Comparison of ultrahigh- and standard-resolution optical coherence tomography for imaging macular pathology.

OBJECTIVE: To compare ultrahigh-resolution optical coherence tomography (UHR OCT) with standard-resolution OCT for imaging macular diseases, develop baselines for interpreting OCT images, and identify situations where UHR OCT can provide additional information on disease morphology.
DESIGN: Cross-sectional study. PARTICIPANTS: One thousand two eyes of 555 patients with different macular diseases including macular hole, macular edema, central serous chorioretinopathy, age-related macular degeneration (AMD), choroidal neovascularization, epiretinal membrane, retinal pigment epithelium (RPE) detachment, and retinitis pigmentosa.
METHODS: A UHR ophthalmic OCT system that achieves 3-microm axial image resolution was developed for imaging in the ophthalmology clinic. Comparative studies were performed with both UHR OCT and standard 10-microm-resolution OCT. Standard scanning protocols of 6 radial 6-mm scans through the fovea were obtained with both systems. Ultrahigh-resolution OCT and standard-resolution OCT images were correlated with standard ophthalmic examination techniques (dilated ophthalmoscopy, fluorescein angiography, indocyanine green angiograms) to assess morphological information contained in the images. MAIN OUTCOME MEASURES: Ultrahigh-resolution and standard-resolution OCT images of macular pathologies.
RESULTS: Correlations of UHR OCT images, standard-resolution images, fundus examination, and/or fluorescein angiography were demonstrated in full-thickness macular hole, central serous chorioretinopathy, macular edema, AMD, RPE detachment, epiretinal membrane, vitreal macular traction, and retinitis pigmentosa. Ultrahigh-resolution OCT and standard-resolution OCT exhibited comparable performance in differentiating thicker retinal layers, such as the retinal nerve fiber, inner and outer plexiform, and inner and outer nuclear. Ultrahigh-resolution OCT had improved performance differentiating finer structures or structures with lower contrast, such as the ganglion cell layer and external limiting membrane. Ultrahigh-resolution OCT confirmed the interpretation of features, such as the boundary between the photoreceptor inner and outer segments, which is also visible in standard-resolution OCT. The improved resolution of UHR OCT is especially advantageous in assessing photoreceptor morphology.
CONCLUSIONS: Ultrahigh-resolution OCT enhances the visualization of intraretinal architectural morphology relative to standard-resolution OCT. Ultrahigh-resolution OCT images can provide a baseline for defining the interpretation of standard-resolution images, thus enhancing the clinical utility of standard OCT imaging. In addition, UHR OCT can provide additional information on macular disease morphology that promises to improve understanding of disease progression and management.