Optical evaluation of new-design multifocal IOLs with extended depth of focus.

In this study, we investigate in vitro the optical performance of new-design extended depth of focus (EDOF) complementary intraocular lenses (IOLs) (ACTIVE, Cristalens Industrie, France), compared with traditional bifocal ones. Evaluation of their optical quality was achieved by measuring the point spread function at multiple distances (through focus) using an optical bench. In addition, the modulation transfer function through focus was calculated, correlating our results with actual visual outcomes. Our results may suggest that these new EDOF IOLs, when implanted together, could possibly better control multifocality, offering an increased DOF at all distances.

The absorption characteristics of the human cornea in ultraviolet-a crosslinking.

OBJECTIVES: With respect to the safety of ultraviolet-A (UVA) crosslinking for the corneal endothelium, an absorption coefficient is used that has been calculated in riboflavin soaked porcine corneas. We aim to validate this value for clinical use by measuring the absorption coefficient for UVA 365 nm in postmortem human corneas after instilling riboflavin on the corneal surface. METHODS: Corneal thickness was measured in nine pairs of human donor eyes of which one eye was subjected to manual removal of the epithelium, whereas the epithelium of the fellow eye was left intact. Both eyes were instilled with riboflavin 0.1% in dextran 20% on the intact globe. After 20 min, the corneas were rinsed, and a corneoscleral button was trephined. The transmission of the cornea for UVA 365 nm was measured by transillumination, which allows calculation of the absorption coefficient. RESULTS: Measurement of average corneal thickness was 658.5 +/- 51.5 microm when the epithelium was removed, and 758.3 +/- 98.8 microm without epithelial removal. The average transmittance for UVA 365 nm was 12.89 +/- 4.10% with epithelial debridement and 28.52 +/- 4.39% without (P<0.05). The resultant average absorption coefficient is 32 +/- 5 cm when the epithelium is removed and 17 +/- 2 cm when it is left intact (P<0.05). CONCLUSIONS: Our results show an absorption coefficient for human corneas that is much lower than the values reported in the literature. This finding may be relevant when considering endothelial safety of the clinical crosslinking treatment.

Keratitis and corneal scarring after UVA/riboflavin cross-linking for keratoconus.

PURPOSE: To report four cases of severe keratitis after standard corneal collagen cross-linking (CXL) treatment for keratoconus. METHODS: Four patients with progressive keratoconus from two different centers were treated by ultraviolet A (UVA) CXL, using riboflavin as a photosensitizer. The epithelium was removed over the central 8 to 9 mm of the cornea. Riboflavin 0.1% in dextran 20% was instilled every 2 minutes for 30 minutes before UVA exposure. The UV-X light source (IROC), calibrated at 3 mW/cm(2), was applied for 30 minutes while instillation was continued every 2 minutes. At the end of the treatment, a bandage contact lens was applied and topical treatment consisting of a combination of antibiotics and/or anti-inflammatory drops was initiated. RESULTS: Patients experienced delayed (after more than 24 hours) symptoms and signs of inflammation. The eyes showed pronounced ciliary redness with cells in the anterior chamber and central keratic precipitates; multiple white infiltrates had developed at the edge and within the area of CXL. High-dose topical or subconjunctival corticosteroids led to rapid initial improvement of symptoms and signs. Herpes virus could not be detected on the ocular surface or on the anterior chamber tap of one patient. CONCLUSIONS: We report four cases of keratitis and corneal scarring from a total of 117 eyes treated with CXL. The location of the scarring determined the amount of loss of visual acuity: in two eyes, there was a persistent decrease in best spectacle-corrected visual acuity.

Predicting refractive aniseikonia after cataract surgery in anisometropia.

