Spherical implantable collamer lenses for myopia and hyperopia: 126 eyes with 1-year follow up

Clinical Observation of Posterior-Chamber Phakic Implantable Collamer Lens V4c Implantation in Myopic Patients with Shallow Anterior Chamber Depth: A Retrospective, Consecutive Observational Study

Purpose

The reference range for the preoperative anterior chamber angle width for ICL surgery is unclear. Our objective was to assess the clinical effect and the range of anterior chamber angle width of posterior-chamber implantable collamer lens V4c (ICL V4c) implantation in patients with anterior chamber depth (ACD) < 2.8 mm.

Methods

Patients who underwent ICL V4c implantation with shallow ACD were included in this retrospective study. The patients' uncorrected and corrected distance visual acuity, angle of trabecular-iris (TIA), angle-opening distance (AOD500), trabecular-iris space area (TISA500), corneal endothelial cell density, vault, retinal nerve fiber layer thickness, intraocular pressure, visual field, and complications were analyzed.

Results

Forty-one patients (68 eyes) completed at least 12 months of follow-up (median follow-up, 30 months). The effectiveness and safety indices were 1.09 ± 0.13 and 1.04 ± 0.21, respectively. The preoperative TIA values on the nasal and temporal sides were 39.78 ± 7.68 degree (range, 25.8-65.1 degree) and 41.54 ± 8.03 degree (range, 28.5-63.00 degree). Forty-seven eyes had uncorrected distance visual acuity ≥1.0, and 55 had corrected distance visual acuity ≥1.0 at the last follow-up visit. The TIA, AOD500, and TISA500 on the nasal and temporal sides were significantly reduced compared to those before surgery (all P < 0.01); no eye had an angle closure or elevated intraocular pressure. The ICL V4c vault was 290.88 ± 153.36 μm (range, 60.0-880.0 μm). No severe complications occurred in any patient.

Conclusions

In patients with myopia with shallow ACD (2.55-2.79 mm), a preoperative TIA >25.8° is safe and effective for a relatively long time after surgery; however, an extended long-term close follow-up is needed.

Causes and outcomes of implantable collamer lens explantation in patients with corneal endothelial cell loss

PURPOSE

To investigate the correlated factors of corneal endothelial cell density (ECD) loss and ECD change in implantable collamer lens (ICL) explantation patients.

SETTING

Seoul St. Mary's Hospital, Seoul, South Korea.

DESIGN

Retrospective analysis.

METHODS

The study cohort consisted of 93 eyes from 50 patients who underwent ICL explantation. Correlation analysis was performed to assess the ocular parameters associated with ECD loss, while percentage of ECD change (ΔECD%) was monitored up to 6 months postoperatively. Receiver operating characteristic (ROC) curve was used to set cutoff values of ocular parameters to prevent ECD loss after explantation.

RESULTS

In multiple regression analysis, high vaulting, high vaulting/anterior chamber depth (ACD), low anterior chamber angle (ACA), and high iris pigmentations are the significant factors of ECD loss. At postoperative 6 months, 14 eyes (15.1%) had decrease (10.5% loss), 47 eyes (51.0%) were stationary, and 32 eyes (34.4%) had increase (12.7% gain) of ECD. The ROC curve analysis showed that vaulting had the highest area under the curve (AUC = 0.822), followed by vaulting/ACD (AUC = 0.821), ECD (AUC = 0.753), and ACA (AUC = 0.723) (all P < .01). Preoperative ECD showed a sensitivity of 77.6% and specificity of 86.7% in preventing ECD loss after explantation, with a cutoff value of 1722 cells/mm 2 , as determined by ROC curve analysis.

CONCLUSIONS

Our study demonstrated that high vaulting is a significant factor in ECD loss among ICL-inserted patients. To prevent continuous ECD loss in ICL patients, close monitoring of ECD and making appropriate decisions regarding explantation may be necessary.

The Distribution of Crystalline Lens Rise in High Myopia Population and Its Influence on Vault After Implanting Intraocular Collamer Lens

INTRODUCTION

As a result of the insufficient ocular anatomical parameters used to customize implantable collamer lens (ICL), many patients still cannot achieve a suitable vault after ICL implantation surgery. This study analyzed the characteristics of a new anatomical parameter crystalline lens rise (CLR) in a population with high myopia and explored the influence of CLR on the vault after ICL implantation.

METHODS

Patients (298 eyes) with high myopia who underwent ICL implantation were enrolled to study CLR characteristics. Postoperatively, patients (159 eyes) were divided into five groups according to the value of CLR (A, CLR ≤ - 150; B, - 150 < CLR ≤ 0; C, 0 < CLR < 150; D, 150 ≤ CLR < 300; E, CLR ≥ 300 μm), and to investigate the correlation between CLR and vault.

RESULTS

In the 298 eyes, the CLR had a normal distribution (P = 0.35) and the mean CLR was 67.93 ± 150.66 μm. Ninety-nine eyes (33.22%) had a CLR ≤ 0 μm, of which 20 eyes (6.71%) had a CLR ≤ - 150 μm; 199 eyes (66.78%) had a CLR > 0 μm, of which 20 eyes (6.71%) had a CLR ≥ 300 μm. In 159 eyes, the CLR was negatively correlated with the vault at 1 day (R = - 0.497, P < 0.001), 3 months (R = - 0.505, P < 0.001), and 6 months (R = - 0.505, P < 0.001) postoperatively. At 6 months, the vault of group A was statistically significantly different compared to groups B-E (all P < 0.05), and that of group E was statistically significantly different compared to groups A-D (all P < 0.001). The remaining groups did not show statistically significant differences (all P > 0.05).

CONCLUSION

The CLR had a normal distribution in the high myopia population, and 13.42% of the CLR values were extreme (CLR ≤ - 150 μm or CLR ≥ 300 μm). A larger ICL diameter than that recommended by the manufacturer should be considered when the CLR is ≥ 300 μm and a smaller ICL diameter should be considered when the CLR is ≤ - 150 μm.

Diagnostic Techniques to Increase the Safety of Phakic Intraocular Lenses

Preoperative and postoperative diagnostics play an important role in ensuring the safety of patients with phakic intraocular lenses (pIOLs). The risk of endothelial cell loss can be addressed by regularly measuring the endothelial cell density using specular microscopy and considering the endothelial cell loss rate and the endothelial reserve in accordance with the patient's age when deciding whether to explant a pIOL. The anterior chamber morphometrics, including the anterior chamber depth and the distance between the pIOL and the endothelium, measured using Scheimpflug tomography and anterior segment optical coherence tomography (AS-OCT), can help to assess the risk of the endothelial cell loss. In patients undergoing posterior chamber pIOL implantation, accurate prediction of the vault and its postoperative measurements using AS-OCT or Scheimpflug tomography are important when assessing the risk of anterior subcapsular cataract and secondary glaucoma. Novel approaches based on ultrasound biomicroscopy and AS-OCT have been proposed to increase the vault prediction accuracy and to identify eyes in which prediction errors are more likely. Careful patient selection and regular postoperative follow-up visits can reduce the complication risk and enable early intervention if a complication occurs.

Evaluation of phakic intraocular lens power calculation using the new Linz-Homburg-Castrop formula and comparison with four conventional methods

PURPOSE

To evaluate the accuracy of phakic intraocular lens (pIOL) power calculation in a middle European patient cohort.

SETTING

EyeLaser Clinic, Linz, Austria.

DESIGN

Single-center single-surgeon retrospective consecutive case series.

METHODS

Patients were included after uneventful pIOL surgery implanting 91 nontoric and toric Visian implantable collamer lens model V4c. Online Calculation and Ordering System (OCOS) software, JPhakic software, Olsen-Feingold formula, Holladay formula, and Linz-Homburg-Castrop (LHC) formula were compared. When possible, lens constants were optimized for the patient cohort. Data of single eye per patient were included. Outcome measures were mean absolute prediction error, median absolute prediction error, mean prediction error with SD, and median prediction error, as well as the percentage of eyes with an absolute prediction error within limits of 0.25 diopters (D), 0.5 D, 0.75 D, and 1.0 D.

RESULTS

91 eyes of 91 patients were assessed. After application of the Cochran Q test, the Olsen-Feingold formula achieved a significantly lower percentage of eyes within an absolute prediction error of 1.0 D than all other methods.

CONCLUSIONS

In the patient cohort, OCOS software, JPhakic software, and Holladay and LHC formulas showed equal results and can be cross-checked. The LHC formula was not published before. A ready-to-use Excel sheet is available as an addendum.

Refractive Surgery for Older Children and Adults with Accommodative Esotropia: A Systematic Review

INTRODUCTION

Accommodative esotropia (AET) is characterized by an esodeviation of the eyes due to uncorrected hyperopia, deficient fusional divergence, or high accommodative convergence. Decreasing hyperopia would reduce accommodative convergence and strabismus. We sought to review the existing evidence regarding the outcomes of refractive surgery in patients with AET.

METHODS

A four-database search (Pubmed, ISI Web of Science, Cochrane, and Scopus) was performed from inception to March 2021 using the following MeSH terms: ("Refractive Surgical Procedures" OR "Keratomileusis, Laser In Situ" OR "Photorefractive Keratectomy" OR "Lens Implantation, Intraocular") AND ("Esotropia" OR "Accommodative Esotropia" OR "Refractive Esotropia" OR "Accommodative Strabismus"). No meta-analysis was performed due to studies' heterogeneity.

RESULTS

Twenty-eight studies including 22 case series enrolling 378 patients and 6 case reports enrolling 8 patients were selected among 185 original abstracts. In the case series, a total of 378 patients (726 eyes) were recruited with an age range of 8-52 years. All studies reported mean follow-up periods of at least 12 months. Photorefractive keratectomy was performed in 7 studies, laser-assisted in situ keratomileusis in 9 studies, laser-assisted sub-epithelial keratectomy was reported in 1 study, and 3 studies implanted intraocular lenses, including iris-fixated and collamer. Considering the adult patients with a preoperative corrected esodeviation ≤10 prism diopters (PD) (n = 129), all but 5 (3.9%) presented orthophoria or ≤10PD after refractive surgery. All children but 4 (4.5%) ended up with an esodeviation ≤10PD after surgery with those exceptions being in the range of 11-15PD. Six case reports were included in this review, comprising a total of 8 patients (16 eyes) with an age range of 7-34 years and a follow-up range of 4-48 months. Six case reports were included in this review, comprising a total of 8 patients (16 eyes) with an age range of 7-34 years and a follow-up range of 4-48 months.

CONCLUSION

Evidence produced so far points out that refractive surgery may be an alternative for spectacle correction for adults with AET ≤10PD. There is not enough evidence to recommend its use for patients under 18 years of age. The safety and predictability of these procedures for this purpose remains unclear as the selection criteria used for these patients are much different than the usual indications and there are no studies with long-term follow-up.

Correlation between intraoperative and postoperative vaulting of the EVO implantable Collamer lens: a retrospective study of real-time observations of vaulting using the RESCAN 700 system

Background

Implantable Collamer lens (ICL) vaulting is one of the most important parameters for the safety, aqueous humor circulation, and lens transparency after ICL implantation. This study aimed to investigate the factors associated with the actual vaulting after refractive EVO-ICL surgery.

Methods

This retrospective study included patients who underwent EVO-ICL surgery at a tertiary eye hospital between October and December 2019. A RESCAN 700 was used for the intraoperative and CIRRUS HD-OCT was used for postoperative observation of vaulting. Subjective and objective refractions, anterior ocular segment, corneal morphology, intraocular pressure (IOP), anterior chamber volume (ACV), crystalline lens rise (CLR), white-to-white distance (WTW), anterior chamber depth (ACD), axial length, corneal endothelial cell density (ECD), and fundoscopy were examined. A multivariable analysis was performed to determine the factors independently associated with 1-month postoperative vaulting.

Results

Fifty-one patients (102 eyes) were included. Compared with the eyes with normal vaulting, those with high vaulting had higher preoperative diopter values (P = 0.039), lower preoperative corrected visual acuity (P = 0.006), lower preoperative IOP (P = 0.029), higher preoperative ACD (P = 0.004), lower preoperative CLR (P = 0.046), higher ICL spherical equivalent (P = 0.030), higher intraoperative vaulting (P < 0.001), and lower IOP at 1 month (P = 0.045). The multivariable analysis showed that the only factor independently associated with high vaulting at 1 month after surgery was the intraoperative vaulting value (odds ratio = 1.005, 95% confidence interval: 1.002–1.007, P < 0.001). The intraoperative and 1-month postoperative vaulting values were positively correlated (R² = 0.562).

Conclusions

The RESCAN700 system can be used to perform intraoperative optical coherence tomography to predict the vaulting value of ICL at 1 month.

Assessment of the Vault After Implantable Collamer Lens Implantation Using the KS Formula

PURPOSE

To examine the vault size after Implantable Collamer Lens (ICL) (KS-AquaPORT; STAAR Surgical) surgery using the KS formula.

METHODS

In this prospective study, the postoperative vault was examined using the KS formula in 121 eyes of 65 patients (28 men and 37 women) who underwent ICL implantation for myopia and myopic astigmatism. The mean horizontal angle-to-angle (ATA), anterior chamber depth, and axial length before surgery were 11.83 ± 0.40, 3.25 ± 0.34, and 26.52 ± 1.17, respectively. Anterior segment optical coherence tomography (CASIA2; Tomey Corporation) was used for ATA measurement.

RESULTS

Multiple regression analysis of the potential factors influencing the predicted vault error (postoperative vault - predicted vault by KS formula) showed that only ICL size was a significant factor (P < .001, r = 0.36). At an ICL size of 12.1 mm, the postoperative vault was smaller than the predicted vault, and the postoperative vault tended to be larger than the predicted vault at ICL sizes of 13.2 and 13.7 mm.

