Intraocular conditions

According to the location of diseases, ocular disorders are grouped as periocular and intraocular conditions. Periocular diseases include ... 

Ocular topical drug delivery is particularly challenging because of the inherent difficulties associated with absorption of topically applied drugs into the eye. Ophthalmic dosage forms are administered via the topical route to treat both surface and intraocular conditions. Consideration of the anatomical and physiological features of the eye, as well as the physicochemical properties of the drug, are all important when developing a topical ophthalmic delivery system. 

Muscarinic agonists and antagonists are used for the treatment of a variety of pathophysiological conditions. For example, muscarinic agonists (pilocarpine, carba-chol, or aceclidine) reduce intraocular pressure when... 

Various types of preparations are used for the treatment of ophthalmic (eye) disorders such as glaucoma to lower the intraocular pressure (IOP), bacteria or viral infections of the eye, inflammatory conditions, and symptoms of allergy related to the eye... 

Gastroenteritis inflammatory condition of the stomach Gingival hyperplasia gum tissue overgrowth Glaucoma a raised intraocular pressure... 

Concomitant ocular conditions When an intraocular inflammatory process is present, breakdown of the blood-aqueous barrier from anticholinesterase therapy requires abstention from, or cautious use of, these drugs. Use with great caution where there is a history of quiescent uveitis. 

Epinephrine also has been used to lower intraocular pressure in open-angle glaucoma. Its use promotes an increase in the outflow of aqueous humor. Because epinephrine administration will decrease the filtration angle formed by the cornea and the iris, its use is contraindicated in angle-closure glaucoma under these conditions the outflow of aqueous humor via the filtration angle and into the venous system is hindered, and intraocular pressure may rise abruptly. 

Osmotic diuretics alter Starling forces so that water leaves cells and reduces intracellular volume. This effect is used to reduce intracranial pressure in neurologic conditions and to reduce intraocular pressure before ophthalmologic procedures. A dose of 1-2 g/kg mannitol is administered intravenously. Intracranial pressure, which must be monitored, should fall in 60-90 minutes. 

A long list of potential therapeutic effects was recorded for THC, including analgesic, bron-chodilatory, antiemetic, anticonvulsant, and anti-inflammatory action, reduction of intraocular pressure, and alleviation of some neurological conditions (such as seizure disorders, spasticity associated with spinal cord injuries, and multiple sclerosis) (Mechoulam et al., 1994). 

Sustained delivery of ophthalmic medications is a novel approach in treating chronic intraocular infections in conditions where systemic administration is accompanied by undesirable side-effects and repeated intravitreal injections carry the risk of infection. The administration of medications by implants or depot devices is a very rapidly developing technology in ocular therapeutics. The various types of implant and mechanisms of drug release have been discussed in general in Chapter 4. 

Like fluorometholone, medrysone is a synthetic derivative of progesterone. As compared with prednisolone, dexamethasone, and fluorometholone, medrysone exhibits limited corneal penetration and a lower affinity for glucocorticoid receptors. In clinical use it appears to be the weakest of the available ophthalmic steroids. Medrysone can be useful for superficial ocular inflammations, including allergic and atopic conjunctivitis, but intraocular inflammatory conditions generally do not respond. Clinical experience with medrysone has also indicated that it is less likely to cause a significant rise in lOP. However, caution needs to be exercised in patients known to respond to steroids with a rise in lOP (so-called steroid responders), because pressure increases can lead to ocular damage. 

Damage to the iris sphincter muscle by high intraocular pressure, trauma, or inflammation may impair pilocarpine s ability to constrict the pupil. Clinically, these conditions can usually be excluded by a careful history taking and biomicroscopic examination. Mechanical foctors associated with malpositioned intraocular lenses or posterior synechiae may also limit movement of the iris. Depending on the extent of iris damage, the pupil may demonstrate complete to nonexistent constriction. 

The measurement of intraocular pressure (lOP) is essential in the initial assessment and ongoing management of uveitis. In the early stages of uveitis the lOP is typically low, due to secretory hypotony within the ciliary body. Over time, however, the lOP may normalize or rise to abnormal levels due to numerous mechanisms, including trabecular blockage by inflammatory debris and synechia formation. Elevated lOP usually indicates a more chronic condition. 

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