Corneal edema

The treatment of choice for PACG is laser iridotomy. Medical therapy is used to lower IOP, reduce pain, and reverse corneal edema prior to the iridotomy. IOP should first be lowered... 

Causes severe eye irritation that can progress to severe corneal edema. Temporary blindness has been reported. Causes skin irritation, nausea, headache, and vomiting. Inhalation is irritating to the mucous membrane and upper respiratory tract. May cause sensitization by skin contact. 

Causes irritation to skin, eyes, and respiratory system, CNS stimulation, skin irritation, sensitization. Causes severe eye and skin burns. May cause severe tearing, conjunctivitis, and corneal edema. Inhalation may cause difficulties ranging from coughing and nausea to accumulation of fluid in the lungs (pulmonary edema). 

Eye irritation and corneal edema in humans have been reported from industrial... 

Toxicology. AT-ethylmorpholine is an irritant of the eyes and mucous membranes prolonged exposure to low concentrations causes corneal edema. 

In an experimental study, humans exposed to 100ppm for 2.5 minutes experienced irritation of eyes, nose, and throat, whereas 50 ppm produced lesser irritation. Distortion of vision can occur at levels much lower than those that cause irritation. Workers exposed to low vapor concentrations (3-11 ppm) for several hours reported temporary fogged vision with rings around lights. Corneal edema has been observed in workers when air concentrations of substituted morpholines exceed 40 ppm. The symptoms usually appear at the end of the workday and clear within 3-4 hours after cessation of exposure. ... 

Human subjects experienced irritation of the nose and throat after brief exposure to 10-20ppm. Workers complained of transient visual disturbances (haloes around lights) after exposure to the vapor for 8 hours, probably due to mild corneal edema, which usually cleared within 3 hours. The liquid is also capable of causing severe eye burns that may cause permanent visual impairment. Isopropylamine in both liquid and vapor forms is irritating to the skin and may cause skin burns repeated lesser exposures may result in dermatitis. ... 

In industrial use, some instances of skin and respiratory tract irritation have been observed but no chronic effects have been reported. A human exposure to 12,000 ppm for 1.5 minutes in a laboratory produced nose irritation and cough mouth pipetting of the liquid caused a severe sore throat and reddened mucous membranes. Workers exposed for several hours to low vapor concentrations complained of foggy vision with rings around lights, the results of corneal edema, which cleared within 3-4 hours after cessation of exposure. ... 

Tests of single drops of aqueous solutions applied to the eyes of animals have shown that 1% solution causes severe irritation, 5% causes hemorrhagic conjunctivitis, and 16% causes severe reaction with conjunctival hemorrhages, corneal edema, and opacities, followed by some clearing but much vascularization. ... 

Ophthalmic - Corneal edema corneal clouding corneal decompensation. 

The primary use of anhydrous glycerin (Ophthalgan) is as an osmotic agent that is applied topically to reduce corneal edema. Orally administered glycerin (Glycerol, Osmoglyn) is used to reduce intraocular pressure and vitreous volume before ocular surgery. 

Corneal edema, eye discharge, eye irritation, eye pain, increased intraocular pressure, ocular discomfort, punctate keratitis, reduced visual acuity, visual disturbance, vitreous floater, vitreous opacities... 

Relief of dry and inflamed nasal membranes Intranasal Use as needed Diagnostic aid in ophthalmoscopic exam, treatment of corneal edema Ophthalmic solution Apply 1-2 drops q3-4h. Ophthalmic ointment Apply once a day or as directed. 

Acute angle closure and difficulty with accommodation can occur from the anticholinergic effects of antipsychotic agents. In addition, pigment deposits may develop in the cornea and lens. Pigmentary retinopathy has been reported with thioridazine. Keratopathy and corneal edema may occur occasionally during pharmacotherapy with chlorpromazine and fluphenazine... 

In a second experiment, Ayers and Stahl studied the effects of discharging a CS pen-gun cartridge into a rabbit eye at a distance of 20 cm. At that distance, the wad caused less damage than the blast and the particles of CS. Only three of 10 animals suffered severe eye lesions, which appeared to combine mechanical damage (lacerations) from the wad and conjunctivitis, intraocular hemorrhage, keratitis, and corneal edema probably from the blast and CS particles driven into the eye. The other animals showed only mild conjunctivitis, which cleared after 3 d. 

