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Biomedical subjects

H Laqua

Publications and source records attributed to H Laqua.

At least 55 records · Page 3Linked to original sources
PubMed1999

Systemic levels of lidocaine after intracameral injection during cataract surgery.

PURPOSE: To evaluate the systemic concentrations of lidocaine after intracameral injection of a 1% solution during cataract surgery and the safety of this application mode. SETTING: Department of Ophthalmology, Medical University of Lübeck, Lübeck, Germany. METHODS: This prospective study included 10 patients who had phacoemulsification and posterior chamber lens implantation with a self-sealing scleral tunnel incision. Topical anesthesia was achieved using cocaine 10% eyedrops combined with 0.5mL of unpreserved lidocaine 1% injected into the anterior chamber. Blood samples were taken from all patients at predetermined intervals before and during the procedure. Consecutive analysis for lidocaine was performed with gas chromatography. RESULTS: In all samples, serum lidocaine concentrations were below a minimum detectable level of 100 ng/mL. No local or systemic intraoperative or postoperative complications were noted. CONCLUSIONS: Intracameral injection of 0.5 mL lidocaine 1% revealed no systemic therapeutic concentrations. In patients in whom other forms of needle-delivered local anesthesia are contraindicated, intracameral injection of lidocaine should be considered to enhance topical anesthesia.

Adult↗
PubMed1999

Treatment of traumatic cyclodialysis with vitrectomy, cryotherapy, and gas endotamponade.

An aphakic patient with severe chronic hypotony had an alternative treatment of a traumatic cyclodialysis cleft: a 3-port pars plana vitrectomy, cryotherapy of the cleft, and fluid-gas exchange with subsequent supine positioning. The therapeutic principle was mechanical apposition of the detached ciliary muscle to the scleral spur by the gas bubble and scar induction by cryotherapy. Intraocular pressure increased to within normal ranges, and visual acuity improved over a 15 month follow-up.

Air↗
PubMed1999

Use of O44 as a solvent for silicone oil adhesions on intraocular lenses.

PURPOSE: To describe a solvent that removes silicone oil adhesions on intraocular lenses (IOLs). METHOD: The solvent O44 is a partially fluorinated alcane that dissolves silicone oil. Silicone oil adhesions on silicone and poly(methyl methacrylate) IOLs were treated with O44. The extent of silicone oil adhesions and the effectiveness of O44 were studied by gross microscopy. RESULTS: The solvent O44 removed silicone oil adhesions from both IOL types. CONCLUSION: The substance O44 may be a successful intraoperative tool to remove silicone oil IOL adhesions, avoiding IOL explantation.

Hydrocarbons, Fluorinated↗
PubMed1999

Continuous-wave diode laser thermokeratoplasty: first clinical experience in blind human eyes.

PURPOSE: To evaluate the safety and stability of laser thermokeratoplasty (LTK) with a continuous-wave diode laser in blind human eyes and to optimize parameters for a study in sighted eyes. SETTING: Department of Ophthalmology, Medical University Lübeck, Germany. METHODS: A continuous-wave diode laser was set to emit radiation with a wavelength of 1.854 microns (Group 1, n = 4) or 1.870 microns (Group 2, n = 4) and 100 to 150 mW power for 10 seconds. A focusing handpiece was coupled with an application mask and fixed by partial vacuum to the conjunctiva or cornea. The radiation was focused into the corneal stroma between 400 and 600 microns in Group 1 and set to 1000 microns in Group 2. Eight (Group 1, single ring) or 16 (Group 2, double ring) coagulations were applied. RESULTS: The refractive change increased with higher laser power and smaller ring diameters. Two rings of coagulations provided higher and more stable refractive changes of up to 5.66 diopters (D) than a single ring. The refractive effect stabilized between 3 and 6 months postoperatively. At 1 year, mean refractive change was +0.99 D +/- 0.39 (SD) in Group 1 and +2.32 +/- 2.24 D in Group 2. Extensive endothelial damage occurred in Group 1 but was minimal in Group 2. CONCLUSIONS: Diode LTK was used to treat hyperopia safely and effectively. Regression occurred mainly in the first 3 postoperative months. With a wavelength of 1.870 microns, corneal endothelial damage was limited.

