Faculty Bibliography

PURPOSE: To compare ultrahigh-resolution optical coherence tomography (UHR-OCT) technology to a standard-resolution OCT instrument for the imaging of macular hole pathology and repair; to identify situations where UHR-OCT provides additional information on disease morphology, pathogenesis, and management; and to use UHR-OCT as a baseline for improving the interpretation of the standard-resolution images. DESIGN: Observational and interventional case series. PARTICIPANTS: Twenty-nine eyes of 24 patients clinically diagnosed with macular hole in at least one eye. METHODS: A UHR-OCT system has been developed and employed in a tertiary-care ophthalmology clinic. Using a femtosecond laser as the low-coherence light source, this new UHR-OCT system can achieve an unprecedented 3-mum axial resolution for retinal OCT imaging. Comparative imaging was performed with UHR-OCT and standard 10-mum resolution OCT in 29 eyes of 24 patients with various stages of macular holes. Imaging was also performed on a subset of the population before and after macular hole surgery. MAIN OUTCOME MEASURES: Ultrahigh- and standard-resolution cross-sectional OCT images of macular hole pathologies. RESULTS: Both UHR-OCT and standard-resolution OCT exhibited comparable performance in differentiating various stages of macular holes. The UHR-OCT provided improved imaging of finer intraretinal structures, such as the external limiting membrane and photoreceptor inner segment (IS) and outer segment (OS), and identification of the anatomy of successful surgical repair. The improved resolution of UHR-OCT enabled imaging of previously unidentified changes in photoreceptor morphology associated with macular hole pathology and postoperative repair. Visualization of the junction between the photoreceptor IS and OS was found to be an important indicator of photoreceptor integrity for both standard-resolution and UHR-OCT images. CONCLUSIONS: Ultrahigh-resolution optical coherence tomography improves the visualization of the macular hole architectural morphology. The increased resolution of UHR-OCT enables the visualization of photoreceptor morphology associated with macular holes. This promises to lead to a better understanding of the pathogenesis of macular holes, the causes of visual loss secondary to macular holes, the timing of surgical repair, and the evaluation of postsurgical outcome. Ultrahigh-resolution optical coherence tomography imaging of macular holes that correspond to known alterations in retinal morphology can be used to interpret retinal morphology in UHR-OCT images. Comparisons of UHR-OCT images with standard-resolution OCT images can establish a baseline for the better interpretation of clinical standard-resolution OCT images. The ability to visualize photoreceptors and their integrity or impairment is an indicator of macular hole progression and surgical outcome.

OBJECTIVE: To introduce the concept of a stage 0 macular hole based on optical coherence tomographic observations of the vitreoretinal interface in fellow eyes of patients with unilateral idiopathic macular holes, and to evaluate the subsequent risk of progression to a full-thickness macular hole. DESIGN: Retrospective observational case series. PARTICIPANTS: Ninety-four patients with a unilateral stage 2, 3, or 4 full-thickness macular hole. METHODS: The medical records of patients with a unilateral macular hole diagnosed between 1994 and 2000 at the New England Eye Center were reviewed. MAIN OUTCOME MEASURE: Development of a full-thickness macular hole in the fellow eye on biomicroscopic fundoscopy or optical coherence tomography (OCT). RESULTS: In 27 (28.7%) of 94 clinically normal fellow eyes, OCT detected an abnormality of the vitreoretinal interface but normal foveal anatomy. The vitreoretinal abnormalities were further subclassified into severe (4 eyes), moderate (8 eyes), and mild (15 eyes) based on the intensity and morphology of the OCT signal. One of the 4 (25%) severe cases progressed to a full-thickness macular hole, 4 of the 8 (50%) moderate cases became full-thickness macular holes, and no (0%) mild cases progressed to a full-thickness macular hole. Severe and moderate eyes seemed to share characteristic features on OCT that increased their risk of macular hole development (stage 0 macular hole). The macular hole-free survival at 48 months was 94% for stage 0-negative patients, versus 54% for stage 0-positive patients. Univariate analysis revealed that the presence of a stage 0 macular hole was significantly associated with an almost 6-fold increase in the risk of macular hole formation (relative risk: 5.8, 95% confidence interval: 1.16-28.61, P = 0.03). CONCLUSIONS: A stage 0 macular hole has a normal biomicroscopic appearance clinically, but has salient features on OCT as a result of oblique vitreous traction. Optical coherence tomographic findings consist of a normal foveal contour and normal retinal thickness and must include the presence of a preretinal, minimally reflective, thin band inserting obliquely on at least one side of the fovea. The presence of a stage 0 macular hole in the fellow eye is a significant risk factor for the development of a second macular hole.

An experimental tracking optical coherence tomography (OCT) system has been clinically tested. The prototype instrument uses a secondary sensing beam and steering mirrors to compensate for eye motion with a closed-loop bandwidth of 1 kHz and tracking accuracy, to within less than the OCT beam diameter. The retinal tracker improved image registration accuracy to <1 transverse pixel (<60 microm). Composite OCT images averaged over multiple scans and visits show a sharp fine structure limited only by transverse pixel size. As the resolution of clinical OCT systems improves, the capability to reproducibly map complex structures in the living eye at high resolution will lead to improved understanding of disease processes and improved sensitivity and specificity of diagnostic procedures.