Pattern of visual field defects in normal-tension and high-tension glaucoma

There are probably two major types of causative factors in open-angle glaucoma: pressure-dependent and pressure-independent. If clinical features such as the pattern of visual field defects differ between normal-tension and high-tension glaucoma, the differences may provide an insight for discriminating between the pressure-dependent and the pressure-independent damage in open-angle glaucoma. This article gives a brief review of the most recent studies including reports wherein progression or pattern of visual field defects in normal-tension and high-tension glaucoma or primary open-angle glaucoma are addressed. Further deterioration of the visual field in 5 years is expected in about 50% of eyes with normal-tension glaucoma in which intraocular pressure is one of the contributing factors. This figure may be greater than that seen in eyes with primary open-angle glaucoma where intraocular pressure is controlled with surgery in the middle teens. When eyes with normal-tension glaucoma and high-tension glaucoma or primary open-angle glaucoma were matched for extent of overall visual field loss, many studies noted a difference in the pattern of visual field defects between the two groups. Visual field defects in normal-tension glaucoma are relatively more localized and closer to fixation, especially in the nasal superior quadrant and may be more predominant in the lower hemifield. Results of other psychophysical tests also appear to support the above findings.