Optical Coherence Tomography Can Be Used to Assess Glaucomatous Optic Nerve Damage in Most Eyes With High Myopia

Abstract

Precis: It is generally assumed that optical coherence tomography (OCT) cannot be used to diagnose glaucomatous optic neuropathy (GON) in high myopes. However, this study presents evidence that there is sufficient information in OCT scans to allow for accurate diagnosis of GON in most eyes with high myopia.

Purpose: The purpose of this study was to test the hypothesis that glaucomatous damage can be accurately diagnosed in most high myopes via an assessment of the OCT results.

Patients and methods: One hundred eyes from 60 glaucoma patients or suspects, referred for OCT scans and evaluation, had corrected spherical refractive errors worse than -6 D and/or axial lengths ≥26.5 mm. An OCT specialist judged whether the eye had GON, based upon OCT circle scans of the disc and cube scans centered on the macula. A glaucoma specialist made the same judgement using all available information (eg, family history, repeat visits, intraocular pressure, 10-2 and 24-2 visual fields, OCT). A reference standard was created based upon the glaucoma specialist's classifications. In addition, the glaucoma specialist judged whether the eyes had peripapillary atrophy (PPA), epiretinal membrane (ERM), tilted disc (TD), and/or a paravascular inner retinal defect (PIRD).

Results: The OCT specialist correctly identified 97 of the 100 eyes using the OCT information. In 63% of the cases, the inner circle scan alone was sufficient. For the rest, additional scans were requested. In addition, 81% of the total eyes had: PPA (79%), ERM (18%), PIRD (26%), and/or TD (48%).

Conclusions: For most eyes with high myopia, there is sufficient information in OCT scans to allow for accurate diagnosis of GON. However, the optimal use of the OCT will depend upon training to read OCT scans, which includes taking into consideration myopia related OCT artifacts and segmentation errors, as well as PPA, ERM, PIRD, and TD.

Figure 1.

Spectralis HRA+OCT commercial circle scan report with an (A) infrared (IR) projection of the disc, (B) averaged circular b-scan image, (C) cpRNFL thickness pie chart, and (D) cpRNFL thickness profile

Figure 2.

Spectralis HRA+OCT commercial MRW, RNFL, & Assymmetry Single Exam Report with (A) retinal nerve fiber layer (RNFL) thickness map; and Thickness Map Single Exam Report with (B) ganglion cell layer (GCL) thickness map

Figure 3.

Spectralis HRA+OCT 30° × 25° cube scan with 61 (A) horizontal b-scans; and 15° × 30° cube scan with 19 (B) vertical b-scans

Figure 4.

Inner circle scans of non-glaucomatous (NG) eyes carrying the following observed features: (A) cpRNFL thickness profile within normal limits (B) blood vessel displacement toward the temporal region, (C) blood vessel displacement toward the nasal region, and (D) NG optic neuropathy

Figure 5.

Inner circle scans of glaucomatous (G) eyes carrying the following observed features: (A) deep cpRNFL thickness defects (B) widespread cpRNFL damage (C) exposed blood vessels, and (D) local cpRNFL defect that was missed by cpRNFL thickness pie chart

Figure 6.

G eye with disruptive co-existing pathology and OCT artifacts (A) Inner circle scan and (B) outer circle scan of a G eye carrying peripapillary atrophy (PPA) (blue arrows), a clipping artifact (green arrows), regions of inadequate contrast (yellow arrows), and indications of glaucomatous damage (red arrows)

Figure 7.

NG eye with potential glaucomatous thinning (A) Inner circle scan, (B) RNFL thickness map, and (C) GCL thickness map of an H eye carrying potential glaucomatous temporal superior (TS) cpRNFL thinning (red arrow), but otherwise thick RNFL bundles

Figure 8.

G eye with potential glaucomatous thinning (A) Inner circle scan, (B) RNFL thickness map, and (C) GCL thickness map of a G Eye carrying subtle glaucomatous temporal inferior (TI) RNFL thinning and localized GCL thinning (red arrows)

Figure 9.

OCT artifacts necessitate use of thickness maps (A) Inner circle scan, (B) RNFL thickness map, and (C) GCL thickness map of a G Eye carrying a region of inadequate contrast (yellow arrows), as well as indications of glaucomatous damage (red arrows)

Figure 10.

Vertical b-scans verify glaucomatous thinning (A) Inner circle scan, (B) RNFL thickness map, (C) GCL thickness map, and (D) vertical meridian b-scan of a G Eye carrying glaucomatous temporal (T) RNFL thinning (red arrows) and GCL thinning

Figure 11.

Co-existing pathologies necessitate use of vertical b-scans (A) Incorrectly centered circle scan, (B) RNFL thickness map disrupted by epiretinal membranes, (C) GCL thickness map, and (D) vertical b-scan of a G Eye carrying indications of glaucomatous damage (red arrows)