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Biomedical subjects

H B Dick

Publications and source records attributed to H B Dick.

At least 19 recordsLinked to original sources
PubMed2006

[Presbyopia treatment using a femtosecond laser].

Presbyopia is by far the most common refractive error worldwide, with no permanent therapeutic option available. All efforts to restore accommodation by the use of surgery have not led to a generally accepted therapy. However, there is evidence from an animal model that the use of a femtosecond (fs) laser might influence the modulus of elasticity in the lens. Fs-laser impulses can create intralenticular disruption in animal eyes as well as human cadaver lenses and improve elasticity. The concept of treating presbyopia with fs-laser requires a new, complex theory combining the optical and the mechanical aspects of accommodation in the eye. Diagnostic tools for measuring optical change in power and geometrical modification as the eye views from far to near are needed to obtain objective clinical data. A non-invasive treatment of presbyopia to restore accommodation might be possible in the future.

Accommodation, Ocular↗
PubMed2006

[Compensation of corneal astigmatism with toric intraocular lens: results of a multicentre study].

UNLABELLED: This clinical trial was conducted to evaluate visual acuity, refraction and rotation after implantation of the foldable toric intraocular lens (IOL) MicroSil Toric. PATIENTS AND METHODS: 68 eyes of 48 patients from four different surgical departments were examined over a follow-up of three months after cataract surgery. RESULTS: An individually produced IOL with cylindrical correction between 2.0 and 12.0 D was implanted in all eyes. Postoperatively, 68 % of the eyes achieved an uncorrected visual acuity (VA) of 0.5 or better, 12 % achieved 1.0 or better. A corrected VA of 0.5 or better was achieved by 85 %, 31 % achieved a corrected VA of 1.0 or better. Corrected VA improved by 3 (+/- 2) lines. The uncorrected VA improved by 6.0 lines in the mean. The increases in uncorrected and corrected VA were statistically significant (p < 0.001). The efficacy index amounted to 1.1 in the median and 1.3 (+/- 1.5) in the mean. Residual refraction (spherical equivalent) was 0.89 D (+/- 0.7 D) in the mean and was reduced by 5.14 D (+/- 4.78 D) in the mean. The total astigmatic error was reduced both in a statistically as well as in a clinically significant manner from 4.6 D (+/- 2.3 D) to 1.12 D (+/- 0.9 D) in the mean. 75 % of eyes needed a postoperative cylindrical correction of less than 1.5 D, 95 % less than 2.25 D. Corneal astigmatism was not changed significantly (p = 0,435). The surgically induced astigmatism (Naeser) amounted to 0.7 D in the median. In 85 % of the cases IOL rotation was less than 5 degrees. 15 % of the IOLs rotated more than 5 degrees, one IOL more than 10 degrees (max. 28 degrees). Patients ranked their surgical outcome on a scale from 1 (very good) to 6 (poor) which resulted in a mean score of 1.9 (+/- 1.0; min. 1.0; max. 5.0). No clinically relevant correlations of clinical parameters and satisfaction were detected. CONCLUSION: Implantation of the foldable, toric IOL with Z-haptics decreased the refractive error and improved postoperative visual outcome. This IOL was suitable for low as well as for high astigmatism. IOL rotation was low during the follow-up of three months resulting in sufficient correction of the pre-existing astigmatism.

Adolescent↗
PubMed2005

Clinical benefit, complication patterns and cost effectiveness of laser in situ keratomileusis (LASIK) in moderate myopia: results of independent meta analyses on clinical outcome and postoperative complication profiles.

