A critical evaluation of longitudinal changes of astigmatism following implantation of toric implantable collamer lens (TICL): a comparison between treated and untreated cases over 4 years

PURPOSE

To evaluate residual astigmatism following correction with toric implantable collamer lens (TICL) (group I) over a period of 4 years and compare with the change of astigmatism in spectacle wearers (group II).

METHODS

Groups I (86 cases implanted with TICL [EVO + Visian ICL, Staar Surgical, Nidau, Switzeland], preop refractive error [sphere and cylinder] - 22.25 DS to - 1.00 DS and - 5.50 DC to - 1.00 DC) and II (80 cases initial refractive error [sphere and cylinder] - 18.00 DS to 0.00 DS and - 7.00 DC to - 1.00 DC) were reviewed annually. Refractive and tomography data were subjected to vector analysis to determine surgically induced astigmatism (SIA), angle of error [Δθ° = angle of target-induced astigmatism (TIA) - angle of SIA], and ΔC [TIA-SIA powers] and total corneal astigmatism (TCA) in group I and induced change in astigmatism (ICA) in group II.

RESULTS

In group I, on all occasions, SIA correlated with TIA (p < 0.05); differences between SIA and TIA means were insignificant and changes in TCA were not correlated with ΔC. Mean (± sd, 95% CI) residual astigmatic powers (RA) in attending group I cases (1-4 years) were - 0.40 DC (0.58, - 0.52 to - 0.28), - 0.40 DC (0.59, - 0.52 to - 0.27), - 0.41 DC (0.58, - 0.54 to - 0.28), and - 0.61 DC (0.74, - 0.82 to - 0.40). In group II, the corresponding ICA powers were - 0.47 DC (0.53, - 0.61 to - 0.32), - 0.49 DC (0.48, - 0.69 to - 0.29), - 0.60 DC (0.40, - 0.76 to - 0.44), and - 0.86 DC (0.71, - 1.19 to - 0.52). Differences between RA and ICA were not significant. Of the group I cases presenting at 1-4 years postop, 23, 18, 16, and 28 had RA powers ≤  - 0.75 DC. Of these 12, 10, 6, and 16 were associated with Δθ° > 5° (ΔC - 0.50 to 0 DC) and 5, 1, 4, and 4 were related to ΔC (Δθ° < 5°).

CONCLUSION

The development of astigmatism after TICL implantation is on par with the natural change in astigmatism in untreated cases. In about 50% of TICL cases presenting with astigmatism ≤  - 0.75 DC, the residual astigmatism could be neutralized by realigning the TICL.

Clinical Effect and Rotational Stability of TICL in the Treatment of Myopic Astigmatism

Purpose

To investigate the clinical outcomes and possible risk factors associated with rotational stability after the implantation of a V4c toric implantable Collamer lens (TICL) for the correction of moderate to high myopic astigmatism.

Methods

A total of 112 eyes of 66 patients with moderate to high myopic astigmatism underwent TICL implantation. All patients were followed up for more than 1 year. The uncorrected and best-corrected visual acuity (UCVA and BCVA), astigmatism and spherical equivalent, intraocular pressure, vault, endothelial cell morphometry, and rotation of the TICL axis were assessed at l day, 1 week, 1 month, 3 months, 6 months, and 12 months postoperatively. Postoperative rotation was defined as the angle between the intended axis and the achieved axis. Regression analysis was used to investigate the possible risk factors for TICL rotation postoperatively.

Results

The mean efficacy index and safety index 12 months postoperatively were 1.03 ± 0.09 and 1.05 ± 0.10, respectively. All patients had the same or better visual acuity than preoperatively. The mean astigmatism value decreased from -1.86 ± 0.79 D preoperatively to -0.37 ± 0.35 D. The mean absolute axis deviation of the TICL at the last follow-up was 2.75 ± 2.04° (range, 0°∼11°). The mean manifest refraction spherical equivalent (MRSE) changed from -9.04 ± 2.67 D preoperatively to -0.67 ± 0.51 D postoperatively. The logistic regression demonstrated that the absolute degree of TICL rotation had a significant association with the fixation angle of the TICL and the size of the lens (P=0.003, P=0.026, resp.).

Conclusion

The results of our study support that TICL implantation is safe, effective, and predictable in the treatment of moderate to high myopic astigmatism, with relatively good postoperative rotational stability.

Implantable collamer lens V4b and V4c for correction of high myopia

PURPOSE

To evaluate the visual outcome and intraocular pressure changes after Visian Implantable Collamer Lens (ICL) implantation V4b and V4c (with central hole) for correction of high myopia.

METHODS

A prospective, consecutive, interventional comparative case series of V4b and V4c ICL implantation was done in high myopic patients who were unsuitable for laser vision. The main outcome measures studied were uncorrected and corrected distant visual acuity (UDVA, CDVA), ICL vault, intraocular pressure (IOP), endothelial cell count (ECC), and development of subcapsular lens opacities. The patients were evaluated at postoperative 1,3,6, and 9 months.

RESULTS

A total of 62 eyes of 32 patients (24.56 ± 4.8 years) underwent V4b ICL implantation (21 non-toric, 41 toric ICL-TICL) with intraoperative peripheral iridectomy (PI), and 10 eyes of 5 patients (26.13 ± 3.8 years) had implantation of V4c ICL (4 non-toric, 6 TICL). The mean preoperative manifest spherical equivalent (MSE) was -9.98 ± 2.8 D and -9.14 ± 2.4 D in the V4b and V4c groups, respectively, which reduced to postoperative values of -0.24 ± 1.3 D and -0.2 ± 1.18 D, respectively. At the end of 9 months follow-up, mean ECC loss was 6.4% and 6.1%, mean vault was 573.13 ± 241.13 μ, and 612 ± 251.14 μ, respectively, in the V4b and V4c groups. Anterior subcapsular opacities were present in 6.9% and 3.14% of eyes with V4b and V4c groups, respectively. Four eyes from V4b (9.75%) and 1 eye from V4c (16.66%) had rotation of more than 30° and required realignment surgery, which was done successfully. Two eyes (3.22%) with V4b ICL implantation had high postoperative IOP (>35 mm Hg) due to blocked PI and required Nd:Yag laser iridotomy, which was done with successful control of IOP. The safety indices were 1.11 and 1.14, and efficacy indices were 1.4 and 1.5 in the V4b and V4c groups, respectively, at the end of 9 months.

CONCLUSION

ICL implantation is a safe and effective surgery for correction of high myopia. Implantation of ICL with a central hole showed negligible postoperative IOP fluctuations without a peripheral iridectomy.