Experimental femtosecond laser-assisted nanosurgery of anterior lens capsule.

PURPOSE: To investigate femtosecond laser-assisted nanosurgery of the anterior lens capsule in a prospective in vitro study. METHODS: Eight anterior lens capsules obtained during conventional phaco surgery were irradiated with a nonamplified 80-MHz near-infrared 800-nm titanium:sapphire femtosecond laser. Line intratissue laser cuts were examined by femtosecond multiphoton laser scanning microscopy (MLSM) and transmission electron microscopy (TEM). RESULTS: Speed parameters of the laser beam, laser ablation time, and pulse power determined the width of the lesions, which ranged from 220±40 nm (SD) to 1.49±0.15 µm. Both MLSM and TEM revealed minimal collateral alterations in the tissue surrounding the laser cuts. CONCLUSIONS: Nonamplified near-infrared femtosecond laser pulses at low pulse energies may be a promising strategy for precise noncontact nanosurgery of the anterior lens capsule with minimal collateral damage to surrounding tissue. High-resolution MLSM offers 3-dimensional, noninvasive, nondestructive imaging at submicrometer resolution within seconds before and after ablation.

In vitro femtosecond laser-assisted nanosurgery of porcine posterior capsule.

PURPOSE: To investigate femtosecond laser-assisted nanosurgery of the posterior capsule in a prospective in vitro animal study. SETTING: Department of Ophthalmology and Eye Hospital, University of Saarland, Homburg, and Fraunhofer Institute for Biomedical Engineering, St. Ingbert, Germany. METHODS: The posterior capsules of 12 porcine eyes were irradiated with a nonamplified 90 MHz near-infrared 750 nm titanium:sapphire femtosecond laser. Intratissue and superficial laser cuts of laser-ablated (5 capsules) and control (1 capsule) specimens were examined by femtosecond multiphoton laser scanning microscopy (MLSM) and transmission electron microscopy (TEM). RESULTS: Laser exposure time and pulse power determined the width of the lesions, which ranged from 0.69 microm+/-0.19 (SD) to 2.81+/-0.5 microm. Both MLSM and TEM revealed minimal collateral alterations in the tissue surrounding the laser cuts. CONCLUSIONS: Nonamplified near-infrared femtosecond laser pulses at low pulse energies may be a promising strategy for precise lamellar noncontact nanosurgery of the posterior capsule, with minimal structural collateral damage to surrounding tissue. High-resolution MLSM offers 3-dimensional, noninvasive, nondestructive imaging at submicrometer resolution within seconds before and after ablation.

In vitro noncontact intravascular femtosecond laser surgery in models of branch retinal vein occlusion.

PURPOSE: To investigate intravenous femtosecond laser surgery in models of branch retinal vein occlusion. MATERIALS AND METHODS: Non-amplified near infrared femtosecond laser was used to ablate polyamide sutures and human hairs inserted into the vascular lumina of porcine retinal veins in vitro. Specimens were subjected to multiphoton laser scanning microscopy and electron microscopy. RESULTS: Regular laser cuts within sutures and hairs were detected with laser microscopy and electron microscopy. Neither laser microscopy nor histology revealed collateral damage of the vascular wall. CONCLUSIONS: Non-amplified femtosecond lasers may allow precise atraumatic non-contact intravenous retinal surgery controlled by high-resolution imaging of the target.

Influence of fibronectin on the adherence of Staphylococcus epidermidis to coated and uncoated intraocular lenses.

PURPOSE: To determine the effect of the modification of intraocular lens (IOL) surface properties on the adhesion of Staphylococcus epidermidis caused by fibronectin (FN) as the predominant proadhesive glycoprotein of the eye's initial foreign body reaction. SETTING: University of Saarland, Homburg/Saar, Germany. METHODS: Eleven IOL types were tested. The IOLs were of poly(methyl methacrylate), acrylate, or silicone. Some were surface modified with heparin or polysaccharide coating. The IOLs, unadsorbed or preadsorbed with fibronectin (FN), were incubated with [(3)H]-thymidine-labeled S epidermidis Rp62a, and the amount of adherent microorganisms was determined. RESULTS: Attachment of S epidermidis adhesion to various types of IOLs, both unadsorbed and FN precoated, varied significantly. The attachment to highly adhesive IOLs was almost 4-fold greater than that to low-adhesive IOLs. Attachment to FN precoated IOLs was generally enhanced compared with attachment to unadsorbed IOLs. Heparin surface modification resulted in no or a modest reduction in bacterial adhesion compared with unmodified IOLs. Bacterial adhesion was highly statistically significantly less on IOLs with polysaccharide surface modification. CONCLUSIONS: There was significant variability in S epidermidis adhesion to IOLs as a function of design, material, surface modification, and FN preadsorption. Application of the findings may foster new developments to further reduce the major complication in cataract surgery, infective endophthalmitis.

