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Biomedical subjects

W Konen

Publications and source records attributed to W Konen.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Revision of iris incarceration after trabeculectomy in congenital glaucoma. A case report].

BACKGROUND: Incarceration of the iris is a potential complication following trabeculectomy in primary congenital glaucoma. Although this complication is mentioned in the literature, nothing is reported about the technique of surgical revision. PATIENT: In a patient with primary congenital glaucoma we had to perform surgical revision of the anterior chamber, because progressive pupil peaking had developed after trabeculectomy and the optical axis had been obstructed. Simple resolving of uveal tissue from the incarceration site was not possible; the iris incarceration had to be cut under gonioscopic control. CONCLUSION: Surgical revision of an incarceration of the iris can be safely performed by means of gonioscopy. The outcome of intraocular pressure is not necessarily influenced.

Female↗
PubMed1998

Development of an endoscopic navigation system based on digital image processing.

We developed a new system to couple the endoscope to an optical position measurement system (OPMS) so that the image frames from the endoscope camera can be labeled with the accurate endoscopic position. This OPMS is part of the EasyGuide Neuro navigation system, which is used for microsurgery and neuroendoscopy. Using standard camera calibration techniques and a newly developed system calibration, any 3-dimensional (3-D) world point can be mapped onto the view from the endoscope. In particular, we can display the coordinates of any anatomical landmark of the patient as it is viewed from the current position of the camera. This and other image-processing techniques are applied to the labeled frame sequence in order to offer the neurosurgeon a variety of control modules that increase the safety and flexibility of neuroendoscopic operations. Several modules, including a new motion alarm system and the "tracking" and "virtual map" modules, were tested in a human cadaveric model using the frontal and occipital approaches. A failure rate of 8.6% was experienced during testing of the first version of the software, but the second version was 100% successful. Thus, an endoscopic navigation system based on digital image processing has been developed that could be a revolutionary advance in image-guided surgery.

Cadaver↗
PubMed1998

The VN project: endoscopic image processing for neurosurgery.

We developed a navigation support system for endoscopic interventions that allows three-dimensional (3-D) information to be extracted from endoscopic video data and superimposed onto such live video sequences. The endoscope is coupled to a position measurement system and a video camera as components of a calibrated system. In this article we show that the radial distortions of the wide-angle endoscopic lens system can be successfully corrected and an overall accuracy of about 0.7 mm is achievable. Tracking on live endoscopic video sequences allows accurate 3-D depth data to be obtained from multiple camera views.

Calibration↗
PubMed1998

Granular corneal dystrophy: treatment with soft contact lenses.

Perforating keratoplasty was performed in both eyes of two siblings (sister and brother) with typical granular corneal dystrophy. Three of the operated eyes showed a recurrence of the underlying disease. In one eye, a recurrence could not be detected 14 years after the operation. This eye had been fitted with a contact lens 16 months after keratoplasty because of aphakia. Thus a contact lens may have a therapeutic effect in this primary epithelial disease.

Adult↗
PubMed1997

[Laser flare measurement with 3 different nonsteroidal anti-inflammatory drugs after phacoemulsification with posterior chamber lens implantation].

In a prospective, randomised, double-masked, parallel-group study we compared the antiinflammatory effect of diclofenac sodium 0.1%, flurbiprofen 0.03%, and indomethacin 1.0% ophthalmic suspension in 99 patients undergoing phacoemulsification and posterior chamber lens implantation. The reduction in anterior chamber flare from day 1, as measured with the laser flare-meter (FM-500, KOWA) on day 4-5 postoperatively was significantly greater in the diclofenac group than with flurbiprofen (p = 0.022). Patients treated with diclofenac had significantly less burning and stinging than patients on flurbiprofen and indomethacin on postoperative days 4-5 (p < 0.0001) and 12-14 (p = 0.001). Diclofenac sodium appears to be more potent than flurbiprofen in controlling intraocular inflammation after cataract surgery, while having better local tolerance than flurbiprofen or indomethacin.

Adult↗
PubMed1997

The artificial iris diaphragm for vitreoretinal silicone oil surgery.

