Detecting optic nerve head deformation and retinal nerve fiber layer thinning in glaucoma progression

Abstract

The application of digital imaging technologies including confocal scanning laser ophthalmoscopy (CSLO), optical coherence tomography (OCT), and scanning laser polarimetry (SLP) has significantly improved the detection of optic nerve head (ONH) deformation and progressive retinal nerve fiber layer (RNFL) thinning for assessment of glaucoma progression. Algorithms for change analysis such as topographic change analysis and guided progression analysis perform event analysis of serial ONH surface height topology maps and RNFL thickness/RNFL retardance maps, respectively, providing a topographical display of the location of significant change. With spectral-domain OCT, it is feasible to delineate and measure the lamina cribrosa surface depth in addition to ONH surface depth and RNFL thickness. Growing evidence from experimental and clinical studies indicates that ONH and lamina cribrosa deformation can be observed prior to detectable RNFL thinning and functional loss in glaucoma. These findings lend support to the notion that upon detection of ONH/lamina cribrosa deformation, a time window for therapeutic intervention for better outcomes may exist. The ONH and the lamina cribrosa are therefore important targets for monitoring glaucoma progression. This review summarizes the latest findings comparing the performance of OCT, CSLO, and SLP for detection of progressive ONH and RNFL damages in glaucoma patients and the clinical implication and limitations of studying the morphological alteration of the ONH, lamina cribrosa, and RNFL in the assessment of glaucoma progression.

Keywords: glaucoma; guided progression analysis; optic nerve head deformation; retinal nerve fiber layer thinning; topographic change analysis.

Fig. 1

(A) Serial retinal nerve fiber layer (RNFL) thickness maps, (B) RNFL thickness change maps, (C) optic nerve head (ONH) surface topology, (D) ONH significance maps, (E) visual field pattern deviation plots, and (F) guided progression analysis (Early Manifest Glaucoma Trial criteria) of the left eye of a 27-year-old glaucoma patient followed for 50.4 months. Diffuse ONH surface depression was detected on November 2, 2009, which was then followed by superior (June 25, 2010) and inferior (November 29, 2012) RNFL thinning and visual field progression. Note. From “Optic nerve head deformation in glaucoma: the temporal relationship between optic nerve head surface depression and retinal nerve fiber layer thinning,” G. Xu, R.N. Weinreb, and C.K. Leung, 2014, Ophthalmology, 121, p. 2362–2370. Copyright 2014. Elsevier. Reprinted with permission.

Fig. 2

(A) An optical coherence tomography cross-sectional image of the optic nerve head illustrating the measurement of (B) the anterior lamina cribrosa surface depth and (C) optic nerve head surface depth after manual detection of the Bruch's membrane opening (pink dots), internal limiting membrane/optic nerve head surface (green), and anterior lamina cribrosa surface (orange). The reference line (pink) is a line joining the Bruch's membrane opening.

Fig. 3

Serial retinal nerve fiber layer (RNFL) thickness maps (A, upper panel), RNFL thickness change maps (A, lower panel), RNFL retardance maps (B, upper panel), and RNFL retardance change maps (B, lower panel) of a glaucomatous eye. Progression was evident in the RNFL thickness change map (on March 4, 2011) approximately 11 months before it became noticeable in the RNFL retardance change map (on February 16, 2012). Note. From “Retinal nerve fiber layer progression in glaucoma: a comparison between retinal nerve fiber layer thickness and retardance,” G. Xu, R.N. Weinreb and C.K. Leung, 2013, Ophthalmology, 120, p. 2493e2500. Copyright 2013. Elsevier. Reprinted with permission.