Comparing the Early Changes in Classified Higher-Order Aberrations Before and After Non-Toric and Toric Implantable Collamer Lens V4c Implantation

PURPOSE

This study aimed to compare early changes in classified higher-order aberrations (HOAs) pre- and postsurgery in patients who received nontoric versus toric implantable collamer lenses (ICL; ICL Model V4c; STAAR Surgical, Monrovia, CA, USA).

METHODS

This prospective study included 124 eyes of 64 patients: 49 eyes were treated using a nontoric implantable collamer lens (ICL), and 75 eyes were treated using a toric implantable collamer lenses (TICL). Refractive parameters and ocular aberrations were examined before and 1 month after surgery.

RESULTS

At one month, the safety indices were 1.24 ± 0.17 in the ICL group and 1.20 ± 0.25 in the TICL group (p = 0.39). The efficacy indices were 1.07 ± 0.17 in the ICL group and 1.15 ± 0.26 in the TICL group (p = 0.02). The root mean square (RMS) values of whole-eye total HOAs, trefoil, corneal total HOAs, spherical aberration, and intraocular spherical aberration significantly increased postoperatively in both groups. The RMS of intraocular total HOAs in the TICL group significantly increased 1 month postoperatively. No statistically significant differences were observed in HOA changes between the ICL and TICL groups.

CONCLUSIONS

The dominant increases in short-term aberrations after ICL and TICL V4c implantation were in corneal trefoil and intraocular spherical aberrations, which were related to the corneal incision and implanted lens. The HOA changes post-surgery were not statistically different between the two lens types.

Meridional analysis for calculation of the toric power of phakic IOLs

PURPOSE

To present a reproducible method to calculate the toricity needed at the intraocular lens (IOL) plane with toric phakic IOLs (ICL, Staar Surgical) and compare its results with those obtained with the online calculator provided by the manufacturer.

DESIGN

Retrospective case series.

SETTING

Private practice, Buenos Aires, Argentina.

METHODS

The formula originally described by Holladay to calculate the IOL power in phakic eyes was used to calculate the required spherical power along the less refractive meridian and along the more refractive meridian. Meridional analysis was applied to calculate the required toricity at the IOL plane and the surgically induced corneal astigmatism was incorporated into the calculations. The refractive cylinder predicted by this method and by the online calculator of the manufacturer were compared to the postoperative refractive cylinder by means of vector analysis. The possible changes in the ratio of toricity in patients with different amounts of astigmatism and anterior chamber depth are assessed in a theoretical section.

RESULTS

In 35 eyes, the measured mean postoperative refractive cylinder was 0.09 D @ 99°, the mean predicted postoperative refractive astigmatism was 0.04 D @ 102° according to the manufacturer's online calculator and 0.09 D @100° according to our method. With both methods, 91.43% of eyes had an absolute cylinder prediction error within ±0.50 diopters.

CONCLUSIONS

The method described in this article to calculate the toricity of phakic IOLs has a refractive accuracy similar to that of the original calculator developed by the manufacturer.

Bibliometric and visualized analysis of posterior chamber phakic intraocular lens research between 2003 and 2023

Introduction

Myopia is causing a major public health concern, with its prevalence increasing globally. This study aimed to discuss posterior chamber phakic intraocular lens (pIOL) research publication trends and hotspots over the past 20 years.

Methods

Bibliometric analysis was performed using the Web Science Core Collection to investigate posterior-chamber pIOL research publication trends. The extracted records were analyzed, and a knowledge map was built using VOSviewer v.1.6.20. The analysis included visualizing the annual publication count, countries/regions distribution, international and institutional collaborations, author productivity, and journal contribution, in addition to identifying knowledge bases and hotspots. Burst keywords were extracted using CiteSpace v.6.1.R.

Results

In total, 791 articles on posterior chamber pIOLs published between 2003 and 2023 were retrieved. China had the highest number of publications, whereas Japanese papers received the most citations. Fudan University had the highest number of publications, with articles from Kitasato University having the highest number of citations. Regarding individual research, Xingtao Zhou has published the most significant number of articles, and Shimizu Kimiya had the highest number of citations. The top productive/influential journal was 'Journal of Cataract & Refractive Surgery'. The top cited references primarily focused on reporting the clinical outcomes of implantable collamer lens (ICL) for individuals with moderate to high myopia. The keywords primarily formed four clusters: posterior chamber pIOL clinical outcomes for myopic astigmatism correction, posterior chamber pIOL implantation complications, ICL size selection and postoperative vault predictions, and postoperative visual quality following posterior chamber pIOL implantation.

Conclusion

This study presents the first bibliometric analysis of research trends in posterior chamber pIOL over the past two decades. We investigated the current state and emerging trends of global collaboration and research focal points in this field, offering fresh insights and guidance for researchers.

