title: Estimated Trans-Lamina Cribrosa Pressure Differences in Low-Teen and High-Teen Intraocular Pressure Normal Tension Glaucoma: The Korean National Health and Nutrition Examination Survey.
abstract: BACKGROUND
  To 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.
  
  
  METHODS
  A 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.
  
  
  RESULTS
  In 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).
  
  
  CONCLUSIONS
  TLCPD 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.
authors: Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea.
authors: Si Hyung
authors: SH
authors: Lee
authors: Department of Statistics, University of Georgia, Athens, Georgia.
authors: Seung Woo
authors: SW
authors: Kwak
authors: Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea.
authors: Eun Min
authors: EM
authors: Kang
authors: Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea.
authors: Gyu Ah
authors: GA
authors: Kim
authors: Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea.
authors: Sang Yeop
authors: SY
authors: Lee
authors: Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea.
authors: Hyoung Won
authors: HW
authors: Bae
authors: Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea.
authors: Gong Je
authors: GJ
authors: Seong
authors: Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea.
authors: Chan Yun
authors: CY
authors: Kim
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D005260:Female; D005901:Glaucoma / Q000453:epidemiology / Q000503:physiopathology*; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000503:physiopathology*; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology