The correction of myopia by lens implantation into phakic eyes

Monte-Carlo simulation for calculating phakic supplementary lenses based on a thick and thin lens model using anterior segment OCT data

BACKGROUND

Phakic lenses (PIOLs, the most common and only disclosed type being the implantable collamer lens, ICL) are used in patients with large or excessive ametropia in cases where laser refractive surgery is contraindicated. The purpose of this study was to present a strategy based on anterior segment OCT data for calculating the refraction correction (REF) and the change in lateral magnification (ΔM) with ICL implantation.

METHODS

Based on a dataset (N = 3659) containing Casia 2 measurements, we developed a vergence-based calculation scheme to derive the REF and gain or loss in ΔM on implantation of a PIOL having power PIOLP. The calculation concept is based on either a thick or thin lens model for the cornea and the PIOL. In a Monte-Carlo simulation considering, all PIOL steps listed in the US patent 5,913,898, nonlinear regression models for REF and ΔM were defined for each PIOL datapoint.

RESULTS

The calculation shows that simplifying the PIOL to a thin lens could cause some inaccuracies in REF (up to ½ dpt) and ΔM for PIOLs with high positive power. The full range of listed ICL powers (- 17 to 17 dpt) could correct REF in a range from - 17 to 12 dpt with a change in ΔM from 17 to - 25%. The linear regression considering anterior segment biometric data and the PIOLP was not capable of properly characterizing REF and ΔM, whereas the nonlinear model with a quadratic term for the PIOLP showed a good performance for both REF and ΔM prediction.

CONCLUSION

Where PIOL design data are available, the calculation concept should consider the PIOL as thick lens model. For daily use, a nonlinear regression model can properly predict REF and ΔM for the entire range of PIOL steps if a vergence calculation is unavailable.

Cystoid Macular Edema 18 Years after Anterior Chamber Phakic Intraocular Lens Implantation

We report a case of a 54-year-old female patient who underwent PAC-IOL implantation 18 years prior to presentation. The patient had a best corrected visual acuity (BCVA) 20/20 in the right eye (OD) postoperatively with normal eye exam on routine follow-up since then. The patient presented for acute onset decreased visual acuity in the right eye. BCVA was 20/60, and exam showed blunted macular reflex with no evidence of inflammation. Optical coherence tomography (OCT) showed CME. She was started on topical treatment (ketorolac 0.5%) OD four times daily. Three weeks later, the patient had a BCVA of 20/20 OD with a normal macular reflex and an OCT showing the resolution of the CME. To our knowledge, this is the first reported case of a CME 18 years post PAC-IOL implantation. The possible cause of this incidence could be related to subclinical intraocular inflammation. Ophthalmologists should be aware of the possibility of such a latent CME post-PAC-IOL implantation.

Ratio of torus and equivalent power to refractive cylinder and spherical equivalent in phakic lenses - a Monte-Carlo simulation study

BACKGROUND

Spherical and astigmatic powers for phakic intraocular lenses are frequently calculated using fixed ratios of phakic lens refractive power to refractive spherical equivalent, and of phakic lens astigmatism to refractive cylinder. In this study, a Monte-Carlo simulation based on biometric data was used to investigate how variations in biometrics affect these ratios, in order to improve the calculation of implantable lens parameters.

METHODS

A data set of over sixteen thousand biometric measurements including axial length, phakic anterior chamber depth, and corneal equivalent and astigmatic power was used to construct a multidimensional probability density distribution. From this, we determined the axial position of the implanted lens and estimated the refractive spherical equivalent and refractive cylinder. A generic data model resampled the density distributions and interactions between variables, and the implantable lens power was determined using vergence propagation.

RESULTS

50 000 artificial data sets were used to calculate the phakic lens spherical equivalent and astigmatism required for emmetropization, and to determine the corresponding ratios for these two values. The spherical ratio ranged from 1.0640 to 1.3723 and the astigmatic ratio from 1.0501 to 1.4340. Both ratios are unaffected by the corneal spherical / astigmatic powers, or the refractive cylinder, but show strong correlation with the refractive spherical equivalent, mild correlation with the lens axial position, and moderate negative correlation with axial length. As a simplification, these ratios could be modelled using a bi-variable linear regression based on the first two of these factors.

CONCLUSION

Fixed spherical and astigmatic ratios should not be used when selecting high refractive power phakic IOLs as their variation can result in refractive errors of up to ±0.3 D for a 8 D lens. Both ratios can be estimated with clinically acceptable precision using a linear regression based on the refractive spherical equivalent and the axial position.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Reasons for explantation of phakic intraocular lenses and associated perioperative complications: cross-sectional explant registry analysis

Background

We discuss the safety, since their introduction, of phakic intraocular lenses (pIOLs) to correct refractive errors in healthy eyes. We investigated the reasons for pIOL explantation and the associated perioperative complications.

Methods

This retrospective, cross-sectional study included 69 pIOLs, explanted at a single tertiary center between July 2005 and March 2020: 34 angle-supported (G1), 28 iris-fixated (G2) and seven posterior chamber (G3) pIOLs. Case data including the reason for explantation was taken from the patient records. Intra- and postoperative complications were evaluated for an association with the pIOL.

Results

The mean duration in the eye was 10.4 (0.2–28) years. Cataractogenesis and subsequent surgery that required pIOL explantation was the reason in 42% of all cases. In 22%, cataract in combination with endothelial damage prompted explantation, with 26, 18 and 14% for G1, G2 and G3 respectively. The second most common reasons were corneal damage alone in the angle-supported group (26%), IOL subluxation in the iris-fixated group (18%), and photopic disturbance in the posterior chamber group (29%). In 68% of all explantations, the surgical course was unremarkable, while in the remaining cases perioperative complications were associated with the lens in 45.7%.

