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Biomedical subjects

J Kammann

Publications and source records attributed to J Kammann.

At least 19 recordsLinked to original sources
PubMed1999

Bilateral implantation of asymmetrical diffractive multifocal intraocular lenses.

OBJECTIVE: To evaluate visual results after bilateral implantation of multifocal intraocular lenses (IOLs) with asymmetrical light distribution for the far and near focus. METHODS: Twenty-nine patients underwent bilateral implantation of silicone-optic, foldable, diffractive IOLs in a prospective, 2-center, noncontrolled interventional study. Each patient had a distant-dominant multifocal IOL implanted in 1 eye and a near-dominant multifocal IOL implanted in the fellow eye. Refractive and visual results, including contrast acuity and binocular visual function, were determined. Patients were questioned for postoperative spectacle usage. RESULTS: Visual and contrast acuity in the dominant focus of either lens was superior to that in the nondominant focus at 3.5 to 12 months postoperatively, i.e., performance was best at distance for the distant-dominant and at near for the near-dominant lens. In binocular viewing, the monocular maximal results added up to an improved binocular visual performance. Binocular visual function was within normal limits. Eighty percent of patients reported no use of spectacles at any time postoperatively. CONCLUSIONS: Bilateral implantation of asymmetrical diffractive IOLs is an effective alternative for restoring simultaneous distance and near vision with a potential for improved contrast sensitivity compared with conventional multifocal IOLs.

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PubMed1999

[The German Ophthalmology Society in the internet. Resources and interest].

OBJECTIVE: The German Ophthalmologic Society is rising to the challenges of the information age by offering comprehensive information resources online. METHODS: The society's board decided on the development of an Internet website in October 1996. Since February 1997, the website has been available under the Internet address www.dog.org. The amount of information offered has been growing fast during the following 12 months. RESULTS: On its website, the DOG offers information about itself, membership, further education, and a catalog of important addresses, patient information, official recommendations, and the program and abstracts of the annual sessions. The ICD10-aug was integrated into the website as a database application. A discussion group is reserved for ophthalmologists who can use this platform to share ideas and discuss clinical topics. CONCLUSIONS: The website of the DOG consists of over 4,900 files that represent the activities of the society. The website's access log indicates steady interest in the information offered. Over 53,000 users visited the DOG website. The discussion group is used by 71 members from 10 countries (all numbers as of 9/98).

Germany↗
PubMed1998

Vitreous-stabilizing, single-piece, mini-loop, plate-haptic silicone intraocular lens.

PURPOSE: To evaluate the clinical and visual results of the Medevec VS5 intraocular lens (IOL) with mini-loops, determine the incision size required for its implantation and its usable optical zone size, and compare the sizes with those of other foldable lenses. SETTING: Ophthalmology Department, St. Johannes Hospitals, Dortmund, Germany. METHODS: The VS5 lens was folded with a forceps and implanted into an intact bag in 27 patients; incision size was measured. Postoperatively, centration was recorded after dilation and the lens periphery observed to ascertain whether the loops were fixed in the capsular bag. Postoperative A-scans were done in 22 eyes, and the preoperative and postoperative vitreous cavity lengths were compared. The size of the optical zone was compared with that of other foldable lenses. RESULTS: Forceps implantation of the VS5 lens required a 2.7 to 3.0 mm incision; all lenses were fixated in the bag. A-scans in 22 eyes showed that the vitreous cavity was shortened by an average of 0.51 mm. Uncorrected visual acuity was 20/40 or better in 96% of eyes. One week postoperatively, the IOLs remained centered and there was no flare or cells. The usable optical zone was larger than that of the staked long-loop lenses. CONCLUSION: The Medevec VS5 fixated in the bag, consistently locating in the posterior bag space and stabilizing the vitreous. It had a full 5.0 mm optical zone and could be implanted through an incision smaller that that required by other foldable IOLs.

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PubMed1998

Endothelial cell loss secondary to two different phacoemulsification techniques.

BACKGROUND AND OBJECTIVE: The endothelial cell count after phacoemulsification serves as a sensitive indicator for the level of corneal damage caused by different phacoemulsification techniques. PATIENTS AND METHODS: In a prospective and randomized study, the "Reversed Tip and Snip" technique and the "Divide and Conquer" technique were performed in groups of 30 patients each. The corneal endothelial cell count was measured preoperatively as well as 4 weeks and 3 months postoperatively. RESULTS: The endothelial cell count showed significant (P < .001) reduction by approximately 10% after the "Reversed Tip and Snip" technique and by approximately 15% (P < .001) after the "Divide and Conquer" technique. The latter produced a significantly (P < .001) greater cell loss. CONCLUSIONS: The "Reversed Tip and Snip" phacoemulsification technique produces less endothelial cell loss than the "Divide and Conquer" technique.