PURPOSE: Laser in situ keratomileusis (LASIK) means a patient investment of 2426 Euro per eye, which usually cannot be funded by European health care insurers. In the context of recent resource allocation discussions, however, the cost effectiveness of LASIK could become an important indication of allocation decisions. Therefore an evidence based estimation of its incremental cost effectiveness was intended. METHODS: Three independent meta analyses were implemented to estimate the refractive gain (dpt) due to conventional LASIK procedures as well as the predictability of the latter (%) (fraction of eyes achieving a postoperative refraction with maximum deviation of +/- 0.5 dpt from the target refraction). Study reports of 1995 - 2004 (English or German language) were screened for appropriate key words. Meta effects in refractive gain and predictability were estimated by means and standard deviations of reported effect measures. Cost data were estimated by German DRG rates and individual clinical pathway calculations; cost effectiveness was then computed in terms of the incremental cost effectiveness ratio (ICER) for both clinical benefit endpoints. A sensitivity analysis comprised cost variations of +/- 10 % and utility variations alongside the meta effects' 95% confidence intervals. RESULTS: Total direct costs from the patients' perspective were estimated at 2426 Euro per eye, associated with a refractive meta benefit of 5.93 dpt (95% meta confidence interval 5.32 - 6.54 dpt) and a meta predictability of 67% (43% - 91%). In terms of incremental costs, the unilateral LASIK implied a patient investion of 409 Euro (sensitivity range 351 - 473 Euro) per gained refractive unit or 36 Euro (27 - 56 Euro) per gained percentage point in predictability. When LASIK associated complication patterns were considered, the total direct costs amounted up to 3075 Euro, resulting in incremental costs of 519 Euro / dpt (sensitivity range 445 - 600 Euro / dpt) or 46 Euro / % (34 - 72 Euro / %). Most frequently reported LASIK complications were "central islands / over- / undercorrection / regression" (meta incidence estimate 24%) and "haze" (15%), which were identified by means of an independent meta analysis. CONCLUSION: Bearing incremental costs of 519 Euro per gained refractive unit in mind, the conventional LASIK procedures showed an encouraging cost effectiveness range; the latter estimate may serve as a rationale for future allocation discussions in ophthalmology.

Cost-Benefit Analysis↗
PubMed2005

Epidemiological and health economical evaluation of intraoperative antibiosis as a protective agent against endophthalmitis after cataract surgery.

OBJECTIVE: To evaluate risk factors for endophthalmitis after cataract surgery and to retest recent findings on the protective effect of intraoperative antibiosis and the promoting effect of the clear corneal as compared to sclerocorneal incision. In addition, the economics of intraocular intraoperative antibiosis as a prophylaxis in cataract surgery are asketched. DESIGN: Survey study. PARTICIPANTS: Five hundred thirty-eight ophthalmosurgical centres in Germany. MAIN OUTCOME MEASURE: epidemiological evaluation: responder specific endophthalmitis incidence in year 2000; economical evaluation: direct cost analysis based on incidence data and local cost estimates (health service's perspective). RESULTS: A total of 310 (58%) questionnaires were computed resulting in an overall count of 404,356 cataract surgeries and 291 self-reported endophthalmitis cases (crude rate 0.072%). The risk of postoperative endophthalmitis for sclerocorneal versus clear corneal incisions was not significantly reduced (relative risk 0.97, 99% confidence interval 0.69-1.38). The hypothesis of a protective effect of intraocular antibiosis could be confirmed by a significantly decreased risk ratio of 0.69 (99% confidence interval 0.48-0.99) indicating a significant benefit from intraoperative intraocular antibiosis. A similar tendency was observed for an intraoperative periocular antibiosis with a significantly reduced risk ratio of 0.68 (99% confidence interval 0.49-0.96). These risk estimates had been adjusted for the size of the surgical centre: a significantly reduced risk ratio of 0.70 (99% confidence interval 0.49-0.98) for postoperative endophthalmitis was observed for local centres. Cost evaluation for the prophylactic use of intraocular intraoperative antibiosis in cataract surgery revealed an economically relevant decrease in direct endophthalmitis associated costs. CONCLUSIONS: Whereas this 2000 appraisal of a recent survey in 1996 could not reproduce the benefit of sclerocorneal incision, the protective effect of intraoperative intraocular antibiotic prophylaxis could be confirmed. However, the results of this survey have to be interpreted with care, since it is not based on individual case information, but rather on aggregate questionnaire data.

Antibiosis↗
PubMed2005

[Microbial keratitis following laser in situ keratomileusis. Prevention, differential diagnosis, and therapy].

