Biomedical subjects

H Laqua

Publications and source records attributed to H Laqua.

At least 73 records · Page 4Linked to original sources

PubMed1998

Initial clinical experience with the picosecond Nd:YLF laser for intraocular therapeutic applications.

AIMS/BACKGROUND: Compared with nanosecond (ns) pulses of conventional Nd-YAG lasers, picosecond (ps) laser pulses allow intraocular surgery at considerably lower pulse energy. The authors report initial clinical experiences using a Nd:YLF ps laser for the treatment of various indications for photodisruption. METHODS: A Nd:YLF laser system (ISL 2001, wavelength 1053 nm) was used to apply pulse series of 100-400 microJ single pulse energy at a repetition rate of 0.12-1.0 kHz. Computer controlled patterns were used to perform iridectomies (n = 53), capsulotomies (n = 9), synechiolysis (n = 3), and pupilloplasties (n = 2). Other procedures were vitreoretinal strand incision (n = 2) and peripheral retinotomy (n = 1). For comparison, 10 capsulotomies and 20 iridotomies were performed with a Nd:YAG ns laser. The ps laser cut of an anterior capsule was assessed by scanning electron microscopy (SEM). RESULTS: Open, well defined iridectomies (mean total energy 4028 mJ, mean diameter 724 microns), were achieved at first attempt in 92% of the cases. In 64% an iris bleeding and in 21% an IOP increase of > 10 mm Hg occurred. All capsulotomies were performed successfully (mean energy 690 mJ/mm cutting length) but with a high incidence of intraocular lens damage. The attempted vitreoretinal applications remained unsuccessful as a result of optical aberrations of the eye and contact lens. Although ps laser capsulotomies and iridectomies required much higher total energy than ns procedures, the resulting tissue effects of the ps pulses were more clearly defined. SEM examination of a ps incision of the anterior lens capsule demonstrated, nevertheless, that the cut was more irregular than the edge of a continuous curvilinear capsulorhexis. CONCLUSION: Series of ps pulses applied in computer controlled patterns can be used effectively for laser surgery in the anterior segment and are considerably less disruptive than ns pulses. The ps laser is well suited for laser iridectomies while the ns laser is preferable for posterior capsulotomies. As vitreoretinal applications remained unsuccessful, the range of indications for intraocular photodisruption could not be extended by the ps laser.

Humans↗

PubMed1998

Intraocular pressure in nonglaucomatous eyes with pseudoexfoliation syndrome after cataract surgery.

BACKGROUND AND OBJECTIVE: To investigate the course of the intraocular pressure (IOP) in nonglaucomatous patients with pseudoexfoliation (PSX) syndrome after cataract surgery. PATIENTS AND METHODS: In a prospective age-matched controlled clinical study, 23 consecutive patients with PSX were studied and compared with a control group of 23 patients. The IOP was measured by applanation tonometry preoperatively, and postoperatively on day 1, after 4 weeks, and after 6 months. All patients were operated on with a self-sealing 7-mm scleral tunnel incision, phacoemulsification, and posterior chamber intraocular lens (IOL) implantation. RESULTS: Preoperatively the IOP was similar between both groups (P = .962). At the first postoperative day the IOP was below 22 mm Hg in all cases. After 4 weeks and 6 months a mean decrease of 3.88 mm Hg (P = .001) in the control group and of 3.15 mm Hg (P = .002) in the PSX group was observed; this difference was not statistically significant (P = .543). CONCLUSIONS: At 1 day postoperatively no pressure increase was observed in the eyes with PSX after scleral tunnel incision and phacoemulsification. Six months after cataract extraction with IOL implantation, the tension level decreased in the presence of PSX similarly as in normal eyes.

Aged↗

PubMed1997

Patient expectations and recollection of information about photorefractive keratectomy.

PURPOSE: To assess the expectations of surgical result and recollection of a standardized information briefing by patients having photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, Medical University of Lübeck, Germany. METHODS: Thirty-two patients were asked to complete a multiple-choice questionnaire immediately after standardized information briefings and 1 month after PRK to establish their comprehension of the information briefing, what they remembered of it, and what they expected from the refractive procedure. RESULTS: Although the estimated intelligence quotient of the patients was above average (115 +/- 7.23) and almost all rated the information briefings as being comprehensible, only simple, basic facts about PRK were remembered immediately after the briefing as well as 1 month postoperatively. Of 12 possible undesired consequences, 6.4 were remembered before surgery and 3.9 after surgery. The latter were mainly side effects the patients experienced themselves. CONCLUSION: As most patients rejected the possibility of serious complications, for medicolegal reasons, careful, accurate documentation of the contents of and patients' satisfaction with the information briefing is necessary.