PURPOSE: To propose a comprehensive classification of anisometropia, a method to calculate the theoretical related aniseikonia (objective aniseikonia) and a purpose-designed eikonometer to measure aniseikonia psychophysically (subjective aniseikonia). SETTING: University Hospital Antwerp, Department of Ophthalmology, Edegem, Belgium. METHODS: The occurrence of anisometropia was evaluated in 263 patients scheduled for cataract surgery. Subjective aniseikonia was evaluated in 77 healthy patients. The theoretical model was validated to calculate objective aniseikonia by implementing data from the literature. Ultimately, an aniseikogram was developed and its practical use illustrated by 4 clinical cases of anisometropia. RESULTS: In a population of 263 patients, the total incidence of anisometropia was 7.6%, with a dominance of axial anisometropia. Subjective aniseikonia between 2% and 4% was found in 3.0% to 7.5% of the cases, depending on the refractive error. The correlation coefficient between objective and subjective aniseikonia was good (R(2) = 0.82). Analysis of 4 clinical cases illustrated the calculated preoperative and postoperative aniseikonia in 4 types of anisometropia planned for lens removal. CONCLUSIONS: Anisometropia is not a rare condition and should be assessed before cataract surgery. A comprehensive method to calculate the objective aniseikonia and to measure the subjective aniseikonia in anisometropia was proposed. If cataract surgery is considered in anisometropic patients, a postoperative aniseikonia of 4% or more may be induced in the case of emmetropization. A method to calculate the intraocular lens power resulting in an acceptable postoperative aniseikonia, especially in axial anisometropic patients, is also proposed.

Bag-in-the-lens: first pathological analysis of a human eye obtained postmortem.

We analyzed an enucleated eye obtained postmortem from an 86-year-old donor who had been implanted with a hydrophilic acrylic bag-in-the-lens 4 months earlier. To our knowledge, this is the first donor eye implanted with this design to undergo pathological analysis. High-frequency ultrasound showed a well-centered IOL, fixated at the level of the capsular bag. Gross and light microscopic analyses of the eye showed that if anterior and posterior capsule openings are well stretched around the optic of this IOL design, proliferative/regenerative material is potentially confined to the intercapsular space of the capsular bag remnant outside the optic rim.

Intacs to stabilize diurnal variation in refraction after radial keratotomy.

We present a patient who was dissatisfied with the refractive results of the radial keratotomy procedure he had 8 years previously, specifically the instability of the visual acuity and refractive error throughout the day. To reverse the biomechanical disturbance caused by the incisions, an intracorneal ring segment (Intacs, Addition Technology, Inc.) was inserted in the inferior cornea. The variation in refraction decreased from 1.50 and 2.25 diopters (D) to 0.25 and 0.50 D, resulting in a very satisfied patient.

Intraocular lens centration and visual outcomes after bag-in-the-lens implantation.

PURPOSE: To examine the centration and visual outcomes after cataract surgery using the bag-in-the-lens (BIL) implantation technique. SETTING: University Hospital Antwerp, Department of Ophthalmology, Edegem, Belgium. METHODS: This study comprised 180 eyes of 125 patients who had cataract surgery with implantation of the BIL intraocular lens (IOL) between March 2002 and September 2005. Postoperative data at 5 weeks, 6 months, and 1 year were evaluated. The geometric center of the IOL, measured on a red reflex slitlamp photograph, was compared with the geometric center of the pupil and the limbus. RESULTS: The mean decentration compared with the limbus was 0.304 mm+/-0.17 (SD) at a mean angle of -24.9+/-113.3 degrees. Compared with the dilated pupil, the mean deviation was 0.256+/-0.15 mm at a mean angle of -5.2+/-119.0 degrees. The amount of decentration was stable during the postoperative follow-up period. There was no correlation between the amount of decentration and the visual outcomes (pupil: r=-0.07, P=.494; limbus: r=0.11, P=.304). CONCLUSIONS: Surgeon-controlled BIL centration was predictable 5 weeks and unchanged 6 months and 1 year postoperatively. It can therefore be concluded that capsular bag healing has no influence on BIL IOL centration over time.

Bag-in-the-lens intraocular lens implantation in the pediatric eye.