Expression of ABC-transporters in human corneal tissue and the transformed cell line, HCE-T.

PURPOSE: The aim of this study was to elucidate the expression pattern of transport proteins relevant to drug absorption in human cornea and to assess the human corneal epithelial cell line, HCE-T, regarding its use as an in vitro model for drug-absorption studies. METHODS: Human corneal tissue and HCE-T cells were examined for the expression of P-glycoprotein (P-gp/MDR1), multidrug resistance-associated protein 1 (MRP1), multidrug resistance-associated protein 2 (MRP2), lung resistance-related protein (LRP), and breast cancer-resistance protein (BCRP), using reverse transcriptase-polymerase chain reaction and immunofluorescence microscopy. Moreover, transporter activity was measured by bi-directional flux studies across excised human cornea and HCE-T cell layers using a P-gp/MDR1 substrate, rhodamine 123 (Rh123). RESULTS: Transport studies of Rh123 revealed no significant differences in fluxes in the apical-to-basolateral and basolateral-to-apical directions across excised human corneas or HCE-T cell layers, suggesting the absence or insignificant, if any, participation of P-gp/MDR1 to Rh123 fluxes. Of all the transporter proteins under investigation, only LRP was found in human cornea. By contrast, a signal for LRP was not found in HCE-T, but the expression of MRP1, MRP2, and BCRP could be confirmed. Of note is the lack of P-gp/MDR1 expression in any of the specimens we examined. CONCLUSIONS: Only a limited array of ABC-transporters is functionally expressed in human cornea. The expression pattern of HCE-T cells appears to be widely different from that of the native corneal tissue. Hence, the in vitro model of human cornea, HCE-T, should be used with much caution when predicting transport rates across the human corneal epithelial barrier in vivo.

Prevalence of ocular manifestations in hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a systemic disorder of the fibrovascular tissue. Few data have been published on the frequency of ophthalmologic manifestations. The aim of this study was to assess this frequency. METHODS: A prospective observational cross-sectional study was conducted in a multitude of clinical practices and in a tertiary referral center. The main outcome measure was the number of vascular malformations detected by an ophthalmologic inspection of the retina and the conjunctivae in both eyes in a random sample of patients with HHT. RESULTS: No retinal telangiectases were observed in any of the 75 patients (150 eyes) examined. Conjunctival telangiectases were detected in 28 of 74 patients (47 of 148 eyes). CONCLUSIONS: The prevalence of retinal telangiectases seems to be lower than 1/75 (< 1.3%). This data does not justify screening procedures to detect retinal telangiectases. Ophthalmologists should be aware of the symptoms of HHT and its systemic character.

Antiphospholipid antibodies in ocular arterial and venous occlusive disease.

PURPOSE: It was the aim of this study to evaluate antiphospholipid antibodies (APA), i.e. lupus anticoagulants (LA) and anticardiolipin (ACA) IgG and IgM, in ophthalmic occlusive disease. METHODS: Over a 3.5-year period, APA were evaluated in 368 patients. RESULTS: Eighty-six patients (23.4%), compared to 5% in the general population, tested positive for APA. APA did not differ significantly between patients with venous (20.6%) or arterial (25.5%) occlusive disease. This included 93 patients with central retinal vein occlusion (18% APA positive), 67 with retinal branch vein occlusion (24% APA positive), 41 with central retinal artery occlusion (22% APA positive), 53 with retinal branch artery occlusion (32% APA positive), 71 with anterior ischemic optic neuropathy (23% APA positive), 12 with posterior ischemic optic neuropathy (33% APA positive) and 31 patients with amaurosis fugax (23% APA positive). Excluding patients with accepted main risk factors, APA were positive in 15.3% of 85 patients. CONCLUSION: The high APA prevalence confirms its relevance in ocular occlusive disorders.

