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Determining the Location of the Fovea Centralis Via En-Face SLO and Cross-Sectional OCT Imaging in Patients Without Retinal Pathology

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Determining the Location of the Fovea Centralis Via En-Face SLO and Cross-Sectional OCT Imaging in Patients Without Retinal Pathology Article Determining the Location of the Fovea Centralis Via En-Face SLO and Cross-Sectional OCT Imaging in Patients Without Retinal Pathology Archana A. Nair1, Rebecca Liebenthal1, Shefali Sood1, Grant L. Hom2, Marc E. Ohlhausen3,ThaisF.Conti2,CarolinaC.S.Valentim2, Hiroshi Ishikawa1, Gadi Wollstein1,JoelS.Schuman1, Rishi P. Singh2, and Yasha S. Modi1 1 Department of Ophthalmology, NYU Langone Health, New York University, New York, NY, USA 2 Center for Ophthalmic Bioinformatics, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA 3 Case Western Reserve University, Cleveland OH, USA Correspondence: Yasha S. Modi, 222 Purpose: The purpose was to establish the position of the fovea centralis to the optic E. 41st Street, 3rd Floor,NewYork,NY nerve via en-face, near-infrared spectral domain optical coherence tomography (NIR- 10017, USA. e-mail: OCT) in healthy patients. This may shed light on physiological variability and be used [email protected] for studying subtle cases of foveal ectopia in macular pathology and after retinal detach- Received: July 15, 2020 ment. Accepted: January 3, 2021 Methods: SD-OCT data of 890 healthy eyes were retrospectively analyzed. Exclusion Published: February 17, 2021 criteria included axial myopia causing tilting of the optic disc, peripapillary atrophy >1/3 Keywords: fovea centralis; OCT; the width of the disc, macular images excluding greater than half of the optic disc, retina and patients unable to maintain vertical head positioning. Two independent reviewers measured the horizontal and vertical distance from the fovea to the optic disc center and Citation: Nair AA, Liebenthal R, Sood optic disc diameter via cross-sectional and en-face scanning laser ophthalmoloscopy S, Hom GL, Ohlhausen ME, Conti TF, OCT imaging. Valentim CCS, Ishikawa H, Wollstein G, Schuman JS, Singh RP, Modi YS. Results: 890 eyes were included in the study. The right and left eyes differed in the Determining the location of the horizontal distance from the fovea to the disc center (4359 vs. 4248 μm, P < 0.001) fovea centralis via en-face SLO and and vertical distance from the fovea to the disc center (464 μm vs. 647, P < 0.001). This cross-sectional OCT imaging in corresponded to a smaller angle between the right and left eyes (6.07° vs. 8.67°, P < patients without retinal pathology. 0.001). Older age was associated with a larger horizontal (P = 0.008) and vertical distance Trans Vis Sci Tech. 2021;10(2):25, (0.025). These differences persisted after correcting for axial length in the 487 patients https://doi.org/10.1167/tvst.10.2.25 with axial-length data. Conclusions: This study compares the position of the fovea centralis among individuals without macular pathology on a micron level basis. The significant variability between right and left eyes indicates that contralateral eye evaluation cannot be reliably used. Rather, true foveal ectopia requires assessments of preoperative and postoperative NIR- OCT scans. This finding is relevant to retinal detachment cases and evaluation of subtle foveal ectopia. Translational Relevance: This finding is relevant to retinal detachment cases and evalu- ation of subtle foveal ectopia. 1–4 Introduction than 90% of individuals. However, a significant minority of patients with macula-off retinal detach- ments report persistent visual symptoms including Outcomes in retinal detachment surgery have dysmetropsia, distortion of image size,5 or metamor- tremendously improved. Modern studies report phopsia, distortion of image form.6,7 These symptoms anatomic success after the first procedure in more are believed to be related to retinal slippage and Copyright 2021 The Authors tvst.arvojournals.org | ISSN: 2164-2591 1 This work is licensed under a Creative Commons Attribution 4.0 International License. Downloaded from tvst.arvojournals.org on 10/01/2021 Location of the Fovea Centralis via En-Face OCT TVST | February 2021 | Vol. 10 | No. 2 | Article 25 | 2 Methods This study was a retrospective cross-sectional review of patients seen at two institutions: New York Univer- sity (NYU) and the Center for Ophthalmic Bioinfor- matics at the Cole Eye Institute, Cleveland Clinic. The study was approved by the Institutional Review Board with a waiver of consent at both NYU and Cleve- land Clinic. The research adhered to the tenants of the Declaration of Helsinki and complied with the Health and Insurance Portability and Accountability Act of 1996. Patient Selection Patients without macular disease or strabismus who underwent spectral domain optical coherence tomog- raphy (SD-OCT) who came for general ocular exami- Figure 1. En-face SLO OCT with fovea centralis and optic disc. nations were included in the study. The protocol was to image patients with their head vertical. Special