Comparison of Astigmatic Outcomes with an Ultra-Low Cylinder Power (0.90 D) Toric versus a Non-Toric Intraocular Lens for Eyes with Low Astigmatism

Purpose: Evaluate postoperative astigmatic outcomes in eyes implanted with an ultra-low cylinder powered toric (ULPT) intraocular lens (IOL) compared with a non-toric IOL for the surgical management of astigmatism in cataract surgery. Patients and Methods: This is a retrospective, controlled consecutive case series from 3 Canadian ophthalmology centers. Cases were included if they were adults (≥ 18 years), qualified for the 0.90D toric based on the Barrett Toric Calculator without “flipping” the axis of astigmatism by 0.2D or more, and underwent surgery either with the enVista Toric 0.9 D IOL (ULPT, Bausch + Lomb) or enVista Non-toric (spherical). All surgeries were performed using standard phacoemulsification and IOL implantation under topical anesthesia with 2.0 to 2.2-mm biplanar square clear corneal incision at 190° for OD and 10° for OS. The mean±SD incision angle was 94.0± 89.70° for the ULPT group and 103.0± 89.37° for the non-toric group. Primary effectiveness endpoint was the mean reduction in cylindrical power of the eye. Other endpoints were manifest refraction, keratometry, visual acuity, IOL axis, and safety. Results: 290 screened patient charts were enrolled and included 383 eyes (192 eyes with the ULPT IOL and 191 eyes with the non-toric IOL). The mean reduction in cylindrical power was 0.432± 0.447 D in the Toric 0.9 D IOL group and 0.071± 0.407 D in the Non-toric group, with the mean difference (0.351 D) in favor of the ULPT IOL (P< 0.0001). Significantly more of the ULPT group than the Non-toric group had plano outcomes or had a cumulative residual cylinder within 0.25 D, 0.50 D, and 0.75 D of plano (P≤ 0.001 for all). There were no serious AEs reported in patient charts. Conclusion: The ULPT IOL was safe and effective for eyes with low to ultra-low preoperative astigmatism and resulted in significantly greater reduction in postoperative manifest cylinder compared to the monofocal IOL. Plain Language Summary: The enVista 0.90D “ultra-low cylinder power” toric (ULPT) intraocular lens (IOL) is Canada’s first commercially available, non-custom order toric IOL correcting < 1.0D at the IOL plane (corresponding to as low as 0.52D at the corneal plane). In patients presenting for cataract surgery, 51% of eyes have 0.25– 1.00D of preoperative corneal astigmatism. This is considered visually significant. Thus, many patients may benefit from an ULPT IOL. In this retrospective, controlled, consecutive case study, charts were reviewed from adults implanted with enVista Toric 0.9 D IOL (ULPT, n=192 eyes) or enVista Non-toric IOL (spherical, n=191 eyes) with data available 4-weeks post-implantation. The ULPT IOL was significantly more effective in correcting astigmatism than the non-toric IOL. This represents an effective option for patients undergoing cataract surgery. The ULPT IOL significantly reduced postoperative cylinder compared to a non-toric IOL (P< 0.0001). The ULPT IOL was safe in the study population. The ULPT IOL was highly effective and safe in reducing the smallest amounts of visually-significant corneal astigmatism when compared to a non-toric IOL. This demonstrates that with widely available biometry technology, modern formulas and surgical techniques, and now ULPT IOLs, surgeons can accurately treat the smallest amounts of visually-significant refractive cylinder. The IOL represents a new stepping-stone in the refinement of postoperative cylinder outcomes. This may lead to better visual function, more satisfied patients, and fewer laser vision correction enhancements. Keywords: enVista, toric, cataract, IOL, intraocular lens, ultra-low powered