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Biomedical subjects

H Laqua

Publications and source records attributed to H Laqua.

At least 19 recordsLinked to original sources
PubMed2006

Detection of Treponema pallidum in the vitreous by PCR.

BACKGROUND: Ocular involvement of syphilis still poses a clinical challenge due to the chameleonic behaviour of the disease. As the serodiagnosis has significant limitations, the direct detection of Treponema pallidum (TP) in the vitreous represents a desirable diagnostic tool. METHODS: Real-time polymerase chain reaction (PCR) for the detection of TP was applied in diagnostic vitrectomies of two patients with acute chorioretinitis. Qualitative verification of TP by real-time PCR and melting point analysis according to a modified protocol was ruled out. Patients underwent complete ophthalmological examination with fundus photographs, fluorescein angiography, serological examination, antibiotic treatment and follow-up. RESULTS: In two cases of acute chorioretinitis of unknown origin, real-time PCR of vitreous specimens of both patients provided evidence of TP and was 100% specific. Initial diagnosis of presumed viral retinitis was ruled out by PCR of vitreous specimen. Patients were treated with systemic antibiotics and showed prompt improvement in visual function and resolution of fundus lesions. CONCLUSIONS: With real-time PCR, detection of TP in the vitreous was possible and delivered a sensitive, quick and inexpensive answer to a disease rather difficult to assess. In cases of acute chorioretinitis, the use of PCR-based assays of vitreous specimens in the diagnostic evaluation of patients is advisable. Although syphilitic chorioretinitis is a rare disease, PCR should include search for TP, as diagnostic dilemmas prolong definitive treatment in a sight-threatening disease.

Adult↗
PubMed2006

[Selective retina therapy in patients with diabetic maculopathy].

Selective Retina Therapy (SRT) is a new laser treatment that selectively targets the retinal pigmen epithelium (RPE). In this study, we treated 39 patients presenting with nonischemic, focal and focal-diffuse diabetic maculopathy with SRT. In the main. the results indicate that SRT had stabilizing effects on visual acuity, angiographic leakage, lipid exudation, and foveal retinal thickness. SRT is safe and is especially useful for treating pathologies that are located close to the fovea, which cannot be treated with conventional argon laser photocoagulation.

Aged↗
PubMed2006

Selective retina therapy in patients with central serous chorioretinopathy.

BACKGROUND: Central serous chorioretinopathy (CSC) is a disease with a localized breakdown of the outer blood-retinal barrier located within the retinal pigment epithelium (RPE) causing subretinal fluid accumulation. Selective retina therapy (SRT) is a new, minimally invasive laser technology that has been designed to selectively target the RPE. SRT spares retinal tissue. METHODS: Twenty-seven eyes of 27 patients with active CSC were treated with SRT using a pulsed double-Q-switched Nd-YLF prototype laser (lambda=527 nm, t=1.7 micros). At baseline, best-corrected visual acuity was determined and fluorescein angiography and optical coherence tomography were performed. The patients were followed for up to 3 months. RESULTS: After 4 weeks 85.2% of patients showed complete resolution of subretinal fluid and in 96.3% there was no leakage visible on fluorescein angiography. After 3 months 100% of patients demonstrated no subretinal fluid and 100% of patients had no leakage activity on fluorescein angiography. Visual acuity, 20/40 at baseline, improved to 20/28 after 4 weeks and to 20/20 after 3 months. CONCLUSION: SRT is a safe and effective treatment for active CSC. Especially if the RPE leak is located close to the fovea, SRT is the favoured therapeutic option. We recommend earlier treatment of patients with acute CSC in order to prevent development of chronic changes due to CSC with irreversible anatomical and functional damage. SRT might be considered as a first-line treatment for active CSC.

Adult↗
PubMed2006

Secondary paracentral retinal holes following internal limiting membrane removal.