atten- micron-to-millimeter–level transposition of the tion was made to ensure vertical alignment of the retina.8 Fundus autofluorescence highlights large- forehead and chin to normalize the torsional correc- scale inferior retinal slippage, often with postoperative tive moments of the eye before scanning. Patients “ghost vessels.” These hyper-autofluorescent “ghost were excluded from the study if they had (a) axial vessels” are thought to be areas of retinal pigmented myopia causing tilting of the optic disc, (b) peripap- epithelium, previously located under the blood vessels illary atrophy greater than 1/3 the width of the disc, but exposed to light postoperatively. Comparing the or (c) OCT imaging excluding greater than half of the “retinal pigmented epithelium ghost vessel” to the optic disc. Additionally, patients with glaucomatous retinal vasculature provides information on the degree cupping, retinopathy, torticollis, and kyphosis were of retinal displacement.9 In fact, foveal ectopia or excluded. retinal displacement after surgery may be seen in up 8–11 to 60% to 72% of patients. Although this imaging Measurements and Data Collection modality can identify large retinal transpositions, it is not ideal for identifying micron-level slippage. Often, SD-OCT measurements were conducted by two patients may be symptomatic despite normal FAF masked readers (A.N. and R.L) at NYU and (M.O and imaging, and thus a search to identify micron-level G.H.) at the Cole Eye Institute. Imaging was conducted changes in retinal transposition may be valuable. on Spectralis Heidelberg (Heidelberg Engineering, One possible imaging modality to assess this Heidelberg, Germany) and Cirrus (Zeiss, Dublin, with greater accuracy is the near-infrared scanning CA, USA) OCT platform. Technical specifications of laser ophthalmoscopy (SLO) image on optical coher- the Spectralis include a scan size of 496 pixels, axial ence tomography (OCT), which highlights the fovea image resolution 3.9 μm/pixel, lateral resolution of centralis with ease (Fig. 1). However, it is unknown 5.7 μm/pixel. Specifications for the Cirrus image where the “true” position of the fovea centralis is on include an axial image resolution 5 μm and lateral OCT and whether this changes with age, gender, axial resolution 10 μm/pixel. For each en-face SLO length, or between eyes. OCT image of the macula, the following measure- The purpose of this study was to establish the ments were conducted: (a) the horizontal distance position of the fovea centralis using both cross from the foveal center to the optic disc center sectional and en-face SLO OCT imaging in a normative (ODC, X on Fig. 2), (b) the vertical distance database of healthy patients of varying ages. Knowl- from the foveal center to the inferior disc margin edge of the normative position of the fovea centralis on (Y on Fig. 2), and (c) vertical disc height (Fig. 2) OCT may inform physiological variations and poten- on the OCT machines using in-built software. All tially, shed light on symptomatic patients after retinal patients were only imaged on one imaging platform. detachment. The apex of the superior and inferior nerves was Downloaded from tvst.arvojournals.org on 10/01/2021 Location of the Fovea Centralis via En-Face OCT TVST | February 2021 | Vol. 10 | No. 2 | Article 25 | 3 Figure 2. En-face SLO SD-OCT imaging. X measures the horizontal distance from the fovea centralis to the optic disc center. Y measures the vertical distance from the fovea centralis to optic disc center. Alpha represents the angle between the fovea centralis and the optic disc center. identified, and a vertical line connecting the two was ensure that the hyperreflective foveal centralis seen on made to identify the vertical disc height. The foveal SLO matched the true anatomic foveal dip. Repeat center was identified on the near-infrared imaging by measurements were done for patients with multiple a hyperreflective spot. This area was cross-referenced imaging studies at different time points to evaluate for with the foveal dip on the cross-sectional OCT to consistency of measurements at different scanning time Downloaded from tvst.arvojournals.org on 10/01/2021 Location of the Fovea Centralis via En-Face OCT TVST | February 2021 | Vol. 10 | No. 2 | Article 25 | 4 Table 1. Demographic Information Heidelberg (n = 218) Cirrus (n = 650) P Value Age (years) 50.49 67.0 <0.001 Age group (%) <0.001 <30 years 34 (15.60) 14 (2.15) 30–39 years 32 (14.68) 12 (1.85) 40–49 years 36 (16.51) 30 (4.62) 50–59 years 50 (22.94) 84 (12.92) 60–69 years 36 (16.51) 210 (32.31) >70 years 30 (13.76) 300 (46.15) points. The angle alpha was calculated from the data. All statistical analyses were conducted using Stata 14.2 Demographic information including age and gender (StataCorp, College Station, TX, USA). along with refraction, when available, were obtained via chart review. Axial length was collected, when available, with chart review. If refraction data were unavailable and patients’ uncorrected visual acuity was Results 20/20 on Snellen testing, refraction was estimated as plano.
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