Adult↗

PubMed1997

Histologic analysis of thermal effects of laser thermokeratoplasty and corneal ablation using Sirius-red polarization microscopy.

PURPOSE: To evaluate how well several histologic techniques differentiate degrees of thermally induced changes in corneal tissue after laser thermokeratoplasty (LTK) or corneal ablation. SETTING: Medical Laser Center Lübeck, Germany. METHODS: Corneas of freshly enucleated porcine eyes were treated with a continuous wave laser diode (1.86 microns) and a pulsed chromium-thulium-holmium: YAG laser (2.1 microns) to produce LTK lesions or ablated with a Q-switched and a free-running chromium-erbium: YSGG laser (2.70 microns), a free-running erbium: YAG laser (2.94 microns), and an argon-fluoride excimer laser (193 nm). The lesions were evaluated by light microscopy (LM) (hematoxylin and eosin, Azan, van Gieson's, and Masson-Goldner's trichrome stains), transmission electron microscopy (TEM), and polarization microscopy after Sirius-red staining. Sirius-red, a strongly elongated, birefringent molecule binding parallel to collagen molecules, was used to enhance corneal birefringence. RESULTS: With routine LM, it was difficult to discriminate the degrees of thermal alterations in LTK lesions. Combined Sirius-red staining and polarization microscopy distinguished between a strongly coagulated central zone and the transition zone to normal tissue. Sirius-red uptake was increased in both zones, reflecting the availability of new binding sites. The central zone appeared darker under polarization than normal collagen because of a loss of birefringence. Intrinsic birefringence was greatly reduced; however, form birefringence partly remained as long as some collagen fibrils were intact. In the center of very strong lesions, where the collagen was hyalinized, birefringence was completely lost because of the complete disintegration of the fibrillar structure, which was visible under TEM. The transition zone toward normal cornea showed increased birefringence because the natural birefringence was largely preserved and enhanced by the increased Sirius-red uptake. Mechanical stretching between neighboring LTK lesions was manifested by increased birefringence. CONCLUSION: Sirius red offered an improved and simple histologic method for analyzing thermal collagen changes. It may contribute to a better understanding of the working mechanisms of LTK and improve analysis of thermal effects in corneal ablation.

Animals↗

PubMed1997

[Outcome after vitrectomy in rhegmatogenous retinal detachment and dense vitreous opacities].

BACKGROUND: In some cases of rhegmatogenous retinal detachment dense vitreous opacities can delay the diagnosis and prevent a scleral buckling procedure. In these cases a primary vitrectomy is necessary. These results of vitrectomy are of current interest, because intra- and postoperative complications are comparable to the group of patients with retinal detachment and clear media, in which primary vitrectomy is discussed today as an alternative method. PATIENTS AND METHODS: After redetachment and trauma were excluded, we reviewed the charts of 40 patients (40 eyes), who underwent vitrectomy and gas endotamponade for rhegmatogenous retinal detachment and dense vitreous opacities. In 31 cases vitreous hemorrhage and in 9 cases other dense non inflammatory vitreous opacities were present. Intraoperatively detected PVR (1), giant tear (1) and retinal holes located at the posterior pole (1) were excluded. The remaining 37 eyes were examined retrospectively. The median follow-up time was 12 months. RESULTS: In 32 of 37 eyes the retina was reattached after the first vitrectomy (86.5%). In 5 eyes a redetachment occurred, in 3 of them caused by PVR. After revitrectomy successful reattachment could be achieved in all cases. As intraoperative complications iatrogenic retinal break formation could be observed in 3 cases and lens-touch in 1 case. Postoperatively secondary tears in attached retina developed in 2 cases, in 1 case an arterial branch occlusion and in 1 case a Macular-Pucker. During the follow-up period a cataract developed in 12 of the 21 phacic patients. CONCLUSIONS: The reattachment rate of primary vitrectomy in eyes with retinal detachment and associated dense vitreous opacities is slightly lower compared to the rate of scleral buckling procedures in cases of retinal detachment with clear media. Comparable good or even better results may be expected for primary vitrectomy in cases of retinal detachment without vitreous opacities. Since the risk of intra- and postoperative complications in our group of patients is small it is promising also for primary vitrectomy in cases with good view on the fundus.

Adolescent↗

PubMed1997

Autosomal dominant vitreoretinochoroidopathy.