Conclusion

Overall, the need for cataract surgery was the most common reason for pIOL explantation. Corneal complications were more frequent in the angle-supported pIOLs and their removal was associated with higher rates of complication compared to the other groups.

Safety and visual outcomes following Iris-claw phakic intraocular lens bilensectomy

PURPOSE

To evaluate the visual outcomes, safety, efficacy, and causes of bilensectomy for iris fixated phakic intraocular lenses (pIOLs).

METHODS

This was a two center consecutive retrospective study that included 43 eyes that underwent iris-claw pIOL bilensectomy. Patients with follow up less than 4 months were excluded from the study. Uncorrected, corrected visual acuity (UCVA, CDVA), refractive outcomes, efficacy, safety (number of eyes in which the postoperative CDVA was worse than the preoperative CDVA), endothelial cell density (ECD), causes of bilensectomy, the time between the implantation of the pIOL and bilensectomy, intra and postoperative complications were analyzed.

RESULTS

There was a statistically significant improvement in UCVA and CDVA after surgery (p = 0.001). The efficacy index was 0.7, four eyes had a postoperative CDVA worse than the preoperative CDVA. The mean spherical equivalent 1 year after bilensectomy was -0.78 ± 1.70 D. There was a statistically significant endothelial cell loss after iris claw lens bilensectomy (p = .003). Cataract development and endothelial cell loss were the only reasons for bilensectomy. The mean time between pIOL implantation and bilensectomy was 12.2 ± 5.5 years. One patient had corneal edema 8 months after surgery and one had a retinal detachment 11 months after surgery.

CONCLUSION

Bilensectomy was successful in improving UCVA and CDVA with an acceptable refractive outcome. Significant loss of ECD was found after surgery. The results recommend a larger ACD as selection criteria when choosing to implant an Artisan lens, and a close postoperative monitoring of the endothelial cell count.

The Influence of Decentration on Higher-Order Aberrations in Artisan Aphakic Intraocular Lens Implantation Eyes

Purpose

To characterize the influence of decentration on higher-order aberrations of Artisan aphakic intraocular lens implantation eyes. Setting. Department of Ophthalmology and Vision Science, Eye and ENT Hospital of Fudan University, Shanghai, China.

Design

Retrospective case series.

Methods

Twenty-three eyes of 18 patients were retrospectively examined. Location of the IOL was imaged using a slit-lamp, and decentration (the distance from the center of a pupil to the geometric center of the IOL) was measured using the AutoCAD 2007 software. Ocular and internal higher-order aberrations were measured using the wavefront analyzer KR-1W (Topcon) and their correlation with decentration were analyzed. Coma, spherical, 3rd-, 4th-order, trefoil, tetrafoil aberrations, ocular, and internal higher-order aberrations were calculated for a 4.0 mm pupil diameter.

Results

The mean age of patients was 33.6 ± 21.4 years (ranging from 7 to 72 years). The mean follow-up period was 28.2 ± 10.5 months (ranging from 12 to 52 months). The mean postoperative best-corrected visual acuity (BCVA) was 0.19 ± 0.19 logMAR (range −0.18–0.52). The mean decentration was 0.57 ± 0.28 mm (range 0.15–1.21 mm). There was no correlation between Artisan IOL decentration and ocular higher-order aberrations, internal higher-order aberrations, coma, spherical, 3rd-, 4th-order, trefoil, and tetrafoil aberrations, respectively. There was a positive correlation between Artisan IOL decentration and 2nd-astig aberrations when 2nd-astig aberrations were less than 0.1.

Conclusions

The position of Artisan IOLs showed slight decentration and the amounts of decentration were not large enough to influence higher-order aberrations.

[Methods of out-of-the-bag intraocular lens implantation]

The article reviews the main modern methods of out-of-the-bag IOL implantation. Literature data shows that the most pressing question to date is comparative assessment of retropupillary iris-claw lens implantation and trans-scleral posterior chamber IOL fixation.

Changes in Endothelial Cell Count Up to Three Years After Implantation of Toric Implantable Collamer Lenses

PURPOSE

To determine the temporal effect of toric implantable collamer lens (TICL) implantation and location on corneal endothelial cell density (ECD) over a period of 36 months after surgery.

METHODS

ECD [number of cells per square millimeter estimated using the Specular Microscope SP-1P (Topcon Europe Medical B.V., Netherlands)] data were collected from cases deemed suitable for the TICL (VTICMO, VTICM5; STAAR Surgical, Nidau, Switzerland). The preoperative refractive error (sphere and cylinder) ranged from -1.00 to -22.25 diopter sphere and from -0.50 to -5.50 diopter cylinder. ECD was evaluated at preoperative and all postoperative sessions.

RESULTS

Key findings were as follows: the mean ECD (±SD, 95% confidence interval) was 2720 cells/mm (±272, 2620-2820 cells/mm) preoperatively, which was reduced to 2372 cells/mm (±325, 2250-2490 cells/mm) at 36 months postoperatively (P < 0.001). Linear regression revealed the following significant correlations between the (1) log of the change in ECD (y1) and log of preoperative ECD (x1) at 2 years postoperatively, y1 = 2.513x1-6.2816 (n = 62, r= 0.3503, P = 0.005); (2) mean ECD (y2) and log time (in months, x2), y2= 2543.7-36.997x2-38.99x2 (r=-0.9654, n = 7, P = 0.0004); and (3) mean axial distance between the front surface of the crystalline lens and the TICL back surface (y3) and time postoperatively (in months, x3), y3 = 0.1035x3-5.2808x3 +473.18 (r = 0.8512, n = 7, P = 0.015).

