Case study helps illustrate the utility of spectral-domain OCT

After surgery, a patient complained of a ‘smudge’ in her vision, which was diagnosed with advanced imaging technology.

Michael D. Bennett

Ophthalmologists are continuing to expand their appreciation of retinal anatomy and its implications thanks to recent advances in imaging. Today’s state-of-the-art technologies provide clinicians with such a comprehensive view of the posterior segment that we are transforming the way in which retinal disorders are diagnosed, monitored and even treated.

One technology that has become integral to my practice is the Spectralis HRA+OCT (Heidelberg Engineering). A spectral-domain optical coherence tomography (SD-OCT) system, the Spectralis produces high-resolution images that capture the fundus and characterize the layers of the retina. Its ability to display images in 3-D and with greater detail than its predecessor, time-domain OCT, has afforded me improved visualization of the retina, which has had an effect on all aspects of diagnostics, treatments and outcome measurements. Being able to clearly differentiate between diagnoses and disease manifestations with the Spectralis has proved to be invaluable for my practice and patients.

Case in point

A recent case illustrated just how advanced the technology has become. The SD-OCT system allowed for a discrete diagnosis in a patient whose symptoms, up to that point, had yielded no verifiable explanation from other means of assessment.

The patient was a 65-year-old, active, self-described “Type-A” woman who at one point had presented to a general ophthalmologist with a visually significant cataract. Although her symptoms had improved at the time with refraction, she had elected to go forward with surgery to achieve emmetropia. The patient had opted to self-pay for a more advanced presbyopia-correcting IOL and had been appropriately educated about postoperative spectacle independence rates, visual acuity, neuroadaptation and enhancement possibilities.

At a follow-up appointment with the surgeon, the patient complained of a “smudge,” or localized area of blurred vision. Upon examination, however, the practitioner found only a clear, well-positioned lens and a visual acuity of 20/20. After persistent complaints, she was referred to a retinal specialist for further assessment, but after visualizing the fundus, he was unable to identify any retinal abnormality or cause for the distortion in her central vision.

From that point, the patient was referred from one ophthalmologist to the next, attempting to find a resolution or explanation for the blurriness she was experiencing. She continued to describe her subjective symptom as a “smudge,” but physicians were unable to find a diagnosis that could justify her complaints. Further testing ruled out standard higher-order aberrations or a residual astigmatism as the cause of her symptom and rendered laser vision correction or a limbal relaxing incision as futile. Despite having 20/20 visual acuity around the localized deficit, she was frustrated that she could not find a definitive diagnosis or answer.

It was at this point that J. Shepard Bryan, MD, a neighbor of the patient and a colleague of mine, suggested that she visit our office — the Retina Institute of Hawaii, the largest retina and research center in the state — to see if we could make any determinations. After a careful vitreoretinal exam, her fundus was scanned with the Spectralis and the source of her complaint became readily apparent (Figure 1). At other practices she had visited, a SD-OCT system had not been available to record detailed images of the posterior segment; the ophthalmologists had been relying on their thorough clinical examinations and older imaging technologies to assess this patient. With this device, however, a discrete premacular vitreal condensation was clearly identified; it appears as a bright yellow spot in the vitreous when processed with the Heat Mode (Figure 2). Clinically, the patient’s “floater” resembled the shape of a dime. It was highly visible when scanned on its long axis and nearly vanished when the line scans were averaged or if an individual scan was performed perpendicular to the long axis.

Figure 1. OCT slice is a scan from the patient showing no obstruction (therefore, why other clinicians/imaging devices were missing the PVD). Images: Pascale Communications

Figure 2. OCT slice is a scan from the same patient, during the same scan, just a different “slice” of the scan. This shows what others had been missing up in the vitreous.

The images clearly showed that there was condensation lying anterior to the retina in the vitreous, which explained the visual “smudge” she had been complaining of since her cataract surgery.

Due to the quality of these images, the patient now had an accurate diagnosis and ended her search. The answer was now easy to explain, by way of a picture. We documented exactly what she had been seeing, happily validating her previously opined “nebulous” symptoms.

After explaining that the standard of care for her premacular posterior vitreous detachment was for her to wait for it to break down, we explained that in all likelihood it would become less noticeable with time; however, the SD-OCT system enabled her to have a better understanding of the situation and a chance at some closure. She was no longer angry with her cataract surgeon, nor did she wish to pursue financial restitution for the out-of-pocket expenses associated with her multifocal lens. Additionally, she could be reassured that her 20/20 visual acuity would not be affected by her condition.

Continually innovating

Imaging has become an integral part of the ophthalmologist’s practice, from clinical care and documentation, to patient education and ancillary services. It is cases such as this that show how much the technology has evolved and how it can continue to advance and assist the clinician with diagnostic challenges.

• Michael D. Bennett, MD, can be reached at Retina Institute of Hawaii, Yacht Harbor Professional Center, 1620 Ala Moana Blvd., Suite 500, Honolulu, HI 96815; 808-955-0255; fax: 808-955-4155; e-mail: mbennett@retinahawaii.com.
• J. Shepard Bryan, MD, can be reached at Associated Retina Consultants, 7600 N. 15th St., Suite 155, Phoenix, AZ 85020; 602-242-4928; fax 602-249-4813.