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Biomedical subjects

G I Duncker

Publications and source records attributed to G I Duncker.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Lid retraction in endocrine orbitopathy. A new indication for "lid loading"].

Lid retraction in thyroid ophthalmopathy may lead to cosmetic and functional problems. Many surgical procedures are available to correct upper lid retraction. Only those procedures should be used that lead either to a limited lid lengthening or can be reversed in cases with complications. Upper lid gold weight implantation was first used to treat lagophthalmos in patients with facial palsy. Since 1995 only a few reports have appeared which discuss platinum as an implantation material. We report our experiences with a female patient who developed an upper lid retraction due to thyroid ophthalmopathy. Through implantation of a platinum weight which was adjusted exactly preoperatively, a symmetric palpebral fissure was achieved. Unilateral upper lid retraction with resultant eyelid asymmetry is a new indication for lid loading.

Blinking↗
PubMed2000

[Wound or suture insufficiency complicating penetrating keratoplasty].

BACKGROUND: With regard to penetrating keratoplasty methods to culture corneal donor tissues, microsurgical techniques, HLA typing and understanding of basic mechanisms in inflammation and especially graft rejection, and postoperative treatment schedules have been improved in recent years. This now enables successful penetrating keratoplasty in many more patients than previously performed. However, in rare cases relevant problems in wound closure may appear. PATIENTS AND METHODS: A standardized treatment protocol was applied to 1,253 penetrating keratoplasties performed in a single center. Patients were continuously followed up. Simple leakage after corneal grafting was not further analyzed if conservative treatment or additional sutures achieved sufficient wound closure. In 21 cases, however, the causes of large wound dehiscence after corneal grafting were analyzed. RESULTS: During the first week early problems in suturing penetrating keratoplasty in five patients were associated with the instability of the recipients' corneal stroma (stromal thinning in keratoconus or corneal herpes, suture problems in keratomalacia, active herpes keratitis, corneal burns, or rheumatic diseases). Long-term complications in 16 patients were associated with alcoholism, herpes keratitis, rheumatic disorders or traumatic suture defects. Overall, nine patients lost functionally or even anatomically one eye because of wound dehiscence after corneal grafting. CONCLUSIONS: When penetrating keratoplasty is indicated, special attention should be given to (1) the compliance of the patient, (2) sufficient treatment of herpes keratitis or other infections, (3) adequate immunosuppression in autoimmune corneal inflammation, (4) double running continuous sutures as primary suture with sometimes additional single sutures to stabilize the graft, and (5) surgery in time.

Adolescent↗
PubMed2000

[Tilorone-induced functional changes in the rat retina].

BACKGROUND: The amphiphilic interferon-inducing drug tilorone belongs to the group of synthetic fluorenone with antitumorus and antiviral effects and is known to cause lipidosis in the human and rat retina. METHODS: We treated female albino Wistar-Kyoto-Rats and Spontaneously-Hypertensive-Rats orally with tilorone for 8 weeks. The animals were submitted to electroretinography, and the retinae were prepared for histological investigations. RESULTS: Tilorone caused moderate lipidosis in the ganglion cells and slight lipidosis in the pigment epithelium after 8 weeks of treatment with a stronger effect in Spontaneously-Hypertensive-Rats. The b-wave amplitude was reduced by 30% compared to controls in Spontaneously-Hypertensive-Rats and by 10% in the Wistar-Kyoto-group. The a-wave amplitude was reduced by 25% in Spontaneously-Hypertensive-Rats. CONCLUSION: Tilorone induced lipidosis shows a clear affinity to ganglion cells. The electroretinographic changes in Spontaneously-Hypertensive-Rats are most likely caused by the severe lipidosis in the neuroretina compared to the Wistar-Kyoto-group.

Animals↗
PubMed2000

[Foreign body granuloma after lower eyelid avulsion and surgical revision with silicone tube splint].

BACKGROUND: Foreign-body-reactions with granulomas after use of silicone-containing biomaterials are of clinical importance [4]. HISTORY AND SIGNS: A 4-year old patient entered our hospital with a reddish vascularised tumor. The tumor's origin was in the conjunctiva of the nasal lid-angle of the right eye. THERAPY AND OUTCOME: After a traumatic disconnection of the canaliculus lacrimalis inferior, a bicanalicular silicon-tube intubation had been performed with the patient in the age of one year. Only 3 years after this intervention a secondary clinical examination could be performed. At this time, an extended solid conjunctival-tumor appeared at the operated eye. After removal and histological examination it could be classified as a foreign body granuloma. CONCLUSIONS: The blood- and tissue compatibility of silicone is only insufficiently guaranteed on the basis of the hydrophobic material-surface. After reconstructive lacrimal surgery postoperative care and the removal of the stabilizing silicone material is necessary.