CONCLUSIONS

Vault prediction by the KS formula was generally good, but the ICL size influenced the vault prediction error; therefore, a modified KS formula was created to reduce the error in measurements of the postoperative vault. [J Refract Surg. 2021;37(9):636-641.].

Intraoperative Versus Postoperative Vault Measurement After Implantable Collamer Lens Implantation in a Large Cohort of Patients

PURPOSE

To compare intraoperative and postoperative central vault measurement after implantable Collamer lens (ICL; STAAR Surgical) implantation using optical coherence tomography (OCT).

METHODS

A total of 574 eyes of 338 consecutive patients undergoing myopic ICL implantation were evaluated (mean age of 30.8 ± 5.7 years, 117 men and 221 women). Central ICL vault was measured both intraoperatively using the microscope-integrated iOCT (Optomedical Technologies GmbH) mounted on a standard surgical microscope (HS Hi-R NEO 900A; Haag-Streit Surgical GmbH), and postoperatively using the CASIA2 swept-source OCT (Tomey GmbH) at 4 and 24 hours.

RESULTS

Mean differences between intraoperative and postoperative vault values were 11.5 ± 29.0% of the mean value 4 hours postoperatively (P < .001) and 2.7 ± 33.5% of the mean value 24 hours postoperatively (P < .001). Correlation analysis shows significant agreement between vault values obtained intraoperatively and at the two postoperative times, 4 hours (Spearman Rho = 0.850, P < .001) and 24 hours (Spearman Rho = 0.745, P < .001). In 73% of cases, postoperative vault values 4 hours after the surgery could be predicted from intraoperative vault values, and so were 56% of vault values 1 day after surgery. Significant differences in vault were found at the different times, grouping cases by ICL size (Kruskal-Wallis, P = .028 for intraoperative vault, and P < .001 for both postoperative vault times), with smaller vault values for the smaller ICL size.

CONCLUSIONS

Intraoperative determination of ICL vault using iOCT is an effective method for predicting postoperative ICL vault and minimizing postoperative vault surprises that could require surgical retouching. [J Refract Surg. 2021;37(7):477-483.].

Phakic intraocular lens implantation for the correction of hyperopia

The prevalence of myopia is much higher than hyperopia. Hence, there are relatively few studies investigating phakic intraocular lens (pIOL) implantation for the correction of hyperopia. This review aimed to summarize the available relevant literature on the efficacy and safety of pIOL implantation for the correction of hyperopia and hyperopic astigmatism. At present, two types of pIOLs are used to correct hyperopia and hyperopic astigmatism: anterior chamber iris-fixated pIOLs and posterior chamber implantable collamer lenses. Both have been found to be safe and effective. No serious events (eg, retinal or choroidal detachment, endophthalmitis) were reported in the reviewed articles. Implantation of pIOLs might be the optimal refractive surgery for the correction of high hyperopia.

The Relationship between Anterior Chamber Angle and Intraocular Pressure Early after V4c Implantable Collamer Lens Implantation

Purpose

To confirm the relationship between anterior chamber angle (ACA) and intraocular pressure (IOP) early after V4c implantable collamer lens (ICL) implantation.

Methods

Patients were assigned to two groups: (1) right eyes (control group) and (2) left eyes (experimental group), with miosis conducted immediately after ICL implantation in the left eyes. IOP, angle opening distance (AOD), trabecular-iris angle (TIA), and pupil diameter (PD) were compared between two groups at postoperative hours 1, 2, and 24. The relationship between ACA, PD, and IOP was analyzed by multiple linear regression.

Result

Thirty-six eyes of 18 patients were enrolled. The prevalence of ocular hypertension (OHT, defined as IOP ≥ 21 mmHg) was 61.11% and 16.67% in the right and left eyes, respectively, (χ² = 7.481, p=0.006). At postoperative hours 1 and 2, IOP and PD were significantly higher (p < 0.001) in the right eyes, and TIA and AOD were significantly lower (p < 0.05) in the right eyes than in the left eyes. There was no significant difference at 24 h postoperative in these parameters. After the right eye ICL implantation, the changes of AOD 500 and PD were both linearly correlated with postoperative IOP change (β = −23.707 and 1.731, respectively; p = 0.013 and 0.002, respectively).

Conclusion

The ACA was significantly narrowed immediately after V4c ICL implantation. There was a negative linear correlation between ACA and early IOP and a positive linear correlation between PD and early IOP. We recommend the use of intracameral miotics immediately after V4c ICL implantation to reduce the incidence of IOP spikes.

