New toric contacts, IOLs improve astigmatism management
Advances in daily disposable toric contact lenses and toric IOLs reduce the need for patients with astigmatism to compromise their vision or comfort.
Experts in cataract surgery comanagement and contact lenses share their clinical pearls for implementing the newest options in both categories.
When it comes to comanaging prospective IOL candidates with astigmatism, patient selection and corneal pathology are of the utmost importance and should be made a priority, our sources say.
It may be misleading to assume that, “toric IOLs might be risky or have more problems than a standard IOL, but the lenses really just correct the astigmatism. There isn’t a higher instance of glare or anything different in that regard,” Ami Halvorson, OD, FAAO, clinic director of Pacific Cataract and Laser Institute, Portland, Ore., said in an interview with Primary Care Optometry News.
“I definitely screen those who want to be independent of spectacles, that’s the first thing,” she said. “Standard or monofocal IOLs will correct the spherical component of a patient’s prescription, but if a patient has corneal astigmatism they will be dependent on glasses or contact lenses postoperatively if they choose just a monofocal standard IOL.”
Halvorson also confirms that the patient’s macula and retinal health are sufficient. Any compromises will hinder the outcome of the postoperative vision, and the patient may not attain the desired surgical benefit.
One of the most common causes of inaccurate biometry measurements is undiagnosed or untreated dry eye, said Sondra Black, OD, former director of clinical services at Crystal Clear Vision in Toronto and a PCON Editorial Board Member.
“The ocular surface is a refractive component that can easily cause a discrepancy in biometry by a couple of diopters,” Black said in an interview. “If a patient has dry eye, you will get incorrect measurements preoperatively and you’ll have an unhappy patient postoperatively because you won’t meet refractive targets.”
She added that 80% of patients booked for cataract surgery have level 2 or 3 dry eye, according to Trattler and colleagues.
Black said she and her colleagues use a variety of tests to evaluate the patient’s ocular surface, including the TearLab Osmolarity Test, HD Analyzer (Visiometrics) and slit lamp exam, including tear break-up time.
“Trust and communication are broken down when the surgeon is the first to tell a patient they have dry eye disease,” Elizabeth Yeu, MD, a partner at Virginia Eye Consultants and medical director at Virginia Surgery Center, Norfolk, told PCON.
Halvorson said results with toric IOLs can be excellent as long as preoperative measurements are accurate and patient selection is appropriate. Residual astigmatism is determined primarily by the preoperative measurements.
It is also important to note that corneal astigmatism determines whether a toric lens is needed, not the refractive astigmatism, Black said.
Corneal astigmatism can be measured in a variety of ways, our sources said.
“I like to see all of the measurements align with one another, which gives me more confidence where the axis is when we are trying to nail down the astigmatism,” Halvorson said.
For every degree of rotation of the IOL, the lens loses about 3% of its power, she said. Just a few degrees can be visually significant, especially in the higher power toric IOLs.
“I think an intraoperative aberrometer is a nice device,” Yeu said. “I used one for a few years at Baylor. I found it to be most useful in post-LASIK eyes; it did not improve my outcomes when compared to careful preoperative measurements in naïve eyes. Now, with more refined post-LASIK online calculators, between the American Society of Cataract Surgery’s resource and the Barrett True K calculator, I am not sure how much more intraoperative aberrometry would add to my cataract surgery outcomes. There are reasons that may impede further accuracy because of potential confounding factors.
“Aberrometry is affected by the pressure of a lid speculum, with wounds that might be edematous and with the preoperative topical drops; these all affect the actual surface and pressure of the globe before the patient even enters the operating room,” she continued.
Postoperatively, Yeu achieves within 0.5 D of the target 86% of the time – 94% of the time using the femtosecond laser.
At Yeu’s office, Lenstar (Haag-Streit) provides excellent keratometric values in both magnitude and axis, she said. OPD-Scan (Nidek) or Atlas (Zeiss) Placido topography is utilized, as is the Cassini LED topographer for a snapshot of the posterior corneal astigmatism.
“There isn’t any one correct way to measure; there are different ways to achieve great outcomes, but you have to pay close attention and refine yourself as a surgeon and utilize your diagnostic equipment to know what is good information,” she said. “The key is to be wise in what you choose to use for your final outcome.”
Black’s practice has an excimer laser, so if the postoperative results are not ideal, they are able to, “do a corneal procedure postoperatively to get the desired outcome,” she said.
If a practitioner does not have access to an excimer laser, having an intraoperative aberrometer makes a huge difference, she added.