Adult↗
PubMed1999

Preparation of autologous platelets for the ophthalmologic treatment of macular holes.

BACKGROUND: Platelet concentrates were recently used for ophthalmologic treatment of macular holes. This strategy was investigated to define standardized blood bank components. STUDY DESIGN AND METHODS: Two different, highly concentrated autologous platelet components, one from whole-blood preparation and the other from plateletpheresis, were evaluated. In the first procedure, platelet-rich plasma was obtained from 250 mL of whole blood. After storage for 20 hours, platelet-rich plasma was concentrated in a second centrifugation step and adjusted to 10 x 10(9) platelets per mL. In the second procedure, platelets were collected by apheresis, stored overnight, centrifuged, and adjusted to 20 x 10(9) platelets per mL. The respective component was instilled during vitrectomy and gas tamponade in patients with stage II to IV macular holes. Patients were followed for 9 months. RESULTS: With regard to the various preparation procedures and final concentrations of platelets in the components, no differences in wound healing were observed. An anatomic closure of the macular hole was achieved in 18 of 19 treated patients. Visual acuity improved in 14 patients. CONCLUSION: Both types of highly concentrated platelet components were effective in achieving high closure rates of macular holes. These autologous platelet components possess the quality standard of blood bank components and could be of great benefit for initiating wound healing in other clinical settings.

Adult↗
PubMed1999

[O44--a solvent for silicone oil adhesions on intraocular lenses].

AIM: To examine the efficiency of O44, a partial fluorinated octane, as a solvent for silicone oil adhesions on intraocular lenses. MATERIALS AND METHODS: After placing silicone- and PMMA-lenses in silicone oil, the adhesions were treated with O44. The extent of silicone oil adhesions and the effectiveness of O44 were studied by gross microscopy by scanning electrone microscopy (SEM) and combined energy dispersive spectrometry (EDX). Furthermore an explanted silicone lens with oil adhesions was treated with O44 and examined. To simulate the effect of adhesion proteins PMMA- and silicone lenses were placed in silicone oil and human plasma. RESULTS: With EDX it was possible to prove that O44 is able to remove silicone oil adhesions from PMMA-lenses. The removal from an explanted silicone lens by O44 could be demonstrated by light microscopy. Silicone oil adhesions on intraocular lenses (IOL's) in vitro showed a different oil coverage than the IOL in vivo. Silicone lenses in vitro were often covered by a homogenous oil film and therefore the demonstration of the silicone adhesions and of the efficacy of O44 was difficult. The adhesions of IOL's placed additional in human plasma did not show any differences. CONCLUSIONS: O44 may be a successful intraoperative tool to remove silicone oil adhesions avoiding explantation of silicone oil contaminated IOL's. Silicone oil adhesions in vivo seem to be influenced by adhesive proteins.

Efficiency↗
PubMed1999

Macular injury by a military range finder.

