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Retinal nerve fibre layer and visual function loss in glaucoma: the tipping point.
- Source :
-
The British journal of ophthalmology [Br J Ophthalmol] 2012 Jan; Vol. 96 (1), pp. 47-52. Date of Electronic Publication: 2011 Apr 08. - Publication Year :
- 2012
-
Abstract
- Aims: To determine the retinal nerve fibre layer (RNFL) thickness at which visual field (VF) damage becomes detectable and associated with structural loss.<br />Methods: In a prospective cross-sectional study, 72 healthy and 40 glaucoma subjects (one eye per subject) recruited from an academic institution had VF examinations and spectral domain optical coherence tomography (SD-OCT) optic disc cube scans (Humphrey field analyser and Cirrus HD-OCT, respectively). Comparison of global mean and sectoral RNFL thicknesses with VF threshold values showed a plateau of threshold values at high RNFL thicknesses and a sharp decrease at lower RNFL thicknesses. A 'broken stick' statistical model was fitted to global and sectoral data to estimate the RNFL thickness 'tipping point' where the VF threshold values become associated with the structural measurements. The slope for the association between structure and function was computed for data above and below the tipping point.<br />Results: The mean RNFL thickness threshold for VF loss was 75.3 μm (95% CI: 68.9 to 81.8), reflecting a 17.3% RNFL thickness loss from age-matched normative value. Above the tipping point, the slope for RNFL thickness and threshold value was 0.03 dB/μm (CI: -0.02 to 0.08) and below the tipping point, it was 0.28 dB/μm (CI: 0.18 to 0.38); the difference between the slopes was statistically significant (p<0.001). A similar pattern was observed for quadrant and clock-hour analysis.<br />Conclusions: Substantial structural loss (∼17%) appears to be necessary for functional loss to be detectable using the current testing methods.
- Subjects :
- Adult
Aged
Algorithms
Cross-Sectional Studies
Disease Progression
Female
Glaucoma, Open-Angle physiopathology
Humans
Longitudinal Studies
Male
Middle Aged
Models, Statistical
Nerve Fibers pathology
Nerve Fibers physiology
Prospective Studies
Retina physiopathology
Severity of Illness Index
Tomography, Optical Coherence statistics & numerical data
Vision Disorders physiopathology
Glaucoma, Open-Angle pathology
Retina pathology
Tomography, Optical Coherence methods
Vision Disorders pathology
Visual Fields physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1468-2079
- Volume :
- 96
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- The British journal of ophthalmology
- Publication Type :
- Academic Journal
- Accession number :
- 21478200
- Full Text :
- https://doi.org/10.1136/bjo.2010.196907