Slow-stimulated multifocal ERG in high- and normal-tension glaucoma.

PURPOSE: To study the ability and sensitivity of the slow stimulation multifocal ERG (mfERG) to detect glaucomatous damage. METHODS: Right eyes of 20 patients with normal-tension glaucoma (NTG), 15 patients with high-tension glaucoma (HTG) and 15 healthy volunteers underwent testing with the mfERG (VERIS 4.1). The central 50 degrees of the retina were stimulated by 103 hexagons (m-sequence: 2(13)-1, Lmax: 100 cd/m(2), Lmin: 1 cd/m(2), background: 50 cd/m(2)). Each m-sequence step was followed by 3 black frames (Lmax: < 1 cd/m(2)). Five response averages of the first order response component (KI) were analyzed: the central 7.5 degrees and the 4 adjoining quadrants. The amplitudes from the first minimum, N1, to the first maximum, P1, and from P1 to the second minimum, N2, were analyzed as well as the latencies of N1, P1, N2 and the latencies of 3 multifocal oscillatory potentials (mfOPs) with their maxima at about 73, 80 and 85 ms. RESULTS: For each parameter the percentage of deviation from the mean of the control group was calculated. These values were then added for each individual to form a deviation index (DI). Seventeen patients (85.0%) with NTG and 3 patients (20.0%) with HTG showed a DI outside the normal range. The major changes were observed in the mfOPs of the NTG patients. MfOPs were then selectively filtered at 100-300 Hz and their scalar product was analyzed over an epoch of 68-105 ms. This confirmed that mfOPs differed significantly from the control in the central 7.5 degrees and, for NTG, in the nasal field. With a logistic regression analysis the mfOPs had a sensitivity to differentiate 85% of the NTG patients and 73% of the HTG patients from normal. CONCLUSIONS: Under these conditions, the slow-stimulated mfERG can detect glaucomatous dysfunction in NTG (85.0%). The differences observed between NTG and HTG are in support of a different underlying pathomechanism.

Influence of dopamine deficiency in early Parkinson's disease on the slow stimulation multifocal-ERG.

PURPOSE: In animal studies intravitreal injection of tetrodotoxin (TTX) results in mfERG waveform changes similar to those observed in glaucoma. As TTX blocks amacrine as well as ganglion cells, there is still a question regarding the underlying cell population responsible for these changes in waveform. In an attempt to assess the contribution of the amacrine cells to these changes, a mfERG was obtained from patients with Parkinson's disease as some amacrine cells are mediated by dopamine, a substance lacking in Parkinson's. METHODS: Eight patients with early Parkinson's disease underwent ophthalmologic examination, testing of contrast sensitivity and electrophysiological examination according to ISCEV standard at least 12 h following their last medication with Dopamine. A slow stimulation mfERG was obtained with a stimulus base interval of 53.3 ms and with a stimulus base interval of 106.6 ms. During MF-ERG recordings 103 hexagons stimulated the central 50 deg of the retina simultaneously and independently (m-sequence 2(13), L(max): 200 cd/m(2), approximately 100% contrast). RESULTS: Contrast sensitivity and ISCEV standard electrophysiological testing was unremarkable. When the mfERG was analyzed, only four patients had an adequate signal-to-noise ratio to allow further data analysis - one of whom was diagnosed with a multi system atrophy in retrospect. The first order response component was analyzed at a filter setting of 10-300 Hz and at 100-300 Hz (OPs) and compared to mfERGs of a control group. On average, in patients, the amplitude of N1P1 was slightly lower in the central and nasal response averages. When the three OPs at a latency of 72-89 ms were analyzed in the 53.3 ms base interval recording, the most marked difference in amplitude was observed in the superior nasal response average of the first OP. Here a mean amplitude of 1.3 nV/deg(2) in patients compared to a mean amplitude of 1.9 nV/deg(2) in the control group (P: 0.08). DISCUSSION: In contrast to our previous findings in NTG, there was a consistent presence of three OPs. Under the stimulus conditions applied, we did not find an influence of dopaminergic amacrine cells on the mfERG in our patients with moderate stages of Parkinsion's. The difficulties in obtaining an adequate signal-to noise ratio due to e.g. muscle artifacts even in Parkinson patients of moderate disease stages render a success of mfERG recording in patients with more advanced stages unlikely. The question of the influence of dopaminergic amacrine cells on the mfERG could possibly be addressed using MPDT in animal research.

