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Biomedical subjects

H B Dick

Publications and source records attributed to H B Dick.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Toric intraocular lens to correct high astigmatism after penetrating keratoplasty in a pseudophakic eye - a case report].

BACKGROUND: After penetrating keratoplasty residual astigmatism can be treated with various options. Correction with spectacles or contact lenses, methods such as radial keratotomy, photorefractive keratectomy (PRK) or Laser-in-situ keratomileusis (LASIK) are limited only to mild and moderate astigmatism. In laser ablation a sufficient corneal thickness must be ensured. On the other hand surgical correction is performed on transplanted tissue which can increase the risk of allograft rejection. In pseudophakic eyes the implantation of an individually designed toric intraocular lens (IOL) according to keratometry and biometry with a cylindrical power up to 12 D provides an alternative method for correcting higher astigmatism. This individually designed IOL can be implanted additionally to the existing IOL. CASE: A 66-year-old patient presented after penetrating keratoplasty and implantation of an IOL 4 years ago with a visual acuity of 20/160 and residual astigmatism of - 10 D x 151(o). After biometry an individually manufactured toric PMMA-IOL of + 12 D cylindrical and - 9.5 D spherical power was implanted via a sclerocorneal tunnel incision additionally to the existing IOL into the ciliary sulcus. Postoperatively a well centered and stable positioned IOL was found. One year after implantation of the toric IOL the position was still unchanged and the graft had remained clear. Spherical equivalent refraction was + 1,5 D - 3,0 D x 141(o), with an uncorrected visual acuity of 20/60. CONCLUSION: Implantation of a toric intraocular lens in pseudophakic eyes allows the correction of high astigmatism after penetrating keratoplasty. The advantage of this method compared to the keratorefractive options lies in its minor manipulation on the allograft.

Aged↗
PubMed2001

Use of internet technologies for data acquisition in large clinical trials.

Data acquisition for automated processing is a central aspect of clinical trials with large numbers of cases because of their extensive demand for manpower. Scientific data can be collected using data forms, which are created in Hypertext Markup Language and published on the Internet. The completed data form can be returned via E-mail or Common Gateway Interface-Script and forwarded into a study database. For the Internet-based data acquisition of a prospective multicenter trial (e.g., on endophthalmitis incidence after cataract extraction), we developed two special HTML forms that can be opened in the ophthalmology department's homepage. A large number of acquired anonymous data has been collected via Internet and automatically transferred into the trial database. The Internet provides a fast and easy avenue for the acquisition of scientific data. This method of data acquisition and data processing will become more common place in multicenter clinical trials.

Clinical Trials as Topic↗
PubMed2001

Lens implant selection with absence of capsular support.

If contact lens or spectacle correction is not viable, little debate exists that the secondary placement of an intra-ocular lens (IOL) is the method of choice in the absence of capsular support. The choice of IOL mainly depends on the preoperative status of the eye (eg, aphakia in children) and the selected location for the implant. Theoretically, there are several IOL implantation approaches in cases without capsular support: an angle-supported anterior chamber (AC) IOL, an iris-fixated ACIOL, an iris-sutured or iris-fixated posterior chamber (PC) IOL and a transsclerally sutured PCIOL. No consensus exists, however, on the indications as well as on the relative safety and efficacy of these different options. Implantation of modern ACIOLs, like the refined open-loop or iris-fixated claw (toric) ACIOLs, have regained popularity and provide a valuable alternative to sutured PCIOLs. However, in the absence of capsular support, the transsclerally sutured PCIOLs offer numerous advantages for certain eyes. Because of its anatomic location, the sutured PCIOL is more appropriate for eyes with compromised cornea, peripheral anterior synechiae, shallow anterior chamber, or glaucoma. Moreover, sutured PCIOLs are appropriate if the patient with aphakia is young or has a life expectancy of 10 years or more. Recent technological advances, including PCIOL with iris diaphragm for aniridia, toric ACIOLs, and small-incision surgery with foldable, transsclerally sutured IOLs, seem to further improve clinical outcomes.

Anterior Eye Segment↗
PubMed2001

Effects of early postfiltration ocular hypotony on visual acuity, long-term intraocular pressure control, and posterior segment morphology.

