Optic Nerve Head Development in Healthy Infants and Children Using Handheld Spectral-Domain Optical Coherence Tomography Aarti Patel, BSc, MBChB, 1 Ravi Purohit, MSc, BMedSci, 1 Helena Lee, PhD, FRCOphth, 2 Viral Sheth, BMedSci, 1 Gail Maconachie, BMedSci, PhD, 1 Eleni Papageorgiou, MSc, PhD, 3 Rebecca J. McLean, MSc, PhD, 1 Irene Gottlob, MD, FRCOphth, 1 Frank A. Proudlock, MSc, PhD 1 Purpose: To determine feasibility of optic nerve head (ONH) imaging and to characterize ONH development in full-term infants without sedation using handheld spectral-domain optical coherence tomography (SD OCT). Design: Prospective cross-sectional study. Participants: Three hundred fifty-two children aged between 1 day and 13 years. Methods: All participants were imaged using handheld SD OCT without sedation during a single scan session. The percentage of successful scans was calculated. Interexaminer reproducibility and differences between right and left eyes were assessed using intraclass correlation coefficients (ICCs). Images were analyzed using ImageJ software. The developmental trajectories over time for ONH parameters were calculated using fractional polynomial modelling. Main Outcome Measures: Disc and cup diameter (expressed as distance in micrometers and visual angle in degrees), cup depth, Bruch’s membrane openingeminimum rim width (BMO-MRW), retinal thickness, and retinal nerve fiber layer (RNFL; 1700 mm and 6  from the disc center). Results: On average, 70% of participants were imaged successfully. Interexaminer reliability was excellent (ICC, >0.89) for diametric and retinal thickness parameters. Right and left eyes were similar for diametric measurements (ICC, >0.79), but more variable for nasal BMO-MRW, RNFL, and retinal thickness. The mean disc and cup diameter increase by 30% and 40%, respectively, between birth and 13 years of age when expressed as a distance measure, but remained constant (at 5  e5.5  and 2  , respectively) when expressed as a visual angle with reference to the eye nodal point. The peripapillary temporal RNFL demonstrated a marked initial decrease of nearly 35% between birth and approximately 18 months of age. This was followed by a slow increase up to 12 years of age when measured at 1700 mm from the disc center, although there was little change when measured at 6  from the disc center. Conclusions: We demonstrated feasibility of handheld SD OCT imaging of the ONH in full-term infants and children without anaesthesia or sedation. This is the first in vivo handheld SD OCT study to describe the development of ONH parameters during the critical early years of visual maturation. Our results provide a normative database for use in routine practice and further studies of ONH pathologic features. Ophthalmology 2016;123:2147-2157 ª 2016 by the American Academy of Ophthalmology. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Supplemental material is available at www.aaojournal.org. The appearance of the optic nerve head (ONH) can indicate both ocular and central nervous tissue pathologic features. Although the ONH retains some plasticity during the early years of life, damage to the ONH can result from conditions such as pediatric glaucoma, one of the leading causes of childhood blindness worldwide. 1,2 Other conditions, including central nervous system tumors, craniofacial syndromes, neu- ropathies, and congenital anomalies, also can involve the visual pathway including the optic nerve and can affect vision. 3e5 Clinical evaluation of the ONH is a combination of functional assessment (for example, visual field and color vision testing) and anatomic assessment (for example, direct visualization and imaging). In young children, many of these tests are not possible because of limited cooperation, communication, and fixation. Routine examination of the ONH often is restricted to funduscopy, providing a quick, noninvasive subjective assessment of ONH appearance. Until recently, fundus photography was the only method for quantifying the ONH of children objectively. Optical coherence tomography (OCT), first described in 1991, has revolutionized imaging and the subsequent clin- ical management of many ocular conditions in adults. 6 Current OCT machines with a theoretical axial resolution of a few micrometers can take a so-called optical biopsy 2147 Ó 2016 by the American Academy of Ophthalmology This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/). Published by Elsevier Inc. http://dx.doi.org/10.1016/j.ophtha.2016.06.057 ISSN 0161-6420/16