Tenon’s capsule

In-depth discussions of the anatomy of the eye and adnexa have been adequately covered elsewhere in the pharmaceutical literature [13-17] and in recent texts on ocular anatomy. Here a brief overview is presented of the critical anatomical features that influence the nature and administration of ophthalmic preparations. In this discussion, consideration will be given primarily to drugs applied topically, that is, onto the cornea or conjunctiva or into the palpebral fornices. Increasingly, drugs are being developed for administration by parenteral-type dosage forms subconjunctivally, into the anterior and posterior chambers, the vitreous chamber, Tenon s capsule, or by retrobulbar injection. 

Conjunctiva and Tenon s capsule 1) Diffusion across these tissues 2) Clearance via conjunctival blood and lymphatic flow 1) In vitro permeability of rabbit conjunctiva and Tenon s capsule 2) Limited data on blood and lymphatic flow and on capillary permeabiUty... 

Cardillo JA, Melo LA, Costa RA, et al. Comparison of intravitreal versus posterior sub-Tenon s capsule injection of triamcinolone acetonide for diffuse diabetic macular edema. Ophthalmology 2005 112 1557-1563. 

Periocular steroids can be administered by subconjimcti-val, sub-Tenon s capsule, or retrobulbar injection. A topical anesthetic often is instilled before the steroid is injected. This route of administration can be effective during surgical procedures, as a supplement to topical and systemic steroids in cases of severe inflammation, and in patients not compliant with the prescribed regimen. 

The conjunctiva proceeds onto the globe from the fornix to form the bulbar conjunctiva, which overlies Tenon s capsule and merges with the limbal cornea. Loosely attached to the capsule over the entire globe, the bulbar conjunctiva forms a homogeneous layer of stratified squamous epithelium at the limbus and contains many goblet... 

Management of the ocular aspects of Reiter s syndrome is directed toward control of inflammation.The uveitis can be fairly severe and resistant to therapy. In most instances such topical steroids as 1% prednisolone acetate or 0.1% dexamethasone are recommended. Dosage is variable but in severe cases should be administered initially every 1 to 2 hours and accompanied by such cycloplegic agents as 5% homatropine or 0.25% scopolamine two to three times daily. Aggressive treatment reduces formation of synechiae and subsequent secondary glaucoma. In patients who have severe uveitis, either sub-Tenon s capsule or oral steroids may be used in conjimction with topical management. 

There is a preponderance of evidence that the incidence of postoperative endophthalmitis is reduced when antiseptics (povidone iodine) and antibiotics are used preoperatively.The use of balanced salt solution, to which an antibiotic has been added, to irrigate the eye during surgery is advocated by some but tempered by concerns of intraocular toxicity and questions of efficacy. Sub-Tenon s capsule injection of an antibiotic just before surgery or subconjunctival injection of antibiotic at the end of the surgery is also used to prevent infection, but risk of inadvertent intraocular injections resulting in retinal antibiotic toxicity must be considered. In addition, oral antibiotics may be used at the time of surgery and 1 day postoperatively as a prophylactic measure. 

Placement of dmg more rostrally than achieved by subconjunctival injection (i.e. imder the outer fascial coat of the globe (Tenon s capsule)) in... 

Duan, Y., Guan, X., Ge, J. et al. 2008. Cationic nano-copolymers mediated IKKbeta targeting siRNA inhibit the proliferation of human Tenon s capsule fibroblasts in vitro. Mol. Vis. 2616-2628. 

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