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.

Intraocular pressure fluctuations in patients implanted with an implantable collamer lens (ICL V4c). Three-month follow-up

INTRODUCTION

Fluctuating elevated intraocular pressure (IOP) is one of the complications of an implantable collamer lens (ICL), and its alteration is a predictive factor for the development of glaucoma.

MATERIAL AND METHODS

A prospective, cross-sectional analytic study was conducted on patients suitable for ICL implantation. Complete clinical and biometric work-ups were performed, as well as night-time IOP curve, in supine position, with 4 determinations, in order to assess fluctuation, considering abnormal with a value higher than 5 mmHg. Patients underwent surgery with conventional technique and three months after the work-ups were repeated, including a night-time IOP curve to assess any changes in IOP fluctuations.

RESULTS

A total of 31 eyes of 16 patients were studied. Mean IOP fluctuation in the preoperative assessment was 3.35 ± 2 mmHg, whereas the postoperative mean was 3.0 ± 2.2 mmHg, with the difference not being statistically significant. Visual acuity and capacity, as well as spheric equivalent did show a statistically significant improvement. There were 6 cases of complications, which were related to a higher vault and a greater ICL size. There was no relationship between these findings and the angle grade, pigment, and the level of training of the surgeon.

CONCLUSIONS

The effect of an ICL on IOP fluctuations, has been studied for the first time, which was found to be not statistically significant. As in previous publications, the procedure was safe and reproducible, adding the fact that the level of training of the surgeon is not a determining factor in these findings.

Intraocular Pressure After Implantation of a Phakic Collamer Intraocular Lens With a Central Hole

PURPOSE

To investigate the middle-term intraocular pressure (IOP) results after implantation of a posterior chamber collagen copolymer phakic intraocular lens (IOL) (V4c Visian; STAAR Surgical Co., Nidau, Switzerland) with a central hole in patients with myopia.

METHODS

This retrospective study enrolled patients who had implantation of a phakic IOL with a central hole. IOP, central vault, and adverse events were evaluated 1, 3, 6, 12, and 24 months postoperatively.

RESULTS

The study enrolled 763 eyes (384 patients, 128 men and 256 women). Mean follow-up was 7.0 ± 7.2 months (range: 1 to 24 months). The mean IOP was 13.2 ± 2.1 mm Hg preoperatively. Postoperatively, the mean IOP was 12.4 ± 1.7 mm Hg at 1 month, 12.5 ± 1.8 mm Hg at 3 months, 12.6 ± 1.3 mm Hg at 6 months, 12.6 ± 1.4 mm Hg at 12 months, and 12.7 ± 1.1 mm Hg at 24 months. Only one case (0.13%) presented an increased IOP (> 21 mm Hg) during the observation period. No pupillary block or acute angle closure was recorded. IOP at the final follow-up visit was 12.8 ± 1.3 mm Hg.

CONCLUSIONS

Implantation of central hole phakic IOL in myopic patients provided good and safe IOP outcomes throughout the 24-month observation period. [J Refract Surg. 2017;33(4):244-249.].

Etiology and Management of Raised Intraocular Pressure following Posterior Chamber Phakic Intraocular Lens Implantation in Myopic Eyes

AIM

To evaluate the etiology and management of elevated intraocular pressure (IOP) following posterior chamber phakic implantable collamer lens (ICL) surgery.

METHODS

Between 2009 and 2015, 638 eyes of 359 subjects with refractive myopia, underwent V4b and V4c (CentraFLOW) model ICL implantation. Ocular hypertension (OHT) was defined as IOP of ≥ 22 mm Hg on two separate occasions and elevated IOP with corresponding optic disc or visual field damage was defined as glaucoma.

RESULTS

Elevated IOP ≥ 22 mm Hg was noted in 33 eyes of 30 subjects (33/638; 5.17%). Median age of subjects with raised IOP was 26 years (Inter quartile range (IQR):22, 29) and median refarctive error was -16 diopters (-19.5, -13). The median follow up was 7.8 months (IQR:0.3, 17.6) and median time for postoperative IOP rise was 12 days, (IQR:2, 24). The various etiologies for elevated IOP were steroid response in 21 eyes (64%; 10 eyes with V4b, 11 eyes with V4c), retained viscoelastic in 5 eyes (15%) (3 with V4b, 2 with V4c), pupillary block in four eyes (12%; 3 with V4b, 1 with V4c), malignant glaucoma in one eye (3%, V4b), and missed pre-existing Juvenile open angle glaucoma (JOAG) in two eyes (6% with V4b). Elevated IOP in 31 eyes resolved with conservative management. One eye (centraFLOW design) with central aquaport block by viscoelastic, needed AC wash and one eye with malignant glaucoma needed parsplana vitrectomy and hyaloidotomy. Ten eyes required longterm (>2 months) antiglaucoma medications (AGM) for IOP control. Except the two eyes with JOAG, none had disc and field damage.