Four-year visual outcomes and optical quality of SMILE and implantable collamer lens V4c (EVO-ICL) implantation for high myopia: a retrospective study

BACKGROUND

To compare the 4-year visual outcomes of implantable collamer lens V4c (EVO-ICL) implantation and small incision lenticule extraction (SMILE) for high myopia and astigmatism.

METHODS

This retrospective case study included 64 eyes of 40 patients. These patients with preoperative manifest refraction spherical equivalent (SE) between - 6.00 and - 10.00 diopters (D) were screened from the database of SMILE and EVO-ICL implantation procedures in 2015. The ICL group [32 eyes of 19 patients (mean age, 29.6 ± 6.3 years); mean SE, -8.71 ± 1.06 D] and SMILE group [32 eyes of 21 patients (mean age, 27.7 ± 5.6 years); mean SE, -8.35 ± 0.65D] were compared. All patients were then prospectively examined at a four-year follow-up for routine postoperative examinations, higher-order ocular aberrations, retinal image quality and a questionnaire.

RESULTS

The safety indexes were 1.15 ± 0.14 and 1.22 ± 0.21 (P = 0.36) for the SMILE and ICL groups, respectively. No eyes lost two or more lines of CDVA in either group. The efficacy indexes were 0.97 ± 0.16 and 0.96 ± 0.19 (P = 0.87), respectively. Twenty-three eyes (72%) in ICL and 26 eyes (81%) in SMILE groups were within ± 0.5 D of the attempted SE (P < 0.01). ICL-treated eyes had significantly less spherical aberration and coma (P < 0.01 and < 0.05, respectively) postoperatively. Halos were the prevalent visual disturbance in both groups.

CONCLUSION

SMILE and EVO-ICL implantation provided safe and effective correction of high myopia. SMILE showed slightly better long-term predictability. Mild postoperative visual disturbances were observed after ICL and SMILE at 4-year follow-up.

Comparison of the optical quality vision between real post-LASIK myopic laser surgery and the simulated implantation of a phakic IOL in low myopia

A phakic intraocular lens (PIOL) of - 4.5 D was characterized from its wavefront aberration profile. A preclinical study was conducted using pre- and post-surgery data from four patients that had undergone myopic laser refractive surgery. All these patients would have needed a PIOL of - 4.5 D. Pre-surgery data were used to simulate the effect of a PIOL implantation. Post myopic refractive surgery data were used to calculate the post-LASIK eye model. Modulation transfer function (MTF), point spread function (PSF) and simulation of optotypes vision were obtained and compared. The PIOL did not worsen the optical quality of the eyes evaluated. High order Aberrations were always higher in the post-LASIK eye model. Optics quality trended to be better in PIOL implantation than post-LASIK surgery as pupil size increased.

Implantable collamer lens implantation (ICL) versus small incision lenticule extraction (SMILE) in low to moderate myopia: study protocol for a randomized, non-inferiority trial

BACKGROUND

Implantable collamer lens implantation (ICL) is a form of 'foldable' posterior chamber phakic intraocular lens refractive surgery that generally does not impair cornea and natural accommodation. The potential advantages of the ICL over keratorefractive laser procedures include less induction of higher-order aberrations (HOAs) and enhanced retinal image magnification. On the other hand, small incision lenticule extraction (SMILE), currently, one of the most popular refractive surgery procedures, also offers excellent visual outcomes, particularly for eyes with low to moderate amounts of myopia. The aim of this study is to evaluate whether ICL/TICL (toric ICL) is comparable to SMILE for low to moderate myopia in terms of refractive outcomes at 3 and 18 months post-operatively.

METHODS/DESIGN

This is a prospective randomized study. A total of 300 participants will be randomized into two groups, the ICL/TICL group and SMILE group. Eligible participants with spherical equivalent (SE) less than - 6.0 diopter (D) will be recruited. Following randomization, participants will be followed at 1, 3, 6, 12, and 18 months. The primary outcome is the refractive predictability at every postoperative point after surgery, which is the proportion of the number of eyes achieving a postoperative SE within ± 0.5 D and ± 1.0 D of the intended target. Secondary outcome parameters include visual acuity, refraction, adverse events, and quality of vision measurements.

DISCUSSION

This trial will provide information on whether ICL has comparable, if not superior, refractive outcomes compared to the established SMILE for low to moderate myopia, thus providing evidence for translation into clinical practice.

TRIAL REGISTRATION

Chinese clinical trial registry (ChiCTR) 2200055372. Registered on 08 January 2022.