Retinal perfusion response to a slow multifocal M-sequence flicker stimulation.

PURPOSE: To assess, if a slow multifocal stimulus (mfS) can provoke a perfusion response that can be measured with the Retinal Vessel Analyzer (RVA). METHODS: Seventeen eyes were examined. Pupils were dilated. A 120-second baseline recording was obtained with the RVA. The subject then turned to view an mfS for 56 s. The mfS consisted of 103 hexagons flickering according to an m-sequence with a stimulus base interval of 53.3 ms (L(max) = 100 cd/m(2), L(min) < 1 cd/m(2)). Immediately thereafter, the subject turned to the RVA, where measurements were resumed as soon as the same retinal vessel was targeted and continued for 104 s. Stimulation and recording was repeated twice. The diameter of a retinal vein and artery was measured for a length of at least 1 mm. The maximum vessel response was obtained by linear interpolation of the measured response within the 20 s following mfS. RESULTS: On average, veins dilated by 6.8% and arteries by 7% following mfS (p > 0.005). Such a dilatation could be observed in 9 veins and 7 arteries. Three venous and 2 arterial measurements did not show a dilatation following mfS. However, 13 of 34 measurements could not be analyzed due to signal problems or because the time from the end of mfS and the uptake of measurement exceeded 20 s. CONCLUSION: This slow multifocal ERG stimulus results in a dilatation of arteries and veins that can be measured with the RVA. Coupling an mfS to the RVA has the potential to topographically map changes in retinal perfusion in relation to the respective retinal area stimulated. When implementing the mfS into the RVA setup in order not to lose time due to the refixation in the RVA following mfS, one is required to take the transient nature of this perfusion change into consideration.

Follow up in open angle glaucoma. A comparison of static perimetry and the fast stimulation mfERG. Multifocal ERG follow up in open angle glaucoma.

PURPOSE: To compare changes in the mfERG to visual field changes observed in OAG. METHODS: Twenty-nine eyes with OAG were included. Visual fields (Octopus d32) and mfERGs (VERIS) were obtained at a mean interval of 9 months (SD 6 months). MfERG recording parameters were as follows: 103 hexagons stimulated the central 50 degrees. M-sequence 2--5, stimulus base interval 13.33 ms, Lmax 200 cd/m2, contrast 99%. First (KI) and second (KII) order response components were analyzed for the individual quadrants of the visual field and compared to the corresponding mean deviation (MD) of the static perimetry. RESULTS: Changes in visual field parameters and changes in the mfERG did not differ significantly. Overall, as mean deviation increased there was a tendency for implicit times to increase and for amplitudes to decrease. However, over the follow up interval of 9 months only minor changes were observed. The second order response component correlated best with changes in MD (p < 0.05). These were the correlation between MD and KII N1 (r: 0.36) in the upper temporal field, between MD and KII N2 (r: 0.40) in the upper nasal field and between MD and KII P1 (r: 0.38) in the lower temporal field. When a subgroup of 10 eyes that had been tested at least 3 times over 16.8 months (SD 5.5) was examined there were still only minor changes observed in either parameter. CONCLUSION: While the changes over time in the mfERG and the visual field showed a reasonable correlation, changes observed in either parameter were extremely small over the time period observed, thus requiring a longer follow up and/or a more sensitive stimulation technique.

Influence of cataract on the multifocal ERG recording--a pre- and postoperative comparison.