BACKGROUND: Autosomal dominant vitreoretinochoroidopathy recently has been described as a condition characterized by peripheral chorioretinal atrophy and areas of hypopigmentation and hyperpigmentation between the equator and the ora serrata circumferentially in the ocular fundus. We describe the clinical features of a family, some members of which have this disorder. This is the first such report of a family outside the United States. METHODS: We examined a family of 15 individuals, seven of whom were affected. RESULTS: The main clinical findings were peripheral pigmentary changes for 360 degrees, with a discrete boundary near the equator. In one patient, a partial vitreous detachment was found that was creating increasing traction to the macula and to the peripheral retina. Vitreous surgery successfully relieved the traction, and vision recovered from 20/100 to 20/25. One patient lost visual acuity at the age of 10 years when complete rhegmatogenous detachment occurred. In two women, a horizontal nystagmus was present showing typical signs of a congenital nystagmus. Results of electrooculography demonstrated a marked reduction of light rise and a clear reduced Arden ratio in one patient. CONCLUSIONS: Autosomal dominant vitreoretinochoroidopathy appears clinically as mainly a peripheral tapetoretinal disease; patients with this disease have been reported in and outside the United States. In addition to the typical peripheral features, significant vitreous traction maculopathy and congenital nystagmus associated with the disease were found.

Adult↗

PubMed1996

[Cyclophotocoagulation with the diode laser in contact procedure with a new focussing tip].

UNLABELLED: During contact cyclophotocoagulation (CPC) energy is transmitted through the conjunctiva and the sclera by direct contact of a plain fibre tip. Alteration and scarring of the conjunctiva and the outer parts of the sclera cannot always be avoided. We used a new fibre tip which defocuses the laser light on the conjunctiva and sclera and focuses the laser light on the ciliar body. The coupling and focusing medium between fibre and sclera is a small glass ball (3 mm diameter). METHODS: Up to now we have treated 52 human eyes of 35 patients affected by refractory glaucoma using a diode laser (Zeiss Visulas II) coupled with a 200-microns fibre and a 3-mm focusing ball tip. In all cases 20-40 spots were applied 1.5 mm posterior of the limbus, power varied between 1.5 and 2.2 W and exposure time was 1.5 s. RESULTS: In all cases the conjunctiva and the sclera was unaltered. The mean follow-up time was 224 days. The mean IOP values +/- SD before treatment and 6 days, 4 weeks and 1 year after treatment were 40.9 +/- 7.1, 19.3 +/- 7.9, 22.4 +/- 14.8 and 17.2 +/- 11.3 mmHg. No positive, linear correlation was found between number of spots and IOP drop after 6 days. There was considerable individual variance. The main complications were anterior fibrinous uveitis (10%), slight vitreous haemorrhage (2/52) and transitory hypotony (2/52). In one enucleated eye structural alterations to the pigmented and non-pigmented epithelial cells of the ciliary body were found histologically. CONCLUSIONS: Contact diode CPC can significantly reduce IOP, and the conjunctiva and sclera can be left totally unaltered by the focusing ball tip used in this study.

Aged↗

PubMed1996

[Follow-up of vitrectomy for central retinal detachment and optic disk pit].

BACKGROUND: The exact pathogenesis of central retinal detachment associated with optic disc pit is still unknown. Vitrectomy has proven to be the most effective therapy. PATIENTS AND METHODS: In two patients with macular detachment associated with optic disc pit, a pars-plana-vitrectomy with surgical posterior vitreous detachment and gastamponade was performed. We report on the interesting clinical course of these patients. RESULTS: After the gas bubble was absorbed, we observed a displacement of the subretinal fluid inferiorly in both patients. Schisislike changes persisted in the macular area. After several months the subretinal fluid resolved completely. CONCLUSION: The fluid displacement and the resolution-characteristics of the subretinal fluid after vitrectomy in cases of retinal detachment associated with optic disc pit are completely different from other rhegmatogenous retinal detachments. The gas bubble separates the central retinoschisis from the peripheral rhegmatogenous part. The reason for delayed resolution remains unclear. It may be due to tangential vitreous traction in the periphery.

Adult↗

PubMed1996

Ultrastructural features of a solitary vitreous cyst.

BACKGROUND: Vitreous cysts are rare, and their origin and morphologic features unclear. The authors present ultrastructural observations made in a case of a 47-year-old woman who, after undergoing retinal detachment surgery on several occasions, developed disturbing vitreous opacities and a solitary cystic structure in the anterior vitreous cavity. METHODS: Clinical and intraoperative biomicroscopy and histologic examination by light microscopy and transmission electron microscopy were performed. RESULTS: The cystic structure was attached at its posterior aspect to a vitreous membrane and enclosed within a vitreous body lacuna. It had an oval form with a smooth surface and was translucent. Histology showed the cyst wall to consist of retinal tissue with gliotic changes that had placed itself within the vitreous. CONCLUSION: The morphologic studies do not rule out the possibility of a congenital cyst. However, the authors presume that in association with the retinal detachment or the operations, a displacement of retinal tissue into the vitreous body occurred from which the cyst developed.