Comparison of Visual Outcomes and Optical Quality of Femtosecond Laser-Assisted SMILE and Visian Implantable Collamer Lens (ICL V4c) Implantation for Moderate to High Myopia: A Meta-analysis

PURPOSE

To compare visual outcomes and optical quality of femtosecond laser-assisted small incision lenticule extraction (SMILE) and Visian Implantable Collamer Lens (ICL V4c; STAAR Surgical) implantation for moderate to high myopia.

METHODS

For this systematic review and meta-analysis, the Cochrane, PubMed, Embase, and Chinese databases (Wan-fang data and CNKI) were comprehensively searched to identify studies comparing SMILE and ICL V4c implantation. Data of interest were extracted and analyzed by Stata V.16.0 software (StataCorp). The weighted mean differences and their 95% confidence intervals were used to assess the strength of the association.

RESULTS

Twelve studies incorporating 1,390 eyes of 822 patients were included. The analysis revealed ICL V4c implantation had a significantly higher safety index and lower high order aberrations, coma, and spherical aberration than SMILE in treating moderate to high myopia (P < .05). Subgroup analysis revealed such differences were more prominent in patients with high myopia who had shorter follow-up duration. When follow-up was longer than 6 months, the differences in safety index and total HOAs became nonsignificant (P > .05). The two procedures had no difference in efficacy index, postoperative visual acuity, spherical equivalent, trefoil, Objective Scatter Index, or modulation transfer function cut-off frequency (P > .05).

CONCLUSIONS

Both SMILE and ICL V4c implantation were safe and efficient for moderate to high myopia. Compared with SMILE, ICL V4c implantation might provide better postoperative visual quality in patients with high myopia in the early postoperative period. [J Refract Surg. 2022;38(6):332-338.].

Comparison of accommodation and accommodative micro-fluctuation after implantable collamer lens and LASIK surgery for myopia

BACKGROUND

To longitudinally analyze and compare the accommodative micro-fluctuation (MFs) and accommodative function between myopic patients after implantable collamer lens (ICL) implantation and laser in situ keratomileusis (LASIK).

METHODS

Patients with good corrected visual acuity (20/20 or better) and underwent ICL (V4c) and LASIK for myopic-correction (ranging from - 3.50 to - 8.50 D) were recruited. Refraction, amplitude of accommodation (AMP), accommodative lag, higher-order aberration (HOA), and MFs were recorded before surgery and 1 and 3 months after surgery. The ACOMEREF automatic refractor was used to measure the high-frequency component (HFC) of the MFs, which suggested tension of the ciliary muscle.

RESULTS

The study comprised 120 eyes. At 3 months after surgery, the manifest refractive spherical equivalent of the ICL and LASIK groups were - 0.11 and - 0.09 D, respectively (p = 0.46). HFC values were significantly higher at 1 month (p = 0.03) and 3 months postoperatively (p = 0.03) in the ICL group compared to that in the LASIK group. The ocular HOA of the ICL group was 1.08 ± 0.43 μm, which was lower than the LASIK group 1.45 ± 0.54 μm (p = 0.01). No significant differences in AMP and accommodative lag between groups were noted at 3 months postoperatively. There was a positive correlation between HFC and vault of the ICL lens (r² = 0.14, p = 0.005). There were no correlations between HFC and ocular HOA and postoperative MRSE in the two groups (all p>0.05).

CONCLUSIONS

The HFC increased significantly after an early period of ICL implantation compared to laser in situ keratomileusis for myopic correction, which indicated increased tension of the ciliary muscle, and had a positive correlation on the vault of the ICL lens; However, studies with longer follow-up time and more structural evaluation are needed.

Implantable collamer lens versus small incision lenticule extraction for high myopia correction: A systematic review and meta-analysis

Purpose

To compare the efficacy, safety, predictability and visual quality between implantable collamer lens (ICL) implantation and small incision lenticule extraction (SMILE) for high myopia correction in adults.

Methods

A systematic review and meta-analysis was conducted. A comprehensive literature search was done based on databases including PubMed, Science Direct, Embase, and the Cochrane Central Register of Controlled Trials. The efficacy index, safety index, changes in Snellen lines of corrected distance visual acuity (CDVA), predictability (difference between post-operative and attempted spherical equivalent error, SER), incidence of halos, and change in higher-order aberrations (HOAs) were compared. Mean difference (MD) and 95% confidence interval (CI) was used to estimate continuous outcomes, risk ratio (RR) and 95%CI was used to estimate categorical outcomes.

