Glaucoma simplex or open angle glaucoma is a slow, progressive illness
with an insidious course which can lead to blindness. According to our
con- temporary state of knowledge, the illness begins with a decreased
outflow of aqueous humor. This leads, sometimes after a period of
decreased aqueous humor production due to a feedback mechanism, to an
increase in intra- ocular pressure (lOP). An elevated lOP can eventually
lead to optic nerve damage, which manifests itself morphologically as
glaucomatous papillary excavation and functionally in the development of
a visual field defect. The classic triad of elevated lOP, papillary
excavation and visual field defect, on which the diagnosis of glaucoma
was also based in earlier times, is then pre- sent. To this can now only
be added that tonography usually shows a de- crease in aqueous humor
outflow and that gonioscopy must reveal an open angle. On the basis of
statistical findings, Goldmann has calculated that there may be an
interval of as long as 18 years between the initial increase in lOP and
the development of visual field defects. This point of view (which has
been confirmed in practice) that the onset of the illness can be demon-
strated by measurement of the lOP has introduced a new element into the
discussion around glaucoma, namely, the concept of ocular hypertension.
This implies simply that there is an (statistically) elevated
intraocular pres- sure, even though the optic nerve may not (yet) be
damaged.