Christoph Lüke

Primary phacoemulsification and intraocular lens implantation for acute angle-closure Glaucoma

OBJECTIVE To evaluate the safety and efficacy of primary phacoemulsification and intraocular lens implantation (PPI) for acute angle-closure glaucoma (ACG). STUDY DESIGN Prospective, nonrandomized comparative trial. PARTICIPANTS AND INTERVENTION Forty-three eyes of 43 patients with acute ACG and uncontrolled intraocular pressure (IOP) were treated by PPI. Thirty-two eyes of 32 patients treated by conventional surgical iridectomy (CSI) constituted the control group. MAIN OUTCOME MEASURES Postoperative visual acuity, IOP, number of antiglaucoma medications, complications, and secondary surgical interventions, if any, required for IOP control. RESULTS Glaucoma control was achieved in 31 eyes (72%) in the PPI group and in 11 (35%) in the CSI group (P = 0.01). Mean preoperative IOP was 40.5 +/- 7.6 mmHg (standard deviation) and 39.7 +/- 7.8 mmHg, respectively (P = 0.46). Mean postoperative IOP was 17.8 +/- 3.4 mmHg (PPI group) and 20.1 +/- 4.2 mmHg (CSI group) after a mean follow-up of 10.2 +/- 3.4 months (P = 0.03). Postoperatively, the mean number of ocular hypotensive medications was 0.18 +/- 0.45 (PPI group) and 0.45 +/- 0.62 (CSI group) (P = 0.0001). Relative increase in postoperative best-corrected visual acuity (logarithm of the minimum angle of resolution) was 0.52 +/- 0.29 (PPI group) and 0.19 +/- 0.21 (CSI group), respectively (P = 0.0001). Additional surgery was necessary in 5 eyes (11.5%) in the PPI group and in 20 eyes (63%) in the CSI group (P = 0.01). Intraoperative and postoperative complications were few and manageable. CONCLUSIONS CSI in patients with acute ACG was effective in reducing IOP initially but was associated with multiple surgical reinterventions. Conversely, primary PPI turned out to be safe and effective in reducing IOP and improving visual acuity. These results affirm that lens extraction may be considered the better procedure in uncontrolled ACG when faced with options of CSI or PPI.

Effects of bevacizumab on retinal function in isolated vertebrate retina.

Background: Bevacizumab (Avastin) is a recombinant protein that targets vascular endothelial growth factor (VEGF). In vitro, bevacizumab inhibits VEGF induced cell proliferation and tissue factor production. Abnormal angiogenesis involving VEGF is a central event during the development of choroidal neovascularisation (CNV). The present study was designed to evaluate the short term toxic effects of bevacizumab on retinal function for a therapeutic intraocular application. Methods: Isolated bovine retinas were perfused with an oxygen pre-incubated nutrient solution. The electroretinogram (ERG) was recorded as a transretinal potential using silver/silver chloride electrodes. Bevacizumab was added in different concentrations to the nutrient solution for 45 minutes. Thereafter the retina was reperfused for 60 minutes with normal nutrient solution. The percentage of a-wave and b-wave reduction during the application of bevacizumab was calculated and compared to control recordings. Results: During the application of three different concentrations of bevacizumab (0.08 mg/ml, 0.25 mg/ml, 0.8 mg/ml) no significant reduction of the a-wave and b-wave amplitude was observed. During the washout, the ERG amplitudes were unchanged. Conclusion: The present study suggests that an intraocular application of 0.25 mg/ml bevacizumab for the treatment of CNV is reasonable. No significant short term effects of bevacizumab on retinal function were detected, but long term effects cannot be excluded.

Retinal tolerance to dyes.