Results

Five observational studies involving 555 eyes were included in this review. Studies’ sample sizes (eyes) ranged from 76 to 197. Subjects’ refraction ranged from -6 diopter (D) to -12D. Study duration of most researches were 6 months or 12 months. Compared to SMILE, ICL implantation showed better efficacy index (MD=0.09, 95%CI:0.01 to 0.16) and better safety index (MD=0.08, 95%CI: 0.00 to 0.16). Compared with SMILE, more ICL-treated eyes gained one or more Snellen lines of CDVA (RR=1.54, 95%CI:1.28 to 1.86), more gained two or more lines (RR=2.09, 95%CI:1.40 to 3.13), less lost one or more lines (RR=0.17, 95%CI:0.05 to 0.63). There was no difference in predictability between two treatments, RRs of predictability of within ±0.5D and ±1D were 1.13 (95%CI: 0.94 to 1.36) and 1.00 (95%CI: 0.98 to 1.02). Compared with SMILE, ICL implantation came with a higher risk of halos [RR=1.79, 95%CI: 1.48 to 2.16] and less increase in total HOAs (MD=-0.23, 95%CI: -0.42 to -0.03).

Conclusion

Compared with SMILE, ICL implantation showed a higher risk of halos, but equal performance on SER control, and better performance on efficacy index, safety index, CDVA improvement and HOAs control. Overall, ICL implantation might be a better choice for high myopia correction in adults.

Comparison of visual outcomes after non-toric and toric implantable collamer lens V4c for myopia and astigmatism

PURPOSE

To evaluate the visual quality of myopic patients after non-toric versus toric implantable collamer lens (ICL and TICL, respectively) V4c, and to investigate the potential risk factors of postoperative night vision disturbances.

METHODS

This prospective cohort study included 42 eyes of 21 patients treated with ICL and 46 eyes of 23 patients treated with TICL. Refractive parameters and ocular aberrations were examined before and 6 months after surgery. Subjective quality of vision was scored by a validated questionnaire.

RESULTS

The efficacy index at 6 months was 1.14 ± 0.20 for ICL and 1.17 ± 0.16 for TICL; the safety index was 1.20 ± 0.17 for ICL and 1.20 ± 0.19 for TICL. The root mean square of total higher-order aberrations (HOAs) and trefoil was significantly increased, and no statistical differences between groups were detected in HOA changes. Many patients reported haloes (85.7% for ICL and 100% for TICL) and glare (76.2% for ICL and 65.2% for TICL), but most (94.4% for ICL and 95.5% for TICL) were satisfied or very satisfied with visual outcomes. Implantable collamer lens (ICL) toricity was the risk factor for frequency (OR = 2.81, p = 0.01), severity (OR = 3.85, p = 0.003) and bothering effect (OR = 2.89, p = 0.01) of haloes.

CONCLUSIONS

Implantable collamer lens and TICL provided comparable efficacy, safety and predictability, induced acceptable level of HOAs and achieved high satisfaction in correcting myopia and myopic astigmatism. Although not severe, haloes and glare have a non-negligible prevalence and ICL toricity is a potential risk factor of haloes.

SMILE Versus Implantable Collamer Lens Implantation for High Myopia: A Matched Comparative Study

PURPOSE

To compare the safety, efficacy, and patient-reported quality of vision of small incision lenticule extraction (SMILE) and implantable Collamer lens (ICL) implantation for the treatment of high myopia.

METHODS

A database of 1,634 SMILE (Carl Zeiss Meditec AG, Jena, Germany) and 225 ICL implantation (STAAR Surgical, Monrovia, CA) procedures was screened for patients with a binocular preoperative manifest refraction spherical equivalent between -6.00 and -10.00 diopters (D) and plano target refraction. One-to-one matching was performed by preoperative manifest refraction spherical equivalent, age, and pupil size. All identified patients were then prospectively examined at their next regular postoperative follow-up visit and presented with the standardized and clinically validated Quality of Vision questionnaire to gauge patient-reported postoperative visual quality.

RESULTS

A total of 80 eyes (40 patients) were eligible for 1:1 matching. Mean postoperative follow-up was 27.8 ± 14.3 months in the SMILE group and 26.6 ± 17.7 months in the ICL group (P = .44). Regarding the percentage of eyes within ±0.50 D of plano target, refractive predictability was better in eyes treated with ICL implantation (90%) than SMILE (72.5%) (P = .045). Mean UDVA was comparable (ICL: -0.09 ± 0.10 logMAR; SMILE: -0.06 ± 0.09 logMAR; P < .09), but the efficacy (1.28 vs 1.05; P < .001) and safety (1.31 ± 0.22 vs 1.10 ± 0.25; P < .001) indices were higher after ICL implantation. ICL implantation induced significantly fewer higher order aberrations (total higher order aberrations: SMILE 0.724 ± 0.174 µm vs ICL 0.436 ± 0.114 µm; P < .01). Regarding subjective quality of vision, patients who had ICL implantation were significantly less bothered by visual disturbances, which were mainly halos after ICL and starbursts and fluctuations of vision after SMILE (P < .05).