PURPOSE: To determine whether hypotony after filtration surgery has any influence on visual acuity and intraocular pressure (IOP) lowering. PATIENTS AND METHODS: We prospectively investigated 43 eyes of 43 patients undergoing trabeculectomy without the use of antimetabolites for 12 months. RESULTS: The lowest postoperative IOP valued 4.9 +/- 3.6 mm Hg (range, 0-14 mm Hg). It correlated statistically significant with the IOP 6 weeks (P = 0.016), 6 months (P = 0.009), and 1 year after surgery (P = 0.027). Eyes with a deterioration of visual acuity 6 weeks after surgery had undergone a stronger postoperative hypotony (correlation with lowest postoperative IOP, P = 0.035). The mean period with an IOP less than 5 mm Hg was 3.5 +/- 8.0 days, and the mean period with an IOP less than 10 mm Hg lasted 45.4 +/- 68.8 days (range, 0-276 days). A hypotony score based on IOP and duration of hypotony was introduced. A correlation was detected between morphologic signs of hypotony, such as tiny retinal folds, at the 6-month follow-up and the duration of hypotony (P = 0.029) and hypotony score (P = 0.001). CONCLUSIONS: Hypotony after filtration surgery may decrease visual acuity in the early postoperative period. Conversely, early postoperative hypotony correlated with better long term IOP control. There was no deleterious effect on visual acuity after 6 months.

Adult↗
PubMed2000

[Bilateral simultaneous LASIK. Pro and contra].

Until recently simultaneous bilateral laser in situ keratomileusis (LASIK) was regarded as contraindicated in Germany. However, the procedure was sporadically performed, because it offers patient comfort and is more cost effective than sequential LASIK. Even though the complication rate is below the calculated rate of 0.01%, bilateral complications may have catastrophic effects on the patient. In addition, there is the theoretical disadvantage that the results from the first eye cannot be used for the second eye. However, this effect has yet to be clinically proven.

Adult↗
PubMed2000

[Online literature search].

The internet offers charge-free access to electronic online databases and thus has revolutionized the handling of information. Today's challenge is the rational management of the large amount of attainable data. This overview presents the various databases--particularly databases for online Medline search--and basic knowledge for effective and successful search strategies. There are numerous important advantages of online access to literature databases: availability at any time and any place in the world, easy handling due to the user-friendly surface of the World Wide Web, capability of linking directly to the private database. Clinicians, scientists, and ophthalmologists in private practice can equally profit from the advantages of fast, easy, and charge-free online-search in medical literature databases. Literature search should thus be an important tool to obtain the latest scientific knowledge for every physician.

Databases, Bibliographic↗
PubMed2000

[Procedure for lens loss into the vitreous body during cataract operation].

Complications during cataract surgery such as dropped nucleus or lens fragment dislocation into the vitreous cavity may become sight threatening. The recommendations regarding possible therapeutic approaches are inconsistent. Several factors like uveitis and/or an increased intraocular pressure play a major role in the decision on the further surgical procedure. Recent publications recommend an early pars plana approach in order to avoid any traction at the peripheral retina during manipulations via a limbal approach.

Cataract Extraction↗
PubMed2000

[Internet presence and home page design for the ophthalmologist].

An increasing number of people uses the internet for information retrieval. In the past three years nearly every University Eye Hospital provides its own information using homepages in the Internet. More and more Eye Departments and comprehensive ophthalmologists use the Internet to provide information on their own. We provide advice for the selection of a provider, use examples on how to deal with an HTML editor program and explain the technical realisation of the own Internet presence. Legal circumstances and strategies to promote the own homepage are discussed.

Advertising↗
PubMed2000

Healon5 versus Viscoat during cataract surgery: intraocular pressure, laser flare and corneal changes.

BACKGROUND: The use of a viscoelastic substance facilitates cataract surgery. Healon 5 is a new viscoelastic product with special rheological properties. We evaluated the postoperative effect of Viscoat and Healon5 on intraocular pressure (IOP), central corneal thickness (CCT), endothelial cell counts and laser flare. METHODS: Forty-eight eyes of 48 patients undergoing routine phacoemulsification followed by foldable IOL implantation were enrolled. Either Healon5 or Viscoat was used according to a block-randomization scheme. The aspiration technique was standardized. IOP, CCT, endothelial cell counts and laser flare were compared pre- and postoperatively. Statistical analysis was performed using the two-sample Wilcoxon test. Data description was based on median and quartiles, while graphic description was performed by non-parametric box plots. RESULTS: Viscoat demonstrated a statistically significant higher IOP than Healon5 at 4 and 8 h postoperatively (P< 0.01 and < 0.05, respectively). Further, the laser flare values were statistically significantly higher for the Viscoat than for the Healon5 group 8 h postoperatively (P<0.05). Endothelial cell loss did not differ significantly between the two groups (relative change in endothelial cell density after 3 months: -4.3% for the Healon5 group and -6.2% for Viscoat group). CONCLUSION: There was neither a statistically nor a clinically significant difference in endothelial cell loss after the use of Healon5 or Viscoat in routine cataract surgery. However, the IOP in the early postoperative period was higher in the Viscoat group than in the Healon5 group.