To study the influence of cataract on the multifocal electroretinogram (mfERG), 18 patients underwent mfERG recordings prior to and following cataract surgery. The central 50 degrees of the retina were stimulated by 103 hexagons alternating independently between white and black according to a binary m-sequence. The frame rate was 75 Hz. The maximum luminance was 200 cd/m2, the minimum luminance < 1 cd/m2 with a mean luminance of 100 cd/m2. For each retinal location, the latencies of the first negative peak (N1), the first positive peak (P1) and the second negative peak (N2) as well as the amplitude from N1 to P1 and the amplitude from P1 to N2 of the first order response were obtained. Concentric ring averages around the foveal response were analyzed. Following cataract surgery, the mean amplitude of the response in the central four degrees increased from 37.83 to 42.37 for N1P1 (p = 0.019) and from 39.44 to 47.20 for P1N2 (p = 0.001). To reduce the influence of retest variability, each response average was divided by the recording's overall amplitude. For the central 4 degrees this ratio increased by 0.18 (p = 0.002) for N1P1 and by 0.27 (p < 0.001) for P1N2. Clouding of the optic media such as produced by cataracts has a slight but significant influence on the multifocal ERG.

[Prevalence of optic atrophy and associated ocular and systemic diseases in a department of paediatric ophthalmology]. / Prävalenz der Optikusatrophie und assoziierte okuläre und systemische Erkrankungen in einer kinderophthalmologischen Sprechstunde.

BACKGROUND: Optic atrophy is one of the most common causes of severe visual impairment in children. So far an analysis of ocular and systemic findings comparing patients with and without optic atrophy has not performed. PATIENTS AND METHODS: Ocular and systemic findings of a total of 1042 patients (examination of all patients in May 1995 [N = 485] and May 2001 [N = 557]) of the department of paediatric ophthalmology in Homburg/Saar were retrospectively evaluated and diagnoses of patients with and without optic atrophy were compared. Optic atrophy was diagnosed ophthalmoscopically and in 1/3rd of the patients by VEP as well. RESULTS: 18 % of all patients (N = 188; 87.2 % [N = 164] were children) had optic atrophy. Nearly half of these children were prematurely born (46.7 %). 53.2 % of patients with optic atrophy (N = 88) showed nystagmus (without atrophy: 10.7 %), especially sensory defect nystagmus. Median of visual acuity level was 0.2 with optic atrophy and 0.8 without. Albinism and buphthalmia were common findings. 69.5 % of all patients with optic atrophy suffered from systemic diseases (without atrophy: 25.2 %), especially mental retardation, neurologic findings and oculocutaneous albinism. In 10.4 % more than two systemic diagnoses could be found. 55.3 % of all the patients with optic atrophy were disabled, 31.9 % multiply disabled. CONCLUSIONS: Sequelae of prematurity, peripartal asphyxia and congenital brain damages are the main findings in patients with optic nerve atrophy. Such children are worst-case patients of any paediatric ophthalmology department with a high prevalence of severe visual impairment, mental retardation and multiple disability. Treatment in a specialised center is therefore necessary for an efficient therapy. In addition, the statistical survey shows that in children who survived the critical phases of prematurity secondary damages can lead to persistent impairment and to alterations of visual and general development.

[First steps with the Zeiss IOLMaster: A comparison between acoustic contact biometry and non-contact optical biometry]. / Erste Erfahrungen mit dem Zeiss-IOL-Master: ein Vergleich zwischen akustischer Kontaktbiometrie und kontaktfreier optischer Biometrie.

BACKGROUND: After having received an IOL-Master (Zeiss, Jena), we compared our actual standard method with this new device. PATIENTS, MATERIALS AND METHODS: From March to June 2002, we examined 175 consecutive cataractous eyes with the IOL-Master as well as with the acoustic biometry (Tomey AL-1000) combined to the Javal-Keratometer (Haag-Streit, Bern). The results were compared and analysed statistically. In all eyes, the intraocular lens to be implanted was chosen by means of the SRK/T formula, based on the measurements conducted with our standard method. The achieved postoperative refraction of 153 eyes obtained, at least six weeks after surgery, by the treating ophthalmologists, was communicated to us. RESULTS: Comparison of eye lengths as well as of the keratometric measurements showed good correspondence between the obtained measurements by both methods, acoustic biometry yielding significantly (p < 0.001) shorter axial lengths than the IOL-Master, and the Javal yielding significantly (p < 0.001) higher mean corneal refraction power than the IOL-Master. For both measurements, regression lines showed good coherence of the results over the refraction sample of our patients. Surprisingly, the accuracy of the refraction obtained postoperatively compared to the preoperative aim was better with our standard method compared to the IOL-Master. CONCLUSIONS: The predicted systemic differences in measurement results could be verified. No improvement in accuracy of our postoperative refraction prediction was achieved so far. The current advantage of the IOL-Master in our clinic is the substantial gain in time, as well as the fact that performance of the measurements may be delegated.