Child, Preschool↗
PubMed1999

Experimental animal myopia models are applicable to human juvenile-onset myopia.

Landmark explorations by Hubel and Wiesel investigating the importance of visual impressions in postnatal development of the visual system demonstrated that neural connections and eye growth can be affected by the absence of a clear retinal image during a critical period of postnatal development. Fundamental theories on neural plasticity and deprivation have recently been established that presume that a reduced quality of the retinal image during infancy and early childhood triggers an elongation of the posterior chamber of the eye, a so-called form deprivation myopia (FDM). In a retrospective multicenter study of 187 patients who suffered from phlyctenular keratitis with corneal opacification since early childhood, we reviewed data on gender, year and age at onset of the disease, refraction, and ultrasound biometry. Compared with the average refraction of +0.5 diopter (D) found in the general population, the mean refraction of -4.43 D that we found in our study demonstrated a marked shift toward myopia of almost 5 D. Patients with an early onset of phlyctenular keratitis had considerably higher myopia (-6.68 D) than those with a late onset (-1.67 D). Additionally, an axial elongation was confirmed by ultrasound biometry. Our average, axial length was 26.53 mm, compared with the epidemiologic mean of 24.00 mm. This myopic shift of 2.53 mm was caused mainly by an enlarged vitreous cavity. These results support the finding that blur can affect eye growth and lead to FDM not only in animal experiments but also in human beings.

Age of Onset↗
PubMed1999

[Chloroquine- and chlorphentermin-induced lipidosis in rat retina].

BACKGROUND: The amphiphilic drugs chloroquine and chlorphentermine are known to cause lipidosis in the human and rat retina. METHODS: We treated femal albino Wistar rats orally with chloroquine for 12 weeks, followed by a period of 4 months with normal feed and another group with chlorphentermine for 4-16 weeks. The animals were submitted to electroretinography, and the retinae were prepared for histological investigations. RESULTS: Chloroquine caused severe lipidosis in the neuroretina and slight photoreceptor cell degeneration after 12 weeks of treatment. The b-wave was reduced to 30% of initial values. After withdrawal the lipidosis remitted, but the degeneration of the photoreceptor cell layer continued to progress. The a-wave and b-wave amplitudes were reduced to 25% and 16% of initial values, respectively. Chlorphentermine caused pronounced lipidosis in the pigment epithelium and less numerous in the neuroretina after 16 weeks; no photoreceptor cell degeneration was found. The b-wave was reduced to 80% of initial values, the a-wave appeared unaffected. CONCLUSION: Whether lipidosis is the primary cause of changes in the electroretinogram and of receptor cell degeneration is doubtful. Excessive lipid storage may be the cause of secondary changes. It is unlikely that lipidosis in pigment epithelium played a role.

Administration, Oral↗
PubMed1999

Experimental intravitreal application of ciprofloxacin in rabbits.

BACKGROUND: Ciprofloxacin (CFLX) is a fluoroquinolone antibiotic with a broad antimicrobial spectrum. This study was performed to examine the retinal toxicity of free and liposome-incorporated CFLX in rabbit eyes after intravitreal injection. MATERIALS AND METHODS: Free CFLX in doses of 100, 250, 500, 1,000 and 2,000 microg was injected into the midvitreous of rabbit eyes (n = 28). To prolong the intravitreal antibacterial level, CFLX was incorporated into multilamellar liposomes: 0.1 ml of this suspension ( wedge 273.6 microg CFLX) was injected into the midvitreous of a second group of rabbit eyes (n = 6). The other eye served as a control and received normal saline solution or empty liposomes, respectively. Before injection and at the end of follow-up an electroretinogram (ERG) was obtained. After a follow-up of 1, 14 and 28 days the animals were perfused with glutaraldehyde and the eyes were examined by light and transmission electron microscopy. RESULTS: Significant reduction of the ERG was observed after 2,000 microg free CFLX in 4 out of 6 eyes after 14 days. Fourteen days after injection of 2,000 microg CFLX the central retina showed pigmentary changes in 4 out of 6 eyes. In the second group the ERG as well as the histologic studies did not reveal any pathologic changes after injection of liposome-incorporated CFLX compared to the control eyes. CONCLUSION: In therapeutic doses of 100-500 microg, free CFLX does not have retinal toxicity in rabbit eyes. No retinal toxicity was observed after intravitreal injection of liposome-incorporated CFLX.

