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Biomedical subjects

C P Lohmann

Publications and source records attributed to C P Lohmann.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Clinical results of intravitreal administration of tissue-type plasminogen activator (tPA) and gas for removal of subretinal hemorrhage in senile macular degeneration].

BACKGROUND: Subretinal hemorrhage in age related macular degeneration (AMD) usually causes acute visual loss and is associated with poor visual prognosis. In order to prevent retinal damage and to perform laser treatment of the underlying choroidal neovascularization (CNV) the subretinal hemorrhage has to be removed from the macular region. This could be achieved by intravitreal injection of tissue plasminogen activator (tPA) and gas. PATIENTS AND METHODS: In 8 consecutive patients, suffering from a massive macular hemorrhage (duration of visual problems: mean 9 days), tissue plasminogen activator (tPA) (40 micrograms in 400 microliters BSS) and SF6-gas (0.75 ml) was transsclerally injected into the vitreous cavity to achieve liquification and displacement of the hemorrhage. RESULTS: In all patients liquification and displacement of the hemorrhage out of the macular region was achieved during follow up. During the first week after operation a significant increase of visual acuity was noticed in all patients, however ophthalmoscopically there was just little reduction of the hemorrhage in the foveolar area. After successful removal of the blood the choroidal neovascularization was treated successfully by laser coagulation in one patient. No laser treatment was performed in the other patients because of the subfoveal location of the neovascularisation or because of disciform scar. Visual acuity increased 4 lines after surgery. In one case the procedure was complicated by a persistent vitreous hemorrhage and vitrectomy had to be performed in another patient due to an endophthalmitis. CONCLUSION: Intravitreal injection of tPA assisted gas displacement of subretinal hemorrhage due to AMD leads to a significant increase of visual acuity during the first week after operation. Although a nearly complete removal of the hemorrhage out of the macular area could be achieved, it was difficult to differentiate this from the spontaneous course. Laser photocoagulation could be performed in only few cases.

Aged↗
PubMed1999

Intraepithelial photorefractive keratectomy for regression after laser in situ keratomileusis.

PURPOSE: To propose a refractive procedure, intraepithelial photorefractive keratectomy (IE-PRK), to treat regression after laser in situ keratomileusis (LASIK). SETTING: IMO Instituto de Microcirugîa Ocular de Barcelona, Cornea and Refractive Surgery Unit, Autonoma University of Barcelona, Barcelona, Spain; Vall d'Hebron Hospital, Department of Ophthalmology, INSERM, University Hospital, Toulouse, France. METHODS: This open but uncontrolled prospective pilot study assessed the efficacy, predictability, and stability of IE-PRK in 21 eyes of 21 patients who had previous LASIK for myopia or myopic astigmatism with a mean spherical equivalent (SE) refraction of -9.80 diopters +/- 2.95 (SD). After LASIK, the eyes regressed to a mean of -1.93 +/- 0.82 D. They were retreated with IE-PRK, in which a photoablation was performed directly in the epithelium without damage to Bowman's membrane. Follow-up was up to 1 year. RESULTS: Eight of the 21 eyes (38%) were emmetropic at 6 months and 11 (52.4%) had a refraction between -0.50 and +0.50 D. Refraction was stable from the second week to the first year, with no significant differences among the mean SEs at 10 days, 6 weeks, and 6 and 12 months. CONCLUSION: The preliminary results of this small series indicate that IE-PRK appears to be safe, especially in selected cases; 1 line of lost best spectacle-corrected visual acuity occurred in 5% of eyes.

Adult↗
PubMed1999

Regression and epithelial hyperplasia after myopic photorefractive keratectomy in a human cornea.

We present the histology of a cornea of a woman who had excimer laser photorefractive keratectomy (PRK) for myopia 6 months before she died in an accident. Preoperative spherical refraction was -6.00 diopters (D) with an astigmatism of -0.50 D. Six months postoperatively, refraction was -4.50 D. Slight corneal haze was noted at 1 and 3 months. The corneal histology showed marked epithelial hyperplasia in the center of the ablation zone without subepithelial deposition of newly synthesized collagen, proteoglycans, or both. The epithelial thickness was 38 microns in the untreated area and 93 microns in the center of the ablation. In conclusion, postoperative epithelial hyperplasia was responsible for regression after PRK in this eye.

