Abstract
Purpose: :
To investigate the structural characteristics of the ROP macula with high resolution adaptive optics scanning laser ophthalmoscopy (AOSLO) for comparison to other results from recent high resolution AO Fourier domain optical coherence tomography (AO-FDOCT) imaging and functional (mfERG) measurements.
Methods: :
Six former preterms, now aged 16 to 28 years, with a history of ROP, and 11 age-similar healthy controls were imaged. A compact AOSLO with a large-stroke (50-µm) deformable mirror (Mirao, Imagine Eyes) was used to sense and correct ocular aberrations for high resolution imaging of photoreceptors and vessels in a 1 deg. field of view. Montages from the central macula and at discrete eccentricities were acquired. Auxiliary wide-field line-scanning laser ophthalmoscope (LSLO) and small field SLO videos were acquired simultaneously during AO correction. The system focus was adjusted depending upon the target: for photoreceptors in the outer retina, the focus was set deep, for capillaries in the inner retina, the focus was pulled more anterior. Automated registration and cone counting software were developed and used to analyze results.
Results: :
AO improved retinal images for all subjects. Photoreceptors could be resolved and counted at eccentricities of only 0.25mm (<1 deg) in some subjects and in more subjects at greater eccentricities. In some of the ROP subjects, even with AO compensation, photoreceptors could not be resolved. Because the AO-FDOCT studies had found no difference in the thickness of the photoreceptor layer between ROP and controls subjects, the AOSLO counts, or lack thereof, may be indicative of some disorder of the photoreceptor arrangement in the ROP eye. The finest capillaries around the foveal avascular zone (FAZ) could also be resolved in some subjects. Capillaries overlay the ROP fovea in agreement with previous AO-FDOCT findings. The nuclear laminae in the central most ROP retinas were thickened as had been predicted by mfERG results and then shown by AO-FDOCT.
Conclusions: :
AO significantly enhances the capabilities of SLO and OCT retinal imagers to resolve and characterize distinct structural differences between the ROP and normal eye. Analysis of the AO images can further delineate the consequences of the ROP disease process on the neurovascular elements in the immature retina.
Keywords: retinopathy of prematurity • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)