Birgit Lackner

Halo size under distance and near conditions in refractive multifocal intraocular lenses

AIMS To calculate the diameter of halos perceived by patients with multifocal intraocular lenses (IOLs) and to stimulate halos in patients with refractive multifocal IOLs in a clinical experiment. METHODS Calculations were done to show the diameter of halos in the case of the bifocal intraocular lens. 24 patients with a refractive multifocal IOLs and five patients with a monofocal IOL were asked about their subjective observation of halos and were included in a clinical experiment using a computer program (Glare & Halo, FW Fitzke and C Lohmann, Tomey AG) which simulates a light source of 0.15 square degrees (sq deg) in order to stimulate and measure halos. Halo testing took place monoculary, under mesopic conditions through the distance and the near focus of the multifocal lens and through the focus of the monofocal lens. RESULTS The halo diameter depends on the pupil diameter, the refractive power of the cornea, and distance focus of the multifocal IOL as well as the additional lens power for the near focus. 23 out of 24 patients with a refractive multifocal IOL described halos at night when looking at a bright light source. Only one patient was disturbed by the appearance of halos. Under test conditions, halos were detected in all patients with a refractive multifocal IOL. The halo area testing through the distance focus was 1.05 sq deg ± 0.41, through the near focus 1.07 sq deg ± 0.49 and in the monofocal lens 0.26 sq deg ± 0.13. CONCLUSIONS Under high contrast conditions halos can be stimulated in all patients with multifocal intraocular lenses. The halo size using the distance or the near focus is identical.

Long-term results of implantation of phakic posterior chamber intraocular lenses

Purpose: To study the incidence and progression of lens opacification after implantation of phakic posterior chamber intraocular lenses for myopia and its correlation with vaulting and endothelial cell density (ECD). Setting: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. Methods: An implantable contact lens (ICL V4, Staar Surgical Inc.) was inserted in 76 myopic eyes. Patients were prospectively followed preoperatively and at 1, 3, 6, 12, 24, and 36 months. The uncorrected visual acuity and best corrected visual acuity (BCVA) were determined. Vaulting was measured optically with a Jaeger II pachymeter, and the crystalline lens was examined at the slitlamp for the presence and characteristics of opacification. Endothelial cell morphometry was performed by specular microscopy, and the ECD was calculated. Eyes in which lens opacification developed were followed for at least 12 months to determine the degree and course of visual impairment. Results: Lens opacification occurred in 11 eyes (14.5%). Opacification was correlated with intraoperative trauma to the crystalline lens, age older than 50 years, and decreased ECD values throughout the observation period. Vaulting of the ICL did not correlate with the risk for lens opacification. After onset of lens opacification, 6 eyes (55%) had a stable BCVA within ±0.5 lines and 5 eyes had progressive opacification, losing between 3.5 lines and 0.5 lines (mean 1.8 lines ± 1.1 [SD]). Three eyes (3.9%) in the progressive group had a 1‐ to 2‐line loss of BCVA over preoperative values and subsequently had cataract surgery. Conclusions: Risk factors for lens opacification after implantation of the model V4 ICL included intraoperative trauma to the crystalline lens and older age. Decreased ECD in eyes with opacification suggests ongoing inflammation as a cause. Patients younger than 45 years may have a significantly lower incidence of opacification.