BACKGROUND: Silicone keratopathy frequently develops as a complication of silicone oil tamponade in the management of severe trauma in eyes with partial or complete aniridia. We therefore designed an "open" artificial iris diaphragm to prevent silicone oil-endothelial contact. In hypotony, where insufficient circulation of aqueous allows silicone in the anterior chamber despite an open diaphragm, a new solution became necessary. The "closed" artificial diaphragm was developed. METHODS: In this retrospective study, two consecutive series of artificial iris diaphragms were compared. Forty-four patients received either an open type (20 eyes) or a closed type (24 eyes) and were observed for 409 +/- 421 days (range, 32-1912). All eyes were aphakic, normotonous, and had a traumatic, compromised iris diaphragm or were aphakic and hypotonic as a result of injury, proliferative vitreoretinopathy, proliferative diabetic retinopathy, or uveitis, with an intact natural iris diaphragm. RESULTS: Silicone oil was retained behind the open diaphragm throughout the observation period in 40% of the eyes. Major long-term complications were hypotony and fibrous overgrowth. Silicone was retained behind the closed diaphragm in 50% of the eyes. CONCLUSION: Because proliferative vitreoretinopathy is active for months and multiple surgical interventions become necessary to avoid phthisis in eyes with highly pathologic changes, longstanding or permanent silicone tamponade is used. The artificial diaphragm prevents silicone-corneal contact in approximately 50% of aphakic eyes for at least 1 year.

Adolescent↗
PubMed1996

Effect of 3.0 mm tunnel and 6.0 mm corneoscleral incisions on the blood-aqueous barrier.

PURPOSE: To study of the effect of silicone intraocular lens (IOL) implantation using a 3.0 mm tunnel incision with that of implantation though a 6.0 mm corneoscleral incision after phacoemulsification in human eyes. SETTING: Department of Ophthalmology, University of Köln, Germany. METHODS: In a prospective, randomized clinical study, 50 patients with senile cataract had phacoemulsification and IOL implantation through a 3.0 mm tunnel or a 6.0 mm corneoscleral incision. To assess blood-aqueous barrier (BAB) disruption, preoperative and postoperative sodium fluorescein concentrations in the anterior chamber were measured with the Fluorotron Master II. Diclofenac sodium 0.1% was applied to the operative eyes five times a day for 5 days. The contralateral eyes served as controls. RESULTS: There was no significant between-group difference in sodium fluorescein concentrations in the 5 days after surgery. CONCLUSION: The findings underline our clinical impression that BAB disruption 5 days after surgery does not differ significantly with the type and length of scleral incision used for IOL implantation.

Analysis of Variance↗
PubMed1996

Efficacy and tolerance of diclofenac sodium 0.1%, flurbiprofen 0.03%, and indomethacin 1.0% in controlling postoperative inflammation.

PURPOSE: To compare the anti-inflammatory effect of diclofenac sodium 0.1% ophthalmic solution, flurbiprofen 0.03% ophthalmic solution, and indomethacin 1.0%. SETTING: Department of Ophthalmology, University of Köln, and Bundesknappschaftskrankenhaus, Sulzbach, Germany. METHODS: One hundred seventeen patients enrolled in this prospective, randomized, double-masked, and parallel-group study had phacoemulsification and intraocular lens implantation and received one of the three solutions. Preoperatively at day 1 and postoperatively at day 4 or 5 and day 12, 13, or 14, they were examined by slitlamp, applanation tonometry, and laser flare meter. RESULTS: Anterior chamber flare reduction from baseline was significantly greater in the diclofenac group than in the flurbiprofen group (P = .022). Patients in the diclofenac group had significantly less burning and stinging than those in the flurbiprofen and indomethacin groups at postoperative days 4-5 and 12-14 (P = .001). CONCLUSION: Diclofenac sodium appeared to be more potent than flurbiprofen in controlling intraocular inflammation after cataract surgery and appeared to be locally tolerated better than flurbiprofen and indomethacin.

Administration, Topical↗
PubMed1996

Effects of bilateral orbital decompression by an endoscopic endonasal approach in dysthyroid orbitopathy.

