Can uncompensated higher order aberration profile, or aberropia be responsible for subnormal best corrected vision and pseudo-amblyopia.

BACKGROUND: Higher order aberrations (HOA) are components of wavefront distortion which cannot be corrected by conventional spectacle correction. Normally they constitute up to 15% of wavefront distortion in the ocular media. The HOA interact in a nonlinear method and tend to compensate each other in most conditions. HYPOTHESES: We hypothesize that abnormally increased and uncompensated higher order aberration profile in certain cases may limit the amount of best corrected visual acuity to subnormal levels and produce a pseudo-ambylopia like picture. We term this entity as aberropia. EVALUATION OF THE HYPOTHESIS: Higher order aberrations (HOA) have been proven to have supporting role in visual function in association with lower order aberrations. Normally HOA tend to compensate for each other and have an effect much less than what would be expected if they would have acted separately. This unique state of compensation may be lost in certain cases, for example, in patients who have undergone laser refractive surgery without consideration for HOA correction or in partial correction of a pathological eye like severe keratoconus. Occasionally investigators have noticed that patients with high induced aberrations after refractive surgery cannot achieve spectacle correction to get a 20/20 vision. Conversely, there is evidence for gain of vision after wavefront guided refractive surgery and phakic intraocular lens implantations in some cases which cannot be explained only by retinal image change. CHALLENGES TO CONCLUSIVELY PROVE THE HYPOTHESES: With the current level of advancement in refractive surgery, we can correct lower order aberration to a near zero level. However it is not as easy to do the same with higher order aberrations because of variability in assessment, evolving laser beam profiles and factors associated with the surgery itself and wound healing. All the four can alter higher order aberrations. IMPLICATIONS OF THE HYPOTHESES: Understanding of uncompensated higher order profiles leading to loss of BCVA, or aberropia, would be a paradigm shift in understanding of the role of higher order aberrations on visual function. With improvement in diagnostic and treatment methods, these patients with a subnormal vision, may be treated to achieve their maximum visual potential.