PURPOSE: To study the efficacy, safety, and feasibility of implantation of a bag-in-the-lens intraocular lens (IOL) in children and babies. SETTING: Departments of Ophthalmology, University Hospital, Antwerp, Belgium, and the University Hospital, Ljubljana, Slovenia, and a private ophthalmology practice, Oudenaarde, Belgium. METHODS: Thirty-four eyes of 22 children had implantation of a bag-in-the-lens IOL. The ages ranged from 2 months to 14 years. Congenital cataract was present in 26 eyes, and persistent fetal vasculature (PFV) was concomitantly present in 4 eyes. Fifteen patients had bilateral cataract, and 6 had unilateral cataract. RESULTS: In 3 eyes, the IOL could not be properly implanted. In these cases, secondary intervention was necessary because of early posterior capsule opacification. The mean postoperative follow-up was 17.45 months +/- 17.12 (SD) (range 4 to 68 months). None of the children except those presenting with PFV had anterior vitrectomy during surgery. The optical axis remained clear during the follow-up in all patients who had successful IOL implantation. CONCLUSIONS: The bag-in-the-lens implantation technique in children and babies was safe and kept the visual axis clear after cataract surgery. In the near future, 4.0 or 4.5 mm IOLs will be available that may improve the success rate of IOL implantation in the small eyes of babies.

Ring-shaped caliper for better anterior capsulorhexis sizing and centration.

We describe a new type of caliper to optimize the size, shape, and centration of the capsulorhexis during intraocular lens (IOL) surgery. This flexible, ring-shaped tool is positioned on the anterior capsule surface, where it is kept in place by an ophthalmic viscosurgical device. When in place, the caliper provides an ideal guide for the surgeon to follow and facilitates optimal capsulorhexis shape and centration.

One-year follow-up of bag-in-the-lens intraocular lens implantation in 60 eyes.

PURPOSE: To report the feasibility and clinical results of implanting a bag-in-the-lens intraocular lens (IOL) designed to prevent posterior capsule opacification after cataract surgery. SETTING: Departments of Ophthalmology, University of Antwerp, Antwerp, Belgium, and University of Munich, Munich, Germany. METHODS: This prospective study comprised 63 eyes (55 patients; 7 children, 48 adults) scheduled for cataract surgery and bag-in-the-lens IOL implantation. A posterior curvilinear capsulorhexis the same size as the anterior capsulorhexis was created for IOL insertion. After surgery, lens epithelial cell (LEC) proliferation was documented every 6 months with a minimum follow-up of 12 months. RESULTS: Sixty of 63 eyes (95%) had implantation of the bag-in-the-lens IOL. Conversion to a conventional IOL was necessary in 2 cases. In 1 eye, postoperative luxation of the IOL into the vitreous occurred as a result of an oversized anterior and posterior capsulorhexis. Three eyes had early postoperative iris incarceration in the lens groove that required surgery. No LEC proliferation on the optic occurred during a mean follow-up of 22.7 months (range 12 to 64 months); LEC proliferation was confined to the peripheral capsular bag. CONCLUSION: Lens epithelial cell proliferation was mild and confined to the periphery of the capsular bag during follow-up, and the bag-in-the-lens IOL optic remained clear.

Cumulative neodymium:YAG laser rates after bag-in-the-lens and lens-in-the-bag intraocular lens implantation: comparative study.