Laser in situ keratomileusis (LASIK) is an effective option and currently one of the most commonly applied surgical techniques in the correction of refractive errors such as myopia, hyperopia, and astigmatism. In contrast to photorefractive keratectomy, it maintains the integrity of Bowman's membrane and the epithelium leading to faster visual rehabilitation as well as less pain and discomfort. Nevertheless, following LASIK the stroma is exposed to infectious organisms. Sight-threatening complications after LASIK are reported to be as rare as 1 in 1000 procedures. However, any infectious keratitis remains potentially devastating. Reports about infectious keratitis following LASIK have increasingly surfaced in recent years. We present a review of the literature on microbial keratitis and present our own cases and recommendations for possible prophylaxis and therapy.

Adult↗
PubMed2005

[Laser in situ keratomileusis (LASIK) and scanning laser ophthalmoscopy].

BACKGROUND: To determine the influence of Laser in situ keratomileusis (LASIK) on the measurements of retinal thickness and optic nerve head topography using the Retinal Thickness Analyzer (RTA). METHODS: RTA measurements were performed before and after LASIK. Forty-eight eyes of 25 healthy subjects were included. Mean age was 40.0+/-10.6 years. Mean preoperative refractive error (spherical equivalent) was -3.3+/-3.6 dpt, and 0.2+/-0.9dpt postoperatively. Correlation between ablation depth and duration and change of retinal thickness postoperatively was performed. All patients received a pachymetry preoperatively. RESULTS: Postoperatively, mean retinal nerve fiber layer thickness (MRNFL) and cross sectional area (RNFL cross section area) significantly decreased after LASIK (MRNFL preop: 0.18 mm, postop: 0.11 mm, P =0.026, RNFL cross section preop: 1.17 mm(2), postop: 0.71 mm(2), P =0.015). Ablation depth revealed a significant correlation with changes in retinal thickness measurements postoperatively (Delta MRNFL: Ablation depth, P =0.001, r=-0.5). Duration of the ablation was not significantly correlated to the MRNFL measurements postoperatively (P =0.27, r=-0.08). No correlation was found between the central corneal thickness and the change in retinal thickness after LASIK (P =0.51). CONCLUSION: Due to changes in corneal architecture after LASIK, measurements using RTA reveal a decrease in MRNFL and RNFL cross section area. These changes are likely artifacts. Further studies with a longer follow-up are desirable.

Adult↗
PubMed2005

[Rotational stability in intraocular lenses with C-loop haptics versus Z haptics in cataract surgery. A prospective randomised comparison].

The aim of the study was to compare the rotational stability of intraocular lenses (IOLs) with C-loop haptics and those with Z haptics. A total of 50 patients with cataracts were prospectively randomised in equal numbers using a design equivalent to IOL MS 612 S (C-loop haptic) and MS 6120 (Z haptic, both HumanOptics, Erlangen). Complete ophthalmological examinations were performed including assessment of the IOL rotation after 1 day, 1 month and 3 months postoperatively. The significances between the groups were evaluated using the Wilcoxon test. The Fisher exact test was used for the primary finding of the study (rotation of at least 10 degrees ). The IOL group with the C-loop haptics showed a median lens rotation of 0 degrees on the first day and 2 degrees clockwise after 1 month and 3 months. In the Z haptic group, there was no median rotation in the IOL group. Moreover, the range of IOL rotation of the C-loop haptics was broader (3 months postoperatively: maximum in the C-loop haptics: 21 degrees with 15.5 degrees in the Z haptics). There was no significant difference at any time. At 3 months postoperatively, 32% of the C-loop haptic IOL and 16% of the Z haptic IOL rotated at least 10 degrees (P=0.32). In 59% of the IOL with C-loop haptics, the direction of the rotation was clockwise. This was 40% for the IOL with Z haptics (P=0.33). At 3 months postoperatively, both IOLs demonstrated good rotational stability with a low mean deviation from the target axis. IOLs with Z haptics showed a tendency to greater rotational stability than C-loop haptics but without any significant difference. There was no significant difference in visual rehabilitation.

Cataract Extraction↗
PubMed2005

[Mitomycin C in refractive corneal surface surgery with the excimer laser: first experience and review of the literature].

