SPECTRALIS Glaucoma Module Premium Edition Clinical Mismatch between

SPECTRALIS® Glaucoma Module Premium Edition

Clinical Mismatch between clinically visible disc margin & SD-OCT-based disc margin SD-OCT BMO Clinically Visible Optic Disc Margin Image Courtesy Dr. Balwantray C. Chauhan, Halifax, Canada and Dr. Claude F. Burgoyne, Portland, USA.

Variable Rim Tissue § Internally oblique § Externally oblique § Non-oblique BMO Image Courtesy Dr. B. C. Chauhan, Halifax, Canada. Reis et al. Ophthalmology 119: 738 -747, 2012. Clinical disc margin

Clinical Disc Margin Conclusion § The clinical optic disc margin is hard to identify § In practice the clinician is looking at 3 different tissues when defining the disc margin § BMO (1), RPE tips (endings; 2), some aspect of border tissue of Elschnig (3) § The clinical disc margin is inconsistent as an anatomical landmark for the outer border of the rim § Each individual ONH can have regions of internally and / or externally oblique border tissues

Overestimation of Rim Tissue Consequences § Inconsistent definition of the disc margin can mean an underestimation of rim tissue. DM BMO § Using Bruch´s membrane opening (BMO) Image Courtesy Dr. B. C. Chauhan, Halifax, Canada. as a stable landmark provides a more accurate measurement of the ONH rim tissue.

Invisible BMO § Bruch's Membrane Opening is a consistent landmark, but it is usually clinically and photographically invisible. BMO Image Courtesy Dr. B. C. Chauhan, Halifax, Canada.

Geometric Orientation § Even if BMO is used as a stable landmark by SD-OCT, we still need to measure the neuroretinal rim in the correct geometric orientation. BMO-MRW Reis et al. Invest Ophthalmology Vis Sci. 53: 1852 -1860, 2012.

Basic Information Correct Rim Measurement § Neuroretinal rim measurement from BMO to nearest point on internal limiting membrane (ILM) BMO-MRW § Shortest distance measurement § Quantification of perpendicular cross section of nerve fibers exiting the eye Reis et al. Invest Ophthalmology Vis Sci. 53: 1852 -1860, 2012. § Taking into account their varying trajectory at all 48 points of measurement Cross Section of RNF

Current Reality § Current sectorial analysis is made with fixed horizontal and vertical axes on the image. AIF Horizontal (N/T) Axis AIF Vertical (S/I) Axis Acquired Image Frame (AIF)

Range of Variability of Fo. BMO Axes § Inter-individual variability in the axis connecting the Fovea and Bruch’s Membrane Opening (BMO) center < + 2° to - 18° * * Examples taken from the HDEng SPECTRALIS normative data collection

Anatomically Normalized Eyes § Anatomically consistent landmark in all human eyes § BMO is a true anatomic boundary of the RGC axons § BMOcentroid is the center of BMO § Fovea is the anatomic center of the retina § RGC axons organized relative to the Fo. BMO axis From: D. Hood et al. , Glaucomatous Damage in the Macula, Prog Retin Eye Res 2013; 1 -21.

Anatomic Positioning System - APS BMO Fovea xis A Fo. BMO -

Anatomic Positioning System - APS § Locates points in the eye using two fixed, structural landmarks § center of the fovea and § center of the Bruch’s Membrane Opening (BMO) § Automatic detection of landmarks during initial APS scan § Automatic alignment of scans relative to patient’s individual Fovea to - Bruch’s Membrane Opening (Fo. BMO) center axis § Consistent, accurate placement of subsequent scans and sectors for data analysis § Automatic adjustment for head tilt during acquisition

Anatomic Positioning System - APS Without SPECTRALIS APS Ø Same eye scanned on separate visits (no APS or Auto. Rescan) Ø Head tilt causes significant variability of classification results

Anatomic Positioning System - APS With SPECTRALIS APS Ø Consistent positioning for each individual’s anatomy Ø Two eyes with different anatomical positions of fovea relative to the center of the BMO (A and B) Ø Scan orientation automatically aligned along the individual’s Fo. BMO axis

Anatomic Positioning System - APS Ø Accurate geometric relations between nerve fiber defects can be established, which are observed in ONH, RNFL and the Posterior Pole Asymmetry Analysis Ø Easy correlation between analysis methods

Anatomic Positioning System - APS Advantages § Automatic § Consistent § Individual / Customized § Reliable

SPECTRALIS Glaucoma Module Premium Edition BMO Rim Analysis

SPECTRALIS Glaucoma Module Premium Edition Garway-Heath Sectors ° 40 Current Sectors Advantages 110° ° 40 40 ° 90° § Sector orientation aligned with nerve fiber bundle trajectory § Better structure-function correlation § Same eye – different sector distribution References: Garway-Heath DF et al. Mapping the Visual Field to the Optic Disc in Normal Tension Glaucoma Eyes. Ophthalmology 2000; 107: 1809– 1815.

SPECTRALIS Glaucoma Module Premium Edition Current Classification New Display Percentile: § Percentage of normal eyes have a rim this thin or thinner Actual thickness (Mean thickness value) Actual thickness (Percentile) § Different eyes – different displays § Remember HRT !!!

SPECTRALIS Glaucoma Module Premium Edition Internally oblique at nasal side Externally oblique at temp. side Within normal limits Borderline Outside normal limits BMO Overview