PURPOSE: To study the cumulative neodymium:YAG (Nd:YAG) laser rate after bag-in-the-lens implantation (Morcher 89A) and lens-in-the-bag implantation (Morcher 92S) of 2 intraocular lenses (IOLs) of the same biomaterial. SETTING: Department of Ophthalmology, University Hospital of Antwerp, Edegem, Belgium. METHODS: This study comprised 100 eyes of 87 patients who had the bag-in-the-lens IOL implantation between January 2000 and August 2004. The postoperative follow-up ranged between 17 and 72 months. One hundred eyes of 94 patients of the same age and with the same follow-up period received the lens-in-the-bag IOL. The cumulative Nd:YAG laser frequency rates in both groups were calculated, and the cumulative incidence rates were defined by Kaplan-Meier survival analysis. RESULTS: No Nd:YAG laser capsulotomy was performed in eyes having bag-in-the-lens IOL implantation. A laser capsulotomy was performed in 20 eyes having lens-in-the-bag IOL implantation; the cumulative frequency in this group was 2% at 1 year and 20% at 71 months, with a plateau beginning at 42 months. The cumulative incidence rate of Nd:YAG posterior capsulotomy was approximately 2% at 1 year, increasing to approximately 28% at 42 months. CONCLUSIONS: The cumulative Nd:YAG laser rate after bag-in-the-lens implantation was zero. A zero rate has not been reported with lens-in-the-bag implantation of an IOL of the same biomaterial or of other biomaterials, as published in the literature. Thus, it can be concluded that the bag-in-the-lens implantation technique has 100% effectiveness against posterior capsule opacification.

Evaluation of UVA Cytotoxicity for Human Endothelium in an Ex Vivo Corneal Cross-linking Experimental Setting.

PURPOSE: To evaluate endothelial cytotoxicity after exposure of human corneas to ultraviolet-A (UVA) (λ = 365 nm; 5.4 J/cm(2)) in an experimental ex vivo corneal cross-linking setting. METHODS: Sixteen pairs of human donor corneas were cut into two pieces. One piece of each cornea was treated with 0.025% riboflavin solution prior to UVA irradiation (5 minutes; 18 mW/cm(2)), whereas the other piece was not irradiated but treated with riboflavin (right eye) or preservation medium (left eye). By irradiating from the endothelial side, the UVA dosage applied to endothelial cells exceeded at least eight times the cytotoxic threshold established in animal models (0.65 J/cm(2)). Endothelial cell counts were performed by two independent investigators after storage (4 to 5 days at 31 °C) and staining (trypan blue, alizarin red). Normality (Q-Q plot; Shapiro-Wilk test) and equivalence (mixed-effects modeling with a 10% equivalence threshold) of the endothelial cell counts of the different groups were evaluated. RESULTS: Equivalence of mean endothelial cell density between both groups was observed: 2,237 ± 208 cells/mm(2) in UVA-irradiated pieces and 2,290 ± 281 cells/mm(2) in control pieces (mean difference of 53 ± 240 cells/mm(2) between both groups). CONCLUSIONS: Despite direct irradiation of human donor endothelium using the clinical dosage for cross-linking, equivalence in endothelial cell counts was observed between irradiated tissues and controls. Ex vivo human corneal endothelial cells seem to be far more resistant to riboflavin-enhanced UVA irradiation than previously estimated by animal experiments.

Double-C loop platform in combination with hydrophobic and hydrophilic acrylic intraocular lens materials.

PURPOSE: To analyze the behavior of a new double-C-loop quadripod symmetrical intraocular lens (IOL) platform combined with a hydrophilic lens material and a new hydrophobic glistening-free acrylic lens material, Ankoris and Podeye, respectively, in silico (computer simulation), in vitro (laboratory investigation), and in vivo (rabbit model). SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA, and Physiol S.A., Liege, Belgium. DESIGN: Experimental study. METHODS: An in silico simulation investigation was performed using finite elements software, an in vitro investigation according to the International Organization for Standardization (ISO11979-3:2012), and an in vivo implantation in a rabbit model with 4 weeks of follow-up. Postmortem data were collected by Miyake-Apple gross examination and histopathologic analyses. Biocompatibility and IOL centration were tested. RESULTS: Both IOLs demonstrated statistically insignificant variations in posterior and anterior capsule opacification and Soemmerring ring formation. They were well biotolerated with no signs of toxicity, inflammation, or neovascularization. Axial and centration stability were noted in vitro and in vivo as a result of significant contact between surrounding tissues and haptics and the posterior portion of the optic. CONCLUSION: The results suggest suitability of the double-C loop IOL platform for the manufacturing of premium (ie, multifocal, toric, and multifocal toric) IOLs. FINANCIAL DISCLOSURE: Drs. Bozukova, Gobin, and Pagnoulle are employees of Physiol S.A., Liege, Belgium. Dr. Pagnoulle has a proprietary interest in the tested intraocular lenses. No other author has a financial or proprietary interest in any material or method mentioned.