CONCLUSIONS

Expected ECD loss after TICL implantation by 2 years postoperatively is predictable. On average, over 3 years after implantation, there is (1) an initial rapid decline in ECD, followed by a gradual fall in the rate of cell loss, and (2) a gradual fall in the distance between the TICL and the crystalline lens by 2 years postoperatively, followed by a reversal by the third year.

Phacoemulsification in phakic iris-claw lens with cataract

In this new technique of cataract surgery in patients with iris-fixated phakic intraocular lens with cataract, phakic IOL is explanted at the end of surgery. Phakic IOL remains stable and securely enclaved to the iris during phacoemulsification which is performed through a small 2.2 mm incision. Endothelial protection is provided by viscodispersive OVD above the phakic IOL and space for surgery is created by high molecular weight viscocohesive OVD beneath the phakic IOL. This technique provides significant advantages from the previously described techniques in terms of chamber stability, endothelial protection, iris trauma and surgical ease.

Dependency of endothelial cell loss on anterior chamber depth within first 4 years after implantation of iris-supported phakic intraocular lenses to treat high myopia

PURPOSE

To evaluate the effect of the anterior chamber depth (ACD) on the central corneal endothelial cell density (ECD) in eyes after implantation of an iris-fixated phakic intraocular lens (pIOL).

SETTING

Department of Ophthalmology, Goethe-University, Frankfurt, Germany.

DESIGN

Retrospective nonrandomized case series.

METHODS

An Artisan pIOL was implanted in eyes of highly myopic patients. Follow-up examinations at 1, 12, 24, 36, and 48 months included evaluation of ECD and adverse events. Three cohorts based on the ACD were established and their ECDs compared. All eyes had 1-year and 4-year postoperative ECD measurements available. Statistical analysis included linear regression analysis to evaluate the influence of ACD on ECD.

RESULTS

The study comprised 95 eyes (52 patients). Four years after surgery the mean spherical equivalent changed from -11.06 diopters (D) ± 4.77 (SD) to -0.42 ± 0.47 D. Severe adverse events were not detected. There was a significantly higher ECD loss after 4 years in patients with an ACD of less than 3.00 mm than in those with an ACD greater than 3.40 mm (-224 cells/mm²) (P < .01). There was no significant difference in ECD between eyes with an ACD of 3.00 to 3.39 mm and eyes with an ACD less than 3.00 mm (P = .23) or more than 3.40 mm (P = .08).

CONCLUSIONS

The iris-claw pIOL precisely and safely corrected high myopia. However, the loss in ECD can be considerable. Establishing stricter exclusion criteria for ACD might reduce this loss.

FINANCIAL DISCLOSURE

Proprietary or commercial disclosures are listed after the references.

Visual acuity, endothelial cell density and polymegathism after iris-fixated lens implantation

PURPOSE

The purpose of this study was to evaluate the visual acuity as well as endothelial cell density (ECD) and polymegathism after iris-fixated lens (Artiflex® AC 401) implantation for correction of moderate to high myopia.

PATIENTS AND METHODS

In this retrospective cross-sectional study, 55 eyes from 29 patients undergoing iris-fixated lens implantation for correction of myopia (-5.00 to -15.00 D) from 2007 to 2014 were evaluated. Uncorrected visual acuity, best spectacle-corrected visual acuity, refraction, ECD and polymegathism (coefficient of variation [CV] in the sizes of endothelial cells) were measured preoperatively and 6 months postoperatively.

RESULTS

In the sixth month of follow-up, the uncorrected vision acuity was 20/25 or better in 81.5% of the eyes. The best-corrected visual acuity was 20/30 or better in 96.3% of the eyes, and more than 92% of the eyes had a refraction score of ±1 D from the target refraction. The mean corneal ECD of patients before surgery was 2,803±339 cells/mm2, which changed to 2,744±369 cells/mm2 six months after surgery (p=0.142). CV in the sizes of endothelial cells before the surgery was 25.7%±7.1% and six months after surgery it was 25.9%±5.4% (p=0.857).

CONCLUSION

Artiflex iris-fixated lens implantation is a suitable and predictable method for correction of moderate to high myopia. There was no statistically significant change in ECD and polymegathism (CV in the sizes of endothelial cells) after 6 months of follow-up.

An angle-supported foldable phakic intraocular lens for correction of myopia: A five-year follow-up

OBJECTIVE

To evaluate the efficacy and safety of an angle-supported foldable phakic intraocular lens (pIOL) for the correction of moderate to high myopia after 5 years follow-up.

METHODS

Prospective and retrospective, observational, longitudinal, non-randomised consecutive series of cases conducted on a total of 100 eyes of 67 patients with moderate to high myopia implanted with an Acrysof Cachet pIOL (Alcon Laboratories Inc.) with the aim of minimising the refractive error. The ages ranged between 18 to 60years. Uncorrected distance visual acuity (UDVA), manifest refraction, corrected distance visual acuity (CDVA), endothelial cells density, pIOL position, intraocular pressure, and complications were recorded preoperatively and during the 5 year follow-up.

