Abstract
Objective: Some studies have hypothesized that an unfavourable higher order aberrometric profile could act as an amblyogenic mechanism and may be responsible for some amblyopic cases that are refractory to conventional treatment or cases of “idiopathic” amblyopia. This study compared the aberrometric profile in amblyopic children to that of children with normal visual development and compared the aberrometric profile in corrected amblyopic eyes and refractory amblyopic eyes with that of healthy eyes. Methods: Cross-sectional study with three groups of children – the CA group (22 eyes of 11 children with unilateral corrected amblyopia), the RA group (24 eyes of 13 children with unilateral refractory amblyopia) and the C group (28 eyes of 14 children with normal visual development). Higher order aberrations were evaluated using an OPD-Scan III (NIDEK). Comparisons of the aberrometric profile were made between these groups as well as between the amblyopic and healthy eyes within the CA and RA groups. Results: Higher order aberrations with greater impact in visual quality were not significantly higher in the CA and RA groups when compared with the C group. Moreover, there were no statistically significant differences in the higher order aberrometric profile between the amblyopic and healthy eyes within the CA and RA groups. Conclusions: Contrary to lower order aberrations (e.g., myopia, hyperopia, primary astigmatism), higher order aberrations do not seem to be involved in the etiopathogenesis of amblyopia. Therefore, these are likely not the cause of most cases of refractory amblyopia.
Highlights
Amblyopia is defined as a decrease in bestcorrected visual acuity due to some form of visual deprivation or abnormality of binocular interaction in the absence of any identifiable pathology of the eye or visual pathway
Treated amblyopia was defined as a best corrected visual acuity (BCVA) of greater than 8/10 (20/25), and refractory amblyopia was defined as a BCVA of less than or equal to 8/10 for more than one year after standard treatment
We considered the following higher order aberrations with greater impact on visual quality: 3rd order vertical coma, 3rd order horizontal coma, secondary astigmatism, spherical aberration, 5th order trefoil, 5th order vertical coma, and 5th order horizontal coma[4]
Summary
Amblyopia is defined as a decrease in bestcorrected visual acuity due to some form of visual deprivation or abnormality of binocular interaction in the absence of any identifiable pathology of the eye or visual pathway. According to the classification developed by Von Noorden et al[1], amblyopia can be categorized into the following three types based on the causative mechanism: strabismic, refractive, and deprivation. Refractive amblyopia includes anisometropia, bilateral high ametropia, and meridional astigmatism. Deprivation amblyopia is caused by anomalies that interfere with unilateral or bilateral visual stimuli, such as media opacities, ptosis, or occlusion. Until a few years ago, refractive errors and aberrations were considered independent concepts. The modern wavefront theory combines all the optical errors and designates them together as wavefront aberrations. The wavefront aberrometer is a relatively new diagnostic tool that allows us to provide a detailed description of the optical characteristics of the human eye based on complex mathematical formulas called Zernike polynomials[3]
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