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PubMed1997

[Endothelial cell loss after phacoemulsification with the "reversed tip and snip" technique compared with the "divide and conquer" technique].

BACKGROUND: The endothelial cell count after phakoemulsification is a sensitive parameter to compare different phakoemulsification techniques. PATIENTS AND METHOD: In a prospective study 30 patients in each group were operated upon the "Reversed Tip and Snip" and with the "Divide and Conquer"-Technique. The corneal endothelial cell count was measured before surgery and 4 weeks and 3 months after the operation. RESULTS: The endothelial cell count was reduced significantly about 10% after the the "Reversed Tip and Snip" and about 15% after the "Divide and Conquer"-Technique. The first mentioned technique had a significantly reduced cell loss than the latter. CONCLUSION: The "Reversed Tip and Snip" phakoemulsification technique causes less endothelial cell loss than the "Divide and Conquer"-Technique.

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PubMed1995

[2 years corneal small-incision surgery. Results and indications].

Small-incision surgery has contributed considerably to accelerated wound healing and minimization of surgically induced astigmatism. A variation of this surgical technique is sutureless cornea small-incision surgery with preparation of a corneal tunnel of 4.5 mm or less. To date, 195 patients have been operated on with this technique. In 130 cases the incision was made in the upper temporal area, in 65 cases laterally. Visual outcome and development of induced astigmatism over a period of 2 years were compared with the results achieved with corneoscleral small-incision surgery. Four weeks postoperatively, the vision in all three groups was > 0.5 in 67% of the patients. Also in the further course no significant changes were found. Regarding the average astigmatism, more severe fluctuations during the whole follow-up period and approximately 0.4 D higher values were observed with clear corneal incision via an oblique meridian at the same initial value. After 2 years, the value found in this group was 1.5 +/- 0.7 D. The development of surgically induced astigmatism, determined according to Jaffe and Clayman, indicates the same relationship. Following clear corneal incision in the upper temporal area, the value decreased within 1 year postoperatively to an average of 0.85 +/- 0.55 D, followed by an increase after 2 years to 1.26 +/- 0.44 D, in contrast to a temporal or corneoscleral approach, where no severe fluctuations were found. Based on our experience, we only apply clear corneal incisions via the oblique or vertical meridian when try to correct preexisting astigmatism. Corneoscleral small-incision surgery remains our standard operation technique. If corneoscleral tunneling is not possible or is unfavorable, a clear corneal incision is placed laterally.

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PubMed1994

[Sutureless wound adaptation. Comparison between corneal and corneoscleral incision].

Fifty-four eyes with concomitant diseases, either a coagulation disorder or previous glaucoma surgery, were implanted with a folded, disc-shaped silicone intraocular lens (IOL) via a 3.5 mm three-step clear corneal tunnel; we developed this technique in 1991. IOLs of the same lens type were implanted through a 3.5 mm corneoscleral tunnel by the same surgeon in a control group consisting of 52 eyes. The final visual outcome was reached after 4 weeks in 44.7% of the patients (compared to 63.5% in the control group). The postoperative astigmatism stabilized after 3 months in 31.4% of the patients belonging to the clear corneal tunneling group and after 1 month in 32.1% of the patients belonging to the corneoscleral tunneling group. Compared to the control group, the continuously decreasing induced astigmatism was significantly greater in the clear corneal tunneling group at all times, except for 1 week postoperatively. After 1 year, the mean astigmatism was 0.91 +/- 0.50 D, compared to 0.57 +/- 0.36 D in the control group. After 18 months, the average induced astigmatism in the clear corneal tunneling group increased to 1.30 +/- 0.54 D, compared to the stable value in the control group amounting to 0.59 +/- 0.52 D. As an alternative to routine corneoscleral small incision surgery, the clear corneal technique is especially suited for patients with a coagulation disorder, with unfavorable anatomic conditions, or with glaucoma; a scleral incision should be avoided in these cases.

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PubMed1994

[Lens implantation in patients treated with anticoagulants].