Adult↗
PubMed1999

[Eye involvement in circumscript scleroderma--manifestation of borreliosis?].

BACKGROUND: The circumscript cutaneous sclerosis is an inflammato-edematous erythema of the skin, usually leading to a plaque-like sclerosis and cutaneous atrophy. The etiology of this disease remains unknown, but some authors presume a systemic infection with Borrelia burgdorferi as the underlying pathological condition. PATIENT: We present a case of a 66-year-old male patient who suffered from episcleritis of his left eye. Funduscopy showed an unilateral papillary edema. Visual acuity was 1.0. The patient had multiple erythemata of the skin of the body-trunk and the arms. On histological examination the lesions were compatible with circumscript sclerosis. Neurological examination was normal. Brain imaging (MRI), CSF examination and serology showed no pathological findings, although the patient presented with raised antibodies against Borrelia burgdorferi (IgG positive, IGM negative). Intravenous antibiotic treatment and topical steroids for three weeks resulted in a complete recovery of the scleritis, but had no effect on the papillary edema. CONCLUSION: Inflammatory pathological findings of the eye can be associated with circumscript sclerosis, a disease, that is normally limited to the skin. The pathological mechanism remains unclear. The presumption of an underlying borreliosis could not be confirmed in this case.

Aged↗
PubMed1998

[Epidermal growth factor (EGF) in tears in excimer laser photorefractive keratectomy. Responsible for postoperative refraction and "haze"?].

BACKGROUND: Corneal wound healing is of critical importance for the postoperative outcome of excimer laser PRK. Wound healing is a complex biological process that is well characterised at the microscopic level, but its regulation is poorly understood at the molecular level. Among various cytokines, epidermal growth factor (EGF) plays an important role in superficial wound healing. The synthesis of EGF varies individually; therefore, by determining the EGF concentration in the tear fluid, patients with increased wound healing activity might be traced. METHODS: In this study we measured the EGF concentration pre- and postoperatively in the tear fluid of 50 eyes using a ELISA test. The preoperative refraction was between -2.00 and -10.00 dioptres. The maximum follow-up was 6 months. RESULTS: Preoperatively, in all eyes the EGF concentration in the tear fluid was between 0.2 and 1.7 ng/ml. In contrast, 1 week postoperatively, these values increased (0.21-22.50 ng/ml); 4 weeks postoperatively, the EGF concentration was in all eyes back to preoperative levels. In eyes with high EGF tear fluid concentration 1 week after surgery, refraction at 6 months was outside the intended correction of +/- 1.0 D. We could not find any correlation between EGF concentration and "corneal haze". CONCLUSIONS: EGF may play an important role in postoperative wound healing after excimer laser PRK. Investigations concerning a pharmaceutical control of EGF should be undertaken.

Adult↗
PubMed1998

Diagnosis of infectious endophthalmitis after cataract surgery by polymerase chain reaction.

PURPOSE: To ascertain whether the use of the polymerase chain reaction (PCR) technique leads to more rapid diagnosis of infectious endophthalmitis after cataract surgery. SETTING: University Eye Clinic Regensburg, Germany. METHODS: The aqueous humor and vitreous of 16 eyes with infectious endophthalmitis (10 acute, 6 delayed) were evaluated by microscopy, diagnostic culture, and PCR to detect the infectious agent. RESULTS: Microscopy of the vitreous was positive in 3 eyes and the culture media results were positive in 7 eyes, all with acute endophthalmitis. Significantly fewer positive results were obtained in the aqueous humor. Using PCR, an infectious agent was detected in the aqueous humor of all 16 eyes and in the vitreous of 14. The vitreous sample was negative in 2 eyes with delayed endophthalmitis