Purpose To identify the quantitative casual link between anisometropia magnitude and the losses of resolution and contrast sensitivity function; whilst also exemplifying how the function of fusion and stereopsis vary with anisometropia magnitude in previously untreated anisometropic amblyopes.
Methods 57 patients with previously untreated anisometropic amblyopia without strabismus (ranged from 8-35 years), were measured refractive error, BCVA, fusion and stereopsis, and 48 patients have completed contrast sensitivity function test. Anisometropia magnitude was determined by dioptric vector addition model, and the amblyopia depth was determined by the difference of BCVA in logMAR units between the amblyopic and fellow eyes.
Results This study suggested that anisometropia magnitude is more detrimental to amblyopia depth (R= 0.728, p<0.001) than it is to the difference of the area under the log contrast sensitivity function (AULCSF) (R=0.505, p<0.001). And it is also demonstratedthat the depth of amblyopia and the difference of AULCSF between the amblyopic and fellow eyes have significant correction (R=0.761, p <0.001), the more severity of amblyopia, the poorer levels of contrast sensitivity. Most pure anisometropes with anisometropia magnitude (AM) less than 3 D retain fusion and some stereopsis, but when AM more than 3.0D, especially for the anisometropes who’s AM larger than 6.0D, fusion and stereopsis function are seriously influenced.
Conclusions In summary, as the degrees of anisometropia increases, the depth of amblyopia becomes more serious, and thelevels of contrast sensitivity, fusion and stereopsis becomes poorer, for the previously untreated anisometropic amblyopia.