RESULTS

Five years after implantation, the mean manifest spherical equivalent refraction reduced significantly from -11.62±3.35 dioptres (D) to -0.33±0.85D. UDVA was 20/20 or better in 5 of 25 cases (20%), and 20/40 or better in 22 cases (88%). CDVA was 20/20 or better in 17 cases (68%), and 20/32 or better in 23 cases (92%) of eyes. The residual refractive error was within ±0.50D of emmetropia in 12 cases (48%), and within ±1.00D in 19 cases (76%). Mean endothelial cell loss at 5 years was 11.8% central, and 13.7% peripheral. Mean endothelium-pIOL distance was 2.11±0.18mm, and mean pIOL-crystalline distance was 0.88±0.20mm.

CONCLUSIONS

This angle supported pIOL provided a favourable refractive correction and predictability, as well as acceptable safety in patients with moderate to high myopia. Although endothelial cell density decreased over 5years, the results are within the range reported in previous studies with other pIOLs.

Asymptomatic haptic migration of phakic anterior chamber intraocular lens through the peripheral iridectomy

OBJECTIVE

Case series of haptic migration in patients with angle-supported phakic anterior chamber intraocular lens (PAC-IOL: Phakic6H) through the superior peripheral iridectomy (PI).

METHODS

Charts of 23 patients (35 eyes) with at least 6 months' postoperative follow-up were retrospectively reviewed. Evaluation included preoperative and postoperative cycloplegic and manifest refractions, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), slit-lamp examination, fundoscopy, corneal topography, and biometry.

RESULTS

Mean UCVA was 1.67 ± 0.30 (1.17-2.00) for all 35 eyes preoperatively and 0.35 ± 0.25 (0.00-1.00) postoperatively (p < 0.001; 95% CI 1.21-1.44). BCVA had a mean of 0.31 ± 0.26 for all 35 eyes preoperatively, and a mean of 0.22 ± 0.25 postoperatively (p < 0.001; 95% CI 0.04-0.14). Haptic migration into the superior PI was noted in 8 eyes (23%). The first migration was noted 2 years postoperatively and the last 8 years after implantation (mean, 5.6 ± 2 years). There was no statistically significant difference in the BCVA and UCVA before and after haptic migration. Follow-up ranged from 8 months to 8.5 years.

CONCLUSIONS

Angle-supported PAC-IOL implantation resulted in significant improvement in both UCVA and BCVA. However, there is a 23% incidence of haptic migration in our series with no sequelae on BCVA or harmful effect on the intraocular structures. This IOL movement may be explained by changes in aqueous dynamics at the level of the PI leading to migration of the haptic into the area of least resistance.

Endothelial distance after phakic iris-fixated intraocular lens implantation: a new safety reference

Purpose

To evaluate the distance between the endothelial surface of the cornea to the anterior edge of an Artiflex® phakic intraocular lens (IOL) implant to improve the safety profile of this implant.

Methods

This is a retrospective clinical case series of 45 patients who had Artiflex phakic IOL implantation (Artiflex p-IOL) with a follow-up period of 3 years. A Pentacam HR imaging system was used to measure the distance from various points of the anterior edge of the Artiflex IOL to the endothelial surface of the cornea, which we called endothelial–IOL (E–IOL) distance, in 45 eyes. The E–IOL distances were assessed at 1, 3, 6, 12, 24, and 36 months. Corresponding correlations of central endothelial distance to temporal and nasal edges and center of the IOL anterior surface were tabulated.

Results

Mean follow-up was 21.39±11.28 months. A statistically significant reduction of the E–IOL distance was observed over the follow-up period (P<0.05), with the mean annual reduction being 24.70 μm. A strong positive correlation between the E–IOL distance of the edges of the IOL and the central distance was observed (correlation coefficients nasal/central: month 1, 0.905; month 36, 0.806; temporal/central: month 1, 0.906; month 36, 0.806; P<0.001). Moderate negative correlations were found between the spherical equivalent power of the implanted IOL and the E–IOL distance (correlation coefficients −0.271 to −0.412, P>0.05). For an E–IOL distance of the IOL edge >1500 μm, the distance from the endothelium to the central point of the p-IOL optic should be a minimum of 1,700 μm to improve the safety profile for Artiflex p-IOL implantation and reduce the potential complication of accelerated endothelial cell loss.

Conclusion

After Artiflex IOL implantation, the mean annual reduction of the E–IOL distance was 25 μm. A negative correlation existed between the spherical equivalent power of the implanted IOL and the postoperative E–IOL distance. The minimum E–IOL distance from the center of the IOL to minimize the risk of endothelial cell loss was 1.7 mm. This distance, as is the 1.5 mm initially proposed by Baikoff, is a postoperative value. We cannot make that assumption for the preoperative evaluation, as the morphometry of the anterior chamber changes with the implant.

Posterior chamber phakic intraocular lens to correct myopia: long-term follow-up

PURPOSE

To evaluate the long-term safety and efficacy of a refractive phakic intraocular lens (pIOL) (PRL) to correct moderate to high myopia.

SETTING

Department of Ophthalmology, University Medicine Charité Berlin, Berlin, Germany.

DESIGN

Retrospective cohort study.

METHODS

Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, intraocular pressure, endothelial cell loss, and adverse events were evaluated.