AIM: To report on a new postoperative finding after delamination of the internal limiting membrane (ILM) for the treatment of different macular pathologies. METHODS: Seven patients are described with paracentral retinal holes, all located temporally to the macula, which developed after pars plana vitrectomy and uncomplicated ILM removal for cystoid macular oedema (n = 3), macular pucker (n = 3), and macular hole (n = 1) with the use of indocyanine green (n = 4), trypan blue (n = 1), triamcinolone acetonide (n = 1), or without dye (n = 1). CONCLUSION: The use of dyes has been incriminated in causing iatrogenic damage to the retina. In this series, the new observation of retinal holes in the macular area is thought to be related to the removal of the ILM itself. The authors speculate that ILM delamination may cause a retinal weakening by Müller cell damage; this may be followed by a structural breakdown and, consequently, hole formation.

Adult↗
PubMed2003

[The influence of a new surface treatment of silicone intracoular lenses with fluoralkylsitan on the adherence of endophthalmitic bacteria in vitro]].

INTRODUCTION: Dynasilan is a fluoroalkylsilan which is able to bind to surface active molecules of intraocular lenses (IOLs), thereby offering a new option for surface modification of silicone lenses. The purpose of this in vitro study was to investigate the influence of this new surface treatment on the adherence of two typical endophthalmitis-inducing bacteria ( Staphylococcus epidermidis, Propionibacterium acnes). MATERIALS AND METHODS: A total of 14 Dynasilan-treated and 14 untreated silicone lenses were incubated at 37 degrees C for 24 h in brain heart infusion broth (10(8) CFU/ml) either with Staphylococcus epidermidis or with Propionibacterium acnes for 1 h. Subsequently, the adherent bacteria were resuspended using ultrasonification at 35 kHz for 3 x 45 s. After a dilution series and incubation at 37 degrees C for 24 h or 3 days the colonies were counted. RESULTS: On untreated IOLs incubated with Staphylococcus epidermidis the average number of bacteria was 3.6 x 10(7)/ml, and on treated IOLs the number of counted colonies was reduced to 1.09 x 10(7)/ml. Incubated with Propionibacterium acnes the average number of adherent bacteria on untreated IOLs was 4.75 x 10(4)/ml and on modified IOLs the number was reduced to 2.94 x 10(4)/ml. CONCLUSION: Dynasilan surface treatment may reduce the adherence of Staphylococcus epidermidis and Propionibacterium acnes on silicone intraocular lenses. Further studies regarding the stability of this treatment, its biocompatibility and influence on lens epithelial cell adhesion are in progress.

Bacterial Adhesion↗
PubMed2003

[Vitreous body floaters and vitrectomy with full visual acuity].

PURPOSE: To evaluate the role of vitrectomy in patients with visually disturbing vitreous body floaters and full visual acuity (VA). METHODS: A total of 9 eyes from 8 patients (2 female, 7 male, median age 57 years) with a preoperative VA of 1.0 were analysed retrospectively. The median duration of symptoms was 12 months. In all eyes a pars plana vitrectomy was performed. The median follow-up period was 13 months. RESULTS: No intraoperative or postoperative complications were observed. In all patients vision improved subjectively and objective VA remained unchanged. In 2 out of 5 phacic patients a cataract extraction was performed during the follow-up period. CONCLUSIONS: In a selected group of patients vitrectomy can improve subjective vision even in eyes with full objective VA. A critical patient selection with respect to psychological criteria and the individual risk of vitrectomy is extremely important.

Adult↗
PubMed2003

[Retinal photoablation with the Erbium:YAG laser. Initial experimental results for traction-free removal of tissue].

