March 2016

 

CATARACT

 

Presentation spotlight

Numerous options available to correct refractive error post cataract surgery


by Louise Gagnon EyeWorld Contributing Writer

 
   

Several scenarios call for an enhancement following cataract surgery where there is residual refractive error, according to Sheraz Daya, MD, medical director, Centre for Sight, London.

Discussing the management of residual refractive error subsequent to cataract surgery at the 55th annual Walter Wright Symposium in Toronto, Dr. Daya explained that the strategy to correct the error should be tailored to the degree of error. It depends on the magnitude of the correction, Dr. Daya said in an interview with EyeWorld. Is the spherical equivalent zero? If it is not, then you have to use some technique to reduce that. Miscalculation of the IOL power or incorrect judgment of where the lens sits in the eye are situations following cataract surgery that will require an enhancement.

The presence of astigmatism can also call for an enhancement if there has been an undercorrection, if it was induced through the cataract wound, or if it has developed because of a tilt in the lens.

When the spherical equivalent is zero and there is residual astigmatism of 1.5 D or less, limbal relaxing incisions are appropriate, but if there is an error in terms of spherical equivalent, limbal relaxing incisions would not suffice, Dr. Daya said.

Limbal relaxing incisions can be performed at the slit lamp or with the femtosecond laser. It is preferable that with the laser these be intrastromal and in turn more controllable, Dr. Daya said.

Laser ablative options like LASIK or PRK are other strategies to correct residual refractive errors after cataract surgery, but a modality like LASIK is perhaps too aggressive a solution. If the magnitude of correction is very low, LASIK is unnecessary, Dr. Daya said. You also want to consider that there are cataract wounds there, and when you use a device for flap creation, there may be induced biomechanical change. You may then get unpredictable changes that can alter the endpoint, especially in older patients. We found that when we did LASIK in older patients, we had higher enhancement rates. Because of this experience in his practice, Dr. Daya no longer uses LASIK to correct refractive error, but instead uses PRK. A consideration in patients who will undergo PRK is the risk of dry eye, and the impact this will have on their visual outcome. Careful screening of patients is thus necessary to determine which patients will likely develop dry eye post-PRK, Dr. Daya said.

A trend that Dr. Daya has observed as early as 1 month postop in PRK patients is that these patients may be overcorrected. We have seen this especially in elderly patients, Dr. Daya said. In situations where a low level of correction is required, such as less than 1 D, the final outcome is much more predictable. For a high level of correction, such as 1.25 D and more, they can get overcorrected. Dr. Daya described patients who have had radial keratotomy as very unstable and not suitable candidates for laser refractive surgery. Another population of challenging patients are those who have had previous PRK because the outcomes are unpredictable following further PRK. I would use a piggyback lens for these patients, even for a very low power, he said.

In patients who have had previous PRK and require enhancement where clinicians choose to do PRK again, they might have underlying epithelial hyperplasia and when the epithelium is removed, they may have an unpredictable outcome.

Remember to measure epithelial thickness, Dr. Daya said. Otherwise, you can get yourself in serious trouble. Dr. Daya noted lens-based surgery is particularly suitable when laser ablative surgery is contraindicated, such as in the presence of keratoconus.

Lens-based surgery is a good option for a high amount of error, and it can be done very soon after the first procedure, he said.

The advantages of lens-based surgery include rapid visual rehabilitation, strong predictability, avoiding the development of dry eye, and a high level of patient satisfaction. The disadvantages include that it is an intraoperative procedure, that there is a risk of rotation of the sulcus-based toric lens, and that there is a risk of pigment dispersion, Dr. Daya said. This type of additive lens surgery does not carry the surgical risk associated with IOL exchange. One such IOL is the Sulcoflex lens (Rayner, West Sussex, U.K.), which is implanted in the ciliary sulcus and is designed so that there is a safe distance between the IOL and the primary implant. The Sulcoflex corrects spherical error and the option of zonal refractive multifocality is available for patients who desire it, Dr. Daya said.

Dr. Daya has performed IOL exchange, exchanging monofocal lenses for multifocal lenses, but cautioned it is important to avoid corneal trauma and capsule trauma in IOL exchange. Be careful not to damage the posterior capsule, he said.

Editors note: Dr. Daya has financial interests with Bausch + Lomb (Bridgewater, N.J.).

Contact information

Daya: sdaya@centreforsight.com

Related articles:

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New focus on NSAIDs for cataract surgery by Maxine Lipner EyeWorld Senior Contributing Writer

Cataract surgery in eyes with compromised corneas by Michelle Dalton EyeWorld Contributing Writer

10 pearls for mastering cataract surgery with ocular comorbidities by Lauren Lipuma EyeWorld Staff Writer

Uveitis: Posterior synechiae, lens deposits, CME, prolonged post-op inflammation, and secondary glaucoma by James P. Dunn, M.D.

Cataract surgery and corneal comorbidities by Clara Chan, MD, FRCSC, FACS, cornea editor

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