Outcome after treatment of ametropia with implantable contact lenses

OBJECTIVE To evaluate long-term results after insertion of implantable contact lenses (ICLs) in phakic eyes. DESIGN Prospective, noncomparative, interventional case series. PARTICIPANTS Seventy-five phakic eyes (65 myopic, 10 hyperopic eyes) of 45 patients aged 21.7 to 60.6 years were included. INTERVENTION STAAR Collamer Implantable Contact Lenses (STAAR Surgical Inc., Nidau, Switzerland) were implanted for correction of high myopia and hyperopia. MAIN OUTCOME MEASURES Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) were determined. Presence of lens opacification and the distance between the ICL and the crystalline lens were assessed by slit-lamp examination before surgery and at 1, 3, 6 months, and yearly after lens implantation. RESULTS Preoperative mean spherical equivalent was -16.23+/-5.29 diopters (D) for myopic eyes and +7.88 +/-1.46 D for hyperopic eyes. After ICL implantation, mean residual refractive error was -1.77+/-2.17 D in myopic patients and +0.44+/-0.69 D in hyperopic patients. Preoperative mean UCVA was Snellen 0.03+/-0.03 for myopic patients and Snellen 0.12+/-0.16 for hyperopic patients. Preoperative mean BCVA was Snellen 0.49+/-0.23 for myopic patients and Snellen 0.82+/-0.23 for hyperopic patients. After ICL implantation, mean UCVA up to the end of individual observation time was Snellen 0.36+/-0.36 for myopic patients and Snellen 0.58+/-0.28 for hyperopic patients. Mean BCVA was Snellen 0.73+/-0.26 for myopic and Snellen 0.80+/-0.24 for hyperopic patients. Mean preoperative IOP was 14.2+/-2.7 mmHg, and mean postoperative IOP was 13.46+/-2.1 mmHg over all follow-up investigations. The main complication was the development of subcapsular anterior opacifications of the crystalline lens in 25 eyes (33.3%), 2 of which showed direct contact to the ICL. Eleven eyes (14.7%) were stable in opacification and 14 eyes (18.7%) had progressive opacifications. The median time to opacification was 27.1 months. In 8 patients (10.7%), the subjective visual impairment mandated cataract surgery. CONCLUSIONS The most significant long-term complication after ICL implantation is the formation of opacifications of the crystalline lens with the risk of the necessity of subsequent cataract surgery (10.7%). Old age, female gender, and contralateral opacification are independent significant risk factors for early formation of opacifications in this patient group.

Influence of operator experience on the performance of ultrasound biometry compared to optical biometry before cataract surgery

Purpose: To compare measurements performed with the IOLMaster (Carl Zeiss, Meditec AG) with those obtained by applanation ultrasound (US) and manual keratometry and to evaluate the effect of operator experience on US biometry. Setting: Department of Ophthalmology, University of Vienna, Vienna, Austria. Methods: The axial length (696 eyes) and anterior chamber depth (ACD) (462 eyes) were measured in 377 patients with cataract using the IOLMaster and applanation US. To assess the effect of operator experience on the biometric results, the operators were divided into 2 groups: experienced and less experienced in performing US biometry. The difference in measurements between the methods and the variability of the difference were compared between the 2 groups. Results: Applanation US measured axial length and ACD shorter than the IOLMaster; the mean numerical difference was 0.13 mm and 0.19 mm, respectively (P<.01). For axial length, the absolute difference was smaller with experienced operators than with less experienced operators (0.15 mm versus 0.22 mm) (P<.01). For ACD, experienced operators obtained a smaller difference between measurement techniques (0.21 mm versus 0.29 mm; P<.05). Conclusions: Experienced US operators had less difference and lower variability in the difference between applanation US and IOLMaster readings for axial length and ACD measurements. The noncontact optical method, which is essentially operator independent, gave significantly more reliable biometry before cataract surgery, especially in the case of less experienced operators.

Long-term endothelial changes in phakic eyes with posterior chamber intraocular lenses

Purpose: To evaluate the long‐term endothelial cell changes in phakic eyes after implantation of a posterior chamber phakic intraocular lens to correct high ametropia. Setting: Department of Ophthalmology, University Hospital of Vienna, Vienna, Austria. Methods: Thirty‐four eyes of 21 patients having implantation of an implantable contact lens (ICL, Staar Surgical) for high myopia or hyperopia were prospectively examined. The minimum follow‐up was 2 to 4 years. Preoperative and serial postoperative specular microscopy (Noncon Robo SP 8000, Konan) was performed to evaluate the long‐term endothelial cell changes. Results: The mean preoperative endothelial cell density was 2854 cells/mm2. The mean endothelial cell loss from preoperatively was 1.8% at 3 months, 4.2% at 6 months, 5.5% at 12 months, 7.9% at 2 years (n = 34), 12.9% at 3 years (n = 13), and 12.3% at 4 years (n = 11). All other endothelial cell characteristics remained stable during the 4‐year follow‐up. Conclusions: Continuous endothelial cell loss was observed after ICL implantation during a 4‐year follow‐up. There was rapid cell loss until 1 year postoperatively, after which the rate of loss was no longer statistically significant. The percentage of hexagonal cells (polymorphism) and the coefficient of variation (polymegethism) remained stable during the 4‐year follow‐up.

