The Relationship between Intraocular Pressure and Progressive Retinal Nerve Fiber Layer Loss in Glaucoma

Abstract

Purpose-To evaluate the relationship between intraocular pressure (IOP) and progressive retinal nerve fiber layer (RNFL) loss, as measured by scanning laser polarimetry with enhanced corneal compensation (GDx ECC), in a cohort of glaucoma patients and individuals suspected of having the disease followed over time. Design-Observational cohort study.Participants-The study included 344 eyes of 204 patients recruited from the Diagnostic Innovations in Glaucoma Study (DIGS). There were 98 eyes (28%) with a diagnosis of glaucoma and 246 (72%) were considered glaucoma suspects at baseline.Methods-Images were obtained annually with the GDx ECC scanning laser polarimeter, along with stereophotographs and SAP. The study included a total of 1211 GDx ECC visits with an average of 3.5 visits per eye. Progression was determined by the Guided Progression Analysis software for SAP and by masked assessment of stereophotographs performed by expert graders.Main Outcome Measures-Random coefficient models were used to evaluate the relationship between IOP and RNFL thickness measurements over time in progressors and nonprogressors. Models were adjusted for baseline diagnosis and central corneal thickness.Results-For all 344 eyes, the overall rate of change for the GDx ECC average thickness at an average IOP of 17 mmHg was −0.25 μm per year (P = 0.002). Each 1-mmHg higher IOP was associated with an additional loss of 0.05 μm per year of RNFL (P = 0.001). Twenty-nine eyes (8%) showed progression on SAP and/or optic disc stereophotographs. These eyes had a significantly higher rate of RNFL change (−0.95μm/year) than nonprogressors (−0.17 μm/year; P = 0.001). For progressors, each 1-mmHg higher IOP was associated with an additional loss of 0.13 μm per year of RNFL.Conclusions-Higher levels of IOP during follow-up were significantly related to higher rates of progressive RNFL loss detected by the GDx ECC. These findings suggest that the GDx ECC may be helpful in monitoring progression and estimating rates of change in patients with glaucoma or suspected of having the disease. Also, they may contribute to a better understanding of the relationship between IOP and structural deterioration in glaucoma. NIH Public Access Author ManuscriptOphthalmology. Author manuscript; available in PMC 2010 June 1. Published in final edited form as:Ophthalmology. 2009 June ; 116(6): 1125-33.e1-3. doi:10.1016/j.ophtha.2008.12.062. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptSeveral prospective clinical trials have provided compelling evidence for the role of intraocular pressure (IOP) as the main risk factor for development and progression of glaucoma. [1][2][3][4][5][6] In the Ocular Hypertension Treatment Study (OHTS), IOP-lowering therapy was associated with a 54% relative reduction in the risk of developing primary open-angle glaucoma during followup. 7 For disease progression, the Early Manifest Glaucoma Trial showed that each 1-mmHg higher mean IOP during follow-up was associated with a 12% increase in the chance o...

Longitudinal observation of the retinal nerve fibre layer in glaucoma patients treated with brimonidine combined with timolol or timolol alone

“…In our study, the mean RNFL loss varied between 1.7 and 1.8 μm/year. It is known that IOP higher than 17 mm Hg induces an additional 0.05 μm/year RNFL loss for each increased 1 mm Hg [14,15]. Surprisingly, even single, short-lasting IOP peaks above 21 mm Hg in our analysis, significantly decreased RNFL thickness, although mean IOP remained within the normal levels.…”

“…Thus, it might be essential to observe daily fluctuations, especially in glaucoma patients who show disease progression. Retinal thickness analysis with the time domain OCT is commonly considered to be less reliable compared with the spectral domain OCT; however, numerous reports suggest that TD OCT is as reliable as SD OCT to measure RNFL thickness and glaucoma progression [15,17].…”

Assessment of rates of structural change in glaucoma using imaging technologies

“…19 (DIGS). Patients who manifested progression of glaucoma on SAP-GPA showed a significantly higher rate of RNFL change compared with non-progressors (À0.95 vs À0.17 mm/year; P ¼ 0.001).…”

“…8 Results from these imaging technologies can be used to predict glaucoma development, [9][10][11][12][13] and have the potential to detect and measure structural progression. 7,[14][15][16][17][18][19][20][21][22][23][24] Recent literature has focused on the ability of these instruments to provide estimates of rates of change over time. In this review, we discuss the evidence with regard to the ability of current imaging technologies in measuring rates of structural change in glaucoma and their relationship to conventional methods for assessment of disease progression.…”

Reducing Variability in Visual Field Assessment for Glaucoma Through Filtering That Combines Structural and Functional Information

“…Examination of the ONH/RNFL normally is conducted through direct observation of the ONH and via imaging techniques, such as confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph [HRT]; Heidelberg GmbH, Heidelberg, Germany) or spectraldomain optical coherence tomography (SD-OCT). It has been reported frequently that structural abnormality can be detected before functional damage in eyes with POAG, [4][5][6][7][8][9][10][11] but sometimes functional damage can occur without apparent structural damage assessed using conventional methods. 7,12,13 However, this observed lack of concordance may be due to variability in test results rather than a true time lag alone.…”