Corneal and external disorders and refractive surgery.
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Eye Diseases↗
Biomedical subjects
G K Lang
Publications and source records attributed to G K Lang.
[Keratoplasty in childhood. Report of 71 keratoplasties].
BACKGROUND: Keratoplasty is a routine method in adults but there are some additional problems in children. These include difficulties in examining the patients, amblyopia and an increased rate of graft rejection. PATIENTS AND METHODS: Between 1980 and 1990 71 keratoplasties in 66 eyes of 61 patients under 16 years of age were performed. The indications and results were studied retrospectively and since 1987 prospectively. The average follow-up was 24 months. Main indications were traumatic scarring (22 eyes), corneal dystrophy (13 eyes), scarring after keratitis (10 eyes), graft failure (7 eyes), and chemical burn (5 eyes). There were 15 lamellar homologous not HLA-matched keratoplasties, 11 autologous penetrating rotating, 42 penetrating homologous not HLA-matched, and 3 penetrating homologous HLA matched. The most frequent complications were loosening or rupture of the suture in 38% and graft rejection in 20% of the homologous penetrating keratoplasties. 10 of 15 eyes after lamellar grafting showed a clear graft at the last control. 40 of 42 eyes after penetrating keratoplasty had also a clear graft, however second keratoplasties were necessary in 4 eyes. 21 of the 42 eyes after penetrating keratoplasty developed a visual acuity of 0.5 or better. CONCLUSION: We recommend interrupted single sutures for keratoplasties in children and an earlier suture removal to avoid severe suture problems. Visual outcome depends on the primary diagnosis and on avoiding irreversible amblyopia. In cases of traumatic corneal and lens opacification an early rehabilitation of the optic system is important, therefore in patients under 7 years of age we prefer a posterior chamber lens implantation for a more effective amblyopia therapy.
Adolescent↗
[193 excimer laser trepanation in perforating keratoplasty. Report of 70 patients].
BACKGROUND: In penetrating keratoplasty, trephination with the 193 nm excimer laser may help avoid the differences in the deformation of the donor and recipient wound margins which occur with the conventional procedure. By varying the shape of the "open metal mask", other cut configurations can be achieved besides circular. Thus, "vertical tilt" and "horizontal torsion", both potential reasons for persistent long-term astigmatism after PK, may be minimized. Following experimental studies, the authors present the results obtained in their first 70 consecutive patients. PATIENTS AND METHODS: 38 women and 32 men were treated (mean age 60.6 years, range 17 to 89 years). Indications were corneal processes without vascularization: Fuchs' dystrophy (n = 32), other stromal dystrophies (n = 5), secondary corneal endothelial decompensation (n = 6), keratoconus (n = 15), nonvascularized corneal scars (n = 4) and miscellaneous (n = 8 ). We used elliptical metal masks with/without orientation teeth and circular masks with four and eight orientation teeth, respectively. The HeNe aiming beam was manually controlled by a micromanipulator ("joystick"). The technical data of the laser were as follows: spot mode, 1.5 x 1.5 mm; repetition rate 30/sec and 25/sec, respectively; pulse energy 15-25 mJ; mean number of pulses 6407 (recipient) and 9150 (donor). With an elliptical outline, wound closure was usually achieved with single sutures. With a circular outline with orientation teeth, wound closure was most commonly achieved with a double running suture. Patients were prospectively documented using modified Erlangen record sheets. Follow-up ranged from 3 months to 3.4 years (mean 11.4 months). RESULTS: With two exceptions, penetration of the anterior chamber with the 193 nm excimer laser was accomplished without deformation of the cut edges. The elliptical outline facilitated fitting of the graft into the recipient wound bed, and the orientation teeth made fitting even easier. Initial intraoperative complications due to excessive laser energy densities included minor thermally induced corneal alterations caused by the heat of the metal mask and in a few cases minimal iris bleeding during corneal penetration. The median duration of re-epithelialization was two days. Wound healing was without complications. In particular, no primary graft insufficiency and no unexpected effects in donor or recipient corneas, iris, lens or posterior segments were observed. Postoperative complications were one corneal ulcer caused by premature fitting of an extended-wear contact lens and two immunologic graft reactions (3%). Mean astigmatism after suture removal was 4.6 D with an elliptical outline, and 3.9 D after trephination with orientation teeth and with the sutures in situ. CONCLUSION: Non-mechanical, "non-thermal" trephination with elliptical and circular metal masks with orientation teeth represents a viable alternative to knife trephination in penetrating keratoplasty. No unexpected complications such as disturbances of wound healing were seen. Further studies are needed to determine the effect on residual long-term astigmatism after suture removal.
Adolescent↗
Corneal and external disorders and refractive surgery.
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Eye Diseases↗
[Ocular carbon dioxide reactivity in retinitis pigmentosa. Perimetry results].
Ocular pulse volumes (POV) measured by oculo-oscillo-dynamography were markedly reduced in Retinopathia pigmentosa (R.P.) patients (n = 52) compared to healthy subjects (n = 107). During breathing increased carbon dioxide concentrations (6.5%) POV returned nearly to normal values [15,17]. In an attempt to evaluate the effects of increased inspiratory carbon dioxide concentrations on the visual field in R.P. patients the following study was performed. In 24 patients (24 right eyes, 23 left eyes) suffering from a clinically and electrophysiologically confirmed R.P. kinetic visual field testing was performed. After a standardized kinetic Goldmann-perimetry (V/4; III/4; I/4; I/3; I/2; I/1) during breathing normal air the visual field testing was repeated during breathing increased carbon dioxide concentrations (6.5%). The visual field area was measured with a planimeter (Hewlett Packard 9874 A Digitalizer) separately for each isopter. For a better comparison of the results the change in the visual field was expressed as a percentage value of the initial visual field area of each isopter. During breathing increased carbon dioxide concentrations the visual field area improved, expressed as the median of all isopters, by x = 29% in 24 right eyes and by x = 18% in 23 left eyes. The results presented suggest that breathing of increased carbon dioxide concentrations improve ocular hemodynamics and furthermore have a beneficial effect on the remaining visual field area in R.P. patients.
Adolescent↗
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↗
[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↗
New developments in curative and refractive surgery for corneal and conjunctival disorders.
Ocular surface diseases especially after severe lye burns are an unresolved challenge. Autologous nasal mucosa transplantation, keratoepithelioplasty, and polytef alloplastic grafting are current tools in surgical management of the ocular surface diseases. "Merest sclera" surgery is an approach in surgical management of pterygium. Procedures for refractive corneal surgery, such as epikeratoplasty, radial keratotomy, and keratomileusis, are discussed. Anterior stromal puncture technique is a surgical treatment of recurrent corneal erosions. Curative corneal surgeries are keratoplasty alone or as combined procedure. Problems of graft-failure are discussed. The new technique of excimer-laser (193 nm) elliptical keratoplasty is described.
Conjunctival Diseases↗
[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↗
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↗
A new elliptical excision for corneal transplantation using an excimer laser.
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Aged↗
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↗
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↗
[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↗
[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↗
[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↗
[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↗
["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↗