Dennis E. Cortés

High-resolution spectral domain anterior segment optical coherence tomography in type 1 boston keratoprosthesis

Purpose: To report the results of imaging using high-resolution, Fourier domain anterior segment optical coherence tomography (AS-OCT) to evaluate patients with a type 1 Boston Keratoprosthesis (KPro). Methods: We performed a retrospective comparative study of patients in whom we implanted the Boston KPro. A total of 26 eyes of 23 patients from the Cornea Service at the University of California Davis Eye Center were included. Subjects were evaluated with the Spectralis AS-OCT (Heidelberg Engineering GmbH). Results: Preoperative diagnoses for KPro surgery included failed corneal transplant (69%), chemical burn (23%), and aniridia (8%). The average age of patients was 63.2 years (range, 17–88 years). Fifty-four percent of the patients were female. The mean duration between the KPro surgery and the acquisition of high-resolution AS-OCT imaging was 35.8 months (range, 2–90 months). The most commonly observed finding was retroprosthetic membrane formation, which we found in 77% of KPro eyes. In 65% of KPro eyes, we identified epithelium behind the front plate, and in 54%, we identified an epithelial lip over the anterior surface of the KPro front plate. In 31% of KPro eyes, we identified periprosthetic cysts, gaps or spaces, and thinning in the corneal carrier graft. Conclusions: Fourier domain AS-OCT is a useful noninvasive imaging technique in patients with a KPro and provides the ability to identify changes that are sometimes difficult to appreciate by clinical evaluation. The higher resolution Fourier domain systems may aid in the clinical diagnosis and management of pathology that might not be imaged with instruments of lower resolution. AS-OCT has the potential for monitoring the anatomic stability of an implanted KPro and may also help to monitor for complications. Moreover, high-resolution imaging may enhance our understanding of periprosthetic anatomy.

Three-dimensional anterior segment imaging in patients with type 1 Boston Keratoprosthesis with switchable full depth range swept source optical coherence tomography

Abstract. A high-speed (100 kHz A-scans/s) complex conjugate resolved 1 μm swept source optical coherence tomography (SS-OCT) system using coherence revival of the light source is suitable for dense three-dimensional (3-D) imaging of the anterior segment. The short acquisition time helps to minimize the influence of motion artifacts. The extended depth range of the SS-OCT system allows topographic analysis of clinically relevant images of the entire depth of the anterior segment of the eye. Patients with the type 1 Boston Keratoprosthesis (KPro) require evaluation of the full anterior segment depth. Current commercially available OCT systems are not suitable for this application due to limited acquisition speed, resolution, and axial imaging range. Moreover, most commonly used research grade and some clinical OCT systems implement a commercially available SS (Axsun) that offers only 3.7 mm imaging range (in air) in its standard configuration. We describe implementation of a common swept laser with built-in k-clock to allow phase stable imaging in both low range and high range, 3.7 and 11.5 mm in air, respectively, without the need to build an external MZI k-clock. As a result, 3-D morphology of the KPro position with respect to the surrounding tissue could be investigated in vivo both at high resolution and with large depth range to achieve noninvasive and precise evaluation of success of the surgical procedure.

Epithelial downgrowth after penetrating keratoplasty: imaging by high-resolution optical coherence tomography and in vivo confocal microscopy.

Purpose: To report the clinical utility of high-resolution anterior segment optical coherence tomography (AS-OCT) combined with in vivo confocal microscopy (IVCM) to diagnose and follow the effectiveness of treatment of 2 cases of epithelial downgrowth after penetrating keratoplasty. Methods: A retrospective case review was performed on 2 eyes of 2 patients with a history of multiple penetrating keratoplasties that developed epithelial downgrowth 4 and 6 months after the most recent penetrating graft. At various time points, high-resolution AS-OCT images were obtained using the Spectralis (Heidelberg Engineering GmbH), and IVCM images were obtained using the Heidelberg Retina Tomograph III Rostock Cornea Module (Heidelberg Engineering GmbH). In 1 case, the diagnosis was confirmed by histopathologic evaluation. Results: Two patients developed epithelial downgrowth after penetrating keratoplasty. In case 1, a 48-year-old man with a history of Acanthamoeba keratitis developed epithelial downgrowth after undergoing 2 therapeutic grafts over a 1-year period. In case 2, a 40-year-old man with a history of a corneal laceration complicated by fungal keratitis was diagnosed with epithelial downgrowth after undergoing 3 penetrating grafts, the placement of a glaucoma drainage device, and a pars plana vitrectomy over a 3-year period. In both cases, at the level of the endothelium, AS-OCT identified a highly reflective layer and IVCM revealed round hyperreflective nuclei consistent with epithelium. Conclusions: Epithelial downgrowth is an uncommon complication after penetrating keratoplasty. High-resolution AS-OCT and IVCM are noninvasive imaging modalities that may potentially be more sensitive in identifying and monitoring epithelial downgrowth than routine light biomicroscopy and may obviate the need for invasive diagnostic measures.