The number of patients undergoing anticoagulation therapy is increasing. Interruption of the treatment can potentially result in complications endangering the patient's life. A new surgical technique with corneal incision, phacoemulsification and sutureless wound closure under maintained anticoagulation therapy is presented. Preliminary results after 36 cases seem to show that this technique is superior to those usually employed in cataract surgery, with corneal incision and suture.

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PubMed1994

[The growth behavior of mouse fibroblasts on intraocular lens surface of various silicone and PMMA materials].

Experience with intraocular lenses (IOL) made of PMMA dates back ca. 40 years, while silicone IOLs have been in use for only about 10 years. The biocompatibility of PMMA and silicone caoutchouc was tested in a comparative study investigating the growth of mouse fibroblasts on different IOL materials. Spectrophotometric determination of protein synthesis and liquid scintillation counting of DNA synthesis were carried out. The spreading of cells was planimetrically determined, and the DNA synthesis of individual cells in direct contact with the test sample was tested. The results showed that the biocompatibility of silicone lenses made of purified caoutchouc is comparable with that of PMMA lenses; there is no statistically significant difference. However, impurities arising during material synthesis result in a statistically significant inhibition of cell growth on the IOL surfaces.

Animals↗
PubMed1993

[Biocompatibility of silicone intraocular lenses].

BACKGROUND: In order to the biocompatibility of silicone intraocular lenses, which is described contradictory in literature, we compared IOLs made of silicone caoutchouc and PMMA-IOLs with regards to the presence of macrophages (i.e. giant cells or spindle-shaped cells) in a prospective, randomized study. PATIENTS AND METHODS: Totally 125 patients were examined 2 months post-operatively with the slitlamp in the refractive zone. The single-piece PMMA-IOLs with an open haptic used in this study had a 6 mm optical zone and a total diameter of 11 mm; the silicone-IOLs were disc-shaped lenses with a total diameter of 9.75 mm and an optical zone of 6 or 5.5 mm, resp. RESULTS: Giant cells were observed with 16% of PMMA-lenses and 19% of the silicone-lenses. The maximal density of the giant cells on the PMMA-lenses at the median was 3/mm2 compared to 2/mm2 on the silicone IOLs. Small and spindle-shaped cells were found in 54% of the PMMA-IOLs and 46% of the silicone-lenses. The maximal cell density at the median was 10/mm2 with both lens types. CONCLUSIONS: The differences between the two lens materials are statistically non-significant. Thus, silicone caoutchouc and PMMA possess a comparable biocompatibility when used as material for intraocular lenses.

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PubMed1991

[Controlled clinical study of two viscoelastic substances].

Viscoelastic substances in correlation with intraocular hypotony have gained great significance in low-irritation cataract surgery within the last few years. The differences in their chemical properties, and thus in their effect on the eye, formed the grounds for a controlled clinical study comparing sodium hyaluronic acid, representing the group of glucosamine glykanes, and hydroxypropylmethyl cellulose (HPMC), representing the group of cellulose ethers. Two hundred cataract patients, excluding those suffering from diabetes mellitus, glaucoma and severe corneal damage, were examined on the 1st, 2nd and 5th postoperative day, as well as 4 weeks postoperatively. Statistically, no significant differences were found as regards IOP and postoperative anterior chamber irritation. From the economical point of view, methocel (HPMC) should be preferred to sodium hyaluronic acid in routine cataract surgery due to the lower costs.

Cataract Extraction↗
PubMed1989

Comparison of contact and immersion techniques for axial length measurement and implant power calculation.

The contact technique for ultrasound biometry was compared to the immersion technique. One hundred eyes were measured by both methods. Two groups were created based upon the axial length measurement: a group of 46 short eyes (axial length less than 23.3 mm) and a group of 54 long eyes (axial length greater than 23.3 mm). In each group the different types of measurement influenced the results obtained for the anterior chamber depth and the axial length of these eyes such that the contact technique yielded shorter measuring values than the immersion technique. In considering both methods, the difference in the anterior chamber depth and the axial length was smaller in the first group. Shorter measurements produced stronger intraocular lens power, which is equivalent to the axial length shortening by using the contact technique. The effect on the implant power calculation and the postoperative deviation of the pseudophakos refraction is shown by comparing the theoretical formula with the SRK formula. This prospective study describes the greater range of refractive pseudophakos deviation when using the contact method.

Anterior Chamber↗