Choosing an IOL
Halvorson works primarily with the Tecnis Toric IOL (Johnson & Johnson Vision) and AcrySof IQ Toric (Alcon) and sees excellent results with both.
“I don’t think there’s a huge drawback to considering a toric lens,” she said. “There are few drawbacks to toric IOLs if the patient is a good candidate from an ocular health standpoint and has reasonable expectations.”
Halvorson added that IOLs can correct up to 4.5 D of corneal astigmatism, which is a common question she is asked.
Yeu recommends a toric IOL for 1.25 D to 1.35 D of anterior astigmatism; she recommends astigmatic keratotomy (AK) for anything less than that.
“If we do a monofocal spherical IOL, anything more than a 0.25 D starts to become visually significant and reduces the quality of vision,” Yeu said. “I recommend femtosecond AKs all the time for a first pass. If there is residual astigmatism postoperatively, I’ll adjust it in the laser suite.”
Yeu said if an IOL rotation causes more than 0.75 D of residual astigmatism, “which is only more commonly seen when trying to correct for higher levels of astigmatism, I will wait until 2 to 3 weeks postoperatively to return to the operating room and re-rotate the IOL. This gives time for some contraction of and stiffness to the capsular bag and, thus, a greater chance that the toric IOL will stay in the intended axis.”
Halvorson said if visually significant residual astigmatism is still present at 3 months, she would consider recommending femtosecond AK or LASIK/PRK.
“This allows the eye to become more stable prior to treatment,” she said. “Serial topography and manifest refraction should be repeated monthly to corroborate refractive stability prior to proceeding.”
Toric multifocal, EDOF IOLs
Halvorson was an early adopter of the Tecnis Symfony IOL, an extended depth-of-focus (EDOF) IOL that the FDA approved in July 2016.
“Patients, in general, have been very pleased with it, both with astigmatism correction and presbyopia mitigation,” Halvorson said.
“Toric multifocals and toric EDOF IOLs are both on a wonderful platform of optics,” Yeu said, “so the quality of vision is definitely less of an issue as with the predecessor presbyopia-correcting IOLs.”
Yeu has implanted nearly 300 toric presbyopia-correcting lenses in the past year and is happy with the results.
“In a 1-year review, 90% of my patients have residual astigmatism of less than 0.50 D,” she said. “Good outcomes can be achieved for the right patient.”
Black said she has experience with the Tecnis Toric and Tecnis Symfony Toric and the enVista Toric and Trulign Toric from Bausch + Lomb.
The EDOF lens gives patients flexibility, and Black uses these lenses the most. Patients can see the computer as well as their up-close tasks without glasses, in addition to correcting the presbyopia and astigmatism, she said.
Misconceptions in optometry
“I don’t think optometrists understand how important the ocular surface is,” Black said. “The last thing you want is to have to delay surgery because of dry eye.”
Not only will the patient be disappointed, but they will lose faith in their optometrist, she said.
Black recommends referring a patient as soon as the cataracts start to affect their life.
“It’s an old-school way of thinking to wait until the cataracts are ‘ripe,’ until the patient can’t legally drive,” she said.
Black added that many patients start to notice visual symptoms from early lens changes years prior to surgery and, if given the opportunity, they would be happy to have surgery at an earlier age while reducing their dependency on glasses at the same time.
If a patient is not yet ready for surgery, Yeu recommends priming them for the conversation.
“Let them know there are great options available and even though the cataract isn’t quite ready, eventually, I have a great surgeon to take care of you and can decrease your dependency on glasses,” Yeu said.
Toric contact lenses
Daily disposable contact lenses have shown clear superiority to 2-week or monthly replacement lenses in terms of safety, comfort and convenience, according to Thomas Quinn, OD, MS, FAAO, who practices in Athens, Ohio, and has 40 years of experience in eye care.
“The daily disposable modality is what’s best for the patient, regardless of whether it is a sphere, toric or multifocal design,” he told PCON.
Practitioners are seeing these benefits and are now commonly offering daily disposables as their recommended modality, Quinn said.
In terms of rotational stability, Quinn finds toric daily disposable lenses perform as well as monthly lenses.
“The clean, smooth surface of a daily disposable lens allows the eyelid to glide over it, making the lens less susceptible to axis mislocation and associated visual disturbance during a blink,” he said.
Daily disposables are limited in some power parameters compared to many available monthly toric lenses, however, Quinn added.
He reports good success with all the major manufacturers’ daily disposable options: BioTrue One Day for Astigmatism (Bausch + Lomb), Clariti 1-Day Toric (CooperVision), Dailies Aquacomfort Plus Toric (Alcon) and 1-Day Acuvue Moist for Astigmatism (Johnson & Johnson Vision Care).
