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Communication essential when addressing astigmatism and cataract surgery
"At Issue" asked a panel of experts: What do you recommend for cataract patients with a significant calculated postoperative residual astigmatism?
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Discuss spectacle freedom
Brooks Alldredge, OD, FAAO: The first question to answer is how important it is to each individual patient to wear eyeglasses as little as possible after cataract surgery. If achieving spectacle freedom is not a goal or not desired or the extra cost is prohibitive, then I reassure those patients that their vision will be just as good as if they didn’t correct the astigmatism with surgery – they will simply need glasses to do so.
One diopter of corneal toricity is generally my threshold to discuss astigmatism correction.
I have little experience with femto-laser relaxing incisions for two reasons. First, we had inconsistent outcomes with manual limbal relaxing incisions. Second – and most important – I have had many years of very happy patients using toric IOLs. It’s my go-to solution. Until there is ample evidence to support equal or superior outcomes with femto-laser incisions over toric IOLs, I will continue to nearly exclusively use toric IOLs in patients wanting astigmatism correction.
The challenging patients are those who have about 0.75 D of corneal toricity and are highly motivated to correct their vision to be as sharp as possible. That’s enough astigmatism to reduce vision a couple of lines postoperatively, but not always. Sometimes I will suggest to the surgeon that the clear corneal incision be moved to the steepest meridian, but that has practical limits on where it can be located and variable results. What I will offer is the possibility of a two-step staged procedure: Correct the majority of the refractive error with a monofocal IOL followed by LASIK or PRK for any residual spherical and astigmatic refractive error. Frequently, these patients will be happy enough with their vision with a monofocal IOL alone, and no LASIK is needed, but the option of precisely correcting any residual postop correction is good to have for the most demanding patients.
- For more information:
- Brooks Alldredge, OD, FAAO, is a staff optometrist at Pacific Cataract and Laser Institute in Tualatin, Ore. He can be reached at: brooks.alldredge@pcli.com.
Disclosure: Alldredge reports no relevant financial disclosures.
Consider ocular history
Kerri Norris, OD, FAAO: Toric IOLs continue to improve in design and range of powers offered, however, there are still high myopes, hyperopes and astigmats who fall outside the offered range. While the highest 6-D toric IOL only has an effective power of correcting about 4.5 D at the corneal plane, I do still recommend this lens for patients with significant corneal astigmatism who will be left with some uncorrected. I educate them that while they will still need some correction for best vision, it will be optically superior vision than if no astigmatism was treated during cataract extraction.
There are patients I am less excited to recommend the toric lens upgrade for, such as those with irregular corneal cylinder, whether it be from keratoconus, corneal transplant or post-laser vision correction (LASIK or PRK). These lenses should also be approached cautiously in patients with compromised capsule or zonule integrity, like in patients with a history of significant blunt ocular trauma or diseases like Marfan syndrome. These patients would likely best benefit from spherical monofocal IOLs and an honest discussion that postoperative correction with spectacles, or gas-permeable lenses in certain cases, would provide the most stable vision.
Our clinics only use femto-laser relaxing incisions on a limited basis, and even then only in certain locations. I do recommend refractive clear corneal incision when indicated, for example, with minor against-the-rule astigmatism.
In those patients with otherwise good ocular health and about 1.25 D of corneal cylinder or more, I have the “toric discussion.” Even then, I make it clear that they can save themselves the money if having more glasses-free distance vision postop is not important to them. I also steer patients away from any lens upgrade if they are amblyopic or have significant concurrent disease such as age-related macular degeneration.
- For more information:
- Kerri Norris, OD, FAAO, is a staff optometrist at Pacific Cataract and Laser Institute in Kennewick, Wash. She can be reached at kerri.norris@pcli.com.
Disclosure: Norris reports no relevant financial disclosures.
Establish a visual goal
Josh Johnston, OD, FAAO: This starts with a discussion about what the visual goal is with the patient. What do they want to achieve by having surgery? What are their lifestyle demands and visual needs? I try to customize each preop surgical discussion to the patient, developing a personalized vision plan. If a patient desires spectacle independence at distance after surgery, any corneal astigmatism in magnitude greater than 0.50 D will need to be analyzed to see if treatment is necessary. For the lowest amounts of astigmatism (less than 0.50 D), a monofocal IOL can be used, as an experienced surgeon can sometimes manipulate the incisions to negate or offset that corneal astigmatism. When you have about 0.50 D to 1.00 D of postoperative corneal astigmatism, we use a femtosecond laser. I find femtosecond lasers to be more accurate and predictable than limbal relaxing incisions, which have too many variables that are not as controllable. Any astigmatism greater than 1.00 D will likely best be suited with a toric IOL. Patients understand astigmatism, and toric IOL patients are very satisfied and happy with their visual outcomes. Toric IOLs can treat about 4.0 D at the corneal plane, and combined procedures with a femtosecond laser and a toric IOL can be used to treat even greater amounts.
- For more information:
- Josh Johnston, OD, FAAO, is the clinical and residency director at Georgia Eye Partners in Atlanta. He can be reached at: josh.johnston@gaeyepartners.com.
Disclosure: Johnson reports he is a consultant to Akorn, Alcon, Allergan, Avellino, BioTissue, Bruder, Johnson & Johnson, Kala Pharmaceuticals, Omega Ophthalmics, Shire and Sun Pharma.