Background: Dye solutions for intraoperative staining of epiretinal membranes and the internal limiting membrane improve the visualisation of these thin structures and facilitate their removal. In the present study the authors investigated the effects of indocyanine green 0.05%, trypan blue 0.15%, and patent blue 0.48% on bovine retinal function. Methods: Bovine retina preparations were perfused with a standard solution and the electroretinogram (ERG) was recorded repeatedly. After recording of stable ERG amplitudes the nutrient solution was substituted by one of the dye solutions. The duration of retinal exposure to a dye solution was varied between 10 seconds and 2 minutes. Thereupon, the preparation was reperfused with standard solution for at least 115 minutes. The percentage of b-wave reduction after exposition was calculated. Results: Reductions of the b-wave amplitude were found for each dye solution tested. The effects after application of patent blue and indocyanine green were completely reversible within the recovery time for an exposure period of 60 and 30 seconds, respectively. The application of trypan blue lead to a loss of the b-wave when the retina was exposed for 15 seconds or longer. This effect was only partly reversible within the recovery time. Conclusion: The ERG showed toxic effects of trypan blue after a short period of retinal exposure. The intraocular application of trypan blue should be limited to selected cases. However, intraocular application of indocyanine green and patent blue in a sufficient concentration and taking account of a short period of retinal exposure seems possible.

Self-application of single-use eyedrop containers in an elderly population: comparisons with standard eyedrop bottle and with younger patients.

Purpose:  To test whether patients aged ≥80 years can safely and successfully apply eyedrops from a single‐use eyedrop container without support, and to compare the results with those of younger patients using single‐use containers and older patients using standard eyedrop bottles.

Morphological variability of the trabecular meshwork in glaucoma patients: implications for non-perforating glaucoma surgery

BACKGROUND/AIMS Morphological variability of the trabecular meshwork could be of considerable importance for the proper intraoperative outcome of non-perforating antiglaucomatous surgery, such as deep sclerectomy and viscocanalostomy. The aim of this study was therefore to assess qualitative and quantitative characteristics of the trabecular meshwork in glaucoma patients undergoing trabeculectomy. METHODS Trabeculectomy specimens from 177 glaucoma patients were prepared for light microscopy; 100 specimens were found to be suitable for qualitative assessment and quantitative computerised image analysis; measurements were taken of the meridional diameter of Schlemms canal as well as the thickness of the trabecular meshwork at different positions. RESULTS The mean meridional diameter of Schlemms canal was 290 μm with the smallest values in the young patients with infantile and secondary glaucomas. the thickness of the trabecular meshwork ranged between 50–70 μm in the anterior region and between 100–130 μm for the posterior portion. The thickness of the anterior meshwork significantly decreased with age. The pigmentation of excised trabecular meshwork was found to be weak or even lacking in 68 patients. In 20 glaucoma patients the uveal meshwork was covered by an endothelial layer. CONCLUSIONS From the morphological point of view the risk of inadvertent perforation during deep sclerectomy in older, white glaucoma patients should be taken into account even by an experienced surgeon, because the anterior meshwork in these cases is very thin and trabecular pigmentation that can be used as a topographic landmark is often lacking. The functional success of non-perforating glaucoma surgery in many patients may be limited by endothelial covering of the trabecular meshwork.

Influence of membrane differential filtration on the natural course of age-related macular degeneration: a randomized trial.

