BLOG: My pearls for toric ICLs
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In September 2018, the FDA granted approval to STAAR Surgical for its Visian toric ICL. This was very exciting news for patients with high myopia and astigmatism who were not candidates for LASIK or PRK.
Here are some of my pearls for optimal visual outcomes.
The toric ICL will commonly come labeled in an astigmatic axis close to the axis that was ordered, but not precisely. For example, the patient could have an axis of 94°, but the delivered toric ICL would be labeled at the 90° axis.
Before ordering the toric ICL, it is important to determine the axis of placement. Resolution of any conflicts between the manifest and cycloplegic refraction has to be done. Look at the axis and magnitude of astigmatism on the glasses and on more than one topographer. If in doubt, bring the patient back for another manifest refraction done by the surgeon. Pay attention to head positioning on the phoropter. Make sure that there is no head tilt or head turn to minimize cyclotorsion.
Pay attention to the refraction and the vertex distance of the eye from the phoropter. The vertex distance will make a difference in high myopia. Always align the apex of the cornea and the first mark on the side mirror of the phoropter.
Marking the horizontal axis of the eye at the slit lamp is much more accurate than using hand-held devices. The toric ICL rarely comes in the exact desired axis. The “implantation orientation form” will guide the surgeon to rotate the toric ICL in either a clockwise or counterclockwise orientation from the horizontal marks that were preplaced. Therefore, marking the 180° axis precisely is imperative in preventing even slight misalignments that will lead to refractive errors.
Make your corneal marks for the final toric ICL position at the beginning of the case based on the toric ICL implantation orientation form’s recommendations for number of degrees of either a clockwise or counterclockwise rotation. Use the same toric marker and toric fixation ring scale that you normally use for toric IOLs.
With non-toric ICLs, my technique involves making only one paracentesis incision to the right of the main incision, about 2 to 3 clock hours away. I use this to tuck the leading foot plates under the iris into the ciliary sulcus. With a toric ICL, I will perform another paracentesis port to the left of the main incision, also 2 to 3 clock hours away. This helps align the axis of the toric ICL as it can be used to push the ICL in a clockwise fashion. The paracentesis on the right of the main incision is used to push the ICL in a counterclockwise direction. These manipulations should be reduced to the minimum to avoid risk of touching the crystalline lens and inducing a cataract.
Reduce manipulating the ICL as much as possible. It is preferable to get it into the right axis alignment from the start
The toric ICL can be rotated in the ciliary sulcus; however, it is more “sticky” or more difficult to rotate than an IOL with cataract surgery.
The toric ICL has two diamond-shaped alignment markers on the 180° axis. After filling the anterior chamber with OcuCoat (2% hydroxypropyl methylcellulose solution, Bausch + Lomb), align the diamond-shaped marks with the corneal marks. Tuck the leading foot plates under the iris into the ciliary sulcus. Next, use the paracentesis ports and the ICL manipulator to position the toric ICL and make sure that the diamond mark and corneal mark are aligned distally.
Next, tuck the trailing foot plates into the ciliary sulcus. The ICL should be aligned; however, the paracentesis ports can be used to fine-tune the alignment.
Gently irrigate the OcuCoat from the anterior chamber. Aggressive irrigation may result in tilting of the ICL and moving from the aligned position, and may also result in iris prolapse.
Once all the OcuCoat is irrigated from the eye, and the toric ICL is perfectly aligned on the corneal marks at the desired axis, inject either Miochol-E (acetylcholine chloride intraocular solution, Bausch + Lomb) or dilute Miostat (carbachol intraocular solution, Alcon) in balanced salt solution (one-sixth concentration) into the anterior chamber to constrict the pupil.
Postoperatively, refract the patient at the 1-week visit. If there is resultant mixed astigmatism and not the desired visual acuity, you should be suspicious of misalignment of the toric ICL.
Many misalignments are secondary to implantation off axis related to preoperative measurement miscalculations because of head tilt or head turn during refraction, and not because of actual rotation of the toric ICL postoperatively.
As ophthalmologists, we are very lucky to be able offer this remarkable technology to our patients. As high myopes, they are usually some of the happiest patients. Although we all have our technique, I hope that my pearls may be of value to my refractive colleagues.
Visit Dr. Iskander’s blog to learn more about Toric ICLs.
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