OBJECTIVE: The authors report the clinical findings of a civilian patient who unintentionally looked into the laser beam of a military range finder. Detailed information on the range finder is given. The objective is to illustrate the potential danger of such devices and to give detailed information on the device, the clinical findings associated with exposure, and the laser-tissue interaction mechanism. METHODS: The patient was examined with fluorescein angiography, indocyanine green angiography, microperimetry, and optical coherence tomography, both in the acute stage (2 hours) and 4 weeks later. Fluorescein angiography was performed again 4 months later. A total of 100 mg prednisone tapered over 9 days was prescribed. Additionally, 50 microg tissue plasminogen activator (TPA) and 0.5 mL pure C2F6 were injected in the vitreous. RESULTS: In the acute phase, hemorrhage was located beneath the retina, primarily beneath the retinal pigment epithelium. Retinal defects as seen initially over the subretinal blood were reduced after 4 weeks, but a retinal defect ranging from the lasered site toward the fovea remained. Visual acuity slightly increased from 20/100 to 20/63 after 4 weeks. Indocyanine green angiography showed a large hypofluorescent spot in the macula. Four months after the accident, a classic choroidal neovascularization developed, originating from the lasered site. The technical parameters of the range finder were: Nd:YAG laser (1,064 nm), pulse duration 10 ns, beam divergence 1.5 mrad, energy 10 mJ. CONCLUSION: A range finder can produce severe macular injury. The primary laser-tissue interaction mechanism seems to be explosive disruption of choroidal tissue. Intravitreal injection of TPA and C2F6 did not show a clear benefit to such laser lesions. A late complication can be secondary choroidal neovascularization.

Adult↗
PubMed1999

N(epsilon)(carboxymethyl)lysin and the AGE receptor RAGE colocalize in age-related macular degeneration.

PURPOSE: To investigate whether glycoxidation products and the receptor for advanced glycation end products (RAGE) are present and colocalize in subfoveal membranes of patients with age-related macular degeneration (ARMD). METHODS: Surgically removed subfoveal fibrovascular membranes from 12 patients, 11 related to ARMD and 1 to an idiopathic membrane, were analyzed for the presence of the glycoxidation product N(epsilon)-(carboxymethyl)lysin (CML), one of the receptors for advanced glycation end products, RAGE, and the activation of NFkB, using immunohistochemistry. RESULTS: CML-like immunoreactivity was found in all ARMD specimens examined adjacent or colocalized with RAGE, but not in the idiopathic membrane. RAGE immunoreactive material was found in CD68-positive cells and in the fibrous matrix. CD68-positive cells and surrounding areas stained for p50, the activated form of NFkB. CONCLUSIONS: These results indicate that glycoxidation products are present in subretinal membranes of patients with ARMD. The concomitant expression of RAGE in these membranes and the finding of activated NFkB is suggestive of an implication of glycoxidation product formation in the pathogenesis of the disease.

Adolescent↗
PubMed1998

[Transplantation of autologous submandibular glands in very severe keratoconjunctivitis sicca. 2 year outcome].

INTRODUCTION: The conservative treatment of the most severe cases of keratoconjunctivitis sicca (KCS) can be sometimes frustrating. Especially with an underlying autoimmunologic disorder, even the application of artificial tears as often as every 5 min may not prevent further damage to the ocular surface. A microvascular transplantation of the autologous submandibular gland (SG) can be performed by a maxillo-facial surgeon as an alternative approach for those cases. We report 2 years of ophthalmological experience with the results of this procedure. MATERIAL AND METHODS: To date 27 operations have been performed in 23 patients. The SG was moved from its natural site into the temporal fossa. The secretory duct was implanted into the conjunctival fornix and the gland's vessels connected to the temporal artery and vein. A complete ophthalmological examination has been performed in 25 eyes of 21 patients up to 1 year and in 11 eyes of 9 patients 2 years after surgery. RESULTS: Three months and 1 year postoperatively 19 of 25, and 2 years postoperatively 8 of 11 transplants remained vital. The baseline secretion increased in patients with a vital transplant from an average of 1.6 +/- 1.3 mm before the operation to 16.2 +/- 11.3 mm after 3 months and 20.6 +/- 10.6 mm after 1 year. Ten of 19 vital grafts were reduced 1 year after transplantation in a minor second procedure to control an increasing epiphora. Subsequently baseline secretion was reduced to 13.6 +/- 8.2 mm 2 years after transplantation. Patients with a vital graft reported in 84% of cases (16 of 19) at 3 months, and 79% at 1 year (15 of 19) and 2 years (7 of 8), a strong relief of dry eye symptoms. In 58% (3 months), 79% (1 year) and 63% (2 years) of the eyes with a vital transplant all artificial tear substitution could be stopped. Break-up time increased significantly, resulting in reduced bengal rose staining. CONCLUSION: The transfer of the autologous SG into the temporal fossa can be used to provide patients with very severe KCS with a continuous, endogenous source of ocular lubrication. Despite surgical denervation the graft maintains a sufficient baseline secretion over a period of years. Subjective symptoms and the application of pharmaceutical lubricating substances are reduced to a large extent. If epiphora occurs, it can be controlled by surgically reducing the transplant. The influence of SG saliva on the ocular surface is the object of ongoing studies.

