SPECTRALIS® Glaucoma Module Premium Edition

Clinical Mismatch Mismatch between clinically visible disc margin & SD-OCT-based disc margin SD-OCT BMO Obvious mismatch between clinician´s opinion and the SD-OCT-based disc margin. Where is the clinician looking for? Brightness changes (reflectivity), scleral ring (pale band), bending vessels, symmetry considerations. How does the SD-OCT define the disc margin? Are there anatomical landmarks the instrument is using as referring points? > Bruch´s Membrane Opening (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 Non-oblique Externally oblique Image Courtesy Dr. B.C. Chauhan, Halifax, Canada. Clinical disc margin BMO Reis et al. Ophthalmology 119:738-747,2012.

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 Clinician sees BMO (1), some aspect of border tissue of Elschnig (2) or indetermined structures of border tissue or Elschnig(3). Most predominant structure recognized as DM is some aspect of border tissue. BMO mostly invisible for clinician and by photography. Only SD-OCT able to detect deeper, relevant anatomical landmarks. Current disc margin delineation often inconsistent, inter-individually not always reproducible.

Overestimation of Rim Tissue Consequences Inconsistent definition of the disc margin can mean an underestimation of rim tissue. Using Bruch´s membrane opening (BMO) as a stable landmark provides a more accurate measurement of the ONH rim tissue. DM BMO Image Courtesy Dr. B.C. Chauhan, Halifax, Canada. An overestimation of rim tissue means the patient appears to be healthier than he/she actually is. The image to the right shows a significant mismatch of the clinical DM and the SD-OCT based DM. Clinical DM underestimates the remaining rim; whereas SD-OCT based disc margin is far outside.

Invisible BMO Bruch's Membrane Opening is a consistent landmark, but it is usually clinically and photographically invisible. BMO ONLY SD-OCT makes the BMO visible. No more vague interpretations of disc margin operator-independent reproducible 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. Reis et al. Invest Ophthalmology Vis Sci. 53: 1852-1860, 2012. BMO-MRW

Correct Rim Measurement Reis et al. Invest Ophthalmology Vis Sci. 53: 1852-1860, 2012. BMO-MRW Neuroretinal rim measurement from BMO to nearest point on internal limiting membrane (ILM) Shortest distance measurement Quantification of perpendicular cross section of nerve fibers exiting the eye Taking into account their varying trajectory at all 48 points of measurement Basic Information 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 FoBMO 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 FoBMO axis Geometric perspectives: The justification of choosing FoBMO axis is based on the anatomy. Both fovea and BMO centroid are anatomically consistent landmarks in human eyes. D. Hood and colleagues: retinal ganglion cell axons organized in a way along the FoBMO axis Figure 15. Changes in the RNFL bundle projections with different locations of the optic disc. (A) A digitally red-filtered fundus photo with tracings of 3 RNFL bundles in red. (B) Tracings as in panel A for 11 eyes. The green square with the red dot is the center of the optic disc. The open green square is the location on the disc associated with the RNFL originating at the 3 o'clock position on the red circles around the fovea. (C) Tracings from panel B after scaling and rotating to align the centers of the optic discs. From: D. Hood et al., Glaucomatous Damage in the Macula, Prog Retin Eye Res 2013; 1-21.

Anatomic Positioning System - APS BMO Fovea FoBMO - Axis

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 (FoBMO) center axis Consistent, accurate placement of subsequent scans and sectors for data analysis Automatic adjustment for head tilt during acquisition Key Feature !!!

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

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

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

Anatomic Positioning System - APS Advantages Automatic Individual / Customized Consistent Reliable No other OCT offers this functionality !!!

SPECTRALIS Glaucoma Module Premium Edition Rim analysis: IR image + SD-OCT B-scan Classification into WNL, Borderline and ONL BMO Rim Analysis

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

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

SPECTRALIS Glaucoma Module Premium Edition Internally oblique at nasal side Externally oblique at temp. side BMO Overview gives information on the overall status of the ONH. Color of arrows (BMO-MRW) dependent on classification of corresponding sector. Corresponding fundus camera image can be loaded and displayed in center instead of IR image showing disc margin based on SD-OCT image. Within normal limits Borderline Outside normal limits BMO Overview

SPECTRALIS Glaucoma Module Premium Edition „Beyond one´s own nose“ Progression

SPECTRALIS Glaucoma Module Premium Edition BMO Size: 1.85 mm2 BMO Size: 1.85 mm2 BMO-MRW OU Report

SPECTRALIS Glaucoma Module Premium Edition BMO-MRW & RNFL Single Eye Report