BACKGROUND: To investigate the potential of an Er:YAG laser for precise and traction-free removal of retinal layers in vitro. MATERIAL AND METHODS: Retinal ablation in porcine retinal explants was performed using a free running Er:YAG laser focused either into a low-OH quartz fiber or a sapphire fiber. The explants were treated under air or perfluorodecaline (PFD). The ablation depth was evaluated by optical coherence tomography (OCT) and histology sections. RESULTS: A radiant exposure of 5.0 J/cm(2) under air and PFD resulted in complete transsection of the neurosensory retina. Between 3.5 and 2.0 J/cm(2) the ablation depth and the defect patterns varied markedly and adjacent thermal zones areas were seen. Below 2.0 J/cm(2) no defects could be created in air, whereas under PFD the ablation extended into the ganglion cell layer. Ablations using a sapphire fiber and 2.0 J/cm(2) showed a significantly higher reproducibility of ablation depth, and homogeneous defect patterns limited to the nerve fiber layer could be produced without thermal damage. CONCLUSIONS: The Er:YAG laser system with a low-OH quartz fiber allowed ablation of inner retinal layers in vitro, but revealed a variable ablation depth and low reproducibility.However, a sapphire fiber showed markedly improved results. Therefore its use during vitreoretinal surgery seems possible not only as a cutting device but also as a tool for the ablation of fine retinal structures.

Animals↗
PubMed2003

[Photodynamic therapy: extended indication].

OBJECTIVE: Evaluation of efficacy of photodynamic therapy (PDT) for classic choroidal neovascularization (CNV) beyond the common indication. METHODS: A group of 256 patients was treated with photodynamic therapy from January to December 2000. Ten of these patients had a predominantly classic CNV due to angioid streaks (5), parafoveal telangiectasia (2), or chorioretinitis (3). In two patients an idiopathic origin of the CNV was presumed. Another 21 patients showed a juxtafoveal classic membrane (12) or a recurrence after laser photocoagulation (9). Visual acuity was evaluated, also in correlation to age and CNV size. Continuous follow-up of CNV and leakage size was performed with fluorescein angiography. RESULTS: Overall 85% of the patients showed visual stabilization or improvement during an average observation period of 10.5 months. A correlation was found between age and visual improvement favoring younger patients; however, no correlation was found between visual improvement and CNV size. CNV and leakage size decreased moderately over the 9-month follow-up from 1.81/3.45 mm(2) to 1.61/2.60 mm(2). CONCLUSION: PDT shows efficacy for classic choroidal neovascularization beyond the common indication.

Choroidal Neovascularization↗
PubMed2002

Transscleral optical coherence tomography: a new imaging method for the anterior segment of the eye.

OBJECTIVE: To present a new imaging method for the anterior segment of the eye. METHODS: Transscleral optical coherence tomographic images were generated in healthy volunteers using a slitlamp-adapted prototype equipped with a superluminescence diode with an infrared wavelength of 1310 nm. RESULTS: The optical coherence tomographic system used allowed penetration of human sclera in vivo and high-resolution, cross-sectional imaging of the anterior chamber angle and the ciliary body. CONCLUSION: The 1310-nm optical coherence tomographic image shows a significant potential as a noninvasive diagnostic tool for the anterior segment of the eye.

Anatomy, Cross-Sectional↗
PubMed2001

Internal transport barrier triggered by neoclassical transport in W7-AS.

The three-dimensional magnetic configuration of a stellarator offers two specific mechanisms for a transition to improved particle and energy confinement. One route goes through the so-called electron-root confinement regime, which leads to a reduction of neoclassical transport via strong radial electric fields. In this Letter evidence for a second route is presented. It opens due to the layer of a strongly varying radial electric field which is present in the transitional region from neoclassical electron to ion-root confinement. This type of improvement acts on turbulent transport.

Journal Article↗
PubMed2001

Quantitative distribution of glycosaminoglycans in young and senile (cataractous) anterior lens capsules.