Glare and halo phenomena after laser in situ keratomileusis

Purpose: To simulate and measure subjectively observed glare and halos after laser in situ keratomileusis (LASIK). Setting: University of Vienna, Medical School, Department of Ophthalmology, Vienna, Austria. Methods: In 16 eyes of 10 patients, the best corrected visual acuity (BCVA) and subjectively observed glare and halo size under mesopic conditions were measured before LASIK and 1, 3, and 6 months postoperatively. Infrared pupillography was used to ensure that all patients had a larger ablation zone than the measured pupil size under mesopic conditions. Results: Preoperatively, the mean Snellen BCVA was 0.88 ± 0.17 (SD) and the mean glare and halo size was 1.97 ± 1.20 square degrees (sqd) before the treatment. One month after LASIK, the BCVA was 0.83 ± 0.29 and the mean glare and halo size, 2.61 ± 3.14 sqd. Three months after LASIK, the mean values were 0.90 ± 0.26 and 1.88 ± 2.37 sqd, respectively. Six months after LASIK treatment, they were 0.85 ± 0.28 and 1.30 ± 1.63 sqd, respectively. The 95% confidence interval for the difference between preoperative glare and halo and glare and halo at 6 months was −1.56 to + 0.51 sqd. Conclusion: Subjectively observed glare and halo size after LASIK reached a peak after 1 month and decreased in the following postoperative period.

Effect of tenascin and fibronectin on the migration of human corneal fibroblasts

Purpose: To investigate the effect of fibronectin and tenascin on the migration of corneal fibroblasts. Setting: Department of Ophthalmology, University of Vienna, Medical School, Vienna, Austria. Methods: Using human corneal fibroblasts, a monolayer migration assay was performed to measure corneal fibroblast movement. The migration on collagen I, fibronectin, and tenascin with and without transforming growth factor (TGF)‐&agr;/fibroblast growth factor (FGF)‐2 stimulation and the effect of soluble tenascin and fibronectin on corneal fibroblast migration on collagen‐I‐coated wells were investigated. Results: The cytokines TGF‐&agr; and FGF‐2 stimulated migrational activity of corneal stromal cells in a dose‐dependent manner, reaching the maximum effect at 100 ng/mL and 10 ng/mL, respectively. The migration of corneal fibroblasts on fibronectin was significantly higher (P < .05) than the migration on collagen I. Transforming growth factor‐&agr; and FGF‐2 increased radial cell displacement independent of the provided matrix composition. Tenascin had a negative effect on corneal fibroblast adhesion/migration in this in vitro model. Conclusion: Fibronectin and tenascin influenced corneal fibroblast migration and adhesion, respectively, and may play a role in stromal cell movement during wound healing. The cytokines TGF‐&agr; and FGF‐2 had an additive effect on corneal fibroblast migration on a fibronectin matrix.

Comparison of visual acuities at different distances and defocus curves

Purpose: To evaluate how visual acuities at different distances correlate with results from defocus curves. Setting: Department of Ophthalmology and Institute of Medical Physics, University of Vienna, Medical School, Vienna, and Department of Ophthalmology, Krankenhaus St. Pölten, St. Pölten, Austria. Methods: This study comprised 15 eyes of 14 patients with a mean age of 67.9 years ± 9.7 (SD) with a monofocal silicone intraocular lens (911A, Pharmacia). The best corrected distance visual acuity was determined at viewing distances of 6 m, 2 m, 1 m, 67 cm, 50 cm, 40 cm, and 33 cm using logMAR charts. Defocus curves were then evaluated from −3.0 to −0.5 diopter (D) at 0.5 D increments from the best distance correction at a viewing distance of 6 m. Results: The mean distance visual acuity was logMAR 0.08 ± 0.07. The visual acuity graph from the testing at different distances was above the defocus graph at all testing points. Comparison of the visual acuity results from the 2 tests revealed statistically significant differences in the range from 2 m (–0.5 D) to 33 cm (–3.0 D). Conclusion: Results of defocus curves disregard the diminutions of minus glasses, the normally restricted viewing distance to 6 m for distance acuity determination, and in particular the physiological miosis caused by the near‐point reaction.