AIMS: The efficacy of endoscopic endonasal orbital decompression in dysthyroid orbitopathy was analysed. METHODS: In 21 consecutive cases of bilateral operation short term (10 (SD 6) days after operation) and long term (156 (12) days after operation) results were recorded. RESULTS: Short term results showed that vision of the more affected eye improved from a mean of 0.35 to 0.59; vision improved in all but one eye which remained unchanged. In the fellow eyes mean visual acuity improved from 0.6 to 0.7; three of these eyes showed a decrease. Mean proptosis returned from 23.0 mm to 20.0 mm. As to motility the mean abductive capacity decreased from 5.5 mm to 4.0 mm of monocular excursion, whereas adduction increased from 7.5 mm to 8.5 mm. Upgaze and downgaze did not show any major change. The mean angle of horizontal squint shifted from 7.5 degrees of convergence to 15.5 degrees while no significant vertical or cyclorotational deviation was induced. These immediate postoperative results proved to be stable for the period of long term follow up with only slight changes. No significant bleeding or specific otorhinolaryngological complication without resolve occurred intraoperatively or perioperatively. CONCLUSION: This method is believed to be superior to non-endoscopic techniques because it avoids external scars and antral pain. With regard to the relief of intraorbital pressure, the technique gives good results for visual acuity improvement, but in proptosis reduction the method is not as efficient as external or combined procedures. There seems to be no difference when compared with other approaches in induction of horizontal squint. The method has a protective long term effect against the recurrence of compressive optic neuropathy.

Adult↗
PubMed1996

[Risks and therapy options in dural arteriovenous fistulas between branches of the external carotid artery and the cavernous sinus. A case report and review of the literature].

INTRODUCTION: Dural arteriovenous fistula of the Arteria carotis externa and the sinus cavernosus are rare vascular malformations. In the literature the prognosis and necessity of treatment is described very variable. PATIENTS AND METHODS: A 90 year old female presents in our outpatient clinic with acute exophthalmus, dilated episcleral veins, cerebral bruits and beginning orbital apex syndrome. After normal computerized axial tomography (CAT) without and with contrast medium, we were able to diagnose a dural AV-fistula by angiography. Shortly after dismission the patient had a spontaneous subarachnoidal haemorrhage with severe neurological symptoms. CONCLUSIONS: The suspect of an intracranial AV-malformation implies a detailed diagnostic search with precise localisation of the process. In any patient with intracerebral and intracranial fistula there has to be an individual check of possible and necessary treatment. It is impossible to classify dural AV-fistula as a benign disease with harmless clinical course.

Aged↗
PubMed1995

Effect of age and astigmatism on the AMO Array multifocal intraocular lens.

Multifocal intraocular lenses (MIOLs) have been designed to provide better uncorrected near visual acuity than monofocal IOLs. However, the increase in depth of focus is combined with a significant decrease in contrast sensitivity and glare. We implanted a new zonal-progressive MIOL (AMO Array) in 31 eyes of 25 patients whose mean age was 60.8 +/- 13.5 years. At 12.1 +/- 2.4 months postoperatively, the uncorrected visual acuity averaged 0.56 +/- 0.09 (20/32) for distance and 0.54 +/- 0.12 (20/40) for near focus. Seventy-five percent of patients achieved a best corrected distance visual acuity of > or = 0.9 (20/22). With distance correction only, mean near visual acuity was 0.72 +/- 0.17 (20/25). Best corrected near acuity reached 0.89 +/- 0.11 (20/22), requiring an additional near add of +1.0 to +2.0 diopters (D). We observed an age-dependent difference in the depth of focus. In younger patients (46 +/- 6 years), the pseudoaccommodation range was 6.25 D; acuity attained was > or = 0.4 (20/50). In older patients (71 +/- 7 years), visual acuity at the near focus was substantially reduced (two lines). Regan contrast sensitivity was lower for MIOL patients at all contrast levels, but the difference was statistically significant only at very low contrast (11%). Contrast sensitivity and glare were dependent on the patient's age but did not change with the amount of postoperative astigmatism. Younger patients were very satisfied with the results of MIOL implantation, and the small loss of contrast sensitivity was counterbalanced by the advantage of improved depth of focus and uncorrected near visual acuity.

Accommodation, Ocular↗
PubMed1995

[Intraocular silicone lenses and silicone oil].

BACKGROUND: Foldable silicone intraocular implants are becoming more popular in conjunction with small incision phacoemulsification. PATIENTS: We observed three patients with silicone oil droplets adherent to the posterior surface of the silicone implant, following silicone oil removal after preceding vitreoretinal surgery with the installation of silicone oil. These droplets could not be dislodged intraoperatively either with focal aspiration or irrigation. They interfered with the patients subjective visual acuity. For this reason, we performed an exchange of the silicone intraocular implant against a PMMA one-piece lens in all three cases. RESULTS: This procedure resulted in an increase of the visual acuity. The mechanism of adherence between the two silicone polymers is finally not known. CONCLUSIONS: With increased use of implantable silicone intraocular lens and silicone oil this complication may be encountered more frequently. Therefore, implantation of silicone lens in vitreoretinal high risk eyes should avoided.