Purpose: Membrane differential filtration is able to optimize rheologic parameters by eliminating high molecular weight proteins and lipoproteins from the blood. Following the hypothesis that these changes result in an improvement of the microcirculation, the authors tested the efficacy of membrane differential filtration in improving visual function in patients with age‐related macular degeneration (ARMD). Methods: Forty patients (40 eyes) were randomized into two groups. The treatment group was treated five times over a period of 21 weeks. In both groups, 9/20 of the eyes showed subfoveolar subretinal neovascularization. The main parameter of the study was visual acuity (VA). Electroretinogram (ERG), electrooculogram, and macular visual evoked potentials were also recorded. Plasma and whole blood viscosity and erythrocyte aggregation were measured. Results: The 20 patients treated repeatedly over a period of 21 weeks showed a mean improvement of 0.63 lines (SD 1.8) of VA on Early Treatment Diabetic Retinopathy Study charts. The control group showed a deterioration of 0.94 lines (SD 1.7) compared to VA at baseline examination. The amplitude of the ERG photopic a‐wave and the flicker ERG was significantly increased. The rheologic parameters were lowered in all treated patients. Conclusion: Repetitive treatment with membrane differential filtration is able to improve visual acuity of patients with ARMD and the natural course of this disease. Several questions arise from the results of this study. Further research will show if it is possible to optimize the selection of patients for subgroups with predictive responses through morphologic and functional tests and how to create an optimized and individual treatment strategy determined by the quality, intensity, and frequency of treatment sessions.

Electrophysiological abnormalities in age-related macular degeneration

Abstract · Background. Results from psychophysical tests indicate that in age-related macular degeneration (ARMD) retinal function is globally impaired. Observations in single ARMD cases showing abnormalities of the electrooculogram (EOG) and electroretinogram (ERG) encouraged us to systematically examine ARMD patients by means of electrophysiological tests to confirm a global retinal dysfunction in ARMD. · Methods. Sixty-six patients with ARMD were examined clinically and by means of EOG, ERG, triple scotopic ERG, and fluorescein angiography (FA). · Results. EOG data were considerably reduced in ARMD. Scotopic a- and b-waves of the ERG were mildly affected. The bright flash response showed reduced b-waves with normal implicit times. The amplitude of the oscillatory potential OP2 was significantly reduced and photopic responses were also pathologic compared with an age-matched control group. Geographic atrophy and pigment epithelium detachment showed specific abnormalities in the ERG, whereas in soft drusen EOG changes were more conspicuous. · Conclusions. In addition to data from psychophysical tests the results from electrophysiological examinations indicated a global reduction of retinal function in ARMD which seemed to be present not only in the macula but also elsewhere in the retina.

Ultrasound biomicroscopy and its value in predicting the long term outcome of viscocanalostomy.

Aims: To examine whether the early postoperative morphology at the site of sclerectomy, as visualised by ultrasound biomicroscopy (UBM), is an indicator of the mechanisms that lower intraocular pressure (IOP) and/or predictors of the long term outcome of viscocanalostomy. Methods: 15 eyes of 14 patients with medically uncontrolled open angle glaucoma and no history of surgery underwent viscocanalostomy according to Stegmann’s technique. Ultrasound biomicroscopy was performed during the first month after surgery. The following parameters were assessed: dimensions of the intrascleral “lake,” presence of a filtering bleb, presence of a subconjunctival cavity or a suprachoroidal hypoechoic area, and the thickness of the residual trabeculocorneal membrane. A complete ophthalmological examination was performed the day before and the day after surgery. Follow up visits were scheduled 1 week, 4 weeks, 6 months, and 12 months after surgery. Results: At 1 year successful control of IOP (<20 mm Hg) was achieved without further manipulation or medication in six of 15 eyes. The size of the intrascleral “lake” (average 0.62 mm3) did not correlate with later IOP; however, a visible route under the scleral flap and accidental perforation of the trabeculocorneal membrane were associated with long term lowering of IOP. Normal thickness of the trabeculocorneal membrane (0.10–0.15 mm) was indicative of IOP control with and without medication. When UBM showed an early collapse of the intrascleral cavity, control of IOP was not achieved. Other UBM findings did not predict long term function. Conclusion: In accordance with previous studies, the authors found that UBM examination is a useful method to evaluate outflow mechanisms after glaucoma surgery. This study shows that UBM imaging of external filtration during the early postoperative period can be used to predict the success of viscocanalostomy. However, to establish conclusively what parameters of UBM predict successful viscocanalostomy a larger number of patients must be studied.

