Myopic astigmatism correction: comparison of a Toric Implantable Collamer Lens and a bioptics technique by an adaptive optics visual simulator

Three-Year Outcomes of Implantable Collamer Lens Followed by Excimer Laser Enhancement ("Bioptics") in the Treatment of High Myopic Astigmatism

Purpose

Describe three-year outcomes of spherical implantable Collamer lens (ICL) followed by excimer laser enhancement (bioptics) in eyes with high myopic astigmatism.

Patients and Methods

Retrospective case series of thirty-four cases that underwent bioptics enhancement at the Johns Hopkins Wilmer Eye Institute. All eyes had a preoperative sphere of −6.00 D or more with a cylinder of at least 2.00 D. Uncorrected and corrected distance visual acuity (UDVA and CDVA), manifest spherical equivalent refraction (MSE), ICL vault measurements and central corneal thickness (CCT) were collected. Endothelial cell counts (ECC), root mean square (RMS) of higher order aberrations (HOAs), adverse events and subsequent surgeries were also assessed.

Results

All patients had a minimum follow-up of 3 years. Preoperative UDVA was 2.29 ± 0.46 logMAR and improved to 0.03 ± 0.23 logMAR at 3 years (p<0.05). MSE was −12.30 ± 4.05 preoperatively and changed to −0.21 ± 0.46 at 3 years (p<0.05). The efficacy and safety indices were 1.28 ± 0.32 and 1.47 ± 0.27 at 3 years post-enhancement. HOA did not significantly change throughout the follow-up (p<0.05). Endothelial cell loss at 12 months was calculated at 5.7%. Two eyes required ICL exchange due to vault-related issues.

Conclusion

Bioptics offered excellent long-term safe, predictable, and efficient outcomes for high myopic astigmatism and can be considered an option if toric ICL is not available. Results confirm that wavefront-guided photoablation remains an excellent option to manage residual refractive error after phakic IOL.

Update on Treating High Myopia With Implantable Collamer Lenses

The purpose of this article is to provide updates on the treatment of high myopia with the implantable collamer lens (ICL). The ICL has become an important technique used in intraocular refractive surgery. With improvements in material, design, and application, the ICL has good efficacy, predictability, long-term safety and stability, manageable complications, and reversibility. More and more refractive surgeons are taking note of the ICL. This article reviews the material characteristics and the latest designs of the ICL along with the clinical applications, visual quality, and future development.

Implantable collamer lens for residual refractive error after corneal refractive surgery

AIM

To assess the safety, efficacy, predictability and stability of implantable collamer lens (ICL) for residual refractive error after corneal refractive surgery.

METHODS

This study evaluated 19 eyes of 12 patients who underwent ICL implantation after corneal refractive surgeries. They were followed up for 1y to 5y of uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractive error, flat and steep K value, axial length, intraocular pressure, corneal endothelial cell density, adverse events after ICL surgery.

RESULTS

The mean follow-up period was 39.05±19.22 mo (range, 1-5y). Spherical equivalent refractive error changed from -7.45±3.02 D preoperatively to -0.85±1.10 D 1wk to 1mo after ICL implantation, with the safety and efficacy indices being 1.12 and 1.15, respectively. A total of 52.63% of eyes were within ±0.5 D of the predicted spherical equivalents, 73.68% were within ±1.0 D. A trend of mild regression towards myopia with axial elongation after 5y was observed. One eye with mild anterior capsule opacity and retinal detachment 1y after surgery were observed.

CONCLUSION

ICL implantation is safe and effective for the correction of residual refractive error after corneal refractive surgeries, especially in moderate to high residual myopia.

Optical quality comparison between 2 collagen copolymer posterior chamber phakic intraocular lens designs

PURPOSE

To compare the optical quality in vitro of 2 designs of the Visian Implantable Collamer Lens phakic intraocular lens (pIOL) for different powers and optical apertures.