CONCLUSION

In our series, OHT was seen in 4.85% and glaucoma in 0.3% eyes that underwent V4b and V4c model ICL implantation. Multiple etiologies were noted and steroid induced ocular hypertension was the most common cause of elevated IOP followed by retained viscoelastic and pupillary block. One third of these eyes required longterm AGM for IOP control.

Ghost-image analysis in phakic intraocular lenses with central hole as a potential cause of dysphotopsia

PURPOSE

To analyse the optical effect of an artificial hole in the optic centre of posterior chamber phakic intraocular lenses.

SETTING

Institute of Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany.

DESIGN

Experimental simulation study.

METHODS

Four eye models with an ametropia of -4 D, -8 D, +4 D, and +8 D were created in the ray tracing software ASAP. Refractive correction of these models was implemented with a model of an Implantable Collamer Lens (ICL). Each eye was set up twice with 1 eye receiving a conventional ICL without a central hole and the second an ICL with a central hole. Ray bundles were traced for lateral visual field angles from 0 to 60 degrees in steps of 1 degree. Ray propagation and retinal illumination were then compared between the 2 ICL models.

RESULTS

All eye models showed ghost images originating from the anterior surface of the ICL. Eye models with the ICL with central hole showed additional light spots in the peripheral areas of the retina originating from reflections at the cylindrical wall of the central hole in the ICL. The average intensity of ghost images in the temporal retinal hemisphere was between 30 and 40 dB less than the maximum intensity of the primary image.

CONCLUSION

A central hole within a posterior chamber phakic intraocular lens may cause stray light and ghost images (positive dysphotopsia) although the on-axis visual quality of the eye with the ICL is mostly unaffected.

FINANCIAL DISCLOSURE

The authors have no financial interest in any of the material presented in this paper.

Meta-analysis and review: effectiveness, safety, and central port design of the intraocular collamer lens

The purpose of this review is to summarize relevant data from publications appearing in the peer-reviewed scientific literature over the past decade since US Food and Drug Administration approval of the implantable collamer lens (ICL), and, in particular, to review studies relating to sizing methodology, safety, and effectiveness, as well as more recent studies reporting clinical outcomes of the V4c Visian ICL with KS Aquaport, VICMO. A literature search was conducted using two databases, PubMed.gov and Science.gov, to identify all articles published after 2005 related to the Visian ICL (STAAR Surgical, Inc.). Articles were examined for their relevance to sizing methodology, clinical safety, and effectiveness, and the references cited in each article were also searched for additional relevant publications. The literature review revealed that all currently reported methods of determining the best-fit size of the ICL achieve similarly satisfactory results in terms of vault, the safe distance between the crystalline lens and the ICL. Specifically, meta-analysis demonstrated that sulcus-to-sulcus and white-to-white measurement-based sizing methods do not result in clinically meaningful nor statistically significant differences in vault (two-sample two-sided t-test using pooled mean and standard deviations; t (2,594)=1.33; P=0.18). The reported rates of complications related to vault are very low, except in two case series where additional risk factors such as higher levels of myopia and older age impacted the incidence of cataract. On the basis of preclinical studies and initial clinical reports, with up to 5 years of follow-up, the new VICMO central port design holds promise for further reduction of complications. Given its safety record and the significant improvement in vision and quality of life that the ICL makes possible, the benefits of ICL implantation outweigh the risks.

Long-term clinical results of posterior chamber phakic intraocular lens implantation to correct myopia

BACKGROUND

The aim of this study was to determine whether implantable collamer lens (ICL) implantation to correct myopia is an effective and safe surgical option even after long-term follow up.

DESIGN

A retrospective observational study was carried out.

PARTICIPANTS

A total of 281 eyes of 145 myopic patients were included in the study.

METHODS

Patients underwent ICL implantation and had the follow-up period of at least 5 years (87 ± 18.9 months).

MAIN OUTCOME MEASURES

Outcome measures included uncorrected and corrected distance visual acuities, refraction for the evaluation of efficacy, safety, stability and predictability, ICL vault and adverse events.