Adult↗
PubMed1998

Therapeutic range of repetitive nanosecond laser exposures in selective RPE photocoagulation.

BACKGROUND: The aim of this study was to investigate whether selective damage the RPE while sparing the adjacent photoreceptors is possible with repetitive 200-ns pulses of Nd:YAG laser (532 nm) and what potential side effects can be expected with higher pulse energies. METHODS: We irradiated the retinas of 19 eyes of 10 chinchilla rabbits with 500 pulses from a Nd:YAG laser, each 200 ns in duration, at a repetition rate of 500 Hz (158 microns, 0-120 microJ). Threshold curves for different effects were established. Representative lesions were investigated by light and transmission electron microscopy. RESULTS: It was possible to produce lesions, which were only visible by fluorescein angiography. The ED50 threshold energy per pulse for visibility by fluorescein angiography was 2.1 microJ per pulse, for visibility by ophthalmoscopy 8.6 microJ. Bubble formation, an uncommon phenomenon in retinal photocoagulation, occurred at energies of 15-25 microJ. Hemorrhage occurred at surprisingly high energy levels of more than 100 microJ. Histology performed on lesions visible only by angiography showed damage primarily to the RPE and outer segments, with very little damage to some inner segments dependent on the energy used. CONCLUSIONS: Selective RPE damage is possible with repetitive 200-ns laser pulses and appropriate energy; however, the collateral damage to the adjacent retina is more pronounced than with repetitive microsecond laser pulses. There is no risk of hemorrhage of retinal photocoagulation with the repetitive 200-ns laser pulses at low energy levels which would be used clinically.

Animals↗
PubMed1998

Photodynamic therapy of subfoveal choroidal neovascularization: clinical and angiographic examples.

BACKGROUND: Conventional photocoagulation of subfoveal choroidal neovascularization (CNV) is often accompanied by visual loss due to thermal damage to adjacent retinal structures. Photodynamic therapy (PDT) allows vascular occlusion by selective photochemical destruction of vascular endothelial cells only. In a pilot study we evaluated the use of PDT in CNV. METHODS: In a clinical phase I/II trial, patients with subfoveal CNV were treated with PDT. Benzoporphyrin derivative monoacid ring A (BPD) was used as sensitizer at a drug dose of 6 mg/m2 or 12 mg/m2. Irradiation was performed via a diode laser emitting at 690 nm coupled into a slit lamp. Safe and maximum tolerated light doses were defined by dose escalation from 25 to 150 J/cm2. Photodynamic effects were documented ophthalmoscopically and angiographically. RESULTS: Sixty-one patients received a single course of BPD-PDT. Preliminary results suggest no damage to retinal structures within the treated area clinically. Retinal perfusion was not altered, while CNV demonstrated immediate absence of fluorescein leakage in the majority of lesions subsequent to PDT. At optimized parameters (6 mg/m2 and 50 J/cm2) complete cessation of leakage from classic CNV occurred in 100% of cases at 1 week and in 50% at week 4. In 70-80% of classic CNV, leakage reappeared at week 12, but markedly less than before treatment. CONCLUSION: PDT allows temporary absence of leakage from CNV with preservation of visual acuity. The long-term prognosis of CNV secondary to age-related macular degeneration treated with repeated courses of PDT is being evaluated in a phase III trial.

