Multicolor OCT: Improving Diagnostic Ability and Educating Patients

The phrase “a picture is worth a thousand words” has never been more true.

By Sanjay G. Asrani, MD

Results from multicentered clinical trials have shown that reducing intraocular pressure (IOP) in patients with open-angle glaucoma significantly delays progression.1 Although few ophthalmologists doubt these recommendations, early detection and treatment compliance have remained significant barriers to implementing them on a consistent basis.

Myriad imaging techniques are used to evaluate patients suspected of having glaucoma. In particular, optical coherence tomography (OCT) has been found to have very good sensitivity and specificity in patients with early visual field loss.2 Early diagnosis remains difficult; however, in many cases, the addition of multicolor scanning laser imaging with the Spectralis (Heidelberg Engineering) increases the clinician’s understanding of the structures of the eye and potential pathology.

The simultaneous use of multiple light sources across the visible spectrum to produce an image in conjunction with OCT allows the capture of information from the individual layers of the retina. Each wavelength of light penetrates to varying depths, thereby enhancing the view of the different layers. In turn, this ability makes it easier to diagnose early glaucoma and provides an image that can easily be shared with patients. In my experience, patients grasp the meaning of an image better than they do a simple number or a graph. Thus, multicolor scanning laser imaging combined with OCT can be useful for early detection, as well as for educating and convincing patients about the presence of disease.

Herein are some sample cases of patients I saw in my clinic that demonstrate the usefulness of the technology. In each case, the availability of multicolor imaging significantly impacted the management of the patient.

CASE No. 1


In this patient, peripapillary retinal nerve fiber layer (RNFL) measurements via OCT imaging are within normal limits for both eyes (Figure 1). The OD-OS comparison, however, shows an unusual asymmetry of macular thickness, with the right eye presenting with inferotemporal thinning compared with the left eye (Figure 2). Multicolor laser scanning (in this case, green reflectance) combined with OCT imaging clearly shows a dark band indicating a significant nerve fiber bundle loss that was not picked up on standard OCT imaging (Figure 3). Based on such findings, this patient shows early signs of glaucomatous damage, which may indicate the need for treatment or close monitoring.

CASE No. 2

This case is of a patient who presents with CME combined combined with an ERM. Mild CME is easily identified with traditional OCT imaging, because the cross sectional images allow for precise assessment of macular layers (Figure 4). OCT imaging, however, does not always detail the presence or extent of an ERM. In this patient, multicolor OCT imaging provides a supplemental view that distinctly shows—and allows visualization of—the presence and extent of the ERM (Figure 5). The areas of white reflectance in the multicolor image show an ERM on the surface of the retina that covers the entire macula. The image also displays the traction on the retinal layers, inferred from the striations, helping to explain the cause of the CME to the patient. Showing this image to the patient makes it much easier to discuss surgical options.

CASE No. 3

This is the right eye of a patient who presented with a suspicious RNFL measurement as detected by OCT imaging. The peripapillary RNFL graph shows borderline results inferiorly, indicating suspicious pathology in this region (Figure 6). Assessment of the macular thickness map indicates a large arcuate loss inferiorly extending to the optic nerve (Figure 7). In this case, multicolor imaging clearly shows a dark band emanating inferiorly from the optic nerve, indicating the presence of a significant RNFL loss inferiorly (Figure 8). Combining the multicolor and OCT imaging modalities clearly identifies the suspicious layer as glaucomatous.

SUMMARY

Multicolor scanning laser imaging is an additional modality that complements visual field tests and OCT imaging to help confirm clinical judgments and educate patients using descriptive images. It provides a full picture of the retina to aid in diagnosis, especially in eyes with coexisting retinal diseases and glaucoma. It is particularly useful for diagnosing glaucoma, because it allows the clinician to visualize the RNFL in exquisite detail. Cross-sectional OCT measurements do not always match a patient’s visual field test results or their description of visual deficits. Multicolor scanning laser imaging combined with OCT imaging helps complete the puzzle.

Sanjay G. Asrani, MD is a professor of ophthalmology and the clinical director at the Duke University Eye Center of Cary, North Carolina. He is a glaucoma specialist with particular interest in new imaging techniques for glaucoma diagnosis. He has received lecture honoraria from Heidelberg Engineering. Dr. Asrani may be reached at sanjay.asrani@duke.edu.

  1. Heijl A, Leske MC, Bengtsson B, et al; Early Manifest Glaucoma Trial Group. Reduction of intraocular pressure and glaucoma progression: results from the Early Manifest Glaucoma Trial. Arch Ophthalmol. 2002;120(10):1268-1279.
  2. Nouri-Mahdavi K, Nikkhou K, Hoffman DC, et al. Detection of early glaucoma with optical coherence tomography (StratusOCT). J Glaucoma. 2008;17(3):183-188.