Biomedical subjects

E Spörl

Publications and source records attributed to E Spörl.

13 recordsLinked to original sources

PubMed2006

[Intraocular pressure measurement during the day and night for glaucoma patients and normal controls using Goldmann and Perkins applanation tonometry].

OBJECTIVE: Our aim was to evaluate intraocular pressure (IOP) levels in primary open angle glaucoma (POAG) patients and healthy controls during both the day and night while measuring in an upright as well as in a supine position. METHODS: In a prospective clinical trial, 30 glaucoma patients on topical treatment and 50 healthy controls received IOP measurements every 4 h for a 24 h period starting at 8 am. Additionally, blood pressure and heart rate were measured and perfusion pressures were calculated. At 12 am IOP was initially measured in a sitting position and then, after 20 min, in a supine position. At midnight this was carried out conversely. At 4 am IOP was measured in a supine position; all other measurements were performed in a sitting position. Measurements in the sitting position were performed by Goldmann and Perkins tonometry and in a supine position by Perkins tonometry. RESULTS: IOP was 1 mmHg lower in Perkins tonometry measurements compared to Goldmann tonometry. There was no difference between the two patient groups. In a supine position, IOP measured by Perkins tonometry was higher than in an upright position. At 12 am the difference was 1.8 mmHg+/-2.7 mmHg (p=0.001) in healthy subjects and 1.3+/-2.7 mmHg (p=0.013) in the POAG patients. At 12 pm the increase of IOP in the supine position was even more pronounced with 2.4+/-3.4 mmHg in healthy subjects and 5.6+/-3.2 mmHg in the POAG patients (p=0.001). The blood pressure and the perfusion pressure were lowest during night measurements. CONCLUSIONS: During diurnal IOP measurements in an upright position there were no statistically significant differences in IOP changes between groups. However, in a supine position IOP was significantly higher than in a sitting position and increased more in the glaucoma patients than in healthy controls. This observation might be due to a faulty regulation of the fluid shift in glaucoma patients and could cause progression of glaucomatous damage.

Aged↗

PubMed2005

[Applanation tonometry in "normal" patients and patients after LASIK].

BACKGROUND: Until now it was thought that morphological parameters of the eye such as corneal thickness, corneal curvature and axial length do not affect tonometry results. However, the aim of this study was to find out whether there actually is an influence of these parameters on applanation tonometry. PATIENTS AND METHOD: In this prospective study we examined 125 eyes of 125 normal patients with a corneal thickness of 568.8 +/- 43.79 microm, a corneal curvature of 7.72 +/- 0.27 mm and an axial length of 23.62 +/- 2.05 mm. Before performing a phacoemulsification, the anterior chamber was temporarily punctured. With a closed system the intraocular pressure (IOP) was manometrically set at 20, 35 and 50 mmHg using an H (2)O column. The IOP was then measured with a Perkins tonometer. With these patients we compared 102 eyes that had undergone LASIK due to a myopia of 6.3 +/- 2.17 D. Before and 6 months after surgery, IOD, k-values and central corneal thickness of these patients were measured. RESULTS: At all set pressure levels there was a highly significant correlation of measured IOP and corneal thickness. At all set pressure levels the measured IOP significantly depended on corneal thickness (r(2) = 0.78 - 0.83). After LASIK, IOP was reduced from 16.5 +/- 2.1 to 12.9 +/- 1.9 mmHg. There was a significant correlation between IOP and corneal curvature as well as corneal thickness (r(2) = 0.631; P < 0.001). The biomechanical characteristics of the cornea are changed so that the measured IOP has to be corrected by an additional 0.75 mmHg. CONCLUSION: Since corneal thickness does affect Goldmann applanation tonometry we recommend to use the "Dresden Correction Table" (Tab. ) to achieve the real IOP. Pressure measurements after LASIK are inaccurate because of a change in corneal biomechanics, corneal thickness and curvature and they should be corrected as follows: IOP (real) = IOP (measured) + (540 - CCT)/71 + (43 - K-value)/2.7 + 0.75 mmHg.

Aged↗

PubMed2003

[Treatment of keratoconus by collagen cross linking].