Animals↗
PubMed1998

[Clearance of liposome-incorporated ciprofloxacin after intravitreal injection in rabbit eyes].

BACKGROUND: Ciprofloxacin (CIP) is a fluoroquinolone-antibiotic with a high antimicrobial activity against all pathogens causing bacterial endophthalmitis. After intravitreal injection, however, elimination half-life of this antibiotic is only 2.2 hours. To prolong intraocular bioavailability this study was performed to incorporate CIP into liposomes and to determine its clearance from the vitreous after intravitreal injection. MATERIALS AND METHODS: CIP was incorporated into multilamellar vesicles by mechanical dispersion. 0.1 ml of this suspension (equiv. 273.6 micrograms CIP) was injected into the midvitreous of pigmented rabbit eyes (Chinchilla-bastards). One day, 3 and 14 days after the injection intravitreal concentration of CIP was determined by means of high-pressure-liquid-chromatography after dissolution of the liposomes by ultrasound. At the same intervals serum concentration of the antibiotic was examined as well. RESULTS: Within 24 hours intravitreal concentration fell to 18.0 micrograms/ml. Three days after the injection the concentration of CIP was 6.9 micrograms/ml. This is still above the minimal inhibitory concentration (MIC90) of the most common ocular pathogens. At 14 days CIP was not detectable in the vitreous any more. The serum concentration was between 0.04 microgram/ml and 0.07 microgram/ml. 3 and 14 days after injection no CIP could be detected. CONCLUSIONS: This study shows that the incorporation of CIP into liposomes can be achieved in sufficient doses by mechanical dispersion method. After intravitreal application the bioavailability of the antibiotic can be markedly improved. Even after 3 days the intravitreal levels were above the MIC90 of the most common endophthalmitis pathogens.

Animals↗
PubMed1996

Excimer laser correction of high astigmatism after keratoplasty.

PURPOSE: To assess the effectiveness of excimer laser correction of high astigmatism after keratoplasty. SETTING: Kiel University Eye Hospital, Kiel, Germany. METHODS: In a prospective study, we treated high astigmatism in 16 patients using a 193 nm excimer laser with a rotating mask system to make a toric ablation. Thirteen patients had postkeratoplasty astigmatism, 3, idiopathic natural astigmatism. Preoperative refractive cylinder ranged from 3.0 to 9.0 diopters (D). Minimum follow-up was 6 months. RESULTS: Mean uncorrected visual acuity increased by 3.3 lines in 13 patients. Best corrected visual acuity decreased by no more than two lines in 6 patients and improved by at least one line in 6 patients. Mean cylindrical reduction was 2.8 D. Haze was classified from 0.5 to 2.0. CONCLUSIONS: In this study, the excimer laser technique effectively reduced high corneal astigmatism. The main problems incurred were development of a hyperopic shift and, in some patients, an uncertain refractive outcome. Reasons for inadequate correction of postkeratoplasty astigmatism included a slightly decentered mask and irregular astigmatism from the circular scar.

Adolescent↗
PubMed1995

Complications of silicone disc intraocular lenses.

Through a 4.5 mm corneoscleral incision, we implanted one of two types of foldable, silicone disc, posterior chamber intraocular lenses (IOLs) in the bag in 35 eyes of 32 patients after phacoemulsification and capsulorhexis. Five lenses were explanted in the early postoperative period because of complications. We followed 24 eyes for an average of 38 months. At the end of follow-up, 5 of the lenses had decentered by 1 mm; 8 (33%) had developed clinically significant posterior capsule opacification (PCO). We believe the IOLs' disc shape may not allow firm fixation, resulting in opacification. On average, there were no significant differences in long-term results between the two silicone disc lens types.

Aged↗
PubMed1995

[Corneal markers for continuous keratoplasty sutures].

