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SPECTRALIS® Glaucoma Module Premium Edition. SD-OCT BMO Clinically Visible Optic Disc Margin Image Courtesy Dr. Balwantray C. Chauhan, Halifax, Canada.

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Presentation on theme: "SPECTRALIS® Glaucoma Module Premium Edition. SD-OCT BMO Clinically Visible Optic Disc Margin Image Courtesy Dr. Balwantray C. Chauhan, Halifax, Canada."— Presentation transcript:

1 SPECTRALIS® Glaucoma Module Premium Edition

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

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

4 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 Clinical Disc Margin

5 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. Overestimation of Rim Tissue

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

7  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. Geometric Orientation Reis et al. Invest Ophthalmology Vis Sci. 53: , BMO-MRW

8 Correct Rim Measurement Basic Information  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 Reis et al. Invest Ophthalmology Vis Sci. 53: , BMO-MRW Cross Section of RNF

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

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

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

12 Anatomic Positioning System - APS Fovea BMO FoBMO - Axis

13 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

14 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

15 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

16 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

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

18 BMO Rim Analysis SPECTRALIS Glaucoma Module Premium Edition

19 Current SectorsGarway-Heath Sectors 40° 110° 90° 40°  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. Advantages  Sector orientation aligned with nerve fiber bundle trajectory  Better structure-function correlation

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

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

22 Progression

23 SPECTRALIS Glaucoma Module Premium Edition BMO-MRW OU Report BMO Size: 1.85 mm 2

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


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