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Biomedical subjects

G K Lang

Publications and source records attributed to G K Lang.

At least 19 recordsLinked to original sources
PubMed1992

Expression of tenascin and fibronectin in the rabbit cornea after excimer laser surgery.

In order to investigate the effects of excimer laser surgery on corneal wound healing, 25 rabbits underwent anterior keratectomy at a depth of 100 or 300 microns with a Meditec MEL 50 excimer laser. After various intervals the animals were killed and the cornea excised and investigated immunohistochemically for the expression of extracellular matrix (ECM) proteins, fibronectin and tenascin. Fibronectin was shown to occur earlier than tenascin, and the two also had different distribution patterns. Wound depth showed no clear effect on the localization and time of ECM protein expression. This study indicates that corneal wounds caused by excimer laser radiation and those caused by mechanical surgery differ as to healing mechanisms.

Animals↗
PubMed1991

[Bilateral traumatic eye avulsion].

A 26 year old patient with a LeFort III fracture after an automobile accident exhibited bilateral luxation of the globes. An avulsio imcompleta with an evulsion of the optic nerve posteriorly was noted on his right eye and an avulsio incompleta with evulsion of the optic nerve anteriorly was seen on his left eye as a cause for the luxation. The said locations may represent predilection sites for an evulsion of the optic nerve.

Adult↗
PubMed1991

[Results of 102 perforating pseudophakic keratoplasties].

Between July 1980 and February 1990 we performed 102 penetrating keratoplasties in 102 eyes of 98 patients with pseudophakic bullous keratopathy. Patients were followed up prospectively with an average follow-up of 14 months. 53 of the implant were iris-supported lenses (ISL), 32 were anterior chamber lenses (ACL), and 17 were posterior chamber lenses (PCL) following extracapsular cataract extraction (ECCE). In 88 eyes the intraocular lens implantation had been performed elsewhere. The interval between lens implantation and keratoplasty ranged from 3 to 451 months (mean 59 months) and was significantly shorter (p less than 0.03) for PCL. Eight intraocular lenses had been removed before keratoplasty. During penetrating keratoplasty, 25 lenses were left in place, 49 were removed, and 20 were exchanged. Since 1988, PCL have been implanted and sutured to the iris after removal of the ACL or ISL in 17 eyes that had undergone intracapsular cataract extraction (ICCE). After keratoplasty, visual acuity improved in 95 of the 102 eyes. However, visual acuity was frequently limited by persisting cystoid macular edema. In eyes that had undergone keratoplasty following ECCE and PCL implantation, visual acuity was significantly better (p less than 0.03) and cystoid macula edema was rarer (p = 0.07) than in eyes with ISL or ACL. the prognosis of penetrating keratoplasty for pseudophakic bullous keratopathy is generally good, although visual acuity is often limited postoperatively by cystoid macular edema. The technique of secondary PCL implantation sutured to the iris appears promising for allowing better optic rehabilitation of patients with pseudophakic bullous keratopathy.

Adult↗
PubMed1990

A 32-year follow-up of the rigid Schreck anterior chamber lens. A clinicopathological correlation.

We describe the clinicopathological findings in an eye after 32 years of successful anterior chamber lens implantation. In 1956, a rigid Schreck total polymethylmethacrylate anterior chamber lens was implanted in the right eye of a 28-year-old white man 1 year after corneo-scleral laceration with traumatic cataract. The postoperative clinical course was subjectively unremarkable for at least 30 years. In 1988, the patient developed secondary angle closure glaucoma, associated with a cavernous Schnabel optic atrophy that was caused by peripheral anterior synechiae and fibrovascular downgrowth into the anterior chamber. The lens implant was encapsulated "cocoonlike." Secondary proliferation of corneal endothelial cells covered the fibrous membrane and the chamber angle structures. No inflammatory reaction and only a very slight foreign-body reaction in the area of the footplate of the anterior chamber lens were present. Clinical and histopathological findings indicate that polymethylmethacrylate is sufficiently inert and biocompatible to be tolerated by the surrounding ocular tissues for more than 30 years.