RESULTS

The final mean logMAR uncorrected and corrected distance visual acuities were 0.02 ± 0.19 and -0.12 ± 0.13, respectively. The mean efficacy and safety indices were 1.04 ± 0.32 and 1.20 ± 0.26. The mean spherical equivalent decreased from -8.74 ± 2.27 diopter (D) to -0.58 ± 0.72 D, and there was high predictability with 69.8% and 87.2% having a postoperative refraction within 0.5 D and 1.0 D, respectively. The mean postoperative vault was changed from 2.53 ± 0.6 to 2.00 ± 0.7. Six (2.1%) eyes developed cataract, and the mean endothelial cell loss was 7.8 ± 8.3%. Increased intraocular pressure was found in two (0.7%) eyes that required the exchange of lenses with different sizes.

CONCLUSIONS

Implantable collamer lens implantation to correct myopia was an effective and safe surgery with high predictability and stability during long-term follow up. Slight myopic shift and cataract formation related with change in vault should be further evaluated.

Causes of elevated intraocular pressure following implantation of phakic intraocular lenses for myopia

The purpose of this study is to present the causes and visual acuity outcomes in patients with elevated intraocular pressure (IOP) following implantable collamer lens (ICL) implantation. A chart review identified patients who developed high IOP at any postoperative examination and a minimum follow-up period of 3 months after ICL implantation. Data are reported out to 6 months postoperatively. Outcome measures included causes of elevated IOP, best-corrected visual acuity (BCVA) at last visit, number of glaucoma medications, other interventions, and glaucomatous damage. Elevated IOP occurred in 58 (10.8 %) of 534 eyes that received ICL. The mean age was 28 ± 7.2 years. The preoperative IOP was 16.3 ± 1.2 mmHg. Elevated IOP most commonly occurred on the first postoperative day (23/58 (39.7 %) eyes) due to retained viscoelastic. This was followed by steroid response in 22/58 (37.9 %) eyes at 2-4 weeks postoperatively. IOP elevation in 6 (10.3 %) eyes was related to high ICL vault and pupillary block, and in 4 (6.9 %) eyes due to synechial angle closure. At last visit, BCVA was 20/40 or better in 56/58 (96.6 %) eyes, and 5/58 (8.6 %) eyes remained on glaucoma medications due to persistent steroid response (2 eyes), synechial angle closure glaucoma (1 eye), and other causes (2 eyes). One eye showed glaucomatous damage. Two eyes with high vault and elevated IOP underwent ICL explantation. There is a moderate risk of transiently developing elevated IOP after ICL implantation. Thorough removal of viscoelastic and use of anti-glaucoma medications during steroid use will reduce the majority of cases with postoperative IOP elevation.

Correction of moderate to high hyperopia with an implantable collamer lens: medium-term results

PURPOSE

To evaluate the medium-term results of phakic posterior chamber implantable collamer lens implantation to correct moderate and high hyperopia.

METHODS

In this retrospective study, patients were treated for hyperopia with the Visian Implantable Collamer Lens (ICH model V3; STAAR Surgical AG, Nidau, Switzerland). Examined parameters were manifest refraction spherical equivalent, uncorrected distance visual acuity, corrected distance visual acuity, vault, anterior chamber depth, anterior chamber angle width, endothelial cell density, intraocular pressure, patient satisfaction, and complications.

RESULTS

The mean age of 15 patients (28 eyes) was 28 years (range: 18 to 36 years), with a mean follow-up period of 3.6 years (range: 3 to 6 years). The mean manifest refraction spherical equivalent decreased from +6.30 ± 1.42 diopters (D) (range: +4.25 to +8.50 D) preoperatively to -0.37 ± 0.56 D (range: -1.25 to +1.00 D) at 3 years postoperatively. The mean uncorrected distance visual acuity improved from 0.77 ± 0.38 logMAR (range: 0.16 to 1.30 logMAR) to 0.20 ± 0.17 logMAR (range: 0.00 to 0.48 logMAR) at the 3-year follow-up. Postoperatively, 62% of eyes gained one line of corrected distance visual acuity or remained unchanged. The mean vault reduced from 367.1 ± 253.6 μm (range: 70.0 to 1,190.0 μm) at 1 month postoperatively to 283.6 ± 210.0 μm (range: 75.0 to 915.0 μm) at the last follow-up visit (P = .005). The mean preoperative anterior chamber depth and anterior chamber angle width also decreased at the last follow-up visit (P = .037 and < .0001, respectively). The mean endothelial cell loss was 4.91% (P = .089). No serious complications occurred. Thirteen (87%) patients were satisfied with the outcomes and no patient was dissatisfied.

CONCLUSIONS

Implantation of a posterior chamber implantable collamer lens is a safe, effective, predictable, and stable method for the correction of moderate and high hyperopia in highly selected patients. No case of cataract or anterior subcapsular opacities formation was recorded in relation to the decrease of vault over the studied period and low vault in some eyes.

