In the August issue of the ARCHIVES (1999;117:1010-1013), Iester and Mikelberg describe a careful study designed "to determine the morphometric parameters in high-tension glaucoma and normal-tension glaucoma with a confocal scanning laser ophthalmoscope." The authors point out that there is a difference of opinion regarding whether disc characteristics are different in these 2 apparent groups. Roughly 15 years ago, some authors described what they believed to be differences in opinion regarding the optic disc in patients with high-tension glaucoma (HTG) and low-tension glaucoma (LTG).1- 5 At that point in the development of the understanding of glaucoma, there was still some disagreement as to whether patients with average (normal) intraocular pressures should be considered to have glaucoma at all, that is, a condition in which the optic nerve becomes progressively damaged, at least partially related to intraocular pressure itself. There is now much agreement that progressive glaucoma can occur in patients who have average intraocular pressure. As this conclusion became more definite, the phrases low-tension or normal-pressure glaucoma became more widely used. These phrases suggest that normal-pressure glaucoma is a specific entity. During those same years, it became clear that the glaucomas that occur in patients with elevated intraocular pressure are associated with a variety of different mechanisms; that is, high-tension glaucoma was a poor term because it falsely suggested a homogeneity of pathogeneses where there is no such homogeneity. What is not as apparent, however, is that normal-pressure glaucoma is also not a single entity. Thus, comparing patients with HTG to those with LTG actually compares one heterogeneous group of conditions with another heterogeneous group. Additionally, these 2 groups are not the same. For example, if we arbitrarily assigned different letters to represent different specific types of glaucoma, such as A through Z, there would be an overlap between the HTG and the LTG group, but the letters in the 2 groups would not be identical. Perhaps diagnoses A, C, D, F, and M would be found in the HTG group, whereas diagnoses A, B, F, Q, and Z would be present in the LTG group. Normal-pressure glaucoma is just as unfortunate a phrase as high-tension glaucoma.
Spaeth GL. Report Does Not Show That There Is No Relationship Between Disc Appearance and Sensitivity to Intraocular Pressure. Arch Ophthalmol. 2000;118(10):1465-1466. doi: