Medical treatment of normal tension glaucoma.

Normal-tension glaucoma was previously thought to be pressure insensitive, as medical treatment hardly reduced intraocular pressure and it did not prevent visual field loss. In the last decade, however, evidence has shown that the treatment of normal-tension glaucoma by lowering intraocular pressure can slow the deterioration of visual fields, hence the glaucomatous process. It was shown that a reduction of IOP of at least 30% is needed to induce a favorable alteration in the course of normal-tension glaucoma. New agents, such as prostaglandin analogs, the alpha(2)-adrenoceptor agonist brimonidine, and carbonic anhydrase inhibitors, have become available and may be of use in the treatment of normal-tension glaucoma. Monotherapy with prostaglandin analogs may meet the target of a reduction of IOP with 30%, but combination therapy will be needed in many cases. Few studies have been performed with brimonidine, travoprost, and bimatoprost, and it is suggested that more attention should be given to studies with these agents, as about 30% of patients with open angles and glaucomatous visual field defects have normal-tension glaucoma. Although neuroprotection is the goal of the future, no hard data are available yet which demonstrate that treatment with these agents will indeed result in preservation of visual fields.