BackgroundTo investigate the association between estimated trans-lamina cribrosa pressure difference (TLCPD) and prevalence of normal tension glaucoma (NTG) with low-teen and high-teen intraocular pressure (IOP) using a population-based study design.MethodsA total of 12,743 adults (≥ 40 years of age) who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) from 2009 to 2012 were included. Using a previously developed formula, cerebrospinal fluid pressure (CSFP) in mmHg was estimated as 0.55 × body mass index (kg/m2) + 0.16 × diastolic blood pressure (mmHg)—0.18 × age (years)—1.91. TLCPD was calculated as IOP–CSFP. The NTG subjects were divided into two groups according to IOP level: low-teen NTG (IOP ≤ 15 mmHg) and high-teen NTG (15 mmHg < IOP ≤ 21 mmHg) groups. The association between TLCPD and the prevalence of NTG was assessed in the low- and high-teen IOP groups.ResultsIn the normal population (n = 12,069), the weighted mean estimated CSFP was 11.69 ± 0.04 mmHg and the weighted mean TLCPD 2.31 ± 0.06 mmHg. Significantly higher TLCPD (p < 0.001; 6.48 ± 0.27 mmHg) was found in the high-teen NTG compared with the normal group. On the other hand, there was no significant difference in TLCPD between normal and low-teen NTG subjects (p = 0.395; 2.31 ± 0.06 vs. 2.11 ± 0.24 mmHg). Multivariate logistic regression analysis revealed that TLCPD was significantly associated with the prevalence of NTG in the high-teen IOP group (p = 0.006; OR: 1.09; 95% CI: 1.02, 1.15), but not the low-teen IOP group (p = 0.636). Instead, the presence of hypertension was significantly associated with the prevalence of NTG in the low-teen IOP group (p < 0.001; OR: 1.65; 95% CI: 1.26, 2.16).ConclusionsTLCPD was significantly associated with the prevalence of NTG in high-teen IOP subjects, but not low-teen IOP subjects, in whom hypertension may be more closely associated. This study suggests that the underlying mechanisms may differ between low-teen and high-teen NTG patients.

BackgroundTo investigate the association between heavy metal levels and open-angle glaucoma (OAG) with low- and high-teen baseline intraocular pressure (IOP) using a population-based study design.MethodsThis cross-sectional study included 5,198 participants older than 19 years of age who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2012 and had blood heavy metal levels available. The OAG with normal baseline IOP (IOP ≤ 21 mmHg) subjects were stratified into low-teen OAG (baseline IOP ≤ 15 mmHg) and high-teen OAG (15 mmHg < baseline IOP ≤ 21 mmHg), and the association between blood lead, mercury, and cadmium levels and glaucoma prevalence was assessed for low- and high-teen OAG.ResultsThe adjusted geometric mean of blood cadmium levels was significantly higher in subjects with low-teen OAG than that of the non-glaucomatous group (P = 0.028), whereas there were no significant differences in blood lead and mercury levels. After adjusting for potential confounders, the low-teen OAG was positively associated with log-transformed blood cadmium levels (OR, 1.41; 95% confidence interval (CI), 1.03–1.93; P = 0.026). For high-teen OAG, log-transformed blood levels of the three heavy metals were not associated with disease prevalence. The association between log-transformed blood cadmium levels and low-teen OAG was significant only in men (OR, 1.65; 95% CI, 1.10–2.48; P = 0.016), and not in women (OR, 1.10; 95% CI, 0.66–1.85; P = 0.709).ConclusionsThe results of this study suggest that cadmium toxicity could play a role in glaucoma pathogenesis, particularly in men and in OAG with low-teen baseline IOP.

PurposeTo investigate associations of estimated cerebrospinal fluid pressure (CSFP) and trans‐lamina cribrosa pressure difference (TLCPD) with glaucomatous optic neuropathy in a population‐based setting.MethodsA total of 6656 adults (≥40 years) who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) from 2009 to 2012 were included. Subjects were divided into non‐glaucomatous and glaucomatous group, and glaucomatous subjects were further divided into normal tension glaucoma (NTG) group and high tension glaucoma (HTG) group. Based on a previous study with lumbar CSFP measurements, CSFP was estimated as CSFP (mmHg) = 0.55 Body Mass Index(kg/m2) + 0.16 Diastolic Blood Pressure(mmHg)‐0.18 × Age(years)−1.91. TLCPD was calculated as intraocular pressure (IOP)‐CSFP. Differences in estimated CSFP and TLCPD were assessed between the non‐glaucomatous and glaucomatous groups.ResultsIn the non‐glaucomatous population (n = 6016), mean estimated CSFP was 11.38 ± 3.11 mmHg and mean TLCPD was 2.54 ± 3.83 mmHg. When compared to the glaucoma group (n = 640), lower IOP (p < 0.001), higher CSFP (p < 0.001), and lower TLCPD (p < 0.001) were observed in the non‐glaucomatous group. Differences between glaucomatous subjects and non‐glaucomatous subjects in estimated CSFP, TLCPD, and IOP were greater for the HTG subjects than for the NTG subjects.ConclusionsEstimated CSFP and TLCPD may play a significant role in pathogenesis of NTG and HTG.