CONCLUSIONS

In this refraction-matched comparative study, ICL implantation for high myopia yielded better refractive accuracy, better uncorrected distance visual acuity, fewer higher order aberrations, and better subjective quality of vision than SMILE. [J Refract Surg. 2020;36(3):150-159.].

The effects of implantable collamer lens implantation on higher order aberrations

AIM

To evaluate the changes in higher order aberrations (HOAs) after implantable collamer lens (ICL; Staar Surgical, Nidau, Switzerland) implantation.

METHODS

Totally 30 eyes of 18 patients with myopia were included in this study with an average age of 25.77y (min: 21, max: 40). Refraction, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), HOAs (entire, corneal and internal) were evaluated preoperatively and three months postoperatively. Ocular aberrations were measured by using iTrace (Tracey Technology, Houston, Texas, USA). SPSS (IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp) was used for the statistical analysis and the interpretation of the data. P values of less than 0.05 were considered statistically significant.

RESULTS

The preoperative mean spherical power was -9.01 D (min: -5.00, max: -13.00) and the mean cylindrical error was -2.40 D (min: -0.50, max: -4.75). The postoperative mean residual spherical power was -0.73 D (min: -0.20, max: -1.75) and the mean cylindrical error was -0.89 D (min: -0.18, max: -2.09). Analyses were made on root mean square (RMS) values of total HOAs (tHOAs), spherical aberration, coma and trefoil as entire, corneal and internal components. The differences in entire tHOAs and in internal tHOAs were significant. There was no significant change found in spherical aberrations. The differences in entire coma and in internal coma were significant. There was no significant change found in corneal coma. With respect to trefoil, the only significant difference was in internal trefoil.

CONCLUSION

The ICL implantation corrects the refractive error successfully and changes entire and internal HOAs of the eye.

Influence of refractive error on pupil diameters in highly myopic eyes with implantable collamer lenses

PURPOSE

To investigate the influence of refractive error on pupil diameters in highly myopic eyes with implantable collamer lenses.

SETTING

Shanghai, China.

DESIGN

A prospective consecutive observational study.

METHODS

Sixty-six eyes of 66 patients that underwent ICL V4c implantation were included. Pupil diameters before and 1 week, 1 month, and 3 months after surgery were measured using an automatic pupillometry system (MonCv3; Metrovision, Pérenchies, France) under four standardized illumination conditions: 0, 1, 10, and 100 cd/m². The correlations between changes in pupil diameter and spherical equivalent values and patient age were investigated.

RESULTS

Based on preoperative spherical equivalent values, included eyes were divided into a high-myopia group (-6.3 to -9.9 D (diopters)) and a super-high-myopia group (-10 to -20 D). Pupil sizes remained unchanged after surgery in the high-myopia group and decreased at 1 and 10 cd/m² in the super-high-myopia group. A between-group comparison showed that pupils were significantly smaller in the super-high-myopia group 1 week postoperatively under all illumination conditions and remained smaller at 1 month and 3 months under 1 and 10 cd/m² lighting conditions. Preoperative spherical equivalent values were significantly correlated with the percent decrease in pupil diameter 1 week postoperatively under 0, 1, and 10 cd/m² illumination conditions; the greater the degree of myopia, the greater the reduction in pupil diameter.

CONCLUSION

Preoperative refractive error significantly affects pupil diameter in highly myopic eyes after implantable collamer lens implantation. Pupils of super highly myopic eyes remained smaller than preoperative levels under mesopic conditions after implantable collamer lens implantation.

The effect of mydriasis on moderate-to-high myopic eyes with implantable collamer lenses V4 and V4c

PURPOSE

To evaluate the vault change and anterior segment movement induced by mydriasis in moderate-to-high myopic eyes with implantable collamer lenses (ICL).

SETTING

Shanghai, China.

DESIGN

A prospective consecutive observational study.

METHODS

A total of 45 eyes of 24 patients with ICL V4 implantation and 128 eyes of 65 patients with ICL V4c implantation were included and analyzed. Anterior chamber depth, posterior corneal endothelium-to-ICL distance, and vault before and after mydriasis were measured by Pentacam (Oculus, Wetzlar, Germany) at 1, 3, and 6 months after surgery.

RESULTS

Significant vault increases and anterior chamber depth increases induced by mydriasis were noted in both ICL V4 and V4c groups at 1, 3, and 6 months postoperatively. The corneal endothelium-ICL distance increased significantly in eyes with implanted ICL V4c after mydriasis at 3 and 6 months. Moreover, mydriasis-induced vault increases were greater in the ICL V4 group than in the ICL V4c group at 3 and 6 months. In eyes with implanted ICL V4c, mydriasis-induced vault increases were significantly greater at 1 month than at 3 and 6 months.

