Life Cycle and Lensing of a Macular Microcyst

Abstract

Introduction: Microscopic details about retinal conditions can provide insight into pathological mechanisms, but these are ordinarily difficult to obtain in situ. We demonstrate how high-resolution imaging and optical modeling can be combined to reveal morphological features of a macular microcyst, offering insight into microcyst formation. Objective: To use adaptive optics scanning laser ophthalmoscopic (AOSLO) images to track a transient retinal microcyst and derive its 3-dimensional shape. Methods: A series of AOSLO images were gathered before, during, and after a transient retinal microcyst developed in an otherwise normal healthy 26-year-old male subject. Optical coherence tomography (OCT) independently confirmed the location of the microcyst. Optical modeling was conducted to quantify the lensing effect of the optically uniform microcyst and to determine its 3-dimensional shape. Increment threshold sensitivity, targeted within and around the microcyst, was tested to see if cone photoreceptor function was affected. Results: A transient microcyst appeared as a 50 µm diameter circle in AOSLO images, localized to the inner nuclear layer. Based on image distortion of the photoreceptor mosaic, optical modeling suggests that the microcyst had the shape of an aspherical lens, distinguishable from a spherical, cylindrical, or elliptical shape, indicative of an edematous expansion of laminar tissue. The microcyst spontaneously resolved about 30 days after first discovery. No changes to the photoreceptor mosaic ensued from the presence of the microcyst, and functional testing of the photoreceptors below the microcyst indicated no loss of light sensitivity. Conclusions: Microcysts have been associated with numerous subtypes of optic nerve degeneration, including multiple sclerosis and various inherited neuropathies. This microcyst appeared in a healthy individual and resolved without intervention. Lensing effects can be used to determine microcyst shape, which cannot be resolved by OCT imaging, and to help infer etiology.

Patches of Dysflective Cones in Eyes With No Known Disease

“…Cone reflectivity measured in the confocal AOSLO can be a challenging metric for retinal health due to significant spatial and temporal variations. 4 Intra-cone reflectivity changes over time could be due to a multitude of factors, including light interference effects, 5 , 6 outer segment length changes due to disc shedding, 7 pigment density changes, 8 and optical waveguiding. 9 Inter-cone differences in reflectivity, however, are unrelated to cone type except under carefully controlled conditions, 10 and local reflectance angle differences are unlikely causes for large reflectivity differences.…”