Ocular aberrations in amblyopic children

Purpose: To study the pattern of ocular aberrations in amblyopic children, and evaluate a possible relation to etiology and treatment outcomes of amblyopia. Methods: The Wave Scan Wavefront System (AMO, Santa Ana, CA, USA) aberrometer was used to assess 75 eyes (60 children) after instillation of 1% cyclopentolate eyedrops. There were 29 males and 31 females with a mean age of 9.23 ± 2.55 years (range, 5–14 years). The study sample was subdivided into four groups; 16 emmetropic non-amblyopic eyes (control group); 24 pre-treatment newly diagnosed amblyopic eyes; 16 eyes of treated amblyopes and; 19 eyes with refractory amblyopia. Results: Amblyopes had statistically significant greater root mean square (RMS) values for whole eye aberrations, 2nd order aberrations, defocus (Z02) and astigmatism (Z22) compared to emmetropes (P 0.0001). The refractory amblyopic group showed statistically significant differences in whole eye RMS, 2nd order- aberrations, defocus (Z02) and astigmatism (Z22) when compared to treated amblyopic groups (P 0.0001). Apart from a statistically significant difference in 5th order RMS of pre-treated amblyopes versus the control group, no other significant differences were found in higher order aberrations (HOAs: coma, spherical, higher order astigmatism, trefoil, or 3rd, 4th, 5th or 6th order terms) between emmetropes and any of the amblyopic groups. Conclusion: Lower order aberrations remain the major factor that affect retinal image quality and hence amblyopia development especially in ametropic eyes. This can be corrected optically. Studying HOA profile in amblyopic eyes failed to explain why refractory amblyopia does not respond to orthoptic treatments. This outcome indicates that theories of central problems in image processing and binocular interaction are likely the main cause of refractory amblyopia.