Haze formation with loss of corneal transparency and surface irregularities and myopic regression are the major complications after corneal refractive surface surgery. The use of mitomycin C (MMC) with its antibiotic and antineoplastic properties is intended to inhibit wound healing mechanisms leading to subepithelial fibrosis. We report the use of MMC to achieve visual rehabilitation in the re-treatment of 3 eyes of 2 patients following refractive corneal surgery. According to the literature, the local use of MMC 0.02 % for 2 minutes is safe and enables one to treat and prevent stromal haze and myopic regression and allows a reduction of the postoperative topical pharmacotherapy. Results are still limited due to small case numbers and short follow-up periods.

Adult↗
PubMed2004

[Visual acuity, quality of life, and patient satisfaction after PDT treatment in AMD patients].

BACKGROUND: The efficacy of PDT to prevent the progression of AMD has been established. This study now assesses the patients' quality of life and self-reported satisfaction after PDT. MATERIAL AND METHODS: All patients who underwent PDT during 2000 and 2001 at the University Eye Hospital of Mainz were interviewed using an AMD-specific modification of a standardized 82-item questionnaire on quality of life and satisfaction in ophthalmological patients. Different aspects of those parameters were derived as scores, which were then related to clinical outcome parameters. RESULTS: During the period of PDT treatment, the median decrease in visual acuity was three stages in the patients examined. Patients who reported a subjective increase in visual function during this period showed for example a median "private flexibility" score of 1.86, and patients with the subjective impression of a decrease in visual function a median score of 2.71. CONCLUSION: The established clinical efficacy of PDT treatment to prevent AMD progression coincides with an encouraging patient satisfaction after the treatment.

Activities of Daily Living↗
PubMed2004

[Phakic intraocular lenses. Current status and limitations].

Phakic intraocular lenses (PIOLs), which are located closer to the eye's nodal points than the anterior corneal surface, can provide superior optical quality for higher corrections because of retention of normal prolate corneal asphericity and larger effective optical zones. Improvements in the material and design of phakic intraocular lenses and their insertion devices combined with advances in the understanding of the anatomical and physiological interactions of the PIOLs with intraocular structures, have increased safety and efficacy. Safety of these implants over the long term remains a concern, but in several situations PIOLs are the refractive correction of choice. The purpose of this review is to compare the different types of PIOLs regarding outcome and complications. Improvements in imaging technologies should improve the accuracy of ICL sizing and allow more precise prediction of effective lens position with more accurate power calculation. It is important to inform patients that phakic lens surgery only corrects the refractive aspect, and that the refractive error itself as well as the changes by surgery still has the potential for serious complications.

Adolescent↗
PubMed2003

[Complications of foldable intraocular lenses requiring explantation. Results of the 2000 and 2001 survey in Germany].

PURPOSE: A survey was sent to all members of the German Society of Ophthalmic Surgeons to evaluate complications that required explantation of foldable intraocular lenses (IOLs). METHODS: Data on preoperative visual acuity, foldable IOL design and material, and the reason for explantation were obtained and analysed. We received 185 surveys for 2000 and 2001. RESULTS: In 2000 and 2001, the most common reasons for IOL explantation were: incorrect lens power (31%) and dislocation (19%) in three-piece acrylic IOLs, incorrect power (31%) and decentration (17%) in monofocal silicone IOLs, and opacification (46%) in hydrophilic IOLs. The most common reasons for the exchange of monofocal IOLs were lens opacification in 2000 and incorrect IOL power in 2001. CONCLUSION: Besides the most frequent complications of decentration and incorrect power observed in rigid IOLs,new complications associated with foldable IOLs occurred (e.g., optic opacification and calcification). Accurate calculation of IOL power and further improvements in material and design are still necessary to minimize the rate of explantations.

Acrylates↗
PubMed2003

[Is a cataract avoidable? Current status with special emphasis on the pathophysiology of oxidative lens damage, nutritional factors, and the ARED study].