BACKGROUND: We were able to show a significant increase in corneal stiffness of rabbit and porcine eyes after combined riboflavin/UVA-induced collagen cross-linking. In this study,we tried to treat keratoconus patients with this method to stop the progression of corneal ectasia. PATIENTS AND METHODS: We treated 16 eyes of 15 patients with progressive keratoconus and mostly moderate keratectasia (48-56 dpt). After removal of the epithelium (7 mm X), riboflavin solution was applied on the cornea, which was irradiated with UVA (370 nm,3 mW/cm(2)) at a distance of 1 cm for 30 min.Post-operative follow-up controls were conducted every 3 months in the first year and then every 6 months, always including visual acuity testing, corneal topography and measurements of endothelial cell density. The follow-up time was between 1 and 3 years. RESULTS: Progression of keratectasia was stopped in all patients. Best corrected visual acuity and the maximal keratometry values improved slightly in about 50% of the cases. In all patients corneal transparency, the degree of keratectasia registered by corneal topography and the density of endothelial cells remained unchanged within the follow-up time. No negative side-effects were observed. CONCLUSIONS: Our results show that collagen cross linking might be a useful conservative treatment modality to stop the progression of keratoconus. By this means the need for keratoplasty might be significantly reduced. Given the simplicity of the technique and minimal costs of the treatment it might also be well suited for developing countries.Further studies are envisaged to exclude long-term side effects and to evaluate the long term durability of the mechanical stiffness effect.

Adolescent↗

PubMed2000

[Studies on the stabilization of the cornea in rabbits].

BACKGROUND: The mechanical stabilization of the cornea in keratoconus may delay progression of this disease. The cross-linking techniques optimized in corneas of enucleated porcine eyes were investigated under in vivo conditions in rabbits to estimate the biocompatibility and duration of the stiffening effect. METHODS: Twenty-eight rabbits were treated monocularly, the fellow eye serving as control. The epithelium was mechanically removed and 19 eyes were treated with riboflavin plus ultraviolet irradiation (365 nm, 2 mW/cm2) for 45 min and 9 eyes with 0.075% glutaraldehyde for 20 min. After treatment, the eyelids were sutured for 3 days. The healing process was controlled by slit-lamp examination and photographically documented. After 1 month, 20 animals and after 3 months 8 animals were sacrificed, the eyes enucleated, and the stress-strain relation of the corneas measured and compared to the fellow eye. RESULTS: The epithelium was closed after 4-5 days. The transparency of the corneas remained clear during follow-up, and there were no signs of inflammatory reaction. Stress for a strain of 6% was higher in the treated corneas by a factor of 1.3 +/- 0.66 (P = 0.319) in the glutaraldehyde group and by a factor of 1.6 +/- 0.75 (P = 0.0408) in the riboflavin group at 1 month, and by 1.3 +/- 0.48 (P = 0.07) at 3 months after treatment. CONCLUSIONS: The cross-linking technique using riboflavin plus UV irradiation is suitable for at least temporarily stiffening the cornea in vivo and seems to be a promising method for conservative treatment of keratectasia.

Animals↗

PubMed2000

[Irradiation of cornea with ultraviolet light and riboflavin administration as a new treatment for erosive corneal processes, preliminary results in four patients].

BACKGROUND: Corneal melting is a serious condition and in many cases maybe managed only by surgery. UV-radiation with Riboflavin is a new method that may stop the melting process of the cornea. PATIENTS AND METHOD: Four patients suffering from melting ulcera of the cornea of various origin underwent a single UV-radiation. Two ultraviolet diodes were used emitting light with an wavelength of 370 nm with an energy of 2.5 mW/cm2. The radiation time was 30 minutes. Before he radiation was performed 2-3 drops of 0.11% Riboflavinsolution were applied to the cornea. The treatment area was 6-7 mm in diameter. RESULTS: After the treatment in three of the four patients the melting process of the cornea stopped. At least temporarily, a surgical procedure could be delayed. CONCLUSION: Because of the absence of any side-effects in serious cases the method is recommended prior to surgery.

Adult↗

PubMed1997

[Laser-induced pressure waves in the eye. Propagation characteristics].