Binocular vision impairment after refractive surgery.

PURPOSE: To illustrate the need for an accurate preoperative orthoptic examination to prevent postoperative changes in binocular vision. SETTING: Department of Ophthalmology, University Hospital Antwerp, Edegem, Belgium. METHODS: Five patients presenting major subjective complaints after refractive surgery were analyzed. RESULTS: In 1 patient, a latent N IV palsy decompensated after laser in situ keratomileusis (LASIK) in the more myopic eye to achieve monovision. A second patient, operated on for N IV palsy 10 years earlier, presented a recurrence of the palsy after bilateral LASIK for myopia. The third patient complained of discomfort in binocular vision caused by aggravation of a preexisting intermittent esotropia that worsened after LASIK for hyperopia. The fourth patient complained of diplopia after LASIK in the highly anisometropic and exotropic eye. The fifth patient experienced a decrease in fusion and stereopsis at the time he became anisometropic after bilateral LASIK. CONCLUSIONS: Special care should be taken of patients who have a preoperative history of strabismus surgery, an overcorrection or undercorrection in 1 or both eyes, or anisometropia and of those who are unhappy with contact lenses. An orthoptic examination should be done with and without spectacle correction to detect underlying vertical phorias. Intended monovision should be examined initially using contact lenses.

Assessment of new-generation glistening-free hydrophobic acrylic intraocular lens material.

PURPOSE: To determine the hydrophobic, antiglistening, and bioadhesiveness properties of a new polymer, GF raw material, and to determine the suitability of this material for use in intraocular lenses (IOLs). SETTING: University of Liege, Liege, Belgium. DESIGN: Experimental study. METHODS: Intraocular lenses made of the new hydrophobic acrylic material were tested and compared with reference acrylic materials. The stability of their polymer matrix was estimated by testing for glistenings. The relative surface hydrophobicity was quantified via contact-angle measurements. The degrees of bioadhesiveness of the reference and test materials were assessed by in vitro porcine lens epithelial cell (LEC) culture. RESULTS: The glistening test showed that the new material had greater stability under worst-case conditions than previous-generation hydrophobic acrylic materials. The new polymer had the same hydrophobic properties as the hydrophobic Acrysof IQ SN60WF material; both materials were less hydrophobic than the hydrophobic Sensar AR40e material and more hydrophobic than the hydrophilic Ioflex IOL material. The in vitro bioadhesiveness tests showed that porcine LEC adhesion levels of the new material were intermediate with respect to those of the 2 reference hydrophobic materials. CONCLUSIONS: When equilibrated in aqueous medium, the new-generation hydrophobic acrylic material reached a low water content at equilibrium, making it glistening free. The hydrophobicity and bioadhesiveness of the new raw material were comparable to those of state-of-the-art reference materials; these properties may resist the formation of posterior capsule opacification. FINANCIAL DISCLOSURE: Dr. Pagnoulle has a proprietary interest in the GF material. Drs. Pagnoulle, Gobin, and Bozukova are employees of Physiol S.A. Mme. V. Bertrand and Dr. Gillet-De Pauw have no financial or proprietary interest in any material or method mentioned.

Spherotoric bag-in-the-lens intraocular lens: power calculation and predictive misalignment nomogram.

