Purpose:

It is widespread practice to under-correct astigmatism with toric IOLs so as not to “flip the axis”. Purpose: To compare the achieved refractive astigmatism in eyes targeted at the least possible remaining refractive astigmatism where this was to be achieved by over-correction and 90 degree axis rotation with the likely refractive astigmatism if under-correction had been targeted and axis “flip” avoided

Methods:

A retrospective review of consecutive eyes receiving toric IOLs between June 2014 and September 2016 was undertaken and over-correction-targeted eyes identified. The refractive astigmatic outcome in these eyes was recorded and compared to a vector-derived likely outcome if an IOL of one step lower in cylinder power (0.5D) had been used

Results:

Out of 116 consecutive eyes, 21 were identified where over-correction was targeted. Achieved refractive astigmatism mean (SD) was 0.45D (0.36). Vector calculated likely outcome of IOL cylinder power reduction by 0.5D was a mean (SD) of 0.82D (0.43) (p=0.009)

Conclusions:

A decision not to over-correct and “flip the axis” would have doubled the remaining refractive astigmatism