Adult↗
PubMed1998

Corneal shape changes after pars plana vitrectomy.

BACKGROUND: The purpose of this prospective, controlled, clinical study was to investigate corneal shape changes due to pars plana vitrectomy (PPV) in patients with potential visual improvement postoperatively. METHODS: A total of 36 consecutive patients undergoing conventional PPV combined with or without macular surgery were studied. Sequential determinations of the corneal curvature by manual keratometry and corneal topography were performed preoperatively, during the first postoperative week, at 4 weeks and after 2-8 months (mean 4 months). RESULTS: The mean surgically induced keratometric astigmatism was 2.92 +/- 1.98 diopters (D) (P < 0.0001) during the first postoperative week. After 4 weeks and 4 months the values decreased to 1.01 +/- 0.97 D and 0.67 +/- 0.43 D, respectively. Videokeratographic analysis confirmed significant curvature changes, with corneal steepening (P < 0.008) which corresponded to the superonasal and temporal semimeridian, and flattening (P < 0.008) along the inferior and inferonasal semimeridians. Corneal changes persisted in some cases for several weeks, partly in an asymmetric and irregular configuration. Shifts in axis to against-the-rule and oblique meridians were noted postoperatively with redistribution within preoperative values in 53% of the cases at 4 weeks after surgery. Subgroup analysis revealed that suture diameter, as well as the use of gas endotamponade, influenced the induced astigmatism. CONCLUSION: A substantial increase of the corneal astigmatism and distinct shape changes can occur after PPV in the immediate postoperative period. Consecutive stabilization at preoperative values was observed after several weeks. The time course of the corneal curvature alterations should be considered in the postoperative management to detect refractive causes of inadequate visual acuity.

Adult↗
PubMed1998

Transplantation of the autologous submandibular gland for most severe cases of keratoconjunctivitis sicca.

OBJECTIVE: This study aimed to examine the long-term qualitative and quantitative function of the secretion of transplanted autologous submandibular glands in patients with most severe keratoconjunctivitis sicca. DESIGN: The study design was clinical. PARTICIPANTS: The authors performed 26 operation in 22 patients. A complete ophthalmologic examination was performed in 16 eyes of 13 patients 1 week and 3 months and in 8 eyes of 8 patients 1 year after surgery. INTERVENTION: The submandibular gland was moved from its natural site into the temporal fossa. The glands supplying vessels were connected to the temporal artery and vein, and its secretory duct was implanted into the conjunctival fornix. MAIN OUTCOME MEASURES: Scintigraphy with Tc 99m Pertechnetate was used to document the graft vitality. Subjective symptoms and application frequency of artificial tears were recorded. Baseline as well as stimulated secretion and breakup time were measured and rose bengal staining and ocular ferning test were performed. In selected cases, the secretory product could be sampled for the detection of electrolytes, amylase, and secretory immunoglobulin A (SIgA). RESULTS: Scintigraphy showed vital gland tissue in 14 of 16 grafts at 3 months and 6 of 8 grafts at 1 year after surgery. Two of the 16 transplants were lost completely during the first 3 postoperative months, 1 because of an underlying autoimmunopolyendokrinopathy and the other because of an insufficient vascular anastomoses. In eyes with a vital transplant, baseline secretion and breakup time were increased significantly at 3 months and 1 year after surgery. Patients with a vital transplant reported a strong relief of symptoms and were able to stop taking artificial tear substitution at 1 year. Electrolytes showed a fluctuating concentration. A year after transplantation, the SIgA and amylase concentrations were more than ten times increased compared to normal tear values. CONCLUSION: Microvascular transferral of an autologous, paralytic submandibular gland results in a significant relief of subjective symptoms, a reduction of artificial tear applications, and an increase of baseline secretion over the first postoperative year. The composition and volume of the secretory product fluctuate, but high values of SIgA and amylase show an actively secreting graft. Although the authors' long-term experience still is limited, they believe that the procedure is a promising alternative approach for desperate dry eye conditions.

