Methodical approach needed to manage refractive surprises
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A methodical approach is needed to identify the cause of and treatment options for refractive surprises after toric IOL implantation, according to OSN Cornea/External Disease Section Editor Elizabeth Yeu, MD.
There are various etiologies for refractive error surprises, according to Yeu. Wrong magnitude of total corneal astigmatism, induced or “false” corneal astigmatism due to dry eye disease or epithelial-based diseases, IOL power miscalculation, wrong effective lens position and malposition of the toric IOL can all contribute to unexpected results.
When observing and treating these eyes, it is also important to understand there will be sources of astigmatism that are not coming from the cornea itself, such as that induced by IOL tilt, and further investigation and patience will be needed in these cases, she said.
In the initial assessment of the postoperative refractive surprise, before any drops are placed, the same preoperative diagnostics and an OCT of the macula should be obtained, followed by an accurate manifest refraction with close attention paid to the magnitude and meridian of the residual astigmatism, Yeu said. In addition, a careful slit lamp examination of the ocular surface and anterior segment should be performed.
“I then dilate the patient in order to assess the toric IOL position,” she said. “At the slit lamp, I align the slit beam to overlie the current steep meridian of the toric IOL and then use a digital level (Axis Assistant app on phone) to determine the exact degree position of the toric lens implant position.”
Then, Toric Results Analyzer (www.astigmatismfix.com) tells her where the implant should be, and she can determine whether re-rotation is warranted.
There are a few considerations in choosing which route to take when correcting refractive error: the amount of the refractive error, whether the error is due to a residual mixed astigmatism vs. a myopic/hyperopic surprise, and the status of the patient’s cornea.
“For toric IOL surprises, refractive errors are one of the most common reasons for subjective dissatisfaction,” Yeu told Ocular Surgery News. “When such a surprise occurs, the error can be corrected with a corneal relaxing incision or femto-astigmatic keratotomy laser vision correction, a potential toric IOL rotation or with an IOL exchange.”
Unless the cause is an obvious IOL malrotation, Yeu recommends seeing the patient after they have finished all of their postoperative drops and repeating diagnostics performed preoperatively for comparison.
“If the astigmatic error is at least 0.75 D, I will check astigmatismx.com to see is if an IOL rotation is warranted. If a toric IOL rotation is the solution, I generally go back into the eye between postoperative weeks 2 and 4, when evidence of capsular healing with wrinkling or brotic changes have occurred,” she said.
If toric IOL rotation is not warranted, there are various surgical manipulations that can be considered. If the patient has a small residual mixed astigmatism (less than 1.25 D), wherein the overall spherical equivalent is close to plano, a corneal relaxing incision/femto-astigmatic keratotomy or laser vision correction can “easily” help reduce that astigmatism, Yeu said.
Laser vision correction can be used to correct any refractive error if the cornea is otherwise a good candidate for it, for example, there is minimal to no dry eye disease, good thickness and regular astigmatism. If the refractive error, either in sphere or astigmatism, is greater than 2 D to 3 D o, the surgeon should consider laser vision correction against IOL exchange, Yeu said. – by Kate Burba
- Reference:
- Yeu E. Management of toric IOL surprises. Presented at: OSN New York 2019; Nov. 15-17, 2019; New York. www.healio.com/ophthalmology/refractive-surgery/news/online/%7B434c4d33-d77a-4fe3-bf01-ca7886301acf%7D/video-management-of-toric-iol-surprises.
- For more information:
- Elizabeth Yeu, MD, can be reached at Virginia Eye Consultants, 241 Corporate Blvd., Suite 210, Norfolk, VA 23502; email: eyeu@vec2020.com.
Disclosure: Yeu reports she has financial interests with Alcon, Allergan, Avedro, Avellino, Bausch + Lomb, Bio-Tissue, Beaver-Visitec, Bruder, EyePoint Pharmaceuticals, i-Optics, Glaukos, Guidepoint, Johnson & Johnson Vision, Lensar, Kala Pharmaceuticals, Melt, Merck, Mynosys, Novartis, Ocular Science, Ocular Therapeutix, Ocusoft, Omeros, Oyster Point Pharmaceuticals, ScienceBased Health, Shire, Sight Sciences, SightLife Surgical, Sun, Topcon, TearLab and Zeiss.
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Yeu E. Management of toric IOL surprises. Presented at: OSN New York 2019; Nov. 15-17, 2019; New York. www.healio.com/ophthalmology/refractive-surgery/news/online/%7B434c4d33-d77a-4fe3-bf01-ca7886301acf%7D/video-management-of-toric-iol-surprises.
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