RESULTS

The study enrolled 53 eyes (mean spherical equivalent [SE] -12.17 diopters [D] ± 4.12 [SD]) of 29 patients. The mean age was 34.6 ± 9.2 years and the mean follow-up, 86 ± 21.2 months. The mean UDVA improved from 1.37 ± 0.28 logMAR preoperatively to 0.14 ± 0.19 logMAR at the last postoperative visit (P<.05). The mean CDVA improved from 0.10 ± 0.18 logMAR to -0.01 ± 0.09 logMAR (P<.05). The overall mean efficacy index and mean safety index were 0.9 and 1.21, respectively, at the last follow-up visit. The mean endothelial cell loss at the last follow-up was 6.4%. The complications were slight posterior chamber (PC) pIOL decentration (5 eyes, 9.4%), severe PC pIOL decentration resulting in pIOL removal (1 eye, 1.8%), glaucoma (4 eyes, 7.5%), clinically significant cortical lens opacification resulting in cataract surgery (4 eyes, 7.5%), clinically asymptomatic anterior subcapsular cataract formation (6 eyes, 11.3%), and retinal detachment (2 eyes, 3.8%).

CONCLUSIONS

Posterior chamber phakic pIOL implantation to correct moderate to high myopia provided predictable and stable refractive results but with a high rate of serious complications over the long term.

FINANCIAL DISCLOSURE

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

Visual and aberrometric outcomes in eyes with an angle-supported phakic intraocular lens

PURPOSE

To evaluate the postoperative changes in spherical aberration and the point-spread function (PSF) induced by the implantation of a new angle-supported phakic intraocular lens (pIOL).

SETTING

Department of Ophthalmology, St. Bassiano Hospital, Bassano del Grappa, Italy.

DESIGN

Prospective nonrandomized cohort study.

METHODS

Eyes with high myopia had implantation of an Acrysof Cachet angle-supported pIOL. Preoperative and postoperative total spherical aberration and PSF were measured using a Luneau 80 Wave+ wavefront aberrometer (high-resolution Hartmann-Shack technology) at a fixed entrance pupil scan size of 5.0 mm under pharmacologic mydriasis. Preoperative and postoperative data were analyzed and compared using the Student t test.

RESULTS

Thirty-five eyes of 18 patients were included in the statistical analysis. The Student t test for paired data (95% confidence interval) showed a statistically significant difference between preoperative data and postoperative data. The mean preoperative total spherical aberration Z(4,0) was -0.001 μm ± 0.076 (SD) preoperatively and -0.13 ± 0.11 μm postoperatively (P≤.05). The mean PSF was 0.28 ± 0.15 preoperatively and 0.34 ± 0.16 postoperatively (P<.05).

CONCLUSION

Implantation of the angle-supported pIOL in eyes with high myopia improved the quality of vision, inducing negative spherical aberration and increasing the PSF under mesopic conditions.

The effect of iris-fixated foldable phakic intraocular lenses on retinal straylight

PURPOSE

To determine changes in straylight after iris-fixated phakic intraocular lens implantation (pIOL) and to investigate the relationship between straylight and several preoperative and postoperative variables.

DESIGN

Institutional, prospective cross-sectional study.

METHODS

Artiflex (Ophtec B.V.) pIOL implantation was performed in 61 eyes (36 patients). Straylight values were measured before surgery and 3 months after surgery using the Oculus C-Quant (Oculus Optikgeräte). Furthermore, correlations were analyzed between straylight and the following parameters: keratometry, axial length, spherical equivalent, astigmatism, pIOL power, best spectacle-corrected visual acuity, and pupil size.

RESULTS

Mean straylight decreased from 1.18 ± 0.17 log units before surgery to 1.13 ± 0.17 after surgery (P = .016). Higher preoperative straylight values were associated with larger postoperative decreases in straylight (r = -0.534; P < .001). Higher postoperative straylight values were correlated to higher axial length (r = 0.444; P = .001) and lower keratometry values in diopters (r = -0.414; P = .001). After regression analysis, only axial length was found to be an independent predictor of preoperative and postoperative straylight (P < .001 and P = .001, respectively). After correcting for the axial length of an emmetropic eye (23.44 mm), all straylight correlations disappeared, indicating that an increase in distance from cornea to retina explains the increase in straylight values in longer eyes.

CONCLUSIONS

Retinal straylight was reduced significantly after Artiflex pIOL implantation. Besides age, axial length was the only predictor of preoperative and postoperative straylight values. The increased tissue length light has to pass from cornea to retina, might explain the increase in straylight values in longer eyes.

Hypermotility of an iris-fixated anterior chamber phakic intraocular lens due to nontraumatic iris laxity

PURPOSE

Permanent immovability of phakic intraocular lenses (pIOLs) for the correction of high myopia is crucial in avoiding injury to the corneal endothelium and maintaining visual acuity. Unstable position of iris-fixated pIOLs due to traumatic or nontraumatic disenclavation of the haptic has been described previously.

METHODS AND RESULTS

We report a different mechanism of repeated excessive implant motility in both eyes of a young woman who developed late nontraumatic elongation of the iris fibers to which an iris-claw pIOL was fixated. This led to increased motility of the pIOLs with blinking causing mild iritis. Subsequent bilateral successful re-enclavation to other iris fibers ameliorated these symptoms. After 2.5 years, these iris fibers, too, were elongated, causing excessive movements of the pIOLs and consecutive endothelial cell loss necessitating removal of the pIOLs. The etiology of this iris fiber laxity remains unclear.

CONCLUSIONS

Surgeons should be aware of this rare potential complication.

Risk factor evaluation for cataract development in patients with low vaulting after phakic intraocular lens implantation

PURPOSE

To evaluate the occurrence of cataract in eyes with low vaulting after phakic intraocular lens (pIOL) implantation for myopia and suggest guidelines for such cases.