Cysts↗

PubMed1995

[Laser coagulation of senile, moist macular degeneration].

Age-related macular degeneration (AMD) is a common disease in ophthalmology. The current status of knowledge in subretinal neovascularisations concerning epidemiology and treatment based on the findings of the macular photocoagulation study is shown. Most important parameters in treatment of subretinal neovascularisations in AMD are exact localization of the membrane in fluorescein angiography, its size and the visual acuity. The treatment of extra-foveal, well demarcated membranes can be recommended. Moreover recent results in the treatment of subfoveal, well demarcated membranes show some benefit for the patient as long as the size of the membrane is lower than 2 discs areas and the actual visual acuity is taken into account. Indocyanin-Green-(ICG)-angiography is recommended in occult subretinal membranes. Guidelines for the treatment are given.

Aged↗

PubMed1995

Autosomal dominant exudative vitreoretinopathy: linkage analysis and its clinical application.

Close linkage without recombination (Zmax = 7.383 at Theta = 0.00) was found between the locus for autosomal dominant exudative vitreoretinopathy (Criswick-Schepens) and the locus D11S388 in 11q14.3-q21. We report on the application of data from linkage studies in the diagnostic management of this disease. To determine the disease risk for two newborn children of two affected mothers more precisely, indirect genotype analysis was performed by typing their DNA for three DNA polymorphisms, the loci of which have been shown to be closely linked to the locus of autosomal dominant exudative vitreoretinopathy.

Adult↗

PubMed1995

[Endotamponade with silicon oil in severe proliferative retinopathy with attached retina].

Silicone oil as endotamponade in cases with attached retina is only indicated in a few very selected cases. These are cases with a high risk of intravitreal hemorrhage and a need for quick visual rehabilitation. We examined 23 patients, who had undergone pars plana vitrectomy and silicone oil filling. All patients were diabetics with proliferative retinopathy and recurrent intravitreal hemorrhage. In 14 cases it was the only eye; 11 eyes previously had a vitrectomy. We analyzed these cases for visual acuity, rubeosis, bleeding tendency, reproliferations, cataract development and glaucoma. The follow-up time was 32 months. In 22 of 23 eyes quick visual rehabilitation was achieved, and the patients had at least ambulatory vision within the first week. In one case poor visual acuity was due to exudative maculopathy. No relevant bleeding occurred. In 14 of 16 phacic patients we observed a cataract. Seven patients developed glaucoma, which was due to neovascularization in 5 cases. It was successfully treated in all cases and no visual loss occurred. In 5 cases we observed a peripheral traction retinal detachment, in one case a traction retinal detachment at the posterior pole. In selected cases silicone oil can prevent recurrent intravitreal hemorrhage, allowing rapid visual recovery. Considering the complications, the silicone oil should be removed as soon as possible.

Diabetic Retinopathy↗

PubMed1995

[Case study of a solitary vitreous body cyst].

Vitreous cysts are rare and their origin unclear. We present a case of a 47-year-old woman who, after undergoing retinal detachment surgery on several occasions, developed disturbing vitreous opacities with which she presented for possible vitrectomy. Besides the typical postoperative vitreous condensations and opacifications, a solitary spherical cystic structure was present in the anterior vitreous cavity. The cystic structure was attached at its posterior aspect onto a vitreous membrane and was otherwise floating within a vitreous body lacuna. The vitreous opacities and the cyst were removed by performing a pars plana vitrectomy. The patient's visual acuity improved from 0.5 to 0.7. We presume that the cyst was acquired in association with the retinal detachment or the operations.

Cysts↗

PubMed1994

Mapping of the autosomal dominant exudative vitreoretinopathy locus (EVR1) by multipoint linkage analysis in four families.

Autosomal dominant exudative vitreoretinopathy is a disorder affecting primarily the development of the human retinal vascular system. The disease locus has recently been assigned to 11q13-q23 by linkage studies in two families. Two-point analysis on a total of four families has now revealed close linkage (Zmax = 8.34 at theta = 0.00) between the disease locus and D11S873. Multipoint linkage analysis mapped the disease locus between D11S527/D11S533 and D11S35 with a maximum lod score of over 11 directly at D11S873. No evidence appeared for genetic/linkage heterogeneity among the four families examined.