BACKGROUND: The characteristics of shock waves during photoablation were investigated for an IR and a UV laser. These stress waves may be harmful to ocular structures. MATERIAL AND METHODS: The amplitude of shock waves was measured by a needle-shaped hydrophone in enucleated porcine eyes during excimer laser (193 nm, 23 ns, diameter of ablation 1.5-7.5 mm) and Er:YAG laser photoablation (2.94 microns, 200 microseconds, 1.2 mJ/cm2, diameter of ablation 4 mm). RESULTS: With the excimer laser at ablation zones larger than 4.5 mm, a pressure focus occurs at a distance of 4-6 mm behind the cornea. The pressure amplitudes are smaller than 80 bar for a fluence of 180 mJ/cm2 and decrease steadily to values below 10 bar towards the retinal level. Higher fluences produce higher pressure values; in the range of 60 to 220 mJ/cm2 the relation is linear. For the Er:YAG laser, pressure amplitudes are smaller than 0.5 bar. CONCLUSIONS: Mechanical damage of the retina is unlikely during excimer-or Er:YAG-laser ablation. The existence of a pressure focus may result in mechanical damages of the posterior lens or anterior vitreous at large ablation diameters. During Er:YAG laser ablation, shock waves could not be detected with our measurements. Theoretical estimations yield values of less than 700 mbar at a fluence of 1.2 J/cm2. The pressure load of the endothelium is independent of diameter but dependent on fluence.

Animals↗

PubMed1997

[Increased rigidity of the cornea caused by intrastromal cross-linking].

PURPOSE: To increase the stability of the cornea by artificial cross-linking (radiation or chemical agents) and to investigate a future therapy for keratoconus. MATERIALS AND METHODS: The epithelium of enucleated porcine eyes was removed. Ten eyes in each of eight test groups were treated with UV light (lambda = 254 nm), 0.5% riboflavin and UV light (365 nm), blue light (436 nm) and sunlight, and the chemical agents glutaraldehyde (1% and 0.1%, 10 min) and Karnovsky's solution (0.1%, 10 min). Strips of 5 mm in width and 9 mm in length were cut from each cornea and the stress-strain behaviour of the strips was measured. For comparison, eight groups of ten untreated corneas each were measured by the same method. RESULTS: Compared to untreated corneas riboflavin and UV irradiation as well as glutaraldehyde and Karnovsky's solution treatment resulted in significantly increased stiffness of the cornea (p < 0.05). CONCLUSIONS: The biomechanical behaviour of the cornea can be altered by low-concentration glutaraldehyde, Karnovsky's solution, and by riboflavin and UV irradiation, which offers potential conservative treatment of keratoconus. To optimize this effect further investigation is necessary regarding the dose-effect relation and the in-vivo conditions.

Animals↗

PubMed1996

[Thermo-mechanical behavior the the cornea].

BACKGROUND: Shrinkage of corneal collagen is used during thermokeratoplasty, a method to remodel the corneal curvature. The goals of our investigations were to determine the optimal temperature range for maximal shrinkage of the collagen fibers with minimal damage. MATERIALS AND METHODS: By means of a commercially available stress-strain-measuring device with a paraffin oil bath of temperatures varying from 35 degrees C to 120 degrees C strips of pig cornea 5 mm in width and 9 mm in length were investigated in the physiological stress range from sigma = (0,5-12,5) . 10(4) N/m2 by stress-strain, stress relaxation and creep measurements. RESULTS: Biomechanical properties of the cornea remain unchanged in the temperature range from 30 to 50 degrees C. Starting at 60 degrees C shrinkage occurs that increases up to 90 degrees C. The maximal rate of shrinkage of (57 +/- 12)% was measured at temperatures of 75 to 80 degrees C. Above 100 degrees C this effect is reduced by the destruction of intermolecular bonds between the collagen fibers. The stress-strain curves of the shrunk corneas are flatter than that of native corneas, which means, the Young's modulus is significantly reduced. CONCLUSIONS: In order to realize optimal shrinkage during thermokeratoplasty temperatures of 65-85 degrees C should be achieved in the coagulated tissue. Higher temperatures cause also a shrinkage effect but also a destruction of tissue.

Animals↗

PubMed1996

Thermomechanical behavior of the cornea.

