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Abstract
Myopic astigmatism is a prevalent condition that can be treated with spectacles, contact lenses, or laser refractive surgery. However, these treatment options have functional limitations at higher levels of refractive error. The toric implantable collamer lens is designed to treat a broad range of refractive error, generally up to −18 diopters with +1 to +6 diopters of astigmatism. Approval for a more limited treatment range of up to 15 diopters of myopia with +1 to +4 diopters of astigmatism is being sought in the US, where this device has not yet received marketing approval. Surgical correction of high-myopic astigmatism can be life-altering and allow people to participate in activities that were not previously feasible because of visual limitations. The toric implantable collamer lens is implanted behind the iris and in front of the natural crystalline lens. With earlier lens designs, it was necessary to create an iridectomy or iridotomy to prevent pupillary block. The newest toric implantable collamer lens model has a small central hole that is not visually noticeable. This eliminates the need to create a hole in the iris, thereby enhancing the safety of the procedure.
Financial & competing interests disclosure
MO Price is a consultant to Staar Surgical and owns stock options in Staar Surgical. FW Price Jr is a consultant to Staar Surgical and Ophtec. He owns stock options in Staar Surgical and has received payment for lectures including services on speakers bureaus from Alcon and Bausch & Lomb. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.
Low to moderate myopic astigmatism can be corrected with spectacles, contact lenses, or laser refractive surgery. The visual quality provided by these options declines with higher levels of correction. Placing the corrective lens closer to the nodal point of the eye (just behind the crystalline lens) decreases the aberrations induced by the corrective lens.
Toric phakic intraocular lenses provide predictable and stable visual correction over a wide range of myopia and astigmatism and address an important need by allowing people with higher levels of myopic astigmatism to participate in normal activities not previously accessible because of visual limitations.
Posterior chamber and iris-supported toric phakic intraocular lens models (manufactured by Staar Surgical and Ophtec, respectively) are approved for use outside the US and have reasonably long track records. No toric phakic intraocular lenses are approved in the US.
The toric implantable collamer lens is a posterior chamber lens that is implanted through a small incision using a technique that is comparatively easy to master. Reported complication rates are low, with the most common being improper lens sizing and vault (treated by exchanging the lens), cataract formation (if visually significant, treated by lens removal and cataract extraction), and axis misalignment or lens rotation (treated by repositioning the lens).
The addition of a small central hole in the toric implantable collamer lens has enhanced the safety profile by obviating the need for an iridotomy or iridectomy and eliminating concerns about pupillary block or glare from holes in the iris. Studies show the small central hole does not affect the optical quality of the lens.