Abstract
Purpose :
Patients with high myopia can be a challenge to test with optical coherence tomography (OCT) due to poor image quality and/or the lack of a high myopia normative group. To improve our understanding of these limitations, OCT scans from eyes with high myopia were examined.
Methods :
83 consecutive eyes, sent for OCT scans and evaluation, had corrected spherical refractive errors worse than -6D and/or axial lengths >26.5mm. Three high-resolution (average of 27 b-scans) OCT circle scans (3.5, 4.1, and 4.7mm dia.) and a cube scan (61 b-scans), which included the macula, were obtained (Spectralis, Heidelberg Eng), as well as 24-2 and 10-2 visual fields (VF). Phase 1: A glaucoma specialist judged whether the fundus photo and en-face images showed peripapillary atrophy (PPA), epiretinal membrane (ERM), paravascular inner retinal defect (PIRD), and/or a tilted disc (TD). Phase 2: The report specialist judged whether the eye had optic nerve damage, based upon the OCT scans. The glaucoma specialist made the same judgement using all available information (e.g. family history, IOP, 10-2 and 24-2 VFs, OCT, etc.). A reference standard (RS) was created after adjudication between the two specialists.
Results :
ERM, PIRD, TD, and PPA were observed in 12, 24, 37 and 62 eyes, respectively. Fig. 1A shows the temporal half of a circle scan (3.5 mm) from an eye with PPA. In 66 eyes, the OCT specialist used the 3.5 mm peripapillary retinal nerve fiber layer (pRNFL) thickness plot, and, when the circle scan was difficult to interpret (Fig. 2C), the RNFL (Fig. 2A) and GCL (Fig. 2B) thickness maps. In the remaining 17 eyes, the other circle scans (Fig. 1B), and/or the line scans through the vertical and horizontal meridians were also examined. The report specialist misclassified two of the RS. In one eye, RNFL thinning, due to a PIRD, was mistaken for optic nerve damage; in the other eye, subtle pRNFL thinning was missed. On the other hand, the best pRNFL and BMO-MRW metrics (1 red and/or 2 yellows) misclassified 9 (10.8%) and 13 (15.7%) RS eyes, respectively.
Conclusions :
OCT scans from most eyes with high myopia can be used to detect optic nerve damage without the need of a high myopia normative group. However, successful use of the OCT depends upon visual inspection of pRNFL, RGC and RNFL plots, as opposed to relying on summary metrics.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.