Twenty four hour blood pressure monitoring in normal tension glaucoma.

BACKGROUND: The few investigations that used continuous 24 hour blood pressure monitoring to investigate whether blood pressure in patients with normal tension glaucoma is lower than in normal subjects yielded conflicting results. Therefore, a prospective controlled trial was carried out. METHODS: Systemic blood pressure was recorded continuously over a 24 hour period in 20 patients with normal tension glaucoma (IOP < or = 21 mm Hg). Eight of them showed a localised loss of the neuroretinal rim area and, in addition, optic disc haemorrhages-that is, focal ischaemic signs. Twenty healthy patients without glaucoma, who were hospitalised for cataract or retinal surgery, served as controls. Blood pressure was automatically measured every 20 minutes during the day and every 40 minutes at night. RESULTS: Both groups showed a significant (physiological) blood pressure drop at night, which was significantly (p < 0.001, ANOVA) more pronounced in the group with normal tension glaucoma than in the control group. There was a weak trend towards lower blood pressure values in the normal tension glaucoma group. Minima, maxima, and mean values of the systolic, diastolic, and mean arterial pressures did not differ significantly between the group with normal tension glaucoma and the control group. The greatest differences occurred with nocturnal systolic and diurnal diastolic values. There were no significant differences between the subgroup with focal lesions and the other patients with normal tension glaucoma. CONCLUSIONS: Patients with normal tension glaucoma tend to have lower blood pressure values (p > 0.05, ANOVA) than normals; this difference is probably much smaller than formerly assumed. Patients with normal tension glaucoma, however, have significantly greater nocturnal blood pressure drops (p < 0.001, ANOVA) than normal controls. Nocturnal blood pressure drops (relative day-night differences) may play a more important role in the pathogenesis of normal tension glaucoma than the absolute height of the blood pressure.

Wide-spread myelinated nerve fibers of the optic disc: do they influence the development of myopia?

PURPOSE: To find correlations between the extent of myelinated nerve fibers with refraction anomalies. METHOD: Searching for myelinated nerve fibers in the slide collection of the University Eye Hospital Freiburg we found 13 patients. We distinguished between eyes with wide-spread myelinated nerve fibers located on and around the optic disc which extended to the midperiphery of the retina (6 patients; Group A) and eyes with circumscribed myelinated nerve fibers, localized merely around the optic disc (7 patients, Group B). In Group A myelinated nerve fibers spared the macula area, but were localized very close to the macula. Color fundus photographs were taken by the Zeiss Fundus camera SK50 (30 degrees and 50 degrees picture size) and by the Olympus Fundus camera GRC-W (same picture size). RESULTS: The myelinated nerve fibers were found to be unilateral in all 13 patients. In all 6 patients of Group A, a strabismus was present. The affected eye had a severe amblyopia and a unilateral myopia (-5.75 to -25.0 D). The nonaffected fellow eye showed a normal visual acuity with no or only a slight refractive error. In the 7 patients of the Group B, no strabismus was present and a normal or a slightly decreased visual acuity of the affected eye was found. No distinct refractive error was present in the affected and non-affected eyes of this group. CONCLUSIONS: Myopia only occurred in eyes with wide-spread myelinated nerve fibers but not in eyes with circumscribed myelinated nerve fibers. We assume that myelinated nerve fibers, if wide-spread, cause myopia.