Anterior Chamber↗
PubMed1990

Forces on intraocular lens haptics induced by capsular fibrosis. An experimental study.

Electronic dynamometry measurements, performed upon intraocular lens (IOL) haptics of prototype one-piece three-loop silicone lenses, accurately defined the relationships between elastic force and haptic displacement. Lens implantations in the capsular bag of dogs (loop span equal to capsular bag diameter, loops underformed immediately after the operation) were evaluated macrophotographically 5-8 months postoperatively. The highly constant elastic property of silicon rubber permitted quantitative correlation of subsequent in vivo haptic displacement with the resultant force vectors responsible for tissue contraction. The lens optics were well centered in 17 (85%) and slightly offcenter in 3 (15%) of 20 implanted eyes. Of the 60 supporting loops, 28 could be visualized sufficiently well to permit reliable haptic measurement. Of these 28, 20 (71%) were clearly displaced, ranging from 0.45 mm away from to 1.4 mm towards the lens' optic center. These extremes represented resultant vector forces of 0.20 and 1.23 mN respectively. Quantitative vector analysis permits better understanding of IOL-capsular interactions.

Animals↗
PubMed1990

Autologous nasal mucosa transplantation in severe bilateral conjunctival mucus deficiency syndrome.

From 1984 to 1989, 24 patients with desperate ocular surface wetting problems due to mucus deficiency syndrome with extensive symblephara or lid fusion were treated by autologous free transplants of nasal mucosa from the nasal conchae. This procedure covers the ocular surface not only with nonkeratinizing epithelium but also with goblet cells and produces a mucus layer. This was proven by biopsy in three patients after 1 to 3 years. In all of the patients, conjunctival transplants were not available. Pronounced relief of pain and modest visual improvements are achieved with this procedure, and free autologous nasal mucosal grafts appear to be superior to buccal mucosa in reestablishing the anterior ocular surface. The authors recommend the technique for all patients with massive and otherwise intractable symblephara following lye burns.

Adolescent↗
PubMed1990

[Pseudo-exfoliation syndrome with and without glaucoma as a major risk factor in extracapsular cataract extraction. A prospective clinical study].

A prospective study was undertaken to evaluate the risk factors in extracapsular surgery for eyes with pseudoexfoliation syndrome (PES) with and without open angle glaucoma. The study included 3095 planned extracapsular cataract extractions performed by 18 surgeons between September 1986 and June 1989. Of the 3095 eyes 153 (4.9%) showed clinical signs of PES. We examined three groups of eyes: nonglaucomatous eyes (2476 eyes), glaucomatous eyes controlled by local antiglaucomatous therapy (342 eyes) and glaucomatous eyes that had undergone antiglaucomatous surgery (277 eyes). For each group, the incidence of capsular breaks and vitreous loss was evaluated for eyes with and without PES. In the group of nonglaucomatous eyes, vitreous loss occurred significantly more frequently (p less than 0.05) in eyes with PES. For the group of glaucomatous eyes, complications were more frequent but not significant in the presence of PES (p greater than 0.15). We conclude that PES is a significant risk factor in extracapsular surgery even in the absence of glaucoma. After introducing special precautionary measures for eyes showing signs of PES, the incidence of complications in extracapsular surgery has decreased considerably in our hospital for these eyes.

Cataract Extraction↗
PubMed1990

[Corneal wound healing after perforating and non-perforating excimer laser keratectomy. An experimental study].

For clinical use of the excimer laser more detailed knowledge of corneal wound healing is necessary. With an ArF excimer laser (193 nm, 750 mJ/cm2, 20 Hz) and a special slit mask system perforating and non-perforating keratectomies were performed in a series of 55 rabbits with a follow-up from one hour to six months post-op. After enucleation the corneas were immediately processed for light microscopy, scanning and transmission electron microscopy and vital staining of the endothelium (trypan blue/alizarin red S). In perforating cuts the endothelial reaction consists of polymegathism, migration, formation of multi-nucleated giant cells, metaplasia-like proliferation and ultimately stable reformation of the cell pattern (1h to 42d). Epithelium fills the anterior wound gap within three days with subsequent regression of the plug. Fibroblastic activity in the adjacent stroma leads to cellular immigration, production of new collageneous lamellae and complete reorganization of the wound cleft (1d to 6m). Nonperforating excisions showed similar healing tendency of stroma and epithelium, but no severe endothelial damage could be detected. Compared with former studies using knife incisions our results do not reveal significant difference regarding epithelial and stromal wound healing events. The encouraging healing tendency of the endothelium--similar to regeneration after ultrasound and Nd:YAG-laser damage--also confirms the applicability of excimer lasers in corneal surgery.