Adult↗
PubMed2000

Inflammation after sclerocorneal versus clear corneal tunnel phacoemulsification.

OBJECTIVE: To compare the postoperative inflammation after phacoemulsification followed by intraocular lens (IOL) implantation by means of sclerocorneal versus clear corneal tunnel incision. DESIGN: Randomized controlled clinical trial. PARTICIPANTS: One hundred eyes of 100 patients were examined at a German University eye hospital. INTERVENTION: One hundred eyes with cataract necessitating phacoemulsification with posterior chamber IOL implantation were randomly assigned to receive a temporal sclerocorneal or clear corneal tunnel incision by a single surgeon. MAIN OUTCOME MEASURES: Preoperative and postoperative inflammation was evaluated by measurement of flare using laser flare photometry. Statistical inference was mainly based on nonparametric group comparisons by use of two sample Wilcoxon tests. RESULTS: Mean anterior chamber flare in the group with sclerocorneal tunnel increased from 7.5 photon counts/ms preoperatively to 19.6 at 6 hours postoperatively and decreased to 11.1 (day 1), 11.7 (day 2), 11.6 (day 3), and 9.2 (5 months) during the postoperative course. The mean flare in the clear corneal tunnel incision group increased from 7.7 preoperatively to 12.9 at 6 hours postoperatively and then decreased to 9.2 (day 1), 9.8 (day 2), 9.1 (day 3), and 9.2 (5 months). Individual postoperative flare changes were significantly lower in the clear corneal tunnel group at the day of surgery (P<0.0001), as well as at day 1 (P = 0.0011), day 2 (P = 0.0079), and day 3 (P = 0.0020). After 5 months, no statistically significant difference was found. CONCLUSIONS: After phacoemulsification and foldable IOL implantation, postoperative alteration in the blood-aqueous barrier was statistically significantly lower with the clear corneal tunnel incision group compared with the sclerocorneal incision group, in the first 3 days postoperatively.

Adult↗
PubMed2000

Solvent for removing silicone oil from intraocular lenses: experimental study comparing various biomaterials.

PURPOSE: To evaluate the effectiveness of a perfluorocarbon-perfluorohexyloctane (PFHO)-in removing silicone oil from different intraocular lenses (IOLs) and determine whether any removal technique enhances the removal of silicone oil. METHODS: Six IOL materials were analyzed: standard poly(methyl methacrylate) (PMMA), heparin-surface-modified (HSM) PMMA, AcrySof, 2 polyHEMAs with different water contents, and a second-generation SLM-2 silicone. One or 2 microL of a highly viscous silicone oil (5700 cs) was applied to the center of each IOL optic. Perfluorohexyloctane (2 mL) was then used to remove the silicone oil by 1 of 3 techniques: immersion of the IOL in PFHO; irrigation of the silicone oil with a small, blunt cannula; mechanical wiping with a PFHO-saturated Merocel swab (used only when irrigation failed). Next, each IOL was examined by light and scanning electron microscopy. The expanse of silicone oil residue remaining on the IOLs was objectively quantified using an integrated computerized analysis system combined with energy-dispersive spectrometry. RESULTS: After application of 1 microL silicone oil, immersion in PFHO did not remove silicone oil from any IOL material. Irrigation with PFHO removed the silicone oil from the HSM PMMA and polyHEMA IOLs, but oil remained on the other lens materials. Mechanical wiping was necessary to remove the oil from the PMMA, AcrySof, and silicone IOLs. Attempts to remove 2 microL of silicone oil produced similar results. Although mechanical wiping of the AcrySof IOL removed all silicone oil, a slight residue remained on the PMMA and silicone IOLs. The PFHO irrigation removed significantly more silicone oil from the HSM PMMA than the unmodified PMMA IOL (P =.001). More silicone oil was removed from polyHEMA IOLs than from the AcrySof or silicone IOLs (P =.05). CONCLUSION: Although PFHO can remove silicone oil, it is of limited usefulness. The effectiveness of PFHO depends on the removal technique, IOL material, and amount of silicone oil present. Based on these results, we recommend PFHO irrigation followed by mechanical wiping with a PFHO-saturated swab.

