Abstract
Purpose :
Birdshot chorioretinopathy (BSCR) may cause loss of visual function without apparent disease activity. Early retinal changes may not be visualized using current imaging technologies. This qualitative study used Adaptive Optics Scanning Laser Ophthalmoscopy (AOSLO) to evaluate photoreceptor (PR) integrity in patients with BSCR to ascertain its utility in assessing outer retinal damage in this disease.
Methods :
29 eyes of 16 patients with HLA-A29 positive BSCR were enrolled between May and October 2015. AOSLO images of the macula were obtained using Apaeros Retinal Imaging System (Boston Micromachines, Boston). 13 patients were imaged once, and 3 patients were imaged twice. Exclusion criteria were retinal pathology except ERM and BSCR, and inadequate image quality. Adequate images were obtained in 4 eyes of 3 patients. Images were manually aligned with infrared reflectance fundus photos (IR) and correlated with optical coherence tomography (OCT).
Results :
In 4 of 29 eyes (13.8%), adequate AOSLO images were obtained. AOSLO images showing healthy photoreceptors correlated with an intact interdigitation zone (IZ) and ellipsoid zone (EZ) on OCT, while disruption of the IZ on OCT was seen as loss of waveguiding outer segments on AOSLO images.
Conclusions :
Photoreceptor loss is an important feature of BSCR, and does not correlate with lesions seen clinically. AOSLO shows significantly more PR detail than OCT. We showed correlation between IZ disruption on OCT and loss of outer segments on AOSLO. As well, intact AOSLO correlates well with normal OCT findings. However, the dark areas that likely represent loss of waveguiding outer segments on AOSLO were not always seen on OCT as disruption of the IZ or EZ. This suggests that AOSLO detects PR loss earlier than is apparent on OCT. We are currently quantifying photoreceptor density in these patients, which could provide an objective measure to monitor disease progression. Media opacities (corneal or lens changes, vitritis), which are common in uveitic conditions, presented a significant optical hurdle.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.