Shrinkage of corneal collagen is used during thermokeratoplasty, a method to remodel the corneal curvature. The goal of our investigations was to determine the optimal temperature range for maximal shrinkage of the collagen fibers with minimal damage. By means of a commercially available stress-strain-measuring device including a paraffin oil bath at temperatures varying from 35 degrees to 120 degrees C, strips of pig cornea measuring 5 mm in width and 9 mm in length were investigated in the stress range of sigma = (0.5-12.5) x10(4) N/m2 by stress-strain, stress-relaxation, and creep measurements. The biomechanical properties of the cornea remained unchanged in the temperature range of 30-50 degrees C. Starting at 60 degrees C, shrinkage occurred that increased up to a temperature of 90 degrees C. The maximal rate of shrinkage of 57 +/- 12% was determined at temperatures of 75 degrees and 80 degrees C. At above 100 degrees C the shrinkage effect decreased because of the destruction of intermolecular bonds between the collagen fibers. The stress-strain curves generated for shrunken corneas were flatter than those generated for native corneas, which means that Young's modulus is significantly reduced. For the achievement of optimal shrinkage during thermokeratoplasty, temperatures of 70-85 degrees C should be reached in the tissue to be coagulated. Higher temperatures are capable of causing a shrinkage effect but also induce the destruction of tissue.

Animals↗

PubMed1995

[Cryotherapy of malignant eyelid tumors].

The treatment of tumors of the eyelids must extend not only to complete removal or destruction of the neoplasm, but also to the maintenance of physiology functions. In addition, cosmetic aspects should be taken into consideration. In a prospective study, 278 cryosurgical operations performed for lid tumors in the years from 1980 to 1985 were followed up for 5 years to decide whether cryotherapy fulfilled these demands. We used spray freezing with liquid nitrogen, because the low temperatures and high freezing rates required for cell destruction are achieved only by this technique. The 5-year recurrence rate was 3.5%. The liquid nitrogen therapy is especially suitable when the eye lids are operated on, because the lacrimal system remains functional. Gas expansion cryotherapy should not be used in in the treatment of tumors, as it may lead to stimulation of growth.

Aged↗

PubMed1993

[Combined cryocoagulation of ciliary body and retina in neovascular glaucoma. Initial experience].

UNLABELLED: Therapeutic success in neovascular glaucoma with conservative and surgical methods is sadly inadequate. Based on the encouraging results we have obtained with transconjunctival cyclocryothermy in primary glaucoma and with peripheral cryopexy (transconjunctival cryotherapy), we applied these two methods in combination to treat neovascular glaucoma. PATIENTS: A total of 25 eyes in 23 patients were treated with the above method. The average preoperative bulbar pressure was 43 mmHg. RESULTS: The highest average reduction of pressure was obtained in weeks 2-4 after treatment (20 mmHg); 40% of the eyes were still compensated after 4 months (below 22 mmHg), 35% showed bulbar pressures between 26-28 mmHg, and 25% showed bulbar pressures about 35 mmHg. These patients had no troublesome symptoms. In all cases, a good improvement of rubeosis iridis was observed. The combined cryotherapeutic method of treating neovascular glaucoma is efficient in controlling the internal bulbar pressure.

Adult↗

PubMed1988

[Localization of the freezing front in tissue by the ultrasound-A picture technic in cryotherapy].

The knowledge of the depth of infiltration of the freezing front in the treated tissue represented an essential demand for an optimal cryotherapy (sprayfreezing and contactfreezing). The hitherto used invasive measuring methods are connected with a tissue traumatisation and therefore only applicable in a limited way. On that account the non-invasive ultrasound-A-picture-technique was applied for defining the freezing front extension. Its qualification was represented in vitro (gelatin), in living biological tissue (muscle of rabbit), and on the human eye (cryotherapy of the primary glaucoma). The use of the sonography in the cryotherapy can be recommended for other special medical branches too.

Animals↗

PubMed1984

[Cryoenucleation in malignant melanoma of the choroid].

The works of Zimmermann, Fraunfelder et al. and Migdal offer reasons for postulating atraumatic procedures for the enucleation of malignant melanoma of the choroid. Cryosurgery represents an effective method of blocking the melanoma prior to enucleation in such a manner that an intraoperative dissemination of tumor cells is unlikely. The technology which is at present widely used for this purpose (Fraunfelder et al.) has considerable disadvantages. For examples cryoapplication is only possible with favorable, i.e., peripheral tumor localization, since the cryoapplicator cannot be introduced into the orbit. Therefore, a cup-shaped cryoapplicator chilled by liquid nitrogen has been developed which can be introduced into the orbit. The operating temperature of -196 degrees C causes the half of the eyeball in which the tumor is located to freeze within 100 seconds. Subsequently the applicator is removed and the enucleation is continued in the traditional manner. The technical suitability of this procedure has meanwhile been demonstrated in 12 enucleations.

Choroid Neoplasms↗