Tritan colour contrast sensitivity function in refractive multifocal intraocular lenses

AIMS To compare tritan colour contrast sensitivity (CCS), without and with glare, in patients with refractive multifocal intraocular lenses (IOLs) and with monofocal intraocular lenses. METHODS Tritan CCS was determined (Moorfields Vision System, CH Electronics) in 15 eyes (14 patients, 75.7 (±6.6) years) with a refractive multifocal IOL (Allergan SA 40N) and in 11 eyes (10 patients, 73.7 (±6.4) years) with a monofocal IOL (Allergan SI 40 NB). Measurements were made monocularly under mesopic conditions at a distance of 2 metres from the monitor with best distance refraction plus 0.5 D at 0.5, 1, 3, 6, 11.4, and 22.8 cycles per degree (cpd). The test was then repeated for the multifocal IOLs, adding minus 2.5 D to the best distance refraction to force the patient to use the near focus. Both lenses were also investigated under glare conditions with the same set-up and using the brightness acuity tester (BAT). RESULTS The tritan CCS function without glare in multifocal lenses through the distance focus was nearly identical to that through the near focus. The following statistically significant differences were measured: the CCS function without glare for the multifocal lens was worse at 0.5 cpd and 1.0 cpd than that of the monofocal lens. In CCS testing of the multifocal group with glare at 6 cpd, the results through the distance focus were better than the results through the near focus. For the CCS function with glare, the values for the distance focus in the multifocal lens were worse than the values for the monofocal lens at 0.5 cpd and 1 cpd. In CCS testing with glare through the near focus and CCS testing through the monofocal lens, the monofocal lens performed better at 0.5 cpd, 1 cpd, 3 cpd, and 6 cpd. CONCLUSION Refractive multifocal intraocular lenses influence tritan CCS function compared to monofocal lenses.

Influence of spectacle-related changes in retinal image size on contrast sensitivity function after laser in situ keratomileusis.

Purpose: To evaluate changes in contrast sensitivity after laser in situ keratomileusis (LASIK) for the correction of myopia using a monitor‐based method and considering the preoperative minification effect of high‐diopter spectacles. Setting: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. Methods: Fifteen eyes of 11 patients had LASIK to correct myopia. The best corrected visual acuity (BCVA) and contrast sensitivity function (CSF) were measured preoperatively and 1, 3, and 6 months postoperatively using the AcuityMax (Science 2020) computer program. The error in contrast sensitivity measurement due to different angular sizes of the test figures deriving from the spectacle refractions before and after LASIK were considered. Results: Preoperatively, and at 1, 3, and 6 months, the mean Snellen BCVA was 0.93 ± 0.19 (SD), 0.80 ± 0.26, 0.85 ± 0.21, and 0.84 ± 0.27, respectively. The best mean CS (measured at 1.1 logMAR) was 1.17 ± 0.05, 1.12 ± 0.07, 1.13 ± 0.08, and 1.18 ± 0.04, respectively. The strongest CS changes were observed at 0.7 logMAR (6 cycles per degree), where CS was 1.10 ± 0.07 preoperatively and 1.06 ± 0.09, 1.07 ± 0.12, and 1.14 ± 0.07, at 1 month, 3 months, and 6 months, respectively. With correction for the spectacle effect, the preoperative CS was approximately 3% higher and CS at 3 months for intermediate optotype sizes was significantly inferior to preoperatively. Conclusions: With correction of different retinal image sizes before and after LASIK (due to different spectacle refraction), the CS was significantly below the preoperative values at 1 and 3 months and approached the preoperative values at 6 months. The proposed method is potentially capable of quality monitoring and method comparisons after photorefractive surgery.