Refractive adaptation in amblyopia: quantification of effect and implications for practice.
OBJECTIVE
To describe the visual response to spectacle correction ("refractive adaptation") for children with unilateral amblyopia as a function of age, type of amblyopia, and category of refractive error.


METHODS
Measurement of corrected amblyopic and fellow eye logMAR visual acuity in newly diagnosed children. Measurements repeated at 6 weekly intervals for a total 18 weeks.


RESULTS
Data were collected from 65 children of mean (SD) age 5.1 (1.4) years with previously untreated amblyopia and significant refractive error. Amblyopia was associated with anisometropia in 18 (5.5 (1.4) years), strabismus in 16 (4.2 (0.98) years), and mixed in 31 (5.2 (1.5) years) of the study participants. Mean (SD) corrected visual acuity of amblyopic eyes improved significantly (p<0.001) from 0.67 (0.38) to 0.43 (0.37) logMAR: a mean improvement of 0.24 (0.18), range 0.0-0.6 log units. Change in logMAR visual acuity did not significantly differ as a function of amblyopia type (p = 0.29) (anisometropia 0.22 (0.13); mixed 0.18 (0.14); strabismic 0.30 (0.24)) or for age (p = 0.38) ("under 4 years" 0.23 (0.18); "4-6 years" 0.24 (0.20); "over 6 years" 0.16 (0.23)).


CONCLUSIONS
Refractive adaptation is a distinct component of amblyopia treatment. To appropriately evaluate mainstream therapies such as occlusion and penalisation, the beneficial effects of refractive adaptation need to be fully differentiated. A consequence for clinical practice is that children may start occlusion with improved visual acuity, possibly enhancing compliance, and in some cases unnecessary patching will be avoided.
Stewart
C E
CE
Department of Visual Neuroscience, Imperial College London, Charing Cross Campus, Margravine Road, London W6 8RP, UK. c.stewart@imperial.ac.uk
Moseley
M J
MJ
Fielder
A R
AR
Stephens
D A
DA
D000221:Adaptation, Ocular / Q000502:physiology*; D000550:Amblyopia / Q000503:physiopathology*; D015858:Anisometropia / Q000503:physiopathology; D001251:Astigmatism / Q000503:physiopathology; D002648:Child; D005139:Eyeglasses; D006801:Humans; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000503:physiopathology; D013285:Strabismus / Q000503:physiopathology; D014792:Visual Acuity / Q000502:physiology