Abstract
Purpose: :
Traditionally, amblyopia has been characterized by neural disruptions rather than anatomical changes in the subject’s retina. Recently, optical coherence tomography (OCT) has been used to investigate changes in retinal thickness in amblyopic eyes, without a clear consensus. The purpose of our study is to use two in vivo ultrahigh resolution imaging modalities, namely, a Fourier-domain (FD) OCT system and an adaptive optics (AO) fundus camera, to investigate the integrity of the outer retina, including cone photoreceptors, between amblyopic, fellow and age-matched emmetropic eyes.
Methods: :
6 subjects (n=4 amblyopes and n=2 emmetropes) were imaged with a FD-OCT system (RTVue) and 3 subjects (n=1 amblyope and n=2 emmetropes) were imaged with the NECO AO fundus camera at horizontal retinal positions up to 4 degrees away from the fovea. All subjects were young adults (age range 22-27) and underwent a basic ophthalmic evaluation with assessment of binocular function and color vision. All amblyopes were mixed and had a history of treatment, which was assessed by a questionnaire. Cone density was analyzed from the AO cone mosaic images using a Matlab program and compared to outer retinal thickness (defined as layers from ELM to RPE) from the FD-OCT images at the same retinal locations.
Results: :
Outer retinal thickness values in amblyopic eyes, as measured by the FD-OCT, do not appear to differ significantly from their fellow or emmetropic eyes (difference <10%). Moreover, we found no difference in the cone density, by AO imaging, at eccentricities up to 4 degrees from the fovea between amblyopic and emmetropic eyes (difference <15%).
Conclusions: :
Although preliminary, the outer retina appears to be unaffected in the eyes of mixed amblyopes, supporting the assertion that the anatomical organization of the outer retina is not affected by amblyogenic factors. Continued investigation is being performed to further study this hypothesis.
Keywords: amblyopia • retina: distal (photoreceptors, horizontal cells, bipolar cells) • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)