Search

The allergic and toxic effects of preservatives found in soft contact lens solutions are reviewed. Thimerosal, a preservative commonly found in soft contact lens solutions, may cause ocular delayed hypersensitivity. Patients with delayed hypersensitivity to thimerosal may develop conjunctival hyperemia, corneal infiltrates and intolerance to lens wear with the use of soft contact lens solutions containing thimerosal. Delayed hypersensitivity to thimerosal can be demonstrated by an occlusive patch test or intradermal injection. Discontinuation of chemical disinfection with substitution of thermal disinfection using unit-dose, non-preserved saline causes resolution of signs and symptoms. Another cause of lens wear intolerance is contact lens-associated giant papillary conjunctivitis. Protein deposits on the lens may act as antigens and initiate an allergic condition which disappears when the lens is discontinued. Alternatively, the giant papillae may be the result of mechanical irritation induced by the contact lenses. The chemical preservatives that are found in soft contact lens solutions cause epithelial toxicity when applied to isolated rabbit corneas. However, corneal toxicity toxicity in a clinical setting has not been demonstrated.

Control of intraocular pressure (IOP) in patients with severe alkaline burns is one of the most difficult problems facing the corneal specialist. Currently, when medical therapy cannot control intraocular pressure, the usual procedure of choice is cyclocryotherapy. This procedure, however, can be complicated by phthisis, retinal detachment, or macular edema. We have used transscleral YAG laser cyclophotocoagulation (TSYLC) to control the IOP in a patient with severe glaucoma after an alkali burn. This patient had previously had an unsuccessful cyclocryotherapy. After the TSYLC procedure, he suffered no complications and his IOP was normal. Our experience with this patient indicated that the TSYLC procedure might be an effective alternate to cyclocryotherapy, especially in corneal patients with uncontrollable inflammatory glaucoma.