How do you determine the appropriate toric IOL when there is a discrepancy in axis or cylinder power between optical biometry and corneal tomography during preoperative evaluation?  

Always difficult. Always re-measure when discrepancies occur. For axis discrepancies, Auto Ks, topography, biometry, and past refraction. Past refraction is where the patient lived their entire life before their cataract surgery. Which of these tests aligns the most? Past refraction, especially pre-...

I recommend double-checking both measurements; poor alignment or dry eye can cause a discrepancy. If the discrepancy is still high (over half a diopter), the patient probably presents with an irregular astigmatism, and a toric IOL is not recommended. If they are slightly different, I usually use t...

Manual Ks are the best. If the topo rings are irregular, look for ABMD. It is often very helpful to focus on DES and have them return for repeats.

In my experience, the most common causes of discrepancies between preop measurements are ocular surface disease or ABMD, as others have mentioned. I like to see a 10° or less difference across my devices. More than that, then I take a hard second look, treat the ocular surface, repeat measuremen...