CONCLUSION

Mydriasis results in a general vault increase in eyes with implanted ICLs. The adjustment of the pressure equilibrium via the central hole of the ICL V4c has an important role in vault change. The mydriasis-induced vault increases tend toward stability after 3 months postoperatively. Mydriasis is relatively safe in eyes with ICL implantation.

Comparison of optical quality after implantable collamer lens implantation and wavefront-guided laser in situ keratomileusis

AIM

To compare the optical quality after implantation of implantable collamer lens (ICL) and wavefront-guided laser in situ keratomileusis (WG-LASIK).

METHODS

The study included 40 eyes of 22 patients with myopia who accepted ICL implantation and 40 eyes of 20 patients with myopia who received WG-LASIK. Before surgery and three months after surgery, the objective scattering index (OSI), the values of modulation transfer function (MTF) cutoff frequency, Strehl ratio, and the Optical Quality Analysis System (OQAS) values (OVs) were accessed. The higher order aberrations (HOAs) data including coma, trefoil, spherical, 2^nd astigmatism and tetrafoil were also obtained. For patients with pupil size <6 mm, HOAs data were analyzed for 4 mm-pupil diameter. For patients with pupil size ≥6 mm, HOAs data were calculated for 6 mm-pupil diameter. Visual acuity, refraction, pupil size and intraocular pressures were also recorded.

RESULTS

In both ICL and WG-LASIK group, significant improvements in visual acuities were found postoperatively, with a significant reduction in spherical equivalent (P< 0.001). After the ICL implantation, the OSI decreased slightly from 2.34±1.92 to 2.24±1.18 with no statistical significance (P=0.62). While in WG-LASIK group, the OSI significantly increased from 0.68±0.43 preoperatively to 0.91±0.53 postoperatively (Wilcoxon signed ranks test, P=0.000). None of the mean MTF cutoff frequency, Strehl ratio, OVs showed statistically significant changes in both ICL and WG-LASIK groups. In the ICL group, there were no statistical differences in the total HOAs for either 4 mm-pupil or 6 mm-pupil. In the WG-LASIK group, the HOA parameters increased significantly at 4 mm-pupil. The total ocular HOAs, coma, spherical and 2^nd astigmatism were 0.12±0.06, 0.06±0.03, 0.00±0.03, 0.02±0.01, respectively. After the operation, these values were increased into 0.16±0.07, 0.08±0.05, -0.04±0.04, 0.03±0.01 respectively (Wilcoxon signed ranks test, all P<0.05). At 6 mm-pupil, the induction of total HOAs was not statistically significant in the WG-LASIK group.

CONCLUSION

ICL implantation has a less disturbance to optical quality than WG-LASIK. The OQAS is a valuable complementary measurement to the wavefront aberrometers in evaluating the optical quality.

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.

Phakic posterior chamber intraocular lens for unilateral high myopic amblyopia in Chinese pediatric patients

AIM

To assess the outcomes of posterior chamber implantable collamer lens (ICL) implantation in Chinese pediatric patients with unilateral high myopic amblyopia.

METHODS

Eleven eyes of 11 amblyopic patients aged 11.02±3.34y underwent ICL (model V4, Staar Surgical Inc.) implantation to treat unilateral anisometropia were studied. Visual acuity, cycloplegic refraction, contrast sensitivity, stereopsis, intraocular pressure (IOP), vaulting, corneal endothelial cell count and complications were evaluated. Patients completed follow-up at 3d, 1, 3mo and the last follow-up time (mean 8.18±2.82mo) after surgery.

RESULTS

The mean myopic anisometropia was -13.70±3.25 D preoperatively and +0.69±2.63 D at 8mo postoperatively. The logMAR corrected distance visual acuity (CDVA) of the amblyopic eye was 1.51±0.72 preoperatively and 0.75±0.40 at 8mo postoperatively. The logMAR CDVA at 3d, 1, 3 and 8mo postoperatively improved by a mean of 0.64, 1.55, 1.82 and 2.64 lines and gained more than 2 lines accounted for 18%, 45%, 45%, 64%, respectively. The contrast sensitivity of 0.5, 1 and 2 cpd in amblyopic eyes was significantly increased after surgery. No patient had near stereopsis recovery. The vaulting at 3 and 8mo was significantly lower than that at 1mo postoperatively. No other intraoperative or postoperative complications were observed, except an acute pupillary block glaucoma happened in a patient at two weeks postoperatively.

CONCLUSION

This short-term results indicate that ICL implantation can be a promising alternative therapy for high myopic anisometropic amblyopia in pediatric patients who have failed with conventional treatments and not suitable to corneal refraction surgery.

ICL versus Veriflex phakic IOL for treatment of moderately high myopia: randomized paired-eye comparison

PURPOSE

To compare the objective and subjective outcome of implantable collamer lenses (ICLs; Staar Surgical, Monrovia, CA) versus Veriflex lenses (AMO, Santa Ana, CA) for the correction of moderately high myopia.

