Aim: To compare the pattern of localised nerve fibre layer (NFL) defects in normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). Methods: 50 NTG eyes and 36 POAG eyes, all with localised NFL defects, were enrolled. On retinal NFL photography, the proximity of the defect to the centre of the fovea (angle α) and the sum of the angular width of the defects (angle β) were determined. Angle α was the angle made by a line from the centre of the fovea to the disc centre and a line from the disc centre to the disc margin, where the nearest border of the defect met. The patterns of localised NFL defects in NTG and POAG were compared with angles α and β. Independent t test was used for statistical analysis. Results: Angle α in NTG (35.1 (SD 20.0)°) was significantly smaller than that of POAG (45.9 (21.9)°) (p=0.02), while angle β in NTG (49.0 (31.9)°) was significantly larger than that of POAG (33.1 (23.9)°) (p=0.01). Conclusions: The pattern of NFL defects in NTG was different from that in POAG. Localised NFL defects in NTG were closer to the fovea and wider in width than those in POAG.

Purpose Homozygous polymorphism of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene and resultant hyperhomocysteinaemia have been established as an independent risk factor for vascular diseases. There are evidences that vascular abnormalities are involved in the pathogenesis and progression of normaltension glaucoma (NTG). In the present study, we were to find out the associations between 677C4T and 1298A4C polymorphisms of the MTHFR gene and NTG. Methods This was a retrospective, casecontrolled study enrolling 78 NTG patients and 100 controls. DNA from peripheral blood lymphocytes was extracted and the genotypes of polymorphisms (677C4T and 1298A4C) in the MTHFR gene were determined using PCR followed by restriction enzyme digestion. The frequencies of the polymorphic genotypes in the patients with NTG and controls were compared. Results The frequencies of the polymorphisms of the MTHFR gene (677C4T and 1298A4C) in the NTG patients were not significantly different from those of controls. But the younger NTG patients (age at diagnosis p45 years) showed significantly higher prevalence of 677C4T polymorphism than the older NTG patients (age at diagnosis 445 years) (TT genotype, 38.9 vs 11.9%, P ¼ 0.006, OR ¼ 4.71, 95% CI ¼ 1.49-14.9) and than the younger control subgroup (TT genotype, 38.9 vs 6.1%, P ¼ 0.001, OR ¼ 9.86, 95% CI ¼ 2.23-42.4). Conclusions The 677C4T polymorphism was significantly associated with NTG in the younger patients, while 1298A4C polymorphism was not. This suggests that 677C4T polymorphism of the MTHFR gene can be a genetic risk factor of NTG in Korean population.