The benefit of long-term nutrient intake to reduce the risk of age-related ocular disease such as cataract or macular degeneration is subject to controversy. Conclusions about the benefits and risks of antioxidant supplements can be expected after reviewing the current literature concerning oxidative-induced lens damage and nutritional effects. Identification of influenceable risk factors for senile cataracts could achieve immense economical relevance. In contrast to former longitudinal epidemiological studies, the AREDS report failed to verify protective properties of highly concentrated vitamin supplements on cataract formation. Although there are enough epidemiological indications for reducing the risk of cataracts by the intake of antioxidants, a general recommendation for the use of supplements is untimely or even wrong until stringent evidence of efficacy is provided. The usefulness of cataract prevention is discussed.

Animals↗
PubMed2003

[Quality of life and patient satisfaction after cataract surgery. Results of an observational study between 04/2001 and 06/2002].

BACKGROUND: Assessment of patient satisfaction and quality of life becomes increasingly important for the overall evaluation of therapy regimes. However, it is not certain whether standard quality of life questionnaires suffice to assess immediate changes in patient conditions such as induced by cataract surgery. METHODS: The increase in visual acuity was observed in 152 cataract patients as an objective efficacy parameter. In addition, subjective patient satisfaction and quality of life was obtained from these patients by means of a cataract-specific questionnaire 1 day before and 4 weeks after surgery. The questionnaire concentrates on the patients' overall flexibility and mobility, their estimation of medical and nursing care, changes in ophthalmological conditions and on complications after surgery. RESULTS: With an internal consistency of 82% the instrument can be regarded as moderately reliable but self-reported quality of life before surgery was found to be remarkably biased. None of the above quality of life determinants showed a clinically relevant correlation with the objective increase in visual acuity (absolute correlations <20%). Significant impact factors for overall quality of life satisfaction were the patients' overall flexibility ( p=0.049) and their estimation of medical and nursing care ( p=0.027). CONCLUSIONS: Standard quality of life determinants provide independent subjective information in addition to the increase in visual acuity as an objective measure of clinical outcome. Overall assessment of patient satisfaction cannot be regarded as sufficient for the subjective evaluation of cataract surgery, since its estimation primarily depends on the patients' appreciation of medical and nursing care. An appropriately extensive means of quality of life assessment seems necessary and post-surgical data seems sufficient for the estimation of subjective therapy outcome measures in cataract patients.

Cataract Extraction↗
PubMed2002

Changes in the tear proteins of diabetic patients.

BACKGROUND: Previous studies have shown a significant increase in tear protein peaks in the tears of diabetic patients suffering from dry eye. The aim of this study was to analyze the tear protein patterns from patients with diabetes mellitus who do not suffer from ocular surface diseases (DIA). METHODS: A total of 515 patients were examined in this study (255 healthy subjects (controls) and 260 patients suffering from diabetes mellitus). Tear proteins were separated by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis. After digital image analysis densitometric data files were created and subsequently used for multivariate statistical procedures. RESULTS: A significant increase in the number of peaks was detected in diabetic patients compared to controls (P < 0.0003). The analysis of discriminance revealed a highly significant discrimination between diabetic patients and controls (Wilks lambda: 0.27; P < 0.000001). Furthermore, a significant difference in the protein pattern of diabetic patients could be detected between those suffering from dry eye or not (P < 0.002). The changes in protein patterns of diabetic patients increased with the duration of the diabetic disease. In diabetic patients with a disease duration longer than 10 years the changes were significantly more expressed than in patients with a shorter diabetic history (P < 0.003) and in healthy subjects (P < 0.0001). CONCLUSIONS: The tear protein patterns of diabetic patients are very different in the number and intensity of spots from those of healthy subjects. Furthermore, it could be demonstrated that the differences found in the tear patterns of diabetic patients are not equal to those found in previous studies in patients suffering from dry-eye disease. The alterations in the diabetic tears were correlated with the duration of the diabetic disease. With longer disease, history changes in the tear protein patterns increased. With the course of the disease some protein peaks appeared that are not present in healthy persons. Our study shows that the analysis of electrophoretic tear protein patterns is a new non-invasive approach in the early diagnosis and analysis of the pathogenesis of diabetes induced ocular surface disease.

Diabetes Mellitus↗
PubMed2002

[Diagnosis and therapy of LASIK-induced neurotrophic epitheliopathy].

