SD-OCT: Enhanced visualization earlier in disease process

July 20, 2016

Spectral-domain optical coherence tomography facilitates detailed evaluation of foveal disorders even in the very earliest disease stages.

Dr. LoewensteinTake-home: Spectral-domain optical coherence tomography facilitates detailed evaluation of foveal disorders even in the very earliest disease stages. 

Reviewed by Anat Loewenstein, MD

Tel Aviv, Israel–Spectral-domain optical coherence tomography (SD-OCT) has become indispensable for visualizing the fovea and diagnosing retinal diseases. Importantly, detailed visualization facilitates diagnosis during the early disease stages, according to Anat Loewenstein, MD, MHA. 

(All images courtesy of Anat Loewenstein, MD)

Solar maculopathy

The first case illustrating the importance of high-detailed imaging was that of a 29-year-old male, as described by Dr. Loewenstein. The patient’s past ocular medical and family histories were not remarkable.

Dr. Loewenstein is professor of ophthalmology, deputy dean of the medical school, Sackler Faculty of Medicine, Tel Aviv University, Israel, and chairman of ophthalmology, Tel Aviv Sourasky Medical Center, Tel Aviv.

The patient reported blurry vision in both eyes over the past 4 days with a yellow spot centrally. He denied any recent exposure to drugs, however, he had used cocaine and cannabis “crystal” 1 year previously.

SD-OCT examination showed a normal flat macula with a small yellow spot, Dr. Loewenstein noted. However, there was a stop in the photoreceptor continuity in the ellipsoid and inter-digitation zones.

“A hyper-reflective material was seen emerging from the retinal pigment epithelium [RPE] toward the outer nuclear layer,” Dr. Loewenstein added.

The patient later admitted that on the day the symptoms began, he had been lying on the beach exposed to sunlight for the entire day. The diagnosis was solar retinopathy, secondary to sun gazing.

(All images courtesy of Anat Loewenstein, MD)

During the follow-up of this patient, SD-OCT showed that the hyper-reflective material was absorbed with abrupt continuation of the photoreceptor layer in the fovea and the external limiting membrane (ELM) was preserved. This status was maintained at 2 and 4 months of follow-up, according to Dr. Loewenstein.

“Solar retinopathy occurs mainly during celestial events­–such as eclipses, religious rituals, and sunbathing and in psychiatric patients,” Dr. Loewenstein explained. “The light is of low power but exposure was usually for a long duration. The light intensity is amplified by the cornea and the lens by a factor of 10,000. The pathophysiology includes both thermal and photochemical damage. While recovery is possible, permanent damage is a possibility.”

The importance of SD-OCT is underscored in this case by the defects that were visible in the ellipsoidal zone as well as the strong correlation between the disruption of the inner photoreceptor junction and the worsened vision.

(All images courtesy of Anat Loewenstein, MD)

Laser-induced retinopathy

A second case was that of a 15-year-old boy who experienced an acute decrease in vision in both eyes after staring at a laser pointer. The patient’s medical and ocular histories and that of his family were unremarkable.

The macula was flat with a yellow spot in the fovea. Similar to the first case report, SD-OCT showed that the contour of the fovea was normal with a stop in the photoreceptors continuity in the ellipsoid and interdigitation zones and the presence of a hyperreflective material emerging from the RPE toward the outer nuclear layer.

(All images courtesy of Anat Loewenstein, MD)

SD-OCT follow-up of this patient showed the reabsorption of the hyperreflective material, abrupt discontinuation of the photoreceptor layer in the fovea, and preservation of the ELM.

“The size of the outer macular hole in the right eye decreased between the examinations at 2 weeks and 2 months,” Dr. Loewenstein reported.

“Laser-induced retinopathy is caused by the coherent, monochromatic, unidirectional, minimally divergent laser beam,” she said. “The exposure to the light is short, about 0.25 second, as a result of the blink reflex. The light intensity is intensified by the cornea and lens by a factor of 10,000. The pathophysiology includes thermal damage primarily in the RPE, and photochemical and mechanical plasma formation damage.”

The vast majority of patients (95%) with laser-induced retinopathy experience improvement; 32% have vision better than 20/40.

In this case, SD-OCT showed defects in the ellipsoid zone, hyper-reflectivity at the retinal surface, and retinal or intraretinal hemorrhages and even neovascularization.

(All images courtesy of Anat Loewenstein, MD)

Hydroxychloroquine retinopathy

A final case was that of a 29-year-old woman who had been treated for 13 years with prednisone, Imuran (azathioprine, Aspen Australia), and hydroxychloroquine for systemic lupus erythemathosus.

The patient presented with the complaint of a central visual defect. Examination showed a paracentral scotoma that developed between 2004 and 2013. This was the consequence of retinal toxicity resulting from hydroxychloroquine.

(All images courtesy of Anat Loewenstein, MD)

Electroretinography

“In this case, SD-OCT showed loss of the perifoveal and macular ellipsoid zones, thinning of the outer nuclear layer, and sparing of the fovea with establishment of the ‘flying saucer’ sign,” Dr. Loewenstein demonstrated.

Electroretinography showed major cone dysregulation bilaterally that was more pronounced in the perifoveal region.

“Hydroxychloroquine maculopathy is characterized by a bull’s eye appearance and a dense central scotoma,” Dr. Loewenstein said. The drug was discontinued but the damage was permanent.

(All images courtesy of Anat Loewenstein, MD)

In summary

 

“SD-OCT has dramatically enhanced the ability to diagnose foveal disorders even during the stage when they are not visible using other technologies, ” Dr. Loewenstein summarized.

(All images courtesy of Anat Loewenstein, MD)

 

Anat Loewenstein, MD, MHA

E: anatl@tlvmc.gov.il

Dr. Loewenstein in a consultant to Allergan, Alcon Laboratories, Bayer Healthcare, Notal Vision, and Novartis. Michaela Goldstein, MD, and Dafna Goldenberg, MD, from Dr. Loewenstein’s department participated in the care of the patients under discussion.