Laure Gobin

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.

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.

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.

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.

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.

Clinical outcomes of cataract surgery after bag-in-the-lens intraocular lens implantation following ISO standard 11979-7:2006

PURPOSE: To assess the clinical outcomes of bag‐in‐the‐lens intraocular lens (BIL IOL) implantation following the International Organization for Standardization (ISO) 11979‐7:2006 in pediatric eyes and eyes with ocular comorbidities. SETTING: Antwerp University Hospital, Department of Ophthalmology, Antwerp, Belgium. DESIGN: Cohort study. METHODS: This cohort included the first series of patients having IOL implantation using the bag‐in‐the‐lens technique. Surgeries were performed between December 1999 and September 2006. In addition to IOL implantation, the technique comprised creation of a primary posterior continuous curvilinear capsulorhexis (PCCC) equal in size to the anterior capsulorhexis. RESULTS: The study enrolled 807 eyes of 547 patients; 326 of the eyes (40.40%) had ocular comorbidity. In the 481 eyes without ocular comorbidity, the mean decimal corrected distance visual acuity was 0.52 ± 0.24 (SD) (0.276 ± 0.206 logMAR) preoperatively and 0.94 ± 0.18 (−0.012 ± 0.053 logMAR) postoperatively. The mean postoperative achieved spherical equivalent was 0.48 ± 0.83 diopter (D) and the mean targeted refraction, −0.24 ± 0.71 D. The A‐constant was modified from 118.4 to 118.04. Posterior capsule opacification (PCO) did not occur in any adult eye during the follow‐up. Retinal detachment after IOL implantation occurred in 10 eyes (1.24%). In 19 eyes, the iris was captured by the IOL haptics postoperatively. Hypopyon occurred in 3 patients and toxic anterior segment syndrome in 1 patient. CONCLUSION: The BIL IOL met the ISO criteria; that is, primary PCCC was safe in healthy eyes and in eyes with ocular comorbidities and no eye developed PCO over a mean follow‐up of 26.1 ± 21.3 months. Financial Disclosure: Drs. Gobin, Mathysen, Van Looveren, and De Groot have no financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes.

Changes in rotation after implantation of a bag-in-the-lens intraocular lens

PURPOSE: To estimate the rotation stability of the bag‐in‐the‐lens (BIL) intraocular lens (IOL) (Morcher 89A) over time and to assess whether the rotational stability of the IOL design is suitable for toric corrections. SETTING: Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium. METHODS: This prospective study evaluated patients who had cataract surgery and BIL IOL implantation. Postoperative red reflex photographs were taken 1 day, 5 weeks, and 6 months after surgery. Intraocular lens rotation was obtained by defining a triangle between a scleral blood vessel, the IOL haptic, and the IOL optic center. Changes in the triangle during the follow‐up were evaluated using purpose‐designed software written in MatLab. RESULTS: Fifty‐nine eyes of 49 patients (mean age 68.0 years ± 11.9 [SD]) were included. There was little postoperative IOL rotation (mean 0.05 ± 2.02 degrees) between 1 day and 5 weeks (n = 46 eyes) and between 5 weeks and 6 months (mean 0.36 ± 1.39 degrees) (n = 15 eyes). The IOL rotation remained unchanged from 1 to 6 months postoperatively (P = .327, analysis of variance). There was no correlation between IOL rotation and patient age (r2 = 0.011) or IOL power (r2 = 0.003). Postoperative IOL rotations were not different between left eyes and right eyes (P = .862, t test). CONCLUSION: The BIL IOL showed good rotation stability, making it suitable for toric correction.

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.

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 &mgr;m when the epithelium was removed, and 758.3 ± 98.8 &mgr;m 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−1 when the epithelium is removed and 17 ± 2 cm−1 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.

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 (R2 = 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.