Aged↗
PubMed1994

Visual outcome of secondary lens implantation after trauma or complicated retinal detachment surgery.

PURPOSE: Visual outcome of intraocular lens (IOL) implantation as a separate surgical procedure after severe trauma of the anterior or posterior segment or after vitreoretinal surgery for complicated retinal detachment resulting in aphakia was evaluated. METHODS: The charts of all patients undergoing secondary IOL implantation for the above reasons between 1988 and 1992 were retrospectively reviewed. A special transcleral suturing technique was developed for the posterior chamber lenses, where needles are primarily passed from the outside through the sclera to enhance correct positioning of the sutures. RESULTS: In all but one of the cases in group 1, visual acuity after surgery was equal to or better than before surgery. In the second group, visual acuity after surgery was equal to or better than before surgery in 9 of 12 cases. CONCLUSIONS: Secondary IOL implantation after severe trauma or vitreoretinal surgery for complicated retinal detachment is a fairly safe technique, with only few transient complications. Visual acuity did not deteriorate after surgery by more than two lines in any the cases discussed. Peripheral binocularity was restored in all cases. The suturing technique described here, in which the needles are primarily passed from the outside through the sclera, offers the advantage of exact positioning of the haptics in the ciliary sulcus.

Adolescent↗
PubMed1994

Reconstruction of the anterior and posterior segment of the eye after massive injury.

We treated 15 patients whose common characteristic was a severe windscreen injury (7 eyes) or an (mine) explosion trauma (8 eyes), nearly always affecting both eyes. In several operations we tried to reconstruct the anterior and posterior segments using a temporary keratoprosthesis for repair of the posterior-segment damage. In cases where the retina could be attached, the initial result was a functional stabilization and improvement. In 4 eyes we implanted an artificial iris diaphragm to prevent silicone-corneal contact. The long-term results will depend on the functionality of the ciliary body.

Accidents, Traffic↗
PubMed1992

Effect of dexamethasone 0.1% and prednisolone acetate 1.0% eye drops on the blood-aqueous barrier after cataract surgery: a controlled randomized fluorophotometric study.

Using non-invasive anterior chamber fluorophotometry, we performed a double-blind, randomized clinical trial on the effects of dexamethasone 0.1% and prednisolone acetate 1.0% eye drops on the blood-aqueous barrier after phacoemulsification and posterior chamber lens implantation. Twenty patients received one of the preparations topically to the surgically treated eye 5 times daily for a period of 5 days, beginning the day after surgery. Patients chosen for the study had no history of eye disease other than senile cataract nor of systemic diseases influencing the eyes. No other steroids or non-steroidal anti-inflammatory drugs were given before or during the investigation. The fluorometric data measured 5 days after surgery show a lower mean concentration of fluorescein in the dexamethasone alcohol 0.1% treated group compared with the prednisolone acetate 1.0% treated group. The difference is statistically not significant. The clinical assessment of postoperative ocular inflammation did correlate with the fluorophotometric measurements. The results of the study indicate that although dexamethasone is the more potent anti-inflammatory agent, with a better binding affinity to glucocorticoid receptors, we are--with the number of cases measured--unable to demonstrate any difference in the efficacy in protecting the blood-aqueous barrier after cataract extraction and posterior chamber lens implantation to prednisolone acetate.

Administration, Topical↗
PubMed1992

Artificial iris diaphragm and silicone oil surgery.

In order to avoid contact between silicone oil and the cornea and subsequent painful corneal dystrophy in aniridial eyes, an artificial iris diaphragm was constructed. It consists of polymethylacrylat (PMMA) and simulates the situation of the iris with a central pupillary opening and inferior iridectomy. To date, these diaphragms have been implanted in 11 cases of the severest ocular trauma with accompanying aniridia and proliferative vitreoretinopathy. In the presence of sufficient residual secretion of the ciliary body (9 cases), the diaphragm assumes the function of normal iris and prevents the silicone oil from coming into contact with the corneal endothelium. The transparent diaphragm ensures a view through to the fundus. In the early postoperative period, there was, as anticipated, a fibrinous reaction in the area of the anterior segment.

Adult↗