METHODS

A prospective randomized comparative eye study was performed on 24 patients with bilateral myopia that ranged from -6 to -14.5 diopters (D). One eye was implanted with an ICL and the other eye was implanted with a Veriflex phakic intraocular lens (PIOL). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), higher-order aberrations (HOAs), contrast sensitivity, patient satisfaction, central endothelial cell count, and PIOL centration were determined 6 months after surgery

RESULTS

The logMAR UDVA and CDVA improved significantly in both groups (P < .001). There was no statistically significant difference in postoperative logMAR UDVA (P = .41) or logMAR CDVA (P = .36) between the two groups. Postoperative deviation from target refraction was -0.06 ± 0.41 D in the ICL group and -0.07 ± 0.49 D in the Veriflex group (P = .15). The difference in both induced and absolute postoperative HOAs between groups was not statistically significant. The area under the log contrast sensitivity function increased significantly in both groups postoperatively. The difference in patient satisfaction between both PIOLs was not statistically significant. A higher but statistically insignificant central endothelial cell count loss occurred in the Veriflex group (P = .11).

CONCLUSION

Both ICL and Veriflex PIOLs have equally satisfactory objective and subjective visual outcomes after surgery.

Visian implantable contact lens versus AcrySof Cachet phakic intraocular lenses: comparison of aberrmetric profiles

Purpose

To evaluate the in vivo aberrometric performance of two phakic intraocular lenses (PIOLs); the Visian implantable contact lens (ICL) and the AcrySof Cachet PIOL.

Methods

Thirty eight eyes from 29 patients with an age range of 23–32 years and more than 9 D of myopia were divided into two groups; one group of 20 eyes received a Visian ICL model V4c, another group of 18 eyes received an AcrySof Cachet PIOL. Total higher order aberrations (HOAs) root mean square, total coma, and total spherical aberrations were recorded pre and 6 weeks postoperatively to evaluate and compare the aberrometric performance of the Visian ICL and the AcrySof Cachet PIOL implanted in highly myopic patients.

Results

Preoperatively, there were no significant differences in any studied parameters, except for preoperative spherical equivalent. Postoperatively, there were no statistically significant differences in the induction of HOAs between both PIOLs. The reduction in spherical aberrations was statistically significant in each group as well as in all study patients.

Conclusion

Both AcrySof Cachet PIOL and ICLs are effective phakic implants to correct high refractive errors. They both induce small amounts of negative spherical aberration that do not affect the total HOAs, yet reduce the positive ocular spherical aberration. This result is expected to improve the quality of vision in such patients.

Optical quality comparison of conventional and hole-visian implantable collamer lens at different degrees of decentering

PURPOSE

To compare the optical quality of implantable Collamer lens (ICL) with and without central hole (Hole ICL and conventional ICL) at different degrees of decentering.

DESIGN

Experimental laboratory investigation.

METHODS

Wavefront aberrations of the -3, -6, and -12 diopter (D) V4b and -3, -6, and -12 D V4c ICLs were measured in 3 conditions-centered and decentered 0.3 and 0.6 mm-at 3-mm and 4.5-mm pupils. The root mean square of total higher order aberrations, trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. In addition, point spread function and simulated retinal images of ICLs were calculated from the wavefront aberrations for each ICL and all conditions of decentering at 4.5-mm pupil.

RESULTS

No statistically significant differences in any Zernike coefficient terms evaluated were found between conventional and Hole ICLs for any ICL powers and pupils evaluated (P > .05). We could not appreciate differences in the point spread function images and in simulated retinal images. Regarding the effect of the ICL decentration, coma aberration increased significantly with ICL decentration (P < .05), although these differences were not visible in the point spread function images and simulated retinal images. The ICL decentration was affected in the same manner on the conventional and Hole ICLs.

CONCLUSIONS

The outcomes showed good and comparable optical quality of the conventional and Hole ICLs for all ICL powers evaluated. Despite that coma aberration increased with ICL decentering, these values were clinically negligible and did not have a significant effect on the simulated visual performance.

Ciliary sulcus diameters at different anterior chamber depths in highly myopic eyes

PURPOSE

To determine the correlation between white-to-white (WTW) diameters and horizontal ciliary sulcus diameters at different anterior chamber depths (ACDs) in highly myopic eyes.

SETTING

First Affiliated Hospital of Anhui Medical University, Hefei, China.

DESIGN

Cross-sectional observational study.

METHODS

Highly myopic eyes were divided into a shallow ACD group (2.8 to 3.2 mm), medium ACD group (3.2 to 3.4 mm), and deep ACD group (>3.4 mm). Ciliary sulcus diameters were measured by full-scale 50 MHz ultrasound biomicroscopy.