SETTING

Samsung Medical Center, Seoul, Korea.

DESIGN

Cross-sectional study.

METHODS

Eyes with low Implantable Collamer Lens pIOL vaulting (<250 μm) were followed 1, 3, and 6 months as well as 1, 2, 3, and 4 years postoperatively. Frequency and time to cataract development were evaluated. Risk factors for cataract development were assessed using logistic regression analysis. Cutoff values for differentiating eyes at higher risk for cataract development were evaluated using Fisher exact and chi-square tests.

RESULTS

Cataract developed in 8 (30.8%) of 26 eyes (6 of 20 patients) a mean of 18.7 months ± 10.1 (SD) postoperatively. Risk factors that were significant for cataract formation included lower vaulting (mean 42.4 ± 34.0 μm versus 141.4 ± 82.2 μm; odds ratio [OR], 1.05), older age (mean 42.6 ± 7.3 versus 34.9 ± 6.9 years; OR, 1.22), and higher preoperative spherical equivalent (SE) (mean -17.1 ± 4.4 diopters [D] versus -10.7 ± 2.7 D; OR, 1.64). The optimum cutoff values were 51.7 μm, 45 years, and -14.00 D (P=.0095, P=.0367, and P=.0342 respectively).

CONCLUSION

In cases of low pIOL vaulting, close follow-up should be considered when central vaulting is less than 52 μm, patient age is more than 45 years, or the preoperative SE is greater than -14.00 D because these factors increase the risk for cataract.

Late onset secondary cataract following implantation of an iris-fixated phakic intraocular lens

PURPOSE

To report a case of bilateral late onset anterior cortical cataract following implantation of an iris-fixated phakic intraocular lens (pIOL).

METHODS

Single observational case report.

RESULTS

Three and a half years following uncomplicated consecutive implantation of iris-fixated pIOL in both eyes, anterior cortical cataract changes inferiorly emanating from the site of enclavation of the lens in the right eye were noted. By 7 years after implantation, anterior cortical cataract changes were seen emanating from the enclavation sites superiorly and inferiorly in both eyes. These cataracts did not cause any loss of corrected distance visual acuity.

CONCLUSIONS

This case demonstrates that a potential complication of an iris-fixated pIOL is late onset secondary cataract formation.

Late-onset nontraumatic dislocation of anterior chamber phakic intraocular lens

Long-term stability of the position of phakic intraocular lenses (pIOLs) is important in maintaining visual acuity as well as avoiding injury to the local tissues. We report a case of late nontraumatic dislocation of an iris-fixated pIOL, with subsequent successful repositioning.

Secondary iris claw intraocular lens implantation for the correction of aphakia after pars plana vitrectomy

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of iris claw intraocular lens implantation for correction of aphakia in vitrectomized eyes without capsular support.

METHODS

This was a prospective interventional case series. Twelve aphakic vitrectomized eyes without capsular support underwent iris claw intraocular lens implantation. The main outcome measures were changes in uncorrected visual acuity, best-corrected visual acuity, spheric equivalent, corneal endothelial cell density, corneal thickness, central macular thickness, and complications.

RESULTS

Mean follow-up was 15.58 +/- 3.80 months with no intraoperative complications. Postoperatively, uncorrected visual acuity increased significantly at all follow-up visits (P < 0.05). Mean best-corrected visual acuity increased 10 letters/2 lines at the final follow-up visit (P = 0.023). Mean postoperative spheric equivalent at the last visit was -1.68 +/- 063 D, and the spheric equivalent was within +/-2.00 D of emmetropia in 9 (75%) eyes. Mean central macular thickness increased only at postoperative Month 3 (P = 0.043). Mean endothelial cell density loss was 23.87% at the last visit. Mean corneal thickness did not change during follow-up (P > 0.05). No corneal edema was observed. Complications were transient intraocular pressure increase (n = 1), cystoid macular edema (n = 1), and haptic dislocation replaced by surgery (n = 1). Retinas remained attached in all eyes.

CONCLUSION

Secondary iris claw intraocular lens implantation is clinically safe and effective to correct aphakia in vitrectomized eyes without capsular support. Larger studies with longer follow-up are warranted.

[Iris-fixated intraocular lenses: reinforced monitoring]

In 1986, the concept of the claw lens was applied to correct myopia in phakic patients. Since then, progress has made iris-fixated phakic intraocular lenses (IOL) relatively safe, predictable, and effective for the correction of myopia, hyperopia, and astigmatism. All these models have undergone a series of design improvements to prevent complications. Despite having excellent refractive results, the principal risk is a potential progressive endothelial cell loss. Many authors have presented encouraging results. Phakic iris-fixated IOL surgery is a potentially reversible procedure, but the surgeon cannot rule out the possibility of complications. Therefore, long-term follow-up is mandatory.

Influence of anterior chamber morphometrics on endothelial cell changes after phakic intraocular lens implantation

PURPOSE

To analyze the position of iris-fixated phakic intraocular lenses (pIOLs) using anterior segment optical coherence tomography (AS-OCT) and evaluate the effect of anterior chamber morphometrics on endothelial cell changes.

SETTING

Department of Ophthalmology, Academic Hospital Maastricht, The Netherlands.

METHODS

In this cross-sectional study, AS-OCT was used to measure the distances from the center and the edges of the pIOL to the corneal endothelium in 242 eyes with various models of myopic pIOLs. Endothelial cell measurements were performed preoperatively and at each follow-up examination.

