The Bedford glaucoma survey. I. Long-term follow-up of borderline cases.

In a survey carried out between I964 and I966, 5,941 persons over the age of forty living in Bedford were screened for glaucoma.The ocular tensions were measured with the Goldmann applanation tonometer by a technician and the subjects were then seen by an ophthalmologist, who took a brief ocular history and family history and carried out an external examination and ophthalmoscopy.Subjects were referred for more detailed examination if the tension was 21 mm.Hg or more, if the optic discs appeared abnormal, and if there was a history of haloes or a family history of glaucoma. 55cases of primary glaucoma (0.93 per cent.) were detected as a result of the survey and a further2 I 2 persons were advised to return annually for further examination (Bankes, Perkins, Tsolakis, and Wright, I968).I90 of these attended on more than one occasion, and this paper presents our findings after following 141 subjects for a period of 5 to 7 years.The reasons for follow-up were ocular hypertension, suspicious optic discs, a family history of glaucoma, symptoms of haloes, or a combination of these factors.The diagnostic categories were defined as follows:OCULAR HYPERTENSION An ocular tension of 2I mm.Hg or above by applanation tonometry, in the absence of glaucomatous field defects and with no evidence of angle closure.CHRONIC SIMPLE GLAUCOMA An ocular tension of 21 mm.Hg or above by applanation tonometry on two or more occasions, glaucomatous cupping of the disc, and visual field defects typical of glaucoma, and with no evidence of angle closure. LOW TENSION GLAUCOMAAs for chronic simple glaucoma, except that the ocular tension is persistently less than 21 mm.Hg by applanation tonometry. CLOSED-ANGLE GLAUCOMAA clear history of haloes typical of corneal oedema with gonioscopic evidence of a narrow angle capable of closure; or an ocular tension of 2I mm.Hg or above in the presence of obstruction of the angle by the root of the iris.