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

Abstract

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.

FIGURE 1

A, In vivo slit-lamp photograph of the Boston KPro. B, AS-OCT of the Boston KPro. The front plate (FP) and optical cylinder (OC) are clearly visible over the corneal graft (CG). The back plate (BP), like the rest of the KPro, appears dark on OCT. It is also possible to identify the graft–host junction (GHJ).

FIGURE 2

Boston KPro with a retroprosthetic membrane (RPM). Corneal graft (CG), the KPro back plate (BP), and one of the holes (H) manufactured into the KPro back plate are visible. The hole (H) has been filled with fibrous tissue. Posterior to the back plate, we can see an RPM.

FIGURE 3

A, In this image, the epithelium (EPI) is clearly visible posterior to the front plate (FP) and anterior to the corneal graft (CG). The bandage contact lens (BCL) and back plate (BP) are also identified. B, Epithelium (EPI) growing over the peripheral edge of the FP of Boston KPro eyes.

FIGURE 4

A, Raster scan showing a periprosthetic cyst (C) in the Corneal graft behind to the front plate (FP). B, AS-OCT showing a KPro patient with a gap (G) in the corneal graft posterior to the FP.

FIGURE 5

Horizontal (A) and vertical (B) scan showing a KPro patient with corneal thinning (CT) in the graft behind to the front plate (FP). The corneal thinning is unmistakable on AS-OCT but was difficult to detect at the slit lamp. A bandage contact lens (BCL) is also identified.