Shields Gray Crescents Masquerading as Glaucomatous Cupping of the Optic Nerve Head  Mohamed S. Sayed, MD, Michael Margolis, MD, Jessica L. Chen, MD, Giovanni Gregori, PhD, Richard K. Lee, MD, PhD  Ophthalmology Glaucoma  Volume 1, Issue 2, Pages 99-107 (September 2018) DOI: 10.1016/j.ogla.2018.08.001 Copyright © 2018 American Academy of Ophthalmology Terms and Conditions

Figure 1 A and B, Type A gray crescent. The colored optic disc photographs show the true edge of the disc as seen clinically, as well as the pseudo-disc margin constituted by the edge of the type A gray crescent. Note the gradual thinning followed by cessation of the retinal pigment epithelium (RPE)-Bruch’s membrane complex, causing an enhancement of signal at the choroid level on spectral-domain (SD) OCT and resulting in clinical gray crescent. The white arrow shows the termination of the RPE-Bruch’s membrane complex, and the yellow arrow points the edge of the type A gray crescent, marking the end of the choroidal hyper-reflectivity zone. Type A gray crescent falls between the white and the yellow arrows on the OCT cross-section. Ophthalmology Glaucoma 2018 1, 99-107DOI: (10.1016/j.ogla.2018.08.001) Copyright © 2018 American Academy of Ophthalmology Terms and Conditions

Figure 2 A and B, Type B gray crescent. Note the clumping of the retinal pigment epithelium (RPE)-Bruch’s membrane complex that appears folded upon itself on spectral-domain (SD) OCT, resulting in a clinical gray crescent. The white arrowheads define the edges of the folded/clumped segment of RPE-Bruch’s membrane complex underlying the clinically identifiable type B gray crescent. A, Temporal type B gray crescent showing clumping of the RPE-Bruch’s membrane complex on SD OCT (white circle) in association with parapapillary atrophy (PPA) with thinning of the RPE-Bruch’s membrane complex and choroidal hyperreflectivity (green circle). Note that in the colored photograph, the true disc margin is obscured and difficult to identify because of the presence of both the type B gray crescent and PPA. B, Type B gray crescent. The colored photograph shows the true edge of the disc as clinically seen and the edge of the type B gray crescent. Ophthalmology Glaucoma 2018 1, 99-107DOI: (10.1016/j.ogla.2018.08.001) Copyright © 2018 American Academy of Ophthalmology Terms and Conditions

Figure 3 A and B, Normal nerve fiber layer assessment in gray crescent. A, Note the difference between the perceived optic disc border (green arrows) and the actual optic disc border (black arrows) in the left eye of a patient with a temporal type A gray crescent, adding a pseudo-cupping component to the cup-to-disc ratio. Also note the presence of parapapillary atrophy (PPA) outside the actual optic disc border. The PPA appears lighter in color compared with the adjacent temporal gray crescent. B, Standard retinal nerve fiber layer (RNFL) analysis (Cirrus; Carl Zeiss Meditec Inc., Dublin, CA) demonstrating normal average RNFL thickness and normal RNFL thickness in the temporal quadrant of left eye, corresponding to the location of the gray crescent, despite suspicious thinning of superior RNFL on the quadratic map. Left eye analyses demarcated by black line; temporal RNFL demarcated by red line in RNFL thickness map. Ophthalmology Glaucoma 2018 1, 99-107DOI: (10.1016/j.ogla.2018.08.001) Copyright © 2018 American Academy of Ophthalmology Terms and Conditions

Figure 4 A–C, The retinal nerve fiber layer (RNFL) thickness as measured by RTVue (Optovue, Fremont, CA) RNFL 3.45 scan and Cirrus RNFL analysis. A, Temporal type A gray crescent in the right eye, with a gradual thinning of the RPE-Bruch’s membrane complex and enhancement of signal at the choroid level on spectral-domain (SD) OCT and resulting in clinical gray crescent. Note the difference between the perceived optic disc border (green arrows) and the actual optic disc border (black arrows). B, RTVue RNFL 3.45 scan showing only borderline temporal thinning on the RNFL, less than would be expected in the apparent degree of cupping implied by the gray crescent. C, Cirrus RNFL analysis showing temporal borderline RNFL thickness, correlating with the measurement obtained by the RTVue RNFL 3.45 scan. Note the lower values of the Cirrus RNFL analysis. Right eye analyses marked by black line on Cirrus printout. Ophthalmology Glaucoma 2018 1, 99-107DOI: (10.1016/j.ogla.2018.08.001) Copyright © 2018 American Academy of Ophthalmology Terms and Conditions

Figure 4 A–C, The retinal nerve fiber layer (RNFL) thickness as measured by RTVue (Optovue, Fremont, CA) RNFL 3.45 scan and Cirrus RNFL analysis. A, Temporal type A gray crescent in the right eye, with a gradual thinning of the RPE-Bruch’s membrane complex and enhancement of signal at the choroid level on spectral-domain (SD) OCT and resulting in clinical gray crescent. Note the difference between the perceived optic disc border (green arrows) and the actual optic disc border (black arrows). B, RTVue RNFL 3.45 scan showing only borderline temporal thinning on the RNFL, less than would be expected in the apparent degree of cupping implied by the gray crescent. C, Cirrus RNFL analysis showing temporal borderline RNFL thickness, correlating with the measurement obtained by the RTVue RNFL 3.45 scan. Note the lower values of the Cirrus RNFL analysis. Right eye analyses marked by black line on Cirrus printout. Ophthalmology Glaucoma 2018 1, 99-107DOI: (10.1016/j.ogla.2018.08.001) Copyright © 2018 American Academy of Ophthalmology Terms and Conditions