Chromosome Mapping↗

PubMed1994

Localization of lysosomal enzymes in the retina and retinal pigment epithelium of RCS rats.

Using ultrahistochemical and immunohistochemical techniques, localization of acid phosphatase and cathepsin D was demonstrated in the retina and pigment epithelium of 1 to 42 day old RCS rats and its nonaffected congenic rat strain. Both enzymes are present in the pigment epithelium of the normal and dystrophic rat eye. As early as the age of 1 week, it was found that the lysosomes in the dystrophic rat retina are less stable in releasing acid phosphatase than those of control animals. Infiltration of cathepsin D into the subretinal space could first be detected with certainty in 2-week-old animals. The fragility of the lysosomal membrane and, therefore, the release of both enzymes became more pronounced as the animals aged. The findings of this study indicate that the instability of the lysosomal membrane in the RCS rat pigment epithelium may initiate degeneration of photoreceptors and pigment epithelium. The demonstration of cathepsin D activity has proved very helpful in revealing the physiological or pathophysiological condition of retinal pigment epithelium.

Acid Phosphatase↗

PubMed1994

[Punctate inner choroidopathy].

BACKGROUND Punctate inner choroidopathy is a rare disease, which involves the outer retina and inner choroid. The ethiology is still unknown. PATIENT The case of a 23-year-old female patient, who noticed a central scotoma on the right eye, is presented. A mild decreased visual acuity of 0.7 was noted and on ophthalmoscopy multiple, yellowish dots on the level of RPE and choroid near the fovea were found. Angiography showed a hyperfluorescence of the dots in the early phase and marked leakage in the late phase. TREATMENT Under systemic treatment with corticosteroids the acuity and the fundus changes improved. Two weeks after corticosteroidtherapy was finished, a new onset with massive exsudation occurred accompanied by a sudden decrease in vision in her right eye to 0.1. On the last examination a parafoveal suretinal scar was discovered. CONCLUSION Punctate inner choroidopathy recurrences are common. However secondary neovascular membranes are described, in general the visual outcome is good.

Adult↗

PubMed1994

[Proliferative retinopathy in chronic myeloid leukemia].

BACKGROUND: In 50% of patients with acute and chronic myelocytic leukemia retinal alterations occur which are similar to those of nonproliferative diabetic retinopathy or hypertensive retinopathy. Retinal neovascularizations, however, are rarely seen and only found in patients with the chronic disease. PATIENTS AND METHODS: We report on the clinical course of three patients with advanced stage of proliferative retinopathy in CML. In two patients, the diagnosis of CML was established after ocular involvement. Therapy was planned according to the principles, which have proven effective in other vasoproliferative retinopathies. Eyes with neovascular changes were only treated by panretinal scatter photocoagulation of the avascular zones. In the cases with complications like vitreous hemorrhage and traction retinal detachment, vitreoretinal surgery was performed. RESULTS: Using this therapeutic principles in 4 of 6 eyes a visual acuity > 0.7 could be preserved. In three eyes impending macular involvement by traction retinal detachment was prevented. CONCLUSION: The therapeutic approach, which is valid for proliferative retinopathies of various etiology is also beneficial for ocular complications in CML.

Adult↗

PubMed1994

[Photodynamic therapy of eyelid basalioma after topical administration of delta-aminolevulinic acid].

Delta-aminolevulinic acid (ALA) induced Protoporphyring IX photodynamic therapy (PDT) is a new method in the therapy of cutaneous malignancies. Topical application prevents photosensibilization of normal skin. Promising results in the treatment of superficial basal cell carcinomas have been reported. To evaluate the efficiency of this method in the therapy of basal cell carcinomas of the lid, 10 patients were treated by PDT 5 h after application of ALA. The lesions were irradiated by an argon-ion-laser-pumped dye laser at a wavelength of 630 or 635 nm and at cumulative radiant exposures of 50 and 100 J/cm2. After 5-8 weeks follow-up, the basal cell carcinomas were excised to assess histologic changes. In the first few days after PDT the lesions seemed clinically to regress, due to erythematous swelling, but after a few weeks all tumours showed the same configuration they had before irradiation. Histological examination revealed small areas of necrotic cells in all irradiated basal cell carcinomas, surrounded by residual tumour formations. The reason for the poor results may be limited penetration of ALA or light. Although ALA-induced Protoporphyrin-IX PDT is a promising approach in the therapy of dermal lesions, it is not yet an acceptable alternative method in the treatment of basal cell carcinomas of the lid.

Administration, Topical↗