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Henriet Springelkamp, Kyungmoo Lee, Albert Hofman, Caroline C W Klaver, Michael David Abramoff, Nomdo M Jansonius; Intraocular pressure decreases thickness of retinal nerve fiber and ganglion cell layers at the preclinical stage of glaucoma.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4339.
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© ARVO (1962-2015); The Authors (2016-present)
Glaucoma is characterized by a decrease of retinal ganglion cell layer (RGCL) and retinal nerve fiber layer (RNFL) thickness. An important risk factor for glaucoma is elevated intraocular pressure (IOP). The aim of this study was to investigate the relationship of IOP and RGCL and RNFL in subjects who have not yet reached the clinical status of glaucoma.
Participants of the population-based Rotterdam Study I (55+ years) underwent an extensive eye exam including IOP measurements (Goldmann applanation tonometry) and OCT scanning (Topcon 3D OCT 1000). Using the automated Iowa Reference Algorithms, macular thicknesses of RNFL and RGCL were determined in a 6x6 mm macular scan; peripapillary RNFL was determined in between two circles with radii of 1.03 and 1.84 mm centered on the optic disc. We performed linear regression analyses between IOP and retinal thicknesses. First, we determined this association in a cross-sectional analysis using the IOP from the same examination round. Second, we investigated IOP measurements 3-5 years prior to the OCT scan. Age and gender were incorporated as covariates, as were central corneal thickness (CCT) and axial length. The analyses were done separately in participants with and without glaucomatous visual field loss (GVFL).
839 individuals without GVFL were included in the analyses. Mean (sd) IOP was 13.9 mmHg (3.2), mean (sd) macular RNFL, macular RGCL, and peripapillary RNFL thicknesses were 36.7 µm (5.7), 26.9 µm (3.9), and 105.6 µm (21.7), respectively. The cross-sectional analyses did not reveal a significant association. The prospective analyses showed that a higher IOP 3-5 years prior to the OCT scan was associated with a lower peripapillary RNFL thickness (β=-0.65 µm, p<0.01), and a lower RNFL (β=-0.19 µm, p=0.04) and RGCL (β=-0.10 µm, p=0.02) macular thickness. The association remained significant after correction for CCT and axial length. The effect of IOP on the retinal layers was larger in individuals with GVFL (β=-1.60 µm, p=0.07 [peripapillary RNFL]; β=-0.30 µm, p=0.17 [macular RNFL]; and β=-0.23 µm, p=0.24 [macular RGCL]).
This study suggests that IOP affects RNFL and RGCL thickness in individuals who have not yet developed functional glaucomatous defects. Whether subjects with a relatively thin RGCL or RNFL benefit from IOP lowering medication is an intriguing question for future research.
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