Animals↗
PubMed1990

[Morphometric analysis of age-dependent changes of the human ciliary body].

Morphometric and stereologic techniques have been applied to human ciliary epithelium and bordering stroma of 31 (respectively 16) normal donor eyes aged 15 to 86, providing quantitative information on the age-related structural changes of ciliary body tissue. Aging appeared to result in a generalized widening of the stromal layer from 19.3 +/- 2.4 microns (10-20 years; n = 4) to 60.0 +/- 11.5 microns (80-90 years; n = 3) in ciliary processes and from 53.0 +/- 6.8 microns to 107.6 +/- 15.2 microns in the ground plate between ciliary valleys and ciliary muscle, a density increase of collagenous fibers from 39.3 +/- 4.9 to 83.5 +/- 14.6 fibers/microns 2 and a concomitant decrease in mean fiber diameter from 62.8 +/- 3.4 nm to 55.7 +/- 1.5 nm, a decline of stromal cell density from 31.4 +/- 1.8 to 9.6 +/- 1.0 cells/0.014 mm2, a progressive thickening of the inner and outer limiting membranes from 0.8 +/- 0.4 micron to 8.1 +/- 1.5 microns and 2.1 +/- 0.6 microns to 4.5 +/- 0.5 microns respectively as well as the endothelial basement membrane from 0.13 +/- 0.004 micron to 0.25 +/- 0.03 micron, a gradual widening of the perivascular space between capillaries and overlying pigment epithelium from 6.2 +/- 1.5 microns to 11.3 +/- 2.9 microns, an increase in number of fenestrations in the capillary endothelium from 39.0 +/- 8.5 to 69.0 +/- 7.0 pores/100 microns, and finally a continuous augmentation of degenerative elements including lipids, lipofuscin granules, and lysosomes from 1.5 +/- 0.06% to 7.2 +/- 0.6% within the non-pigmented epithelium (NPE) over the 71-year period studied. Regression analysis yielded a highly significant impact of age on these morphometric parameters, while the relative volumes of the remaining cell compartments of the NPE-cells revealed no statistically significant correlation with age. Rather, the variations in volume densities of Golgi bodies (0.34 +/- 0.25%; n = 16) and pigment granules (0.36 +/- 0.27%; n = 16) seemed to be random with respect to age, whereas the relative volumes of mitochondria (21.7 +/- 1.8%; n = 16) and RER (5.9 +/- 0.7%; n = 16) remained fairly constant indicating that the NPE-cells maintain their functional capacity with advancing age. Age-related reduction of aqueous humor formation therefore appears to be rather due to impaired fluid passage from vasculature to ciliary epithelium than to functional incompetency of the NPE.

Adolescent↗
PubMed1990

[Electronic data processing at the clinic].

Since 1 October 1986, all cataract, keratoplasty and glaucoma operations have been evaluated prospectively in the Department of Ophthalmology and Eye Hospital at the University of Erlangen-Nürnberg. The medical history data and preoperative status, intraoperative details and the postoperative course are standardized and stored. For each eye, the diagnosis is made according to the system called the "Erlanger Schlüssel." The present status of the Erlanger Ophthalmological Documentation System for Cataract, Keratoplasty and Glaucoma surgery is outlined. The difficulties encountered when the project was started are pointed out. The importance of electronic data processing in research, teaching and patient care is discussed.

Computer Systems↗
PubMed1990

["Early" immunologic transplant reactions following perforating keratoplasty. A prospective clinical study].