SETTING

University of Valencia, Valencia, Spain.

DESIGN

Experimental study.

METHODS

The Nimo TR1504 deflectometry device was used to measure the V4c pIOL, which has a smaller optic diameter, and the V5 pIOL, which has a larger optic diameter. The pIOLs were measured for -3.00 diopters (D), -6.00 D, -9.50 D, and -10.50 D at different optical apertures from 3.00 to 6.00 mm depending on the IOL power and model. The root mean square of higher-order aberrations (RMS HOAs) was analyzed. The Strehl ratio, point-spread functions (PSFs), and simulated images were calculated from wavefront aberrations.

RESULTS

There were no statistically significant differences in any Zernike RMS or RMS HOAs between the 2 pIOL models with the same power and optical aperture (P > .05). Both pIOLs had negative spherical aberration that increased with the pIOL power. Strehl ratio values showed no statistically significant differences between the pIOLs with the same power and pupil aperture. Minimal differences were seen in the PSFs and simulated images between the pIOLs.

CONCLUSIONS

Both pIOLs showed good and comparable in vitro optical quality similar that of a perfect lens in that they should not affect visual performance after implantation. Patients with larger pupil diameters could benefit from the pIOL with the larger optic diameter because it showed better in vitro optical quality than the previous design with a smaller optic diameter.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Evaluation of the toric implantable collamer lens for simultaneous treatment of myopia and astigmatism

Myopic astigmatism is a prevalent condition that can be treated with spectacles, contact lenses, or laser refractive surgery. However, these treatment options have functional limitations at higher levels of refractive error. The toric implantable collamer lens is designed to treat a broad range of refractive error, generally up to -18 diopters with +1 to +6 diopters of astigmatism. Approval for a more limited treatment range of up to 15 diopters of myopia with +1 to +4 diopters of astigmatism is being sought in the US, where this device has not yet received marketing approval. Surgical correction of high-myopic astigmatism can be life-altering and allow people to participate in activities that were not previously feasible because of visual limitations. The toric implantable collamer lens is implanted behind the iris and in front of the natural crystalline lens. With earlier lens designs, it was necessary to create an iridectomy or iridotomy to prevent pupillary block. The newest toric implantable collamer lens model has a small central hole that is not visually noticeable. This eliminates the need to create a hole in the iris, thereby enhancing the safety of the procedure.

Optical and visual simulation of standard and modified spherical aberration implantable Collamer lens post myopic LASIK surgery

PURPOSE

To evaluate the visual quality achieved in patients undergoing standard or modified implantable Collamer lens (ICL) to correct residual myopic error after laser-assisted in situ keratomileusis (LASIK) surgery.

METHODS

The adaptive optics visual simulator was used to simulate LASIK surgery of moderate and high myopia with a myopic regression corrected by a standard and modified ICL. Visual acuity (VA) and contrast sensitivity (CS) were measured in 14 subjects at 3- and 4.5-mm pupil. Point spread function and simulated retinal images were calculated.

RESULTS

Comparing LASIK plus standard ICL and LASIK plus modified ICL simulations, for moderate myopia, VA improvement was less than 1 line in all VA contrasts and both pupils evaluated. No statistically significant differences were found in CS between the simulations at any spatial frequency evaluated and for 3-mm pupil (p>0.05), but differences were significant at 4.5-mm pupil (p<0.05). For high myopia, the VA improvement was less than 1 line at 3-mm pupil, although it increased 2 or more lines at 4.5-mm pupil. Statistically significant differences were found in CS between the simulations for all spatial frequencies and both pupils evaluated (p<0.05), except for low and medium spatial frequencies at 3-mm pupil (p>0.05).

CONCLUSIONS

These outcomes suggest that an ICL is a good option to correct the myopic residual error after myopic LASIK. When the ICL's spherical aberration is modified, the post-LASIK eyes of high myopia are the most benefited, as these eyes are more aberrated than after moderate myopic LASIK.