Abstract
Purpose::
To demonstrate the utility of high-resolution retinal imaging using adaptive optics scanning laser ophthalmoscopy (AOSLO) in studying subtle photoreceptor disruptions in patients with otherwise unexplained visual disturbance.
Methods::
High resolution retinal images of patients with unexplained visual disturbance were obtained using an AOSLO instrument located at Doheny Eye Institute. The instrument provides real time video imaging, axial sectioning and high lateral resolution, combining a scanning laser (860nm wavelength) with adaptive optics. The AO system corrects for high and low order ocular aberrations using a cascade of a deformable bimorph mirror and a deformable MEMS mirror. In one case example, a 64 year old male patient complained of deterioration in vision with a "ring-like" paracentral distortion in the left eye of one year’s duration. Complete ophthalmic evaluation including visual function testing (acuity, color vision, perimetry), funduscopy, fluorescein angiography, fourier domain optical coherence tomography (OCT), and a detailed AOSLO examination were performed.
Results::
In this case, Snellen visual acuity testing measured 20/20 in both eyes. Color vision was slightly reduced on the left (14/19 HRR plates), and Amsler grid testing demonstrated a small ring-like scotoma. 24-2 Humphrey perimetry revealed a small central scotoma with foveal sensitivity loss. Funduscopy and angiography were unremarkable. On high-resolution OCT images, a slight disruption of the inner segment/ outer segment photoreceptor junction could be noted in the parafoveal retina of the left eye. AOSLO examination revealed a parafoveal circular disruption of the photoreceptor mosaic approximately 5 degrees in diameter which precisely corresponded to the ring of visual disturbance perceived by the patient.
Conclusions::
AOSLO imaging allows non-invasive in vivo visualization of retinal pathology at a cellular level. Visualization of cone photoreceptor outer segments with high resolution imaging can reveal alterations of the cone mosaic which may not be identified with other methods and may enable early detection of retinal diseases.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • photoreceptors • degenerations/dystrophies