ADVANTAGES OF ICLS

The Toric Visian Implantable Collamer Lens (TICL, STAAR Surgical) is an excellent option for correcting moderate to high myopic astigmatism that successfully outperformed LASIK in terms of postoperative visual outcomes, according to a study presented here. “The Visian ICL performed very well in correcting moderate to high myopic astigmatism with one year follow-up,†Kimiya Shimizu MD told delegates attending the XXIX Congress of the ESCRS.

“One of the advantages of the ICL is that it is adapted to many patients and the results showed superior visual function compared to LASIK. In addition, the ICL may also be used as an effective treatment for early-stage keratoconus and for piggyback implantation when required,†he said.

Dr Shimizu, professor and chairman of the Department of Ophthalmology at the University of Kitasato School of Medicine, Kanagawa, Japan, said that toric ICLs are a potentially viable solution for patients with corneal astigmatism between 1.0 D and 1.50 D, with an earlier Japanese study of 121 patients indicating that about 73 per cent of ICL candidates were suitable for toric lens implantation.

Dr Shimizu noted that the Toric Visian ICL can correct a wide range of spherical and cylindrical errors and is available in spherical powers of -3.0 D to -23.5 D and cylindrical powers from +1.0 D to +6.0 D. The lens has an overall diameter of between 11.5mm and 13.0mm and it is implanted into the posterior chamber through a microincision of 3.0mm.

Dr Shimizu’s study included 56 eyes with a mean age of 35.5, a mean spherical equivalent of -10.36 D and a mean manifest cylinder of -2.32. Axis marking was performed at the slit lamp before surgery.

Looking at the results, the safety index of 1.18 was excellent, said Dr Shimizu. Changes in Snellen lines of best-corrected visual acuity showed a loss of one line in three eyes (six per cent), no change in 19 eyes (40 per cent), with a gain of one line in 18 eyes (38 per cent) and a two-line gain in seven eyes (15 per cent).

In terms of the efficacy index, 100 per cent of eyes achieved 20/40 (0.5 or better) and 86 per cent attained 20/20 (1.0 or better), for an index score of 1.0. Predictability was also very good, said Dr Shimizu, with 87 per cent of eyes within 0.50 D and 98 per cent within 1.0 D of intended refraction.

For refractive stability, Dr Shimizu said there was no evidence of overshoot or regression over the one-year follow-up period either for sphere or for cylinder. This was in marked contrast to the results obtained using LASIK.

Underscoring the importance of rotational stability in a toric lens, Dr Shimizu said that five eyes in his series experienced a lens rotation of more than 10 degrees.

“Two of those eyes were from a patient who practised a lot of boxing and the rotation was associated with trauma. Interestingly the rotations all seemed to occur in the early postoperative period,†he said.

Comparing the performance of the toric ICL in 30 patients to wavefront-guided LASIK in 24 patients, Dr Shimizu said that the ICL outperformed LASIK in all key parameters tested, even allowing for the fact that there was a higher preoperative spherical equivalent and manifest cylinder in the toric lens group.

Six months after surgery, the safety index was 1.28 for toric ICL and 1.01 for LASIK, with an efficacy index of 0.87 for toric ICL and 0.83 for LASIK. Predictability was 100 per cent for toric and 71 per cent for LASIK, while stability was -0.04 D after six months for toric ICL and -0.60 D for LASIK. The incidence of higher order aberrations was also found to have increased in LASIK postoperatively but not in toric ICL implantation. Finally, contrast sensitivity also improved postoperatively in toric ICL compared to LASIK.

To illustrate the effectiveness of using the toric ICL for early-stage keratoconus, Dr Shimizu cited the case of a 38-year-old female patient who was implanted with a -22.5 D sphere and +5.0 D cylinder toric ICL.

“The result was very good indeed. Another advantage of the toric ICL is that it can also be used as a piggyback lens in particular situations,†he said.

The superior performance of toric ICLs compared to LASIK was also confirmed in a separate study presented at the ESCRS Congress by Xiaoying Wang MD, PhD, of the EENT Hospital of Fudan University in Shanghai, China.

Dr Wang’s study compared quality of vision, stability and satisfaction of ICL and toric ICL implantation in one eye and LASIK/LASEK in the fellow eye of 26 patients with high myopic astigmatism.

At two years postoperatively, the mean spherical equivalent refraction was -1.25 D in eyes with the ICL/TICL and -1.12 D in eyes that underwent LASIK/LASEK. All eyes with the ICL/TICL and 78 per cent of eyes with the LASIK/LASEK were within 0.50 D of the targeted SE correction at six months.

The mean change in manifest refraction from one week to six months was -0.14 D in eyes with the ICL/TICL and -1.70 D in eyes with LASIK/LASEK. One eye with LASIK underwent enhancement ablation 12 months after the initial surgery.

For a 4.0mm pupil, the changes in coma, spherical aberration and total higher order aberrations in eyes with the ICL/TICL were significantly less than those in eyes with the LASIK/LASEK. Less night vision problems such as glare and haloes were experienced in eyes with the ICL/TICL compared to eyes with the LASIK/LASEK. Greater patient satisfaction was also reported in eyes with the ICL/TICL compared to eyes with the LASIK/LASEK.