The ocular lens is surrounded by the lens capsule, which is an elastic and unusually thick basal membrane. Anionic sites are thought to be responsible for charge-selective permeability barriers in basal membranes. We have used cationic colloidal gold as a tracer for anionic binding sites to investigate the distribution of glycosaminoglycans in young and senile (cataractous) lens capsules. Using electron microscopy, combined with the cationic colloidal gold post-embedding technique, glycosaminoglycans were localized distinctively in a continuous layer immediately apposed to the lens epithelium, which has been referred to as the lamina lucida. The amount of gold particles decreased from the internal (lenticular) side of the capsule, toward the center, followed by an increase of label intensity toward the external (humoral) side. The humoral surface is characterized by a highly anionic layer measuring 1.5--4 micro m. Immunofluorescence microscopy localized three main types of glycosaminoglycans (heparan-, chondroitin- and dermatan sulfate) within this distinctive layer. Quantitative electron microscopy demonstrated reduced amounts of glycosaminoglycans at the lenticular and humoral side of senile (cataractous) lens capsules. The distinctive spatial distribution of glycosaminoglycans in human lens capsules is discussed in terms of age-related structural and functional changes.

Adult↗
PubMed2001

[Biomorphometry of corneal epithelium with slit lamp-adapted optical coherence tomography].

INTRODUCTION: The purpose of this study was to evaluate the biomorphometry of the corneal epithelium with slitlamp-adapted optical coherence tomography (OCT). PATIENTS AND METHODS: In a clinical study, slitlamp-adapted OCT of the cornea was performed in 15 patients before and immediately after therapeutic corneal abrasion. Central corneal epithelium thickness measurements were compared to the pre- and postoperative central corneal thickness. RESULTS: Preoperatively, the corneal epithelium could be visualised from the highest OCT light reflections at the interfaces air-tear film and epithelium-Bowman's membrane. The preoperative mean geometrical central epithelial thickness determined with OCT ranged from 65 +/- 12 microns to 72 +/- 14 microns (45-92 microns). The mean difference of the pre- and postoperative central corneal thickness was 48 +/- 19 microns (9-79 microns). This resulted in a deviation from the direct epithelial thickness measurements of 26-33%. The reproducibility of the geometrical epithelial thickness was +/- 9 microns. CONCLUSIONS: Slitlamp-adapted OCT enabled a noncontact evaluation of the corneal epithelium. The difference between direct and indirect corneal epithelium thickness measurements could be related to the partial optical inclusion of the precorneal tear film and the Bowman's membrane. With some restrictions the biomorphometry of the corneal epithelium with slitlamp-adapted OCT seems to be a valuable technique to monitor therapeutical and refractive procedures of the cornea.

Adult↗
PubMed2001

[Is scleral buckling still current?].

We report a survey among German-speaking vitreo-retinal surgeons, considering their decisive factors and preferred surgical techniques in simple and complicated rhegmatogenous situations. In cases of simple retinal detachment conventional buckling surgery is the favoured surgical approach. Minimal-invasive techniques like the balloon operation or pneumatic retinopexy are chosen by less than 5% of the surgeons. For more complicated retinal detachments a strong trend towards primary vitrectomy becomes apparent. In difficult rhegmatogenous situations which are still treatable with conventional buckling procedures, 45% of surgeons prefer a primary vitrectomy and only 55% chose scleral buckel or encircling band procedures.

Attitude of Health Personnel↗
PubMed2001

[Conventional ablation surgery or primary vitrectomy in complicated retinal holes].

