High Resolution Spectral Domain Optical Coherence Tomography (SD-OCT) in Multiple Sclerosis: The First Follow Up Study over Two Years

“Non-invasive, faster and less expensive than MRI” and “the eye is a window to the brain” are recent slogans promoting optical coherence tomography (OCT) as a new surrogate marker in multiple sclerosis (MS). Indeed, OCT allows for the first time a non-invasive visualization of axons of the central nervous system (CNS). Reduction of retina nerve fibre layer (RNFL) thickness was suggested to correlate with disease activity and duration. However, several issues are unclear: Do a few million axons, which build up both optic nerves, really resemble billions of CNS neurons? Does global CNS damage really result in global RNFL reduction? And if so, does global RNFL reduction really exist in all MS patients, and follow a slowly but steadily ongoing pattern? How can these (hypothesized) subtle global RNFL changes be reliably measured and separated from the rather gross RNFL changes caused by optic neuritis? Before generally being accepted, this interpretation needs further critical and objective validation.We prospectively studied 37 MS patients with relapsing remitting (n = 27) and secondary progressive (n = 10) course on two occasions with a median interval of 22.4±0.5 months [range 19–27]. We used the high resolution spectral domain (SD-)OCT with the Spectralis 3.5 mm circle scan protocol with locked reference images and eye tracking mode. Patients with an attack of optic neuritis within 12 months prior to the onset of the study were excluded.Although the disease was highly active over the observation period in more than half of the included relapsing remitting MS patients (19 patients/32 relapses) and the initial RNFL pattern showed a broad range, from normal to markedly reduced thickness, no significant changes between baseline and follow-up examinations could be detected.These results show that caution is required when using OCT for monitoring disease activity and global axonal injury in MS

Comparison of Geographic Atrophy Growth Rates Using Different Imaging Modalities in the COMPLETE Study

To compare the measurements and growth rates of geographic atrophy (GA) secondary to age-related macular degeneration (AMD) obtained using different imaging modalities. Thirty patients with AMD and GA measuring from 1.25 mm² to 18 mm² based on spectral-domain optical coherence tomography (SD-OCT) fundus imaging were enrolled. Imaging was performed at baseline and at follow-up months 3, 6, 9, and 12, including autofluorescence (AF) imaging with a fundus camera-based flash system (TRC-50DX; Topcon Medical Systems, Oakland, NJ; AF excitation λ: 535-585 nm; detection λ: 605-715 nm), AF and fluorescein angiography (FA) imaging with a confocal scanning laser ophthalmoscopy (SLO) system (Spectralis; Heidelberg Engineering, Heidelberg, Germany; AF excitation λ: 488 nm; detection λ: > 500 nm), and SD-OCT en face imaging (Cirrus; Carl Zeiss Meditec, Dublin, CA). Average baseline square root measurements and enlargement rates of square root areas appeared similar across all modalities; 0.2 mm was the largest difference between any pair of measurement means. The intraclass correlation coefficients (ICC) were essentially equal to 1 for all comparisons of area measurements but were lower for growth rates than area measurements. Comparison of 26-week average enlargement rates showed no significant difference between the SLO AF image and enhanced SD-OCT en face image (mean difference: 0.01 mm; SD: 0.10; P = .70). Agreement among all imaging modalities in measuring the areas of GA at baseline diminished when the growth rates of GA were compared over 26 weeks, likely because each imaging technique identifies different anatomic features along the border of GA, which may appear similar but change at different rates

Three-dimensional spectral domain optical coherence tomography and light microscopy of an intravitreal parasite.

BACKGROUND: Various imaging modalities play a role in diagnosing parasitic infections of the eye. We describe the spectral domain optical coherence tomography (SD-OCT) findings of an intravitreal parasite with subsequent evaluation by light microscopy. FINDINGS: This is a case report of a 37-year-old Ecuadorian man who presented with uveitic glaucoma and a new floater in his left eye for 1 week's duration. Full ophthalmic examination revealed an intravitreal parasite. Color fundus photography, fluorescein angiography (FA), ocular ultrasonography (US), and SD-OCT were performed. The parasite was removed via 23-gauge pars plana vitrectomy and sent to pathology for evaluation. Color fundus photography and ocular ultrasonography demonstrated an elongated foreign body within the vitreous above the retina. FA demonstrated minimal vascular changes in the vicinity of the parasite. SD-OCT was utilized to visualize the parasite and to create a three-dimensional (3D) image. The parasite was determined to be most consistent with Gnathostoma spp. by morphologic analysis. CONCLUSIONS: This is the first reported case of SD-OCT of an intravitreal parasite with corresponding evaluation by pathology. SD-OCT allows non-invasive, high-resolution visualization and 3D reconstruction of parasitic anatomy which may help establish tomographic criteria for species identification