Anterior segment OCT and confocal microscopy findings in atypical corneal intraepithelial neoplasia

Purpose: To report a case of biopsy-proven corneal intraepithelial neoplasia (CIN) diagnosed and followed clinically using high-resolution anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM). Methods: Observational case report. Results: A 57-year-old man presented with decreased vision in the right eye for 2 months before presentation. His best-corrected visual acuity was 20/70 in the affected eye, and the slit-lamp examination revealed superficial opacification of the anterior cornea originating from the temporal limbus with a “leopard-spot” pattern more centrally. The lesion was excised at his 2-month follow-up, and the histological examination revealed squamous dysplasia consistent with CIN. Visual acuity improved, and the slit-lamp examination revealed barely visible residual disease at the temporal limbus. However, AS-OCT showed a thicker and highly reflective epithelial layer near the temporal limbus, similar to initial presentation, highlighting this residual disease. IVCM demonstrated dysplastic cells consistent with residual disease. Therefore, we treated the patient with topical interferon alpha-2b (1 million IU/mL) 4 times daily in the affected eye. At 3-month follow-up, the patients best-corrected visual acuity was 20/20 in the affected eye with persistent but improved residual disease adjacent to the temporal limbus. In the mid-periphery of the inferonasal cornea, focal areas of iatrogenic linear scarring were confirmed to be limited to the anterior stroma by AS-OCT and IVCM at 6-month follow-up. Conclusions: AS-OCT and IVCM are noninvasive techniques that can be used to diagnose and aid in the management of CIN, which may present as subclinical disease through slit-lamp biomicroscopy alone.

In vivo volumetric depth-resolved vasculature imaging of human limbus and sclera with 1 μm swept source phase-variance optical coherence angiography

We present nnnnnin vivo volumetric depth-resolved vasculature images of the anterior segment of the human eye acquired with phase-variance based motion contrast using a high-speed (100 kHz, 105 A-scans/s) swept source optical coherence tomography system (SSOCT). High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. The human corneo-scleral junction and sclera were imaged with swept source phase-variance optical coherence angiography and compared with slit lamp images from the same eyes of normal subjects. Different features of the rich vascular system in the conjunctiva and episclera were visualized and described. This system can be used as a potential tool for ophthalmological research to determine changes in the outflow system, which may be helpful for identification of abnormalities that lead to glaucoma.

Application of full range swept source optical coherence tomography for imaging of the anterior eye segment in patients with type I Boston Keratoprosthesis

We present a high-speed complex conjugate resolved 1 μm swept source optical coherence tomography [SS-OCT] system using coherence revival of the light source for clinical imaging of the anterior segment of the eye. High-speed of 100,000 A-scans/sec and 1 μm imaging window of OCT permits dense 3D imaging of the anterior segment, minimizing the influence of motion artifacts and deep penetration of images for topographic analysis. The swept laser performance with internal clocking was adapted to achieve extended imaging depth requirements. The feasibility of our instrument for visualization of the anterior segment of patients with the Boston Keratoprosthesis (KPro) was discussed. The relations between of the KPro and the surrounding tissue were also demonstrated.

Erratum: Publisher's Note: Three-dimensional anterior segment imaging in patients with type 1 Boston Keratoprosthesis with switchable full depth range swept source optical coherence tomography (Journal of Biomedical Optics (2013) 18 (086002))

Publisher’s Note: Three-dimensional anterior segment imaging in patients with type 1 Boston Keratoprosthesis with switchable full depth range swept source optical coherence tomography Raju Poddar Dennis E. Cortes John S. Werner Mark J. Mannis Robert J. Zawadzki Downloaded From: http://biomedicaloptics.spiedigitallibrary.org/ on 02/10/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx