Influence of image compression on the interpretation of spectral-domain optical coherence tomography in exudative age-related macular degeneration

Choroidal Changes Associated With Subretinal Drusenoid Deposits in Age-related Macular Degeneration Using Swept-source Optical Coherence Tomography

PURPOSE

To compare choroidal vascular features of eyes with and without subretinal drusenoid deposits (SDD), using swept-source optical coherence tomography (SS OCT).

DESIGN

Multicenter, cross-sectional study.

METHODS

We prospectively recruited patients with intermediate age-related macular degeneration (AMD), without other vitreoretinal pathology. All participants underwent complete ophthalmic examination, color fundus photography (used for AMD staging), and spectral-domain OCT (to evaluate the presence of SDD). SS OCT was used to obtain automatic macular choroidal thickness (CT) maps, according to the Early Treatment Diabetic Retinopathy Study (ETDRS) sectors. For data analysis, we considered mean choroidal thickness as the arithmetic mean value of the 9 ETDRS sectors. SS OCT en face images of choroidal vasculature were also captured and converted to binary images. Choroidal vascular density (CVD) was calculated as a percent area occupied by choroidal vessels in a 6-mm-diameter submacular circular. Choroidal vessel volume was calculated by multiplying the average CVD by macular area and CT. Multilevel mixed linear models (to account for the inclusion of 2 eyes of same subject) were performed for analysis.

RESULTS

We included 186 eyes (n = 118 subjects), 94 (50.5%) presenting SDD. Multiple regression analysis revealed that, controlling for age, eyes with SDD presented a statistically thinner mean CT (ß = -21.9, P = .006) and CT in all the individual ETDRS fields (ß ≤ -18.79, P ≤ .026). Mean choroidal vessel volume was also significantly reduced in eyes with SDD (ß = -0.003, P = .007). No significant associations were observed with mean CVD.

CONCLUSION

In subjects with intermediate AMD, choroidal thickness and vessel volume are reduced in the presence of subretinal drusenoid deposits.

SPECTRAL DOMAIN-OPTICAL COHERENCE TOMOGRAPHY IMAGE CONTRAST AND BACKGROUND COLOR SETTINGS INFLUENCE IDENTIFICATION OF RETINAL STRUCTURES

PURPOSE

To evaluate image contrast and color setting on assessment of retinal structures and morphology in spectral-domain optical coherence tomography.

METHODS

Two hundred and forty-eight Spectralis spectral-domain optical coherence tomography B-scans of 62 patients were analyzed by 4 readers. B-scans were extracted in 4 settings: W + N = white background with black image at normal contrast 9; W + H = white background with black image at maximum contrast 16; B + N = black background with white image at normal contrast 12; B + H = black background with white image at maximum contrast 16. Readers analyzed the images to identify morphologic features. Interreader correlation was calculated. Differences between Fleiss-kappa correlation coefficients were examined using bootstrap method. Any setting with significantly higher correlation coefficient was deemed superior for evaluating specific features.

RESULTS

Correlation coefficients differed among settings. No single setting was superior for all respective spectral-domain optical coherence tomography parameters (P = 0.3773). Some variables showed no differences among settings. Hard exudates and subretinal fluid were best seen with B + H (κ = 0.46, P = 0.0237 and κ = 0.78, P = 0.002). Microaneurysms were best seen with W + N (κ = 0.56, P = 0.025). Vitreomacular interface, enhanced transmission signal, and epiretinal membrane were best identified using all color/contrast settings together (κ = 0.44, P = 0.042, κ = 0.57, P = 0.01, and κ = 0.62, P ≤ 0.0001).

CONCLUSION

Contrast and background affect the evaluation of retinal structures on spectral-domain optical coherence tomography images. No single setting was superior for all features, though certain changes were best seen with specific settings.

The Evolution of Teleophthalmology Programs in the United Kingdom: Beyond Diabetic Retinopathy Screening

Modern ophthalmic practice in the United Kingdom is faced by the challenges of an aging population, increasing prevalence of systemic pathologies with ophthalmic manifestations, and emergent treatments that are revolutionary but dependent on timely monitoring and diagnosis. This represents a huge strain not only on diagnostic services but also outpatient management and surveillance capacity. There is an urgent need for newer means of managing this surge in demand and the socioeconomic burden it places on the health care system. Concurrently, there have been exponential increases in computing power, expansions in the strength and ubiquity of communications technologies, and developments in imaging capabilities. Advances in imaging have been not only in terms of resolution, but also in terms of anatomical coverage, allowing new inferences to be made. In spite of this, image analysis techniques are still currently superseded by expert ophthalmologist interpretation. Teleophthalmology is therefore currently perfectly placed to face this urgent and immediate challenge of provision of optimal and expert care to remote and multiple patients over widespread geographical areas. This article reviews teleophthalmology programs currently deployed in the United Kingdom, focusing on diabetic eye care but also discussing glaucoma, emergency eye care, and other retinal diseases. We examined current programs and levels of evidence for their utility, and explored the relationships between screening, teleophthalmology, disease detection, and monitoring before discussing aspects of health economics pertinent to diabetic eye care. The use of teleophthalmology presents an immense opportunity to manage the steadily increasing demand for eye care, but challenges remain in the delivery of practical, viable, and clinically proven solutions.