Because all perform well, he recommends choosing the daily disposable toric based on the practitioner’s relationship with the manufacturer.
“The important thing is to fit a daily disposable, whichever the brand,” Quinn said.
“By and large, the benefits of a daily disposable toric contact lens more than justify the cost of an annual supply,” he continued. “For those with financial concerns, we’ve found CareCredit to be a great option. For a modest processing fee, CareCredit provides the patient with a manageable payment plan while taking the financial risk away from the doctor.”
Quinn also noted that CooperVision’s Lens Ferry S service offers patients the option of making small monthly payments for quarterly shipments of any company’s lenses for a small fee.
The ProClear multifocal toric lens (CooperVision) is a hydrogel lens that many practitioners have good success with, according to Gary Orsborn, OD, MS, FAAO, FBCLA, vice president, global professional and clinical affairs at CooperVision.
“Work is well underway to develop and introduce a silicone hydrogel multifocal toric soft monthly replacement lens that will bring together the proven technology of leading toric and multifocal designs that we currently have within our Biofinity family of lenses,” Orsborn said in an interview.
He does not have a release date yet, but said that good progress is being made.
The availability of a silicone hydrogel multifocal toric lens will fill a gap that exists in how presbyopic patients with significant astigmatism can be managed, Orsborn said.
Currently, monovision or multifocal toric lenses in a hydrogel material are the only soft contact lens options available for these patients.
“It seems that many eye care professionals are reluctant to revert to a hydrogel lens when a current wearer of silicone hydrogel toric lenses needs a correction for presbyopia,” Orsborn said. “Having a silicone hydrogel multifocal toric will provide a new approach on how to keep their patients in a healthier silicone hydrogel lens.”
Soft toric lenses are still the first choice for most practitioners, particularly for patients with low cylinder, according to Susan J. Gromacki, OD, MS, FAAO, FSLS, director of the contact lens service at Washington Eye in Silver Springs, Md.
As the astigmatism or prescription increases, many doctors opt for a hybrid or gas permeable lens. The rigid material provides excellent optics and durability, she told PCON.
“In patients with corneal cylinders greater than 3.0 D, a back toric or bitoric lens would need to be employed, and hybrid lenses are currently manufactured with only spherical base curves,” Gromacki said.
For these patients, more providers are selecting a GP scleral lens, even if they have healthy, “regular” corneas, she continued.
“More and more scleral lenses are being designed with toric peripheral curves to more closely match the sclera, but some patients do just fine with spherical peripheral curves,” she added.
Gromacki believes the industry is getting closer to a well-performing toric multifocal soft disposable lens, and the current materials and optics are better than ever.
“We are so fortunate to practice in a time where we have so many excellent options to help our patients,” she said. “Soft toric lens optics, materials, comfort and oxygen permeability are better than ever.”
Gromacki also remarked that there are custom soft toric lenses for high cylinder, presbyopic or difficult-to-fit patients. – by Abigail Sutton
- Trattler W, et al. Clinical study report. Cataract and dry eye: Prospective health assessment of cataract patients ocular surface study. 2010. Unpublished data.
- For more information:
- Sondra Black, OD, can be reached at: firstname.lastname@example.org.
- Susan J. Gromacki, OD, MS, FAAO, FSLS, can be reached at: Sgromacki3@hotmail.com.
- Ami Halvorson, OD, FAAO, can be reached at: email@example.com.
- Gary Orsborn, OD, MS, FAAO, FBCLA, can be reached at: GOrsborn@CooperVision.com.
- Thomas G. Quinn, OD, MS, FAAO, can be reached at: firstname.lastname@example.org.
- Elizabeth Yeu, MD, can be reached at: email@example.com.
Disclosures: Black reports she is a consultant for Johnson & Johnson. Gromacki has consulted or lectured this past year for Alcon, Acculens, Bausch + Lomb SVP, Bioscience Communications, Blanchard, Contact Lens Manufacturers Association, Gas Permeable Lens Institute, Johnson & Johnson Vision Care, Scleral Lens Education Society and Valeant. Halvorson reports no relevant financial disclosures. Orsborn is employed by CooperVision. Quinn reports he is a consultant, speaker or has done research for Alcon, Allergan, Bausch + Lomb, BioScience Communications, CooperVision, GPLI, STAPLES Program, Johnson & Johnson Vision Care and Vistakon. Yeu reports she is a consultant for Alcon, Bausch + Lomb, Johnson & Johnson Vision Care and Zeiss.