Laser in situ keratomileusis (LASIK) has emerged as the standard surgical procedure for the correction of refractive errors and in the last years a lot of experience has been gained. Consequently, the amount of intraoperative, early and late postoperative complications have significantly decreased. Keratitis punctata superficialis and dry eye symptoms are the most frequent postoperative complications. A decreased corneal sensitivity attributable to the cutting of the corneal sensory nerves has been described after LASIK. In addition pathological tear secretion tests and typical dry eye symptoms have been reported. Until know it has not been completely evaluated, if these symptoms are a combination of the dry eye disease and LASIK-induced symptoms or if they are due to an independent LASIK complication, the so-called LASIK-induced neurotrophic epitheliopathy. Independently of the incompletely understood etiology, much care and a sufficient therapy with artificial tears should be applied to such patients. To increase the comfort of LASIK, adequate intra- and postoperative treatment is necessary to enhance the patient satisfaction.

Dry Eye Syndromes↗
PubMed2002

[Complications with foldable intraocular lenses with subsequent explantation in 1998 and 1999. Results of a questionnaire evaluation].

PURPOSE: A questionnaire was sent to all members of the German Society of Ophthalmic Surgeons to evaluate complications of foldable intraocular lenses (IOLs) that required explanation. METHODS: Information on preoperative visual acuity, foldable IOL design and material as well as the reason for IOL explantation was obtained and analysed. We received 167 completed questionnaires for 1998 and 1999. RESULTS: In 1998 and 1999 the most common reasons for IOL explantation were as follows: incorrect lens power for 56% of the 3-piece hydrophobic acrylic IOLs, 16% because of glare or other photic phenomena, 40% of the 1-piece hydrophilic acrylic IOLs were explanted because of incorrect lens power and 30% for IOL damage. For the 3-piece monofocal silicone IOLs, 41% were explanted because of incorrect IOL power and 32% because of IOL decentration. For the 1-piece Hydrogel IOL, 76% were explanted because of opacification of the optic and 14% because of incorrect lens power. Most multifocal IOLs were explanted because of photic phenomena. CONCLUSION: In addition to the most common complications such as decentration and incorrect IOL power observed in rigid IOLs, new complications associated with foldable IOLs occurred such as optic opacification, glare and photic phenomena. Some complications seemed to appear in particular IOL types (opacification: SC-60BOUV, MDR), while others were observed in all types of foldable lenses. Accurate calculation of the IOL power and further improvement of the IOL material and design seem to be necessary to minimise the rate of explantations.

Device Removal↗
PubMed2002

[Dynamic aberrometry during accommodation of phakic eyes and eyes with potentially accommodative intraocular lenses].

Since the introduction of potentially accommodative intraocular lenses (IOLs), it was hard to perform an objective evaluation of the accommodative amplitude in pseudophakic eyes. Laser interferometric measurements were performed to evaluate anterior chamber depth changes, which provides information on the functionality of potentially accommodative IOLs. By means of wavefront analysis, the dynamic behaviour of potentially accommodative IOLs can be determined. All measurements in this study were performed using a Hartmann-Shack aberrometer at a frequency of 7 Hz. Six to 8 weeks after implantation of potentially accommodative IOLs (CrystaLens AT-45, C&C Vision, 1CU, Humanoptics), 43 eyes were investigated using this dynamic wavefront analysis. Patients focussed at a distance target for 10 s, followed by focussing at a near target for 10 s and then again at a distance target for a further 10 s. During these 30 s, a total of 200 single measurements were performed. The same measurements were also conducted in healthy eyes of young persons as well as in eyes after implantation of standard IOLs for comparative purposes. The dynamic course of changes in low-order aberrations (defocus, astigmatism) as well as high-order (e.g., fourth-order spherical aberration) were analysed. Dynamic wavefront analysis allowed objective and observer-independent measurement of changes in accommodation in phakic and pseudophakic eyes. Dynamic aberrometry is capable of objectively quantifying the effect of any surgical option for the treatment of presbyopia. We recommend use of this technology in addition to the common psychophysical examinations to attain objective information on the efficacy of the treatment modality used.

Accommodation, Ocular↗