Adhesiveness↗
PubMed2000

Effect of large positioning holes on capsule fixation of plate-haptic intraocular lenses.

PURPOSE: To compare the centration and fixation of silicone plate-haptic intraocular lenses (IOLs) with different-sized positioning holes. SETTING: Eye Clinic of the Johannes Gutenberg-University Mainz, Mainz, Germany. METHODS: In a prospective randomized study, 51 Chiroflex C10 and 56 Chiroflex C11 IOLs were implanted under standardized conditions by the same surgeon. The IOL position was documented at the end of surgery and by retroillumination on the first day and 5 months postoperatively. The positioning-hole area was evaluated by ultrasound biomicroscopy (50 MHz) 5 months postoperatively. RESULTS: One day postoperatively, no IOL in either group was decentered more than 1.0 mm. After 5 months, 33% of the C10 and 42% of the C11 IOLs were decentered between 0.5 and 1.0 mm, and 11% of the C10 and 8% of the C11 IOLs were decentered more than 1.0 mm (maximum 1.23 mm and 1.41 mm, respectively). Up to the first postoperative day, 20% of the C10 and 22% of the C11 lenses were rotated more than 15 degrees. At 5 months, an additional 15% of the C10 and 19% of the C11 lenses were rotated. Ultrasound biomicroscopy showed no tissue or capsule adhesion in the holes in most cases (85% C10 group; 71% C11 group). No difference was statistically significant. CONCLUSIONS: Larger positioning holes did not prevent IOL decentration or rotation; thus, this IOL design appears unsuitable for correcting astigmatism. Because tissue in the positioning hole was rare with both lens types, it is doubtful that enlarged plate-haptic perforations will prevent IOL luxation into the vitreous cavity after capsulotomy.

Aged↗
PubMed2000

Ultrasonic transmission in viscoelastic substances.

PURPOSE: To study the propagation of ultrasonic shock waves in viscoelastic agents and the resulting corneal load. SETTING: University Siegen, Institute for Mechanics and Control Engineering, Siegen, Germany. METHODS: The anterior chamber of a manufactured artificial eye was constructed according to anatomic dimensions. Three openings were drilled--for the phaco tip, for the exchange of a viscoelastic agent or water, and for the shock-wave sensor. The sensor was fixed to the area corresponding to the corneal apex. The sensor signal was analyzed using a direct oscilloscope that measured the amplitude reaching the corneal apex. Shock-wave propagation in several viscoelastic agents was compared with that in balanced salt solution. RESULTS: In hydroxypropyl methylcellulose, the shock wave was amplified or influenced slightly. In hyaluronic-acid preparations, acoustic dampening occurred. CONCLUSION: Removal of hyaluronic-acid derivatives prior to phacoemulsification is not necessary.

Anterior Chamber↗
PubMed2000

Osmolality of various viscoelastic substances: comparative study.

PURPOSE: To determine the osmolality of various viscoelastic substances. SETTING: Department of Ophthalmology, Johannes Gutenberg-University, Mainz, and Institute for Medical Device Testing, Memmingen, Germany. METHODS: The analysis was carried out according to the European Pharmacopoeia by means of a calibrated osmometer using the freezing-point depression method. Each syringe was analyzed as a duplicate analysis. RESULTS: Mean osmolalities (mOsmol/kg) of the sodium hyaluronate viscoelastic substances were Allervisc 299; Allervisc Plus 307; Amvisc Plus 335; AMO Vitrax 284; Biolon 279; Dispasan 311; Dispasan Plus 314; Healon 295; Healon GV 312; Healon5 322; HYA-Ophtal 376; Microvisc 313; Microvisc Plus 341; Provisc 307; Rayvisc 312; Viscoat 340; Visko 296; Visko Plus 319. Mean osmolarities of the hydroxypropyl methylcellulose viscoeslatic substances were Adatocel 278; HPMC Ophtal L 358; HPMC Ophtal H 360; La Gel 317; OcuCoat 309; Visco Shield 376. CONCLUSIONS: There were significant differences in osmolality among viscoelastic substances, which may explain the differences in corneal thickness after cataract surgery. A viscoelastic substance with an osmolality of 305 mOsmol/kg or slightly higher is preferable, especially in patients with a compromised corneal endothelium.

Anterior Chamber↗
PubMed2000

Contrast sensitivity and glare disability by halogen light after monofocal and multifocal lens implantation.