[Anatomical differences in optic nerve, chiasma and tractus opticus in human albinism as demonstrated by standardised clinical and MRI evaluation]. / Anatomische Unterschiede der Nervi optici, des Chiasmas und der Tractus optici bei normal- und hypopigmentierten Personen: eine standardisierte MRI- und fMRI-Untersuchung.

BACKGROUND: There has been long-standing clinical and electrophysiological evidence that in patients with albinism the visual pathways cross atypically: most fibres from one eye cross to the contralateral visual cortex. PURPOSE OF THE STUDY: to determine whether the size and configuration of the optic chiasm in human albinos is different from normally pigmented controls. PATIENTS AND METHODS: 17 patients (11 female, mean age 35.8 years) with oculocutaneous albinism underwent a standardised graded morphological and functional evaluation. Magnetic resonance images were reformatted to the region of the optic chiasm and analysed using observer-independent morphometry. In addition, fMRI of the visual cortex was performed during VEP analysis (1.5 Tesla Siemens Vision). Morphological and fMRT results were compared to an age-correlated group of n = 16 normally pigmented healthy volunteers with normal visual acuity and stereopsis. RESULTS: 65 % of the patients (n = 10) showed signs of dysplasia of the optic nerve head. Statistical morphometry showed distinct differences in chiasmal morphology between albinos and normally pigmented probands (smaller optic nerves, different angles of optical entry into the chiasm and of the beginning of the Tractus optici leaving the chiasm, overall chiasmal width and height). CONCLUSIONS: Optic nerve head anomalies are frequent in albinism and influence visual outcome. Size and configuration of the optic chiasm in human albinos is distinctly different from normally pigmented control persons and reflects the atypical crossing of optic fibres.

Detection of retinal dysfunction in vitelliform macular dystrophy using the multifocal ERG (MF-ERG).

Vitelliform macular dystrophy (VMD) is widely known for an abnormal EOG in the presence of a normal ERG. In this study the multifocal electroretinogram (MF-ERG) is described as an additional tool to detect retinal dysfunction in VMD. Three patients aged 30, 37 and 59 years with VMD and a visual acuity of OD: 0.4; OS 0.05 (patient 1), 1.25 OU (patient 2) and OU: 0.6 (patient 3) underwent additional electrophysiological testing with the MF-ERG. A multifocal-ERG of the central 50 degrees of the retina was obtained using the VERIS-system. During recording 103 hexagons flickered according to a binary m-sequence of 2(15). Mean luminance was 100 cd/m2, contrast was set at 99%. The MF-ERG recordings were compared to age matched control groups. In all three patients the MF-ERG of the central 6 degrees showed reduced amplitudes for N1P1 (first negative peak to first positive peak) and for P1N2 (P1 to the second negative peak). Implicit times were not affected. Therefore the MF-ERG can detect focal retinal dysfunction in VMD which would not be apparent in the summed retinal response recorded with the ganzfeld ERG. In contrast to other diseases, amplitudes rather than implicit times seem to be affected in the MF-ERG of vitelliform macular dystrophy.

Malignant glaucoma due to drug-related angioedema.

PURPOSE: To report postsurgery angioedema resulting in malignant glaucoma. Interventional case report. METHODS: Three hours after uncomplicated cataract surgery on the right eye, a 61-year-old woman developed angioedema with swelling of the parapharyngeal tissue. Visual acuity deteriorated, and tonometry revealed an intraocular pressure of 60 mm Hg, with shallow anterior chambers, in both eyes. RESULTS: Ultrasound showed choroidal effusion on both eyes. Intraocular pressure could only be controlled surgically by procedure to deepen the anterior chamber. The angioedema regressed after withdrawal of candesartan, an angiotensin II antagonist that the patient had taken for 1 year. CONCLUSIONS: Angioedema without urticaria is well documented in patients receiving angiotensine-converting enzyme inhibitors or angiotensin II antagonists. Drug-related angioedema may lead to a choroidal effusion syndrome with malignant glaucoma. Surgical intervention may trigger angioedema. Most important in treatment is withdrawal from the implicated medication and control of intraocular pressure.