An investigation by Australian-based cataract surgeons found: posterior corneal surgically induced astigmatism (SIA) could not be predicted pre-operatively using biometric features; centroid posterior corneal SIA is extremely small (near zero); and no difference in posterior corneal SIA was found when the steep axis aligned with the temporal incision.
The research by Adelaide-based Associate Professor Michael Goggin and New Zealand ophthalmologist Dr Ben LaHood, and Melbourne’s Dr Jack Kane, studied SIA associated with temporal 1.8mm incisions, with biometry taken pre-operatively and six weeks post-operatively for 258 eyes of 258 cataract patients.
Although the findings may not translate to larger incisions, said Dr LaHood, they support three concepts: ophthalmologists cannot currently adjust for posterior corneal SIA and probably don’t need to if incisions are small; smaller incisions produce lower magnitude SIA; and operating on the steep axis of the cornea does not have a predictable effect on reducing astigmatism in that meridian.
For the full paper, see https://tinyurl.com/m4xv4bmp and for more from Dr LaHood on this topic see, https://crstoday.com/articles/july-2023/surgically-induced-astigmatism