Amylases↗
PubMed1998

Delayed intraocular lens dislocation after neodymium:YAG capsulotomy.

A poly(methyl methacrylate)(PMMA) intraocular lens (IOL) dislocated into the vitreous cavity in 2 patients after a neodymium:YAG (Nd:YAG) laser posterior capsulotomy. In Case 1, the capsulotomy was performed 19 months after extracapsular cataract extraction (ECCE) and sulcus fixation of an IOL. Six months later the IOL dislocated posteriorly. In Case 2, ECCE with intracapsular IOL implantation was followed 4 years later by an Nd:YAG capsulotomy; 6 months later the IOL dislocated into the vitreous cavity within the intact capsular bag. Different mechanisms were responsible for the dislocation: in case 1, radial tearing of the large capsular defect with IOL loosening and dislocation into the vitreous cavity; in Case 2, zonulysis and IOL dislocation within the intact capsular bag. A neodymium:YAG capsulotomy may cause delayed IOL dislocation into the vitreous cavity.

Aged↗
PubMed1998

[Subretinal neovascular membranes in membranoproliferative glomerulonephritis type II].

BACKGROUND: So called 'dense deposits' in the retina of a patient suffering from membranoproliferative glomerulonephritis type II (MPGN II) were first demonstrated in 1989. Appearence of subretinal neovascular membranes associated with MPGN II in three patients was described in 1990. PATIENT AND METHODS: We present a 45-year-old male patient, whose insufficiency of the kidney due to a membranoproliferative glomerulonephritis type II required peritoneal dialysis and later transplantation. In both eyes fundus examination revealed typical disseminated, partly confluencing, drusen-like 'dense deposits' and exsudative degeneration of the macula due to subretinal neovascular membranes. Visual acuity was less than 20/400 and visual fields were reduced to small excentrics islands. There was an atrophy of the optic nerve with nearly extinguished VEP in both eyes. CONCLUSION: Flecked changes of the retina called 'dense deposits' associated with membranoproliferative glomerulonephritis type II have to be differentiated in particular from drusen, as well as metabolic-toxic and degenerative retinopathy. Development of subretinal neovascular membranes is attributed to altered retinal pigment epithelium, similar to age-related macular degeneration. An atrophy of the optic nerve associated with this disease has not been described so far. It is possible that vascular damage because of hypertensive changes due to renal dysfunction is the reason for the optic nerve atrophy. With another hypothesis this could be caused by intraocular pressure due to a risen flow of water into the vitreous cavity following the altered osmotic gradient after peritoneal dialysis.

Cell Membrane↗
PubMed1998

The vascular component of proliferative vitreoretinopathy membranes: an immunohistochemical and ultrastructural study.

BACKGROUND: The basic cellular components of proliferative vitreoretinopathy (PVR) membranes are well studied. Endothelial cells have also been documented. The importance of the vascular element in PVR has received little attention, as vascular components are clinically inapparent. The aim of this study was to obtain a better characterization and quantification of occurrence of the vascular component. METHODS: Serial sections of surgically excised PVR membranes were examined with Lectin histochemistry (25 membranes with ulex europaeus agglutinin I [UEA I] and rhicinus communis agglutinin I [RCA I]), immunohistochemistry for von Willebrand factor (31 membranes), and electron microscopy. RESULTS: Vascular endothelial cells were identified by visualization of UEA I and RCA I binding sites or by marking for von Willebrand factor. A total of 28.6% of the PVR membranes showed a vascular component. Vascular components consisted mostly of capillary-sized vessels; larger vessels were rarely found. Ultrastructurally, most vascular elements were found to be capillaries of the nonfenestrated type. Membranes from eyes that underwent PVR surgery with silicone oil tamponade showed vascular components less frequently (18.5%) than did membranes from eyes without silicone oil (43.8%).

Endothelium, Vascular↗