in SCS is not sufficiently studied.
Experimental study of drug delivery system with TPM-U 0,3/0,5 polyurethane tube was conducted in the Military Medical Academy and approved by a local Ethics Committee.
Ten chinchilla rabbits (20 eyes) (mean weight 3.5 kg, mean age 1 year) were underwent suprachoroidal implantation of TPM-U polyurethane tube (diameter of lumen 0.3 mm, outer diameter of 0.5 mm and 1.5 cm length). The long-term outcome of drug delivery system implantation in SCS was evaluated clinically and histopathologically. Biomicroscopy, indirect ophthalmoscopy, and fluorescein angiography were performed on a daily basis during 2 weeks after implantation (AI), and then weekly during the follow-up period. The animals were sacrificed by air embolism day 30 and 90 postoperatively after implantation. Enucleated globes were fixed in 10% neutral-buffered formaldehyde and embedded in paraffin. Serial sections (4-6-μm thick) were cut, deparaffinized and stained with hematoxylin and eosin. Histologic evaluations of retinal and choroidal tissues in the site of the tube bed were performed by light microscopy.
Biomicroscopy during the 1 week AI revealed conjunctival injection and mild conjunctival chemosis that were resolved in 10 days AI with topical antibiotic and steroid. A conjunctival filtering bleb was found above the outer tip of the drainage tube. Ophthalmoscopy at 1 day AI showed area of retinal edema over the tube which reduced in 5 days AI, without significant anatomical changes in adjacent choroid and sclera. Fluorescein angiography showed normal retinal and choroidal perfusion. The histopathologic examination at day 30 AI revealed the implant located under the choroid surrounded by a connective tissue capsule and characterized by a prominent cellular component, including melanocytes from the choroid and lamina fucsa. No inflammatory reaction in the implant bed area was identified. The histopathology examination at day 90 AI revealed degenerative changes of the retina including thinning of outer retinal layers and fibroglial proliferation in the inner retinal layers as well as local structural abnormalities in Bruch's membrane.
Implantation of TPM-U 0,3/0,5 polyurethane tube in the SCS for a period of time at least 30 days appears to be a safe approach for drug delivery into SCS. Long-term implantation of TPM-U 0,3/0,5 polyurethane tube in SCS for a period of 90 days leads to significant structural changes in choroid and sclera.