A Morphological Study of Retinal Changes in Unilateral Amblyopia Using Optical Coherence Tomography Image Segmentation

Abstract

ObjectiveThe purpose of this study was to evaluate the possible structural changes of the macula in patients with unilateral amblyopia using optical coherence tomography (OCT) image segmentation.Patients and Methods38 consecutive patients (16 male; mean age 32.4±17.6 years; range 6–67 years) with unilateral amblyopia were involved in this study. OCT examinations were performed with a time-domain OCT device, and a custom-built OCT image analysis software (OCTRIMA) was used for OCT image segmentation. The axial length (AL) was measured by a LenStar LS 900 device. Macular layer thickness, AL and manifest spherical equivalent refraction (MRSE) of the amblyopic eye were compared to that of the fellow eye. We studied if the type of amblyopia (strabismus without anisometropia, anisometropia without strabismus, strabismus with anisometropia) had any influence on macular layer thickness values.ResultsThere was significant difference between the amblyopic and fellow eyes in MRSE and AL in all subgroups. Comparing the amblyopic and fellow eyes, we found a statistically significant difference only in the thickness of the outer nuclear layer in the central region using linear mixed model analysis keeping AL and age under control (p = 0.032). There was no significant difference in interocular difference in the thickness of any macular layers between the subgroups with one-way between-groups ANCOVA while statistically controlling for interocular difference in AL and age.ConclusionsAccording to our results there are subtle changes in amblyopic eyes affecting the outer nuclear layer of the fovea suggesting the possible involvement of the photoreceptors. However, further studies are warranted to support this hypothesis.

In vivo optical imaging of amblyopia: Digital subtraction autofluorescence and split-spectrum amplitude-decorrelation angiography

“…Park et al discovered significant thinning of the ganglion cell layer plus the inner plexiform layer in amblyopic eyes, as well as in the outer nuclear layer in inner and outer temporal locations of the parafovea. Moreover, a statistically significant difference as observed only in the thickness in the central region of the outer nuclear layer using the linear mixed model analysis adjusting for axial length and age , suggesting the potential involvement of photoreceptors . The significant difference in the central (foveal) outer nuclear layer suggests that the photoreceptors rather than the ganglion cells could be affected by amblyopia, in contrast to previous speculation .…”

Interocular anatomical and visual functional differences in pediatric patients with unilateral cataracts

“…CMT is significantly correlated with VA in preterm children [32] or pediatric patients with diagnosed retinal diseases [33]. CMT is also correlated with BCVA in children with amblyopia based on long-term follow-ups and treatments [34, 35]. Kim et al reported that spectral-domain OCT analysis of deprivational amblyopic eyes with unilateral pediatric cataracts demonstrated no significant differences in macular thicknesses compared with fellow non-amblyopic eyes and age-matched normal eyes [36].…”

Retinal thickness in children with anisohypermetropic amblyopia

“…At these ages, the retina is still developing as a normal course of development 9. Hendrickson, from a histological study of the retinas of adults and newborn babies, predicted that the human foveal cone density increased until around 5–8 years of age 19.…”

“…Additionally, the retinal thickness was determined manually because there is no commercially available automated software to make these measurements. Szeigeti et al 9 used the custom-built OCT retinal image analysis (OCTRIMA) software to measure the retinal thickness, and Ooto et al 13 measured the retinal thickness manually by two independent ophthalmologists just as we did. If segmentation errors occurred in measuring the retinal thickness by the software, manual correction of the boundary detection is needed 23.…”

“…This indicated a possible abnormal development of the photoreceptors in amblyopic eyes. There are also subtle changes in the outer nuclear layer (ONL) of the fovea of amblyopic eyes suggesting possible alterations of the photoreceptors 9. However, there is no consensus about the microstructure of the retina of amblyopic eyes.…”