BACKGROUND: In penetrating keratoplasty adaptation of wound edges, mode of trephination of both donor and patient cornea and last but not least techniques of suture style are the factors determining postoperative astigmatism. A new corneal marking device for keratoplasties and epikeratophakias is introduced. This marker helps the surgeon both to center the trephine and to perform a perfect double running torque antitorque suture. METHODS: The marker has the shape of an 8-bite star. It can be stained and printed on the cornea. The cross hair of the marker has to be right in the optical center. After trephination we fix the graft with temporal single sutures. Then we mark the dried cornea, so that an 8-bite star can be printed on the cornea. Now a first 10-0 running suture is done. The second continuous suture can be set just in between. In our experience it turns out more precisely, if this second running suture is previously marked, too. RESULTS AND CONCLUSIONS: After 35 perforating keratoplasties performed with this new marking device the mean astigmatism was 2.0 +/- 0.75 dpt (x +/- sx). Only a prospective, randomized study comparing different suture styles with and without star marker can elucidate the definite value of this new surgical instrument.

Astigmatism↗
PubMed1995

[Phototherapeutic keratectomy as the primary option before perforating keratoplasty].

BACKGROUND: Argon fluoride excimer laser (193-nm) can perform precise corneal ablation with submicron accuracy and minimal reaction to the adjacent tissue. A possible application is anterior lamellar keratectomy to remove superficial corneal opacities and to smooth corneal irregularities. PATIENTS AND METHODS: Between August 1993 and June 1994 we performed a phototherapeutic keratectomy (PTK) in 35 patients with different corneal diseases by excimer laser (Aesculap-Meditec). 3 cases (2 corneal dystrophies and 1 patient with a traumatic corneal opacity after chemical burn) are described more exactly with operative methods and postoperative results. RESULTS: By slitlamp microscopy we observed an improvement of the primary corneal disorder in all cases. Changing of refraction (hyperopic shift and newly formed astigmatism) arose in 2 out of 3 patients. CONCLUSIONS: Phototherapeutic keratectomy by excimer laser represents a secure, less invasive alternative to surgical methods promising quicker visual recovery. Often a penetrating keratoplasty can be avoided or delayed.

Adult↗
PubMed1995

A new cornea-marking device for penetrating keratoplasty and refractive corneal procedures.

In penetrating keratoplasty, postoperative astigmatism is determined by a number of factors, including adaptation of wound edges, mode of trephination of both donor and patient cornea and, last but not least, suture techniques. We would like to introduce a new cornea-marking device for use in keratoplasty and epikeratophakia. This device helps the surgeon to center the trephine and to perform a perfect double running torque-antitorque suture. Additional single sutures are not necessary. A study of postoperative astigmatism following operations in which this device was used is under way.

Astigmatism↗
PubMed1994

[Keratoconus in Mulvihill-Smith syndrome].

BACKGROUND: The Mulvihill-Smith syndrome consists of a large number of stigmata. A few of them are also seen in the LEOPARD syndrome. In both syndromes keratoconus has not yet been reported. PATIENT: We present a twenty-year-old male patient suffering from keratoconus in connection with a Mulvihill-Smith syndrome. A keratoplasty à chaud was done after perforation of the corneal ulcer. CONCLUSION: As a major complication corneal graft rejection is known after keratoplasty à chaud. However, in our patient immunological graft failure may be prevented by the T-cell defect.

Abnormalities, Multiple↗
PubMed1994

Prospective, randomized, placebo-controlled, double-blind testing of colour vision and electroretinogram at therapeutic and subtherapeutic digitoxin serum levels.

In a prospective, randomized, double-blind study with 10 healthy probands, changes in colour discrimination and in the pattern electroretinogram (P-ERG) and visually evoked cortical potentials (P-VECP) were monitored at therapeutic and subtherapeutic digitoxin serum levels. There was a slight increase in the total error score in the Farnsworth-Munsell 100-hue test at 0.1 mg digitoxin per day in comparison with the placebo. P-ERG and P-VECP did not show any significant changes.

Adult↗
PubMed1994

Cefmenoxime in corneal organ culture.

Before introducing new antibiotics for corneal organ culture solutions, information about the endothelial cell toxicity is necessary. Therefore, we preserved 132 pig corneas in minimum essential medium with 2% fetal calf serum and 5% dextran T 500 and added 50, 100, 250 and 500 micrograms/cm3 cefmenoxime. Slight endothelial cell damage occurred at a concentration of 100 micrograms/cm3. Damage to endothelial cells was demonstrated by the inhibited uptake of fluorescein diacetate and by other staining procedures. 30% of the substance remained stable during a 10-day culture period as demonstrated by an HPLC method.

Animals↗