High myopia eyes implanted with Vivinex Toric intraocular lenses (IOLs) are at no greater risk of post-operative rotation than ‘normal’ eyes, according to a study published in the Journal of Refractive Cataract Surgery.1
Exact on-axis positioning of a toric IOL is essential for a satisfactory refractive outcome. The efficient and safe use of toric IOLs requires not only exact determination of the amount and axis of corneal astigmatism to be corrected and precise primary axis alignment, but also rotational stability.
Post-operative rotation of a toric IOL can completely negate the effectiveness of the astigmatic correction, and even induce additional astigmatism, with both requiring surgical repositioning.
While several ‘human error’ factors can impact the rotational stability of toric IOLs, high myopia patients (i.e. eyes with high axial length (AL)), are considered to be more at risk of this problem due to the presence of large capsular bags.
This was evidenced in 2011, when a study by Shah et al. observed a higher rotation in eyes with high AL and reported a worse outcome for toric IOL implantation in eyes with high AL.2
However, a study published in 2024 by Dr Sheetal Brar and her team from Nethradhama Eye Hospital, Bangalore, found that high myopia patients fitted with Vivinex Toric IOLs were at no greater risk of lens rotation than their counterparts with ‘normal’ eyes.
The retrospective study set out to evaluate the visual outcomes, predictability, and rotational stability after implantation of the Vivinex Toric monofocal IOL in eyes with normal and high preoperative ALs. It included 114 eyes of 114 patients divided into two groups – 62 eyes with normal AL (<23.9 mm) and 52 eyes with high AL (24.00 mm and above).
All eyes underwent a standard capsulorhexis size of 5.2 mm with femtosecond laser.
Clinical outcomes and rotational stability were evaluated at one week, and at three months.
Study Findings
The study found that at three months postoperatively, refractive astigmatism accuracy was achieved within ≤0.50 diopter, in 100% (n=62) of the normal group vs 94% (n = 49) in the high AL group. They reported that all eyes were <5° of the intended axis.
The mean change in postoperative rotation from one week to three months was 0.28 ± 0.09° in the normal, and 0.30 ± 1.11° in the high AL group (P = .80). They observed no significant correlation between AL and white-to-white diameter with one-week postoperative rotation values.
Furthermore, there was no significant misalignment that required toric IOL repositioning.
With all variables well controlled across both groups, the researchers hypothesise that the success of this relatively new lens may be attributed to its uniquely frosted haptics with textured haptic and optic edges, which together provide friction that reduces postoperative toric IOL rotations.
Noting that this was the first study comparing the outcomes of the HOYA Vivinex Toric monofocal IOL with textured haptics in variable ALs to demonstrate “excellent predictability and rotational stability in normal and high ALs for preexisting astigmatism correction during cataract surgery”, they said that to verify the results, further comparison studies should be undertaken with nontextured toric IOLs in different surgical settings.
References
- Brar, S, Ganesh, S, Karegowda M. Clinical outcomes and rotational stability after implantation of a monofocal toric intraocular lens with textured haptics in normal vs high axial lengths. J Cataract Refract Surg 2024; 50:718–723. doi: 10.1097/j.jcrs.0000000000001429.
- Shah GD, Praveen MR, Shastry LR et al. Rotational stability of a toric intraocular lens: Influence of axial length and alignment in the capsular bag. J Cataract Refract Surg. 2012;38:54-59. doi: 10.1016/j.jcrs.2011.08.028.