Acute injuries of the eyes, primarily from effects of blast and missiles, may occur from tear-gas weapons, such as pen guns. The lnmeulate effects of these Injuries include swelling and edema of the lids, with penetration of skin, conjunctiva, cornea, sclera, or globe by gunpowder and CN conjunctival ischemia and chemosls corneal edema, erosion, Inflammation, or ulceration and focal hemorrhage. 13,20... 

There is a parallel to draw between the Thill and assistant study and the study by Kubota and Fagerlhom [15] who have demonstrated that the importance of the initial corneal edema, resulting from a bum, is correlated to the importance of the sequelar cicatricial leukoma that causes the drop of vision. The stromal lacunae, fonned by the edema, will be colonized by the keratocytes. After the resorption of the edema and at the level of these lacunae, the keratocytes form a zone of cicatricial tissue, which is the origin of the leukoma. These keratocytes also produce an unorganized network of collagen fibrillae, thus causing the drop of transparency of the cornea. 

There are several most interesting observations concerning osmolarity. We have found that there is an important difference of osmolarity between the hyperosmolar stroma with 420 mOsmol/kg and the extra and intraocular fluids with lower osmolarities of about 320 mOsmol/kg. This results in an inversion of the water flux, when barriers like endothelium and epithelium are damaged. The immediate result of any membrane damage is that water starts to flow from the outside into the comeal stroma. This results in a corneal edema with turbidity. This is an indirect proof of the pumping function of the endothelium. 

Dilated episcleral vessels are a clue to abnormal anastamoses between branches of the external carotid artery and orbital branches of the internal carotid artery, distal to severe internal carotid artery disease. With extreme ischemia, ischemic oculopathy may develop, with impaired visual acuity, eye pain, rubeosis of the iris (dilated blood vessels), fixed dilated pupil, low-pressure glaucoma, cataract and corneal edema. 

Topically applied anesthetics may cause corneal endothelial toxicity when used after perforating ocular trauma or when used topically for cataract extraction. When injected inttacametally, benzalkonium chloride, the primary preservative used in topical ocular anesthetics, can cause irreversible corneal edema in rabbits. 

Osmotherapy was introduced to ocular therapeutics in 1904 with the use of oral hypertonic saline to reduce elevated intraocular pressure.Topical ocular use of hyperosmotic agents has been proven clinically useful in the treatment of corneal edema, particularly when the cause is endothelial dysfunction. 

The following discussion considers the pharmacologic properties of hyperosmotic agents available for topical use. Chapter 26 discusses the clinical uses of topical osmotherapy in the management of conditions characterized by corneal edema. 

A variety of clinical situations can give rise to corneal edema (Box 15-1). Because the endothelium is the main structure involved in maintaining normal corneal deturges-cence, it plays a role in stromal hydration and compensates for the driving force of intraocular pressure. Also, the active transport system involved in the movement of water and electrolytes from the cornea to the aqueous humor must be maintained to prevent fluid retention. Endothelial feilure, a frequent cause of corneal edema, can occur due to defects in the transport system or stromal compression resulting from elevation of intraocular pressure, which can induce water movement toward the epithelium. 

It is clinically useful to consider corneal edema as epithelial, stromal, or a combination of both. In general, epithelial edema is more responsive to topical hyperosmotic therapy. 

Sodium chloride is a component of all body fluids, including tears. A solution of 0.9% is approximately isotonic with tears. Of the various concentrations tested, 2% to 5% formulations have proven effective, with an irritation level acceptable to most patients. Studies comparing various hyperosmotic agents in human subjects have confirmed the usefulness of hypertonic sodium chloride in the treatment of corneal edema. Use of 5% sodium chloride in ointment form can be effective in reducing corneal thickness and in improving vision.The maximum reduction in corneal thickness occurs 3 to 4 hours after instillation of the ointment (Figure 15-1). 

Despite their apparent efficacy, the usefulness of sodium chloride solutions in the treatment of edematous corneas with a traumatized epithelium appears to be limited. The intact corneal epithelium exhibits limited permeability to inorganic ions. In the absence of an intact epithelium the cornea imbibes salt solutions, which reduces the osmotic effect. In the management of corneal edema associated with traumatized epithelium, hypertonic saline solutions may be of limited value due to their increased ability to penetrate the epithelial barrier. 

Adapted from Boruchoff SA. Clinical causes of corneal edema. Int Ophthalmol Clin 1968 8 581 -600. 

Sodivim chloride is useful for reducing corneal edema of various etiologies, including bnllons keratopathy. Generally, one to two drops are instilled in the eye every 3 to 4 hours. Sodium chloride ointment reqnires less frequent instillation and is generally reserved for nighttime nse. 

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