Optical quality of hyperopic and myopic phakic intraocular lenses

AIMS

To assess and compare the optical quality of the myopic and hyperopic implantable collamer lens (ICL) from its wavefront aberrations for different powers and pupil diameters.

SETTINGS AND DESIGN

Prospective study.

MATERIAL AND METHODS

The wavefront aberrations of two myopic (-3 and -6 diopters (D)) and two hyperopic V4b ICLs (+3 and +6D) were measured in vitro. To assess and compare the optical quality of different powers of ICLs, we analyzed the root mean square (RMS) of total higher order aberrations (HOAs), trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration at 3- and 4.5-mm pupil. In addition, the point spread functions (PSFs) of each ICL evaluated were calculated from the wavefront aberrations at 3- and 4.5-mm pupil.

STATISTICAL ANALYSIS

A Student's t-test for unpaired data was used for comparison between myopic and hyperopic ICLs.

RESULTS

Myopic ICLs showed negative spherical aberration, in contrast hyperopic ICLs showed positive spherical aberration, which increases when the ICL power increases, due to the innate optical properties of the lens. All ICLs evaluated had negligible amounts of other aberrations. We did not find statistical significant differences in any Zernike coefficient RMS values analyzed between myopic and hyperopic ICLs at 3- and 4.5-mm pupil (P > 0.05).

CONCLUSIONS

Myopic and hyperopic ICLs provide good and comparable optical quality for low to moderate refractive error. The ICLs evaluated showed values of wavefront aberrations clinically negligible to affect the visual quality after implantation.

Refractive surgery for accommodative esotropia: past, present, and future

INTRODUCTION

Refractive surgery has the potential to be a definitive treatment for accommodative esotropia, yet it has not been widely embraced. This article reviews the current literature on refractive surgery to treat accommodative esotropia.

METHODS

A literature search was performed using the following terms: refractive surgery, photorefractive keratectomy, laser-assisted keratomileusis, intraocular lens, hyperopia, accommodative esotropia, children, pediatric.

RESULTS

Fifteen series of patients treated with refractive surgery for accommodative esotropia were identified and summarized.

CONCLUSIONS

Refractive surgery holds promise for the treatment of accommodative esotropia, although treatment risks are present and additional investigation is needed.

Refractive lens exchange versus phakic intraocular lenses

PURPOSE OF REVIEW

To review the evidential basis of current practice in refractive lens exchange (RLE) vs. phakic intraocular lens (pIOL).

RECENT FINDINGS

Visual outcomes after pIOLs are better than RLE. With RLE, there still remain risks of retinal detachment, cystoid macular oedema, glare, halos and posterior capsule opacification. With pIOLs, risks include pigment dispersion, cataract formation, glaucoma and inflammation. The decision to choose between either is broadly based on age and type of refractive error, and the choice follows thorough evaluation and counselling taking into consideration patient's needs and expectations.

SUMMARY

With advancing technology, newer IOL models for RLE and phakic correction are becoming available. pIOLs provide better visual outcomes for distance correction and currently do not provide near-vision correction possible with RLE.

Implantable collamer posterior chamber intraocular lenses: a review of potential complications

PURPOSE

To review the peer-reviewed literature reporting postoperative complications of the most recent models of Visian Implantable Collamer posterior chamber intraocular lenses (ICL, STAAR Surgical Co).

METHODS

A literature search of the PubMed database was performed to identify all articles related to ICL complications. Articles were obtained and reviewed to identify those that reported complications using the latest ICL designs.

RESULTS

Cataract was the major postoperative complication reported: 136 (5.2%) in 2592 eyes. Of those, 43.4% (n=59) were reported within 1 year, 15.4% (n=21) between 1 and 3 years, and 35.3% (n=48) ≥ 3 years after ICL implantation. Twenty-one (15.4%) cataracts were reported as surgically induced, 46 (33.8%) eyes had poor vault (<200 μm), and cataract surgery was carried out in 27.9% (n=38) of eyes. Early acute intraocular pressure increase was also reported to be relatively frequent, whereas acute pupillary block was less frequent and mostly resolved with additional iridotomies. A total of 42 ICLs were explanted due to cataract and IOP. Reported endothelial cell loss varied from 9.9% at 2 years to 3.7% 4 years postoperatively. This loss was reported to be more pronounced within the first 1 to 2 years, with stability or lower progression after that time.

CONCLUSIONS

The majority of reported complications after ICL implantation are cataract formation. The improvements in lens geometry and more accurate nomograms applied to the selection of the lens to be implanted, in addition to the surgeon's learning curve, might be factors in the decreased occurrence of postoperative complications reported currently.