New IOL formula, LAL piggyback data target accuracy in complex eyes

A constant-free ray-tracing IOL formula had a lower mean absolute error than eight established formulas, and primary piggyback implantation of the Light Adjustable Lens (RxSight) brought residual astigmatism to 0.5 D or less in every treated eye, according to posters presented at AAO 2026.^1,2 A third poster comparing Yamane and Gore-Tex scleral fixation for secondary IOL implantation found comparable vision but distinct complication profiles.³

Modern IOL formulas still depend on lens constants and give surgeons no preoperative warning for eyes likely to miss target, even when axial length is normal.¹ Fixed IOLs offer little margin for error in short eyes, keratoconus, or post-refractive corneas, and eyes lacking capsular support add a fixation decision with limited head-to-head data.^2,3

Noguchi FS IOL formula accuracy vs Kane, Barrett, and EVO

Santaro Noguchi, MD, PhD, of ASUCA Eye Clinic in Sendai, Japan, compared his Noguchi FS formula with 7 modern formulas on the ESCRS calculator at default constants, plus SRK/T, in 486 eyes of 486 patients.¹ All eyes received an SY60WF monofocal or toric IOL from a single surgeon between April 2022 and April 2026, with biometry on the IOLMaster 700 (Carl Zeiss Meditec) and refraction at 3 months.

Noguchi FS had a mean absolute error of 0.280 D vs 0.297 D for Kane, 0.300 D for EVO 2.0, 0.313 D for Barrett Universal II, and 0.332 D for SRK/T, and the difference was significant against all eight comparators after Holm adjustment.¹ The share of eyes within ±0.50 D was 84.2% vs 82.9% for Kane and 79.8% for Barrett, significant only against Barrett, Cooke K6, Pearl-DGS, and SRK/T.¹ In 38 short eyes, Kane had the lowest error, at 0.310 D vs 0.318 D (not significant).¹

The formula also assigns a 5-level preoperative alarm class. Across all 9 formulas, mean absolute error averaged 0.343 D in 160 higher-risk eyes vs 0.296 D in 326 lower-risk eyes (difference, 0.047 D; 95% CI, 0.004-0.090), and the gap widened among 283 eyes with normal axial length and keratometry (0.407 vs 0.296 D; P = .002).¹

Light Adjustable Lens piggyback and Yamane vs Gore-Tex scleral fixation outcomes

John Doane, MD, of Discover Vision in Leawood, Kansas, reported a retrospective series of 29 eyes of 17 patients with refractive extremes, including prior LASIK, PRK, radial keratotomy, or keratoplasty, keratoconus after crosslinking, and staphyloma.² Each eye received a primary IOL in the bag plus a Light Adjustable Lens in the bag or sulcus. The mean manifest cylinder fell from 3.1 D before surgery to 1.1 D before light adjustment and 0.1 D after (adjustment effect, −0.96 D; 95% CI, −1.29 to −0.62; P <.001).²

Among 18 distance-target eyes, mean absolute spherical equivalent error fell from 1.39 D to 0.33 D with adjustment (P <.001), and 88.9% finished within 1.0 D of target. All 12 binocular patients reached their best potential binocular uncorrected distance acuity.²

Karanvir Gill, MD, of the University of British Columbia, and colleagues compared 245 Yamane and 139 four-point Gore-Tex fixations performed by 3 surgeons from 2019 to 2024.³ Final logMAR acuity did not differ (0.79 vs 0.66; P = .14), but Yamane eyes had more vitreous hemorrhage (12.2% vs 3.6%; P = .005) and IOL dislocation or subluxation (7.8% vs 0.7%; P = .003). Endophthalmitis and suture exposure each occurred in 3.6% of Gore-Tex eyes and no Yamane eyes (both P = .003).³

"Surgical decision-making should be individualized based on patient history, surgeon experience, and risk profile," Gill and colleagues wrote.³

The fixation comparison was retrospective, the technique tracked closely with individual surgeons, and Yamane eyes more often had prior vitrectomy (32.7% vs 22.3%; P = .032), limiting causal conclusions.³ Doane disclosed stock ownership in and consulting for RxSight, and Noguchi developed the formula, which he reports is freely available and unpatented.^1,2

References

1. Noguchi S, Noguchi A. External validation of a novel IOL formula and preoperative risk classification for predicting refractive accuracy. Presented at: 2026 American Academy of Ophthalmology Annual Meeting; October 9-12, 2026; New Orleans, LA. Poster PO015.

2. Doane J. Primary piggyback implantation of an adjustable IOL for management of refractive extremes in cataract surgery. Presented at: 2026 American Academy of Ophthalmology Annual Meeting; October 9-12, 2026; New Orleans, LA. Poster PO017.

3. Gill K, Alashhab Z, Khaira A, Levasseur S, Kim DTT, Gizicki R. Comparison of Yamane vs Gore-Tex scleral fixation for secondary IOL implantation. Presented at: 2026 American Academy of Ophthalmology Annual Meeting; October 9-12, 2026; New Orleans, LA. Poster PO029.