BACKGROUND: Standard examination of contrast sensitivity under conditions of glare disability is performed with incandescent light. A new halogen glare test that simulates glare as seen with oncoming vehicle headlights was used to measure glare disability in patients implanted with multifocal and monofocal intraocular lenses (IOLs). METHODS: 28 patients with an average age of 69 years (SD 12 years) were implanted with a monofocal IOL (SI-40NB, Allergan) and 28 patients with an average of 66 years (12 years) were implanted with a refractive multifocal IOL (Array-SA-40N, Allergan). All patients were followed for 5 months postoperatively. Contrast sensitivity at four spatial frequencies (3, 6, 12, and 18 cycles per degree, cpd) with and without a glare source were measured using the halogen glare test (CSV-1000 HGT). Statistical analysis was performed using the two sample Wilcoxon test. The local significance level was set at 0.05. RESULTS: When tested at the lowest spatial frequency (3 cpd) without halogen glare, contrast sensitivity was lower in the multifocal group than in the monofocal group (p=0.0292). With additional glare, there was no difference between both groups. At all other spatial frequencies (6, 12, and 18 cpd), when tested without halogen glare (6 cpd, p=0.5250; 12 cpd, p=0.8483; 18 cpd, p=0.9496) and with moderate (3 cpd, p=0.7993; 6 cpd, p=0.4639; 12 cpd, p=0.7456; 18 cpd, p=1.0) and high halogen glare (3 cpd, p=0. 1513; 6 cpd, p=0.2016; 12 cpd, p=0.3069; 18 cpd, p=0.9933), there was no statistically significant difference between groups. Patients in both groups of age 70 or older had reduced contrast sensitivity without halogen glare and with moderate and strong glare. When monofocal and multifocal patients older than 70 years of age were analysed separately, there was no statistically significant difference in contrast sensitivity with and without glare. Astigmatism >1 dioptre had no significant influence on contrast sensitivity and glare disability when monofocal and multifocal eyes were compared. CONCLUSION: Reduced contrast sensitivity was found in the multifocal group only at the lowest spatial frequency without halogen glare. The monofocal and multifocal groups had no statistically significant differences in contrast sensitivity with moderate and strong glare. These results suggest no difference in glare disability induced by halogen light similar to oncoming vehicle headlights for patients implanted with monofocal and multifocal IOLs.

Adult↗
PubMed1999

Endophthalmitis in cataract surgery: results of a German survey.

OBJECTIVE: To document perioperative prophylactic treatment and to evaluate the risk factors for endophthalmitis after cataract surgery. DESIGN: Cross-sectional study via anonymous survey. PARTICIPANTS: Four hundred sixty-nine centers in Germany were queried. RESULTS: A total of 311 (67%) questionnaires were received, with each center reporting an average of 900 cataract surgeries per year (total, 340,633 surgeries in 1996). Respondents reported a total of 267 cases of endophthalmitis, which resulted in a mean responder-specific endophthalmitis rate of 0.148% versus a median rate of 0%. Statistical analysis via Poisson regression suggested that sclerocorneal incisions were associated with a reduced incidence of endophthalmitis (odds ratio, 0.35; 95% confidence interval, 0.24-0.51). Antibiotics used intraocularly (odds ratio, 0.65; 95% confidence interval, 0.43-0.98) and the preoperative application of diluted povidone-iodine on the conjunctiva (odds ratio, 0.59; 95% confidence interval, 0.36-0.99) were associated with a reduced risk of postoperative infection. Immune deficiencies (66%), diabetes mellitus (62%), occlusion of the lacrimal system (40%), and skin diseases (33%) were regarded as risk factors for endophthalmitis by the respondents. When cataract surgery is performed solely under inpatient conditions, the use of systemic antibiotics as well as the periocular injection of antibiotics at the end of the operation were associated (although not significantly) with a trend toward reducing the incidence of postoperative infection. Conversely, flushing the lacrimal drainage system, using eye shields, and cutting the eyelashes had no demonstrable effect in preventing endophthalmitis. The use of preoperative topical antibiotics (odds ratio, 2.38; 95% confidence interval, 1.21-4.68) and the performance of more than 20% of the surgeries in an outpatient center (odds ratio, 2.0; 95% confidence interval, 1.24-3.21) were associated with a detrimental effect on the development of endophthalmitis. CONCLUSIONS: Although the appropriate antibiotic agent and dosage are not yet established, the administration of intracameral antibiotics and the application of povidone-iodine on the conjunctiva significantly reduced the relative risk of postoperative endophthalmitis in this survey. Because the study was not individual based but rather on aggregate questionnaire, the results have to be interpreted with care.

Ambulatory Care↗