The retinal tolerance to bevacizumab in co‐application with a recombinant tissue plasminogen activator

Aim: To investigate the retinal toxicity of bevacizumab in co-application with a commercially available recombinant tissue plasminogen activator (rt-PA), and to facilitate a new therapeutic concept in the treatment of massive subretinal haemorrhage caused by neovascular age-related macular degeneration (AMD). Methods: Isolated bovine retinas were perfused with an oxygen-preincubated nutrient solution. The electroretinogram (ERG) was recorded as a transretinal potential using Ag/AgCl electrodes. Bevacizumab (0.25 mg/ml) and rt-PA (20 μg/ml) were added to the nutrient solution for 45 min. Thereafter, the retina was reperfused for 60 min with normal nutrient solution. Similarly, the effects of rt-PA (20 μg/ml, 60 μg/ml and 200 μg/ml) on the a- and b-wave amplitudes were investigated. The percentages of a- and b-wave reduction during application and at washout were calculated. Results: During application of bevacizumab (0.25 mg/ml) in co-application with 20 μg/ml (rt-PA), the ERG amplitudes remained stable. The concentrations of rt-PA alone (20 μg/ml and 60 μg/ml) did not induce significant reduction of the b-wave amplitude. In addition, 20 μg/ml rt-PA did not alter the a-wave amplitude. However, 60 μg/ml rt-PA caused a slight but significant reduction of the a-wave amplitude. A full recovery was detected for both concentrations during the washout. At the highest tested concentration of 200 μg/ml rt-PA, a significant reduction of the a- and b-wave amplitudes was provoked during the exposure. The reduction of ERG amplitudes remained irreversible during the washout. Conclusion: The present study suggests that a subretinal injection of 20 µg/ml rt-PA in co-application with bevacizumab (0.25 mg/ml) for the treatment of massive subretinal haemorrhage seems possible. This is a safety study. Therefore, we did not test the clinical effectiveness of this combined treatment.

Multifocal Intraocular Lens Implantation in Prepresbyopic Patients with Unilateral Cataract

OBJECTIVE To evaluate the benefits of implantation of a zonal-progressive multifocal intraocular lens (IOL) in prepresbyopic patients with unilateral cataract. STUDY DESIGN Prospective, nonrandomized, comparative trial. PARTICIPANTS Ninety-five eyes of 95 prepresbyopic patients aged between 14 and 40 years with either multifocal or monofocal IOL implantation at two institutions and with more than 6 months follow-up. INTERVENTIONS Temporal clear corneal phacoemulsification and foldable IOL implantation was performed in all eyes. In 54 patients, a zonal-progressive optic multifocal IOL (Array SA40-N, Allergan, Irvine, CA) was implanted, whereas 41 patients received a monofocal IOL and served as controls. RESULTS Preoperative patient demographics, mean postoperative spherical equivalent, astigmatism, and uncorrected and best-corrected distance visual acuities were similar in the two groups. Patients with a multifocal IOL achieved a significantly better uncorrected near visual acuity than patients with monofocal IOL (0.18 versus 0.37; P = 0.0001). With distance correction only, mean near visual acuity was 0.17 versus 0.43 (P = 0.0001). Best-corrected near visual acuity was 0.11 for both groups (P = 0.91), with +1.43 diopters (D) for the multifocal group and +2.35 D for the monofocal group (P = 0.0001). Spectacle dependency differed significantly between the two groups, with 21 patients (51%) of the monofocal group commonly requiring an additional plus add for near tasks compared with 5 patients (9%) in the multifocal group (P = 0.001). Stereopsis was superior in the multifocal group (P < 0.001), with 42 (77%) and 33 (61%) patients with a multifocal IOL responding positively to the Lang and Titmus tests, respectively. In the monofocal group; only 20 (48%) and 9 (22%) patients gave correct answers. CONCLUSIONS Multifocal IOL implantation is a viable alternative to monofocal pseudophakia in prepresbyopic patients with unilateral cataract.