PURPOSE: To propose a method of calculating the power of the 1-sided posterior chamber toric bag-in-the-lens (BIL) intraocular lens (IOL) and propose a misalignment nomogram to calculate the postoperative rotational misalignment or predict the effect of preoperative existing irregular corneal astigmatism. SETTING: Antwerp University Hospital, Department of Ophthalmology, Antwerp, Belgium. DESIGN: Cohort study. METHODS: The new IOL calculation formula uses the steepest corneal meridian and flattest corneal meridian separately (regular spherical IOL formula) followed by a customized A-constant approach based on the changes in the IOL principal plane depending on the spherical and cylindrical powers (thickness) of the IOL. The calculation of the remaining astigmatism (power and axis) in cases of postoperative rotational misalignment resulted in a nomogram that can also be used to predict the degree of tolerance for irregular corneal astigmatism correction at the lenticular plane. The calculation is performed using a worksheet. RESULTS: Because 10 degrees of misalignment would result in 35% refractive inaccuracy, it is the maximum acceptable corneal astigmatic irregularity for correction at the lenticular plane. CONCLUSIONS: Calculation of spherocylindrical power is specific to each toric IOL. Because the surgeon must fully understand the optical properties of the toric IOL that is going to be implanted, a comprehensive outline of a new calculation method specific to the toric BIL IOL is proposed. Primary rotational misalignment of the toric BIL IOL can be fine tuned postoperatively. FINANCIAL DISCLOSURE: Drs. Gobin and Mathysen have no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Design and qualification of a diffractive trifocal optical profile for intraocular lenses.

PURPOSE: To theoretically and experimentally assess a new aspheric diffractive trifocal intraocular lens (IOL). SETTING: Centre Spatial de Liège, Liège, Belgium. DESIGN: Evaluation of diagnostic test or technology. METHODS: The theoretical profile of the IOL was designed using software simulation and validated by optical calculation software tools that enabled complete theoretical characterization. These data resulted in a new aspheric diffractive trifocal IOL. The IOL theoretically allows improved intermediate vision without impairing near and far vision and favors distance vision in mesopic conditions without increasing halos or glare perception under dim light or large pupil conditions. The theoretical findings were compared with those of in vitro testing on the optical bench. RESULTS: There was good agreement between the theoretical profile and achieved IOL profile. The simulated and achieved light distribution and focus distribution showed good concordance. The FineVision aspheric trifocal IOL provided intermediate addition at 1.75 diopters. CONCLUSION: The combination of 2 diffractive profiles to achieve far, intermediate, and near correction is validated. Further clinical investigations are required to validate these principles. FINANCIAL DISCLOSURE: Dr. Houbrechts has no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Clinical results after spherotoric intraocular lens implantation using the bag-in-the-lens technique.

PURPOSE: To evaluate the clinical results after implantation of a spherotoric intraocular lens (IOL) using the bag-in-the-lens (BIL) technique. SETTING: Antwerp University Hospital, Department of Ophthalmology, Antwerp, Belgium. DESIGN: Evidence-based manuscript. METHODS: Consecutive eyes with cataract and corneal astigmatism had implantation of a spherotoric BIL intraocular lens (IOL). The IOL was centered based on the patient's pupillary entrance using Purkinje reflexes of the surgical microscope light. RESULTS: The study enrolled 52 eyes of 35 patients (23 women) with corneal astigmatism ranging from 0.90 to 6.19 diopters (D). The toric power was between 1.00 D and 8.00 D. One-third of eyes had an additional ocular comorbidity (including amblyopia) that could influence the clinical outcomes; 5.2% had an irregular astigmatism up to 15 degrees. Twelve eyes had high myopia (axial length [AL] >26 mm) and 5 eyes, high hyperopia (AL <21 mm). The mean preoperative corrected distance visual acuity was 0.58 ± 0.25 (SD). Postoperatively, the uncorrected distance visual acuity (UDVA) was 0.5 or better in 92% of eyes, the mean UDVA was 0.85 ± 0.21 D, the mean magnitude of error was 0.05 ± 0.49 D, and the mean angle of error was 0.29 ± 0.89 degree. Astigmatism correction was successful in 82% of eyes. CONCLUSION: Spherotoric BIL IOL implantation yielded outcomes similar to those with other spherotoric IOLs, even in eyes with ocular comorbidity or irregular astigmatism up to 15 degrees.