[Current topics in glaucoma]

Abstract

Among the many factors involved in the development of glaucoma, the elevation of intraocular pressure (IOP) is the most important. The treatment of glaucoma aims to lower IOP in order to maintain visual function. New anti-glaucoma drugs, latanoprost and nipradilol, have been shown to effect a reduction in IOP equal to that achieved with the equivalent dosage of timolol, with no adverse systemic side effects. The mechanism of the reduction of IOP by these drugs mainly involves the increase of uveoscleral outflow. The success rate of filtering surgery for glaucoma has been increased by using antimetabolites such as mitomycin C (MMC) and 5-fluorouracil (5-FU). The use of MMC during surgery has resulted in a better outcome than with 5-FU. Normal tension glaucoma (NTG) cases are reported to constitute more than 60% of total glaucoma cases in Japan. NTG is different from primary open-angle glaucoma not only in IOP but also in the pattern of the visual field defect, cupping and peripapillary atrophy of the optic nerve head (ONH). The first choice of treatment for NTG is using drugs for reducing IOP and, if necessary, argon laser trabeculoplasty. In addition to these treatments a drug for increasing the blood circulation in the brain, brovinecamine fumarate, has shown beneficial effects in the treatment of NTG. NTG patients whose visual field can be shown by static perimetry to be deteriorating are indicated for filtering surgery. The results of filtering surgery for NTG have been confirmed that it is more effective than drugs for maintaining the visual field. We have developed an instrument using the laser speckle phenomenon for determining the microcirculation in the eye, as well as in the ONH, noninvasively, quantitatively, and repetitively. With the same instrument, the effects of anti-glaucomadrugs on ocular circulation, especially in the ONH, can also be determined. Timolol has no effect on the circulation in the ONH, but carteolol and betaxlol increase the circulation significantly. The Ca(+2)-blocker, nilvadipine, increases the circulation in the ONH. These findings indicate that the drugs increasing the ONH circulation many be beneficial for the control of glaucoma.