BACKGROUND: We retrospectively evaluated 100 difficult cases out of 803 consecutive eyes with retinal detachment in order to determine the best surgical procedure in cases with difficult break configurations such as multiple, large, and central holes. METHODS: We treated the eyes either with conventional buckling surgery (n = 60) encircling buckle (EB) plus sponge exoplant (SP) (n = 45) or multiple sponge exoplants (n = 15) or with primary vitrectomy (PV) (n = 40). From the 40 patients in the PV group, 10 underwent vitrectomy plus intraocular gas only, in the other cases an encircling band was used (n = 30). RESULTS: In the EB/SP group the retina was attached directly after surgery in 59/60 cases. During a mean follow-up of 14.5 months redetachment occurred in 4/60 cases. In the PV group the retina was attached in 37/40 cases after resorption of gas and during the mean follow-up of 9.3 months redetachment occurred in an additional 4/40 cases. Complications during surgery in the EB/SP group were retinal incarceration (n = 2) and subretinal hemorrhage (n = 2). In the PV group intraoperative complications included choroidal detachment (n = 1) and iatrogenic holes (15%). Postoperative complications were choroidal detachment in 6/60 vs 0/40, transitory increased intraocular pressure (30% vs 68%). Double vision, however correctable by means of prisms, occurred in 4/60 vs 0/40. CONCLUSIONS: The primary attachment rate is high and similar with both procedures. The spectrum of intra- and postoperative complications is however different between both groups.

Aged↗
PubMed2001

[Examination of the cornea using optical coherence tomography].

INTRODUCTION: This study evaluated the clinical use of optical coherence tomography (OCT) for two-dimensional representation of the cornea. PATIENTS AND METHODS: Noncontact slitlamp-adapted OCT was used in selected cases to evaluate pathologically altered corneas and to measure the central corneal thickness and curvature. RESULTS: OCT provided correlation between differences in reflection and morphological changes. Scar tissue resulted in hyper-reflective light scattering, whereas cystic lesions were hyporeflective. Precise biomorphometry also allowed representation of intrastromal and retrocorneal changes. Central corneal thickness measured by OCT yielded reproducible values and corneal curvature could be calculated from the optical signals of the corneal surface. CONCLUSIONS: OCT provides high-resolution representation of the cornea and exact evaluation of its morphology, thickness, and curvature. Due to the noncontact, simple, and rapid examination using the slitlamp the corneal OCT method is a promising additional diagnostic modality.

Adolescent↗
PubMed2001

Immunohistochemical and charge-specific localization of anionic constituents in pseudoexfoliation deposits on the central anterior lens capsule from individuals with pseudoexfoliation syndrome.

BACKGROUND: Pseudoexfoliation (PSX) syndrome is a degenerative systemic disorder that is characterized primarily by deposits of distinct fibrillar material on the surface lining the anterior and posterior chambers of the eye and is often associated with cataract and glaucoma. Although some components of the PSX material have been identified, the precise composition is obscure. METHODS: High-resolution scanning electron microscopy in conjunction with colloidal cationic gold labeling was used to localize anionic constituents at the surface of PSX aggregates. Transmission electron microscopy was applied for the immunocytochemical detection of glycosaminoglycans, and to monitor the charge-specific distribution of colloidal thorium dioxide and ferritin in PSX material. The specific binding of antibodies was confirmed by immunohistological staining of paraffin-embedded specimens. RESULTS: Paraffin-embedded tissue sections revealed immunoreactivity for keratan sulfate and dermatan sulfate proteoglycan within PSX material deposited on the surface of the anterior lens capsule. Post-embedding immunogold labeling of keratan sulfate demonstrated an intense label of PSX aggregates primarily associated with mature PSX fibrils, whereas dermatan sulfate proteoglycon appeared to be present in low quantities. Additionally, keratan sulfate was found at the humoral periphery of the lens capsules. To further investigate the distribution of anionic sites in PSX material, we used cationic colloidal tracers of different size, such as gold, thorium dioxide and ferritin. PSX aggregates exhibited a strong negative charge, resulting very likely from glycosaminoglycan chains of proteoglycans. The density of anionic sites was higher at the interfibrillar matrix. Lens capsules associated with PSX material revealed a diminished accumulation of cationic ferritin at the humoral surfaces. CONCLUSIONS: Increased amounts of different glycosaminoglycans identified in PSX material suggest an important role of proteoglycans for the pathogenic pathway in PSX.

Aged↗