RESULTS

In the shallow ACD group, linear regression showed that horizontal sulcus diameters were a significant predictor of WTW diameters (P<.001). The difference between them was greater than 0.50 mm in 13.1% of eyes. In the medium ACD group, linear regression showed horizontal sulcus diameters were a significant predictor of WTW diameters (P<.001). The difference between them was greater than 0.50 mm in 25.7% of eyes and greater than 1.0 mm in 2.8% of eyes. In the deep ACD group, linear regression did not show that horizontal sulcus diameters were a significant predictor of WTW diameters (P=.126). The difference between them was greater than 0.50 mm in 31.6% of eyes and greater than 1.0 mm in 5.3% of eyes. In all eyes, vertical diameters were greater than horizontal diameters.

CONCLUSIONS

The WTW technique was inaccurate at predicting the horizontal diameter of the ciliary sulcus, and predictive errors increased with increasing ACDs. The posterior chambers were not perfectly circular, with vertical diameters being greater than horizontal diameters.

FINANCIAL DISCLOSURE

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

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

PURPOSE

To compare the optical and visual quality of a simulated Toric Implantable Collamer Lens (TICL) and a bioptics technique to treat high myopic astigmatism.

METHODS

An adaptive optics visual simulator was used to simulate the vision after TICL implantation and a bioptics procedure from the wavefront aberration pattern for moderate and high-myopic astigmatism. Visual acuity (VA) at different contrasts and contrast sensitivity (CS) at 10, 20 and 25 cycles degree(-1) were measured for 3 and 5-mm pupils. Modulation Transfer Function (MTF) and Point Spread Function (PSF) were calculated for a 5-mm pupil.

RESULTS

At a 3-mm pupil we only found statistically significant differences in VA between the two simulated surgeries at low-contrast for moderate- and high-myopic astigmatism (p < 0.05). Statistically significant differences were found in CS at 3-mm pupil between both procedures at the highest spatial frequency for moderate-myopic astigmatism and at all frequencies for high-myopic astigmatism (p < 0.05). At a 5-mm pupil we found statistically significant differences in VA and CS between both simulated surgeries at all contrasts and frequencies evaluated for both groups (p < 0.05). In all cases VA and CS were better with the TICL than with the bioptics technique. MTFs for the bioptics technique were worse than those computed for the TICL. The TICL showed less spread out of the PSF than the bioptics procedure.

CONCLUSIONS

Simulated TICL and bioptics procedures provided good optical and visual quality, although TICL implantation provided slightly better outcomes than the bioptics procedure, especially when the pupil diameter was increased.

Optical quality of the Visian Implantable Collamer Lens for different refractive powers

PURPOSE

To evaluate the optical quality of the Visian Implantable Collamer Lens (ICL) for different powers and pupil diameters.

METHODS

Wavefront aberrations of the -3, -6, -9, -12 and -15 diopters (D) V4b ICLs were measured at 3- and 4.5-mm pupils. The root mean square (RMS) of total higher order aberrations (HOAs), trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. In addition, modulation transfer function (MTF) of the five ICL powers was measured for a 3-mm pupil. The point spread functions (PSFs) of each ICL evaluated was calculated from the wavefront aberrations at 4.5-mm pupil.

RESULTS

The ICLs evaluated had negative spherical aberration and negligible amounts of other aberrations. The negative spherical aberration increases when the ICL power increases being related with its innate optical properties. At 3-mm pupil, no statistically significant differences between ICLs were found for all the Zernike coefficient RMS values analyzed (p > 0.05). At 4.5-mm pupil, significant RMS values for the spherical aberration and total HOAs were found between medium-low and high powers (p < 0.05). Similar MTFs were obtained for all ICLs, although they slightly worsened when increased the ICL power.

CONCLUSIONS

ICLs evaluated provide good optical quality in terms of wavefront aberrations, MTF, and PSF. Although spherical aberration increases with ICL power, these values are clinically negligible to affect the visual quality after its implantation.

Role of the human lens gradient-index profile in the compensation of third-order ocular aberrations

The open question regarding the compensation of the ocular aberrations between the cornea and the lens is currently being investigated. We report additional insights considering the role of the lens gradient-index (GRIN) profile in third-order ocular aberrations, since this profile changes through life. Thus, we have calculated the contribution of that profile to the ocular aberrations with aging by applying the Seidel third-order theory of tilted and decentered elements, and by using a schematic-eye model. The results show the GRIN profile is needed to account for the decoupling of the aberrations between the cornea and the lens because the geometrical changes of the ocular surfaces with aging are not enough. Therefore, the current developments of aging human-eye models, as well as the experimental studies, cannot neglect the changes of the lens GRIN structure through life when modelling mechanisms of the compensation of ocular aberrations.