RESULTS

The mean follow-up was 34.1 months+/-24.7 (SD) (range 3 months to 7 years). The mean distance between the edge of the pIOL and the endothelium was 1.37+/-0.22 mm. Although this distance was smaller than the safety value of 1.50 mm in 68.6% of the eyes, no eye developed corneal decompensation. There was a significant endothelial cell density (ECD) loss of 1.28%+/-8.46%, 3.25%+/-8.24%, and 5.02%+/-10.40% at 2 years, 5 years, and 7 years, respectively. Linear mixed-model analysis predicted a yearly ECD loss of 0.98% for a mean edge distance of 1.37 mm, 0.15% for an edge distance of 1.59 mm (mean plus 1 SD), and 1.80% for an edge distance of 1.15 mm (mean minus 1 SD).

CONCLUSIONS

A shorter distance between the edge of the pIOL and the endothelium was significantly associated with higher ECD loss. For safety reasons, the postoperative examination should include long-term evaluation of the anterior chamber morphometrics in addition to ECD counts.

Phakic intraocular lens correction of high ametropia in children with neurobehavioral disorders

PURPOSE

A subset of children with high ametropia and neurobehavioral disorders have chronic difficulties with spectacle or contact lens wear. We report the results of refractive surgery in a series of these children treated using bilateral or unilateral phakic intraocular lenses (IOLs) for ametropia >10 D.

METHODS

Clinical course and outcome data were collated prospectively in a group of 12 children (mean age, 10.1 years; range, 4-17 years) with neurobehavioral disorders exacerbated by poor compliance with spectacles. Myopia in 18 eyes ranged from -10.0 to -22.75 D (mean, -15.2 D) and in 2 hyperopic eyes from +10.25 to +10.75 (mean, +10.5 D). Goal refraction was approximately 0 to +1 D. Correction was achieved by implantation of an iris-enclaved phakic IOL under general anesthesia. Mean follow-up was 9.1 months (range, 3-15 months).

RESULTS

Myopia correction averaged 14.5 D and hyperopia correction 9.4 D. Eighty-six percent of eyes (17/20 eyes) were corrected to within +/- 1 D of emmetropia and the remaining 14% (3 eyes) to within +/- 2 D. Uncorrected visual acuity improved substantially in all 20 eyes (60-fold; from a mean of 20/3400 to a mean of 20/57). Ocular comorbidities in each child accounted for residual postoperative, subnormal visual acuity (eg, amblyopia, nystagmus, albinism, regressed retinopathy of prematurity). Visual functions (measured using a 23-item validated survey) improved. One eye required IOL exchange; no other clinically significant complications have been encountered.

CONCLUSIONS

Phakic IOL implantation improves visual function substantially in neurobehaviorally impaired children who have high ametropia and difficulties wearing glasses.

Position of rigid and foldable iris-fixated myopic phakic intraocular lenses evaluated by Scheimpflug photography

PURPOSE

To evaluate the postoperative intraocular positional stability of 1 rigid poly(methyl methacrylate) (PMMA) phakic intraocular lens (pIOL) model and 2 foldable polysilicone-PMMA iris-fixated pIOL models.

SETTING

Department of Ophthalmology, Johann Wolfgang Goethe-University Frankfurt am Main, Germany.

METHODS

One of 3 iris-fixated pIOL models (Artisan, Artiflex I, and Artiflex II, Ophtec BV) was implanted in 45 eyes of 26 patients with myopia or myopic astigmatism. The central distance between the pIOL and corneal endothelium and between the pIOL and anterior surface of the crystalline lens was evaluated using Scheimpflug photography 6 and 12 months after surgery.

RESULTS

The mean preoperative spherical equivalent was -9.32 diopters +/- 1.78 (SD) (range -6.5 to -13.5 D). Each IOL model was implanted in 15 eyes. The median distance from the central corneal endothelium to the anterior surface of the pIOL at 6 months and 12 months was 2.65 mm and 2.64 mm, respectively, in the Artisan group, 2.47 mm and 2.50 mm, respectively, in the Artiflex I group, and 2.48 mm and 2.52 mm, respectively, in the Artiflex II group. The median distance between the posterior surface of the pIOL and the anterior surface of the crystalline lens at 6 months and 12 months was 0.40 mm and 0.48 mm, respectively, in the Artisan group, 0.53 mm and 0.55 mm, respectively, in the Artiflex I group, and 0.68 mm and 0.66 mm, respectively, in the Artiflex II group. At 12 months, the distance between the pIOL and crystalline lens was statistically significantly greater in the Artiflex II group than in the Artisan group (P<.01).

CONCLUSION

The intraocular position of rigid pIOLs and foldable silicone iris-supported pIOLs showed a difference between the 3 pIOL models in space to the crystalline lens and the corneal endothelium, which may affect long-term results in terms of IOL interaction with surrounding tissue.

Posterior iris fixation of the iris-claw intraocular lens implantation through a scleral tunnel incision

PURPOSE

To evaluate the technique, efficacy, and safety of posterior iris fixation of iris-claw intraocular lens (IOLs) implantation through a scleral tunnel incision for aphakia correction.

DESIGN

Noncomparative, interventional case series.

METHODS

A secondary posterior iris fixation of the Artisan iris-claw IOL (Ophthec BV, Groningen, The Netherlands) was implanted for aphakia correction in the authors' clinical practice. Uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), astigmatism, manifest refraction, lens position, pigment dispersion, and intraocular pressure (IOP) were evaluated in 32 consecutive eyes of 32 patients.

