Incidence of Normal Tension Glaucoma (NTG) in Health Check-up Examinees and Circulatory Factors before and after Fundus Changes

It is generally understood that the prevalence of normal tension glaucoma (NTG) is 2% in adults, and is related to some changes in the circulatory system. We surveyed NTG in our Medicine & Health Sciences Institute and compared check-up data before and after appearance of fundus abnormalities. Method Fundus photos were closely examined by ophthalmologists concerning four aspects: (1) bayoneting at the edge of the optic disc, (2) notching at the disc's edge, (3) Nerve fiber layer defect (NFLD), and (4) splinter hemorrhage at the disc's edge. Then the abnormal fundus findings were retrospectively checked and the data on check-up before and after the appearance of fundus abnormality were discussed. Results There were 69 patients with visual field change in NTG among 10, 490 examinees who visited during the previous 12 months. There were also another 76 with abnormal results but in whom follow-up was not possible in our institution. If we assume that they had a similar rate of visual field change in NTG, we can predict that the incidence would be approximately 1.0%. Circulatory factors were compared between the normal and abnormal visual field groups. but no significant difference was found. Furthermore, the fundus photos of the 69 patients with NTG were retrospectively searched from their initial to the latest visit. We found that 57 (83%) patients had actually had fundus changes from their initial visit while 12 (17%) developed the changes during follow-up. Then circulatory factors before and after fundus changes in the latter 12 patients were compared but no significant trends were seen. Conclusion The prevalence of NTG was 1% in adults in our Medicine & Health Sciences Institute. It was not suggested that NTG might reflect circulatory factors. To detect NTG in health check-ups, it is important that the examination on the four points described above should be checked on fundus photos.