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Preoperative strategies manage astigmatism before cataract surgery
Careful preoperative measurements from several devices can help ensure patient satisfaction.
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Determining if astigmatism is regular or irregular before cataract surgery can greatly improve postoperative outcomes and patient expectations.
A patient with regular astigmatism can expect to undergo a routine cataract surgery with a toric IOL placement, but if a patient has greater than 1.5 D of astigmatism or irregular astigmatism, then additional preoperative steps are needed to ensure positive outcomes, OSN Cataract Surgery Board Member Audrey Talley Rostov, MD, said.
“In regard to determining the axis and amount of astigmatism, there are many different ways of doing this. I personally get measurements by using a Pentacam (Oculus), which is great for axis of astigmatism. For IOL calculations, I have a Lenstar (Haag-Streit), but now I have the new IOLMaster 700 (Zeiss), which also works extremely well. I like to see what the K values are, where the axis is, and I like to compare all of my measurements,” Talley Rostov said.
Steps for astigmatism
If greater than 0.5 D of astigmatism is noted, the patient undergoes an examination with the Cassini (i-Optics), and the measurements are imported into the Lensar femtosecond laser system (Lensar), which enables Talley Rostov to make small laser markings denoting the axis of astigmatism on the patient’s cornea. This is also helpful for planning corneal relaxing incisions in case of regular astigmatism and/or patients with corneal transplants.
“This allows for toric placement. In addition, I use intraoperative aberrometry; I have an ORA system (Alcon). Essentially, what that allows you to do is to have a very nice placement of a toric IOL. For cataract surgery cases with regular astigmatism, this is very straightforward,” she said.
Talley Rostov said she has found success using both the Tecnis (Johnson & Johnson Vision) and AcrySof (Alcon) toric IOL platforms for patients with astigmatism.
Irregular astigmatism needs to be addressed and potentially corrected before surgery — for example, a patient with a corneal scar or severe keratoconus may need to have a cornea transplant before cataract surgery — and patient expectations need to be tempered, she said.
“It’s important to identify why they have the irregular astigmatism, and afterward if there is still residual astigmatism, to set the expectation that the patient may require glasses or contact lenses for best corrected vision. If they have keratoconus, for example, or a previous cornea transplant, then I look at the astigmatism, let them know that they will not be glasses independent, but we can certainly reduce their need for glasses but not eliminate it. For the keratoconus patient, we can use toric IOLs, in a very similar fashion to what I described, knowing that it’s trickier to get the axis of astigmatism. I look at several sources and try to see the best axis of astigmatism while knowing that I may not be able to correct all the astigmatism,” she said.
Patient expectations
For a patient with a previous corneal transplant, corneal relaxing incisions in the transplant combined with a toric IOL work well for reducing astigmatism. This combination leads to a greater effect and can be “extremely helpful,” Talley Rostov said.
With any strategy to reduce astigmatism, a surgeon needs to ease patient expectations and give them an accurate outlook on their lives after cataract surgery, she said.
“If someone has really unrealistic expectations, then you want to avoid doing any kind of vision corrective procedure. I’d avoid a multifocal or [extended depth of focus] lens in that patient because they will never be happy. There are some patients who have a baseline of unhappy; you can’t have a 20/400 brain see 20/20. If you have a glass-is-half-empty type of person, a lot of times there aren’t a lot of things to change that. Listen to your staff and listen to your gut instincts because sometimes there are just patients who are extremely unrealistic and you’ll never make them happy,” she said.
With whatever decision is made, Talley Rostov said it is important to stay consistent with the measurements.
“Be consistent with your measurement techniques and get to know your equipment and what it can do,” she said. – by Robert Linnehan
- For more information:
- Audrey Talley Rostov, MD, can be reached at Northwest Eye Surgeons, 10330 Meridian Ave. N., Suite 370, Seattle, WA 98133; email: atalleyrostov@nweyes.com.
Disclosure: Talley Rostov reports no relevant financial disclosures.