Between September 1986 and June 1988 310 penetrating keratoplasties were performed and prospectively analyzed. The purpose of this prospective study was the evaluation of graft rejections and the underlying corneal diseases. The mean follow-up time was 6.9 months. We found early graft rejections in 5.8% of the eyes. The increased rate of graft rejection in eyes with herpetic corneal ulcers was remarkable.

Cornea↗
PubMed1990

[Chromosome mutagenicity of a 193 nm Excimer laser].

Considering the fundamental role somatic mutations play in carcinogenesis, inducing mutations by any form of therapy should be avoided as far as possible. The mutagenicity of UV irradiation in the wavelength range of 248 to 310 nm is well established. The data on shorter wavelengths, e.g. 193 nm, however, are so far not clear-cut. Therefore, the potential chromosome-damaging effect of a 193 nm excimer laser was examined in the present study. Cultures of primary human fibroblasts and the Chinese hamster cell line CHO were the object of examinations. The in situ preparation technique used allowed detection of a locally limited clastogenic (chromosome damaging) effect in the neighborhood of the irradiated area. A slight increase in the frequency of chromosome aberrations could be observed in the area close to the laser-exposed field, which was attributed to the fluorescence generated by the laser under the given experimental conditions. Quantitative comparison with the data obtained from experiments with 254 nm irradiation from a UV lamp or exposure to 248 nm excimer laser-pulse irradiation, however, made the former activity appear somewhat insignificant. If one considers the practical aspects of the new laser surgery, the chromosome-damaging effect of the 193 nm pulse laser seems to be negligible.

Animals↗
PubMed1989

[Pseudokeratoconus in trisomy 21 and posterior polymorphous corneal dystrophy].

The authors examined three members of a family with an autosomal dominant trait of posterior polymorphous corneal dystrophy of varying expressivity. The 67-year-old white mother had a visual acuity of 20/30, with only discrete irregularities at the level of Descemet's membrane. The daughter developed bullous keratopathy with polymorphous ring-shaped opacities in the central area of Descemet's membrane early, in her 34th year. The 25-year-old son, who also had Down's syndrome, presented with the clinical symptoms of acute keratoconus. Light microscopy revealed a thickened, multilaminated Descemet's membrane with vesicles, breaks, and dislocation of endothelial cells into the deep stroma. Transmission electron microscopy showed a normal anterior, ribbonlike portion of Descemet's membrane and a fibroblastic differentiation of the corneal endothelial cells.

Adult↗
PubMed1989

[Fulminant gas gangrene panophthalmia following perforating scleral injury].

A 13-year-old boy developed Clostridium perfringens panophthalmitis due to a penetrating scleral injury. The characteristic symptoms were unusually severe periocular pain, lid edema, decreased motility and protrusion of the eye, severe conjunctival chemosis, pus covering the conjunctiva and cornea, green-brown hypopyon, gas bubbles in the anterior chamber, and amaurosis within 60 hours. In view of the patient's ocular status and impaired general condition enucleation was unavoidable. The results of laboratory workups are reported in addition to the clinical and ophthalmologic findings.

Adolescent↗
PubMed1989

Clinical observations of six cases of laser injury to the eye.

During the last decade, five patients with laser injuries were examined at the University of Munich Eye Clinic, in addition to one laser-injury patient at the University of Erlangen Eye Clinic. From a review of these cases, it is possible to gain an insight into factors that led to the eye injuries and to predict the clinical sequelae of laser retinal injury. A possible means of treatment, using an ophthalmic Q-switched Nd:YAG laser, is suggested for some types of retinal injury involving vitreal hemorrhage.

Accidents, Occupational↗
PubMed1989

[Configuration of corneal incisions with the excimer laser: an experimental study].

The potential applications of an ophthalmic excimer laser at 193 nm include its use as a precise trephine in keratoplasty procedures. In a series of 20 human autopsy and 40 pig cadaver eyes the histological and ultrastructural results of donor and recipient trephination and full-thickness corneal grafting using new mask systems were evaluated. In comparison with other beam delivery systems the "open mask system" allows the performance of excimer laser trephinations with reproducible wound configuration and geometry, with easy handling and high reliability. This technique enables the surgeon to surmount the mechanical limitations of cutting direction and makes non-circular trephinations possible.

Animals↗