BLOG: Considerations in cataract surgery for your keratoconic patient
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As a scleral lens fitter working in an ophthalmology group with cornea and cataract specialists, I try to hold off on sending a keratoconic patient for cataract surgery until it is absolutely necessary.
I consider it absolutely necessary when the cataracts are truly affecting the patient’s activities of daily living (ADLs) such as driving, reading and working. As we know, many of these patients — especially the moderate to advanced cases — will still require a specialty contact lens afterward. Worse yet, they will not be able to compare their surgical outcomes to other non-keratoconic patients they know that no longer need much in the way of visual correction after cataract surgery. This is where the OD comes in.
With premium cataract services advancing and being marketed very well to patients these days, the question naturally comes to the keratoconic patient’s mind: “Can I have that and not depend on my visual correction too?” As their primary eye care provider and the one who will hopefully be comanaging their postoperative care, it is important to be able to educate and guide them on their options as well as their expectations.
Another important factor to assist with is getting them through the required time the surgeon wants them to be out of their contact lenses to obtain the best possible measurements for cataract surgery (longer for those who wear lenses that actually touch that cornea vs. scleral lenses that vault the cornea). This alone can present a major hardship for the patient who struggles with best corrected acuity in spectacles. I tend to focus on getting them completely through one eye’s operation, healing process and lens refit before getting the other eye done so at least one eye can stay in a contact lens to allow some level of functionality.
The most complicated part of planning cataract surgery for a patient with an irregular cornea is choosing which keratometry values to use to choose the correct IOL. The difference in astigmatic power from the apex of the cone to the peripheral cornea can vary widely and result in deviations in IOL power, leading to poor visual outcomes for the patient. Because accurate IOL calculations require reliable and stable keratometry values, performing preoperative corneal collagen cross-linking and/or inserting intrastromal corneal ring segments can be beneficial to the outcomes. Not all surgeons use these techniques to treat the cornea in advance, so these discussions about where to send your patient for cataract surgery should also be taken into consideration.
In terms of premium IOL options, the vast majority of surgeons would agree that the array of multifocal IOL designs are contraindicated in this population. The already aberrated surface of the cornea does not lend itself well to the design of these IOLs and will lead to increased higher order aberrations postoperatively. Some surgeons will consider (and are studying) extended depth of focus or accommodating IOLs in keratoconic patients as well as light adjustable lenses, but this is still atypical practice at this time.
It is highly debated whether a patient with keratoconus should have a toric IOL implanted at the time of cataract surgery. With advancements in technology and surgical procedures, surgeons are more willing to implant a toric IOL in those with stable, mild corneal ectasias. The expectations have to be placed that this implant may not correct the vision to the degree the patient finds satisfactory, and they may still need glasses or specialty contact lenses. If the rotation is off, the patient may suffer from worsening of higher order aberrations as well.
When a toric IOL is implanted into a patient with moderate to advanced levels of corneal ectasia, and the patient wants a specialty contact lens for best acuity after surgery, be prepared to fit a front toric lens. Remember that the toric IOL is designed to counteract the patient’s corneal astigmatism, but so is a specialty contact lens. What is left is now residual astigmatism that comes from the lenticular astigmatism generated from the IOL.
For best corrected acuity, this then needs to be corrected as a front toric contact lens design (usually high powered) or in over-spectacles. The patient has now paid for premium services at the time of cataract surgery and came out of it wearing specialty contact lenses and over spectacles. The discussion is important to avoid this scenario.
Monofocal IOLs have traditionally performed the best in these patients, especially when the expectation that corrective eye wear — likely specialty contact lenses — will still be needed after surgery just as it was before surgery. Because the surgeon is not operating on the cornea during the cataract procedure, they will still be left with the level of keratoconus they had, but the improved contrast, the reduction of glare, the best corrected acuity and their ADLs should all see improvement.
You know your keratoconic patients best. Make sure to educate the cataract surgeon on the patient’s wants, needs, successes or failures with contact lenses and, most importantly, their expectations. Comanage these patients and start the specialty lens refitting about a month after surgery.
References:
- Moshirfar M, et al. Curr Opin Ophthalmol. 2018;doi:10.1097/ICU.0000000000000440.
- Vastardis I, et al. Ophthalmol Ther. 2019;doi:10.1007/s40123-019-00212-1.
For more information:
Katie Greiner, OD, MS, MBA, FAAO, is chief operating officer and a practicing optometrist at Northeast Ohio Eye Surgeons, located in Stow, Kent and Akron. She completed a surgical comanagement and contact lens residency at Davis Duehr Dean in Madison, Wis. She can be reached at: kgreiner@neohioeye.com.
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