RESULTS

BSCVA was 20/40 or better in 28 eyes (87.50%) during the mean follow-up time (nine months). Mean postoperative spherical equivalent was -0.70 diopters (D; standard deviation [SD], 0.47 D) at six months after surgery. Mean prediction error was -0.13 D (SD, 0.28 D), and mean absolute prediction error was 0.26 D (SD, 0.15 D). Preoperative mean astigmatism was -1.08 D (SD, 0.55 D; range, 0.0 to -2.0 D). At six months after surgery, mean astigmatism was -2.1 D (SD, 0.81 D; range, -0.75 to -3.75 D). There was no significant postoperative IOP increase. Lens position, evaluated by Oculus Pentacam (Pentacam 70700: Oculus, Wetzlar, Germany) and ultrasound biomicroscopy [UBM] (Ophthalmic Technologies Inc, Toronto, Ontario, Canada), was parallel to the iris plane.

CONCLUSIONS

Posterior iris fixation of the iris-claw IOL implantation through a scleral tunnel incision is a safe procedure and an effective option for aphakic eyes without capsule support.

Long-term endothelial changes in phakic eyes after Artisan intraocular lens implantation to correct myopia: five-year study

PURPOSE

To evaluate long-term endothelial cell changes in eyes that had implantation of an iris-fixated phakic Artisan intraocular lens (IOL) for moderate to high myopia.

SETTING

Casa di Cura Villa Igea, Ancona, Italy.

METHODS

Forty-nine eyes of 30 patients having implantation of Artisan IOL for moderate to high myopia were prospectively examined. Preoperative specular microscopy and serial postoperative specular microscopy (Noncon Robo SP 8000, Konan Medical) were performed to evaluate endothelial cell changes over 5 years. Endothelial cell images were collected in the central region of the cornea before surgery and 4, 12, 24, 36, 48, and 60 months after surgery. The endothelial cell density (ECD), coefficient of variation, and percentage of hexagonal cells were determined.

RESULTS

Preoperatively, the mean ECD was 2616 cells/mm(2) +/- 347 (SD), the mean coefficient of variation was 39.6% +/- 4.7%, and the mean percentage of hexagonal cells was 49.2% +/- 6.7%. The mean endothelial cell loss from preoperatively was 2.3% at 4 months, 3.5% at 12 months, 4.7% at 24 months, 6.7% at 3 years, 8.3% at 4 years, and 9.0% at 5 years. Five years after surgery, the mean coefficient of variation was 35.9% +/- 6.9% (P = .1946) and the percentage of hexagonal cells was significantly higher (mean 54.7% +/- 10.3%) (P = .087).

CONCLUSIONS

Continuous endothelial cell loss was observed after surgery during a 5-year follow-up, especially during the first 2 years. A decrease in the coefficient of variation and an increase in the percentage of hexagonal cells were observed over time, reflecting the increasing stability and remodeling of the corneal endothelial cells 5 years postoperatively.

Implantation of Artisan toric phakic intraocular lens following Intacs in a patient with keratoconus

We report a 24-year-old man with bilateral keratoconus in whom Intacs (Addition Technology, Inc.) were implanted in both eyes. The procedure was followed by Artisan toric phakic intraocular lens (Ophtec) implantation to correct the residual myopic and astigmatic refractive error.

Outcomes of ZB5M Angle-supported Anterior Chamber Phakic Intraocular Lenses at 12 Years

PURPOSE

To evaluate the visual and refractive stability and the potential long-term risks associated with ZB5M phakic intraocular lens (PIOL) implantation.

METHODS

A retrospective, non-randomized, cumulative clinical study was performed over 12 years in a consecutive group of 225 eyes implanted with the ZB5M PIOL. The main analyzed variables were visual and refractive outcomes (best spectacle-corrected visual acuity [BSCVA], uncorrected visual acuity [UCVA], and spherical equivalent), endothelial cell density, and postoperative complications.

RESULTS

Mean preoperative spherical equivalent refraction was -17.23 +/- 7.69 diopters (D) and 12 years postoperatively it was -1.80 +/- 0.80 D. Mean BSCVA at 1- and 12-year follow-up was 0.38 +/- 0.19 and 0.57 +/- 0.18, respectively (Wilcoxon test, P < .001). At 12 years postoperatively, 3.5% of eyes lost > or = 2 lines of BSCVA. An initial 10.6% reduction in endothelial cell density was noted in the first year, followed by a mean annual rate of decrease of 1.78%. The cumulative incidence of pupil ovalization was 34.7% (78 eyes), and there was no statistical correlation with endothelial cell impairment. Bilateral hypertensive uveitis was diagnosed in 3 (1.33%) eyes.

CONCLUSIONS

The ZB5M PIOL offers good refractive outcomes and stability in the long-term; however, endothelial cell loss increases over 12 years, requiring annual endothelial cell counts.

Surgical Correction of Hyperopia

Surgical attempts to correct hyperopia have yielded varying results over the last 130 years. These techniques include the reshaping of the cornea through incisions, burns, or lamellar cuts with removal of peripheral tissue; the addition of central inlays; laser ablations; and the replacement of the crystalline lens. By examining the success of each surgical technique, the refractive surgeon may be able to make an informed decision on its indications and limitations, based on the specific patient's characteristics. Reporting the outcomes and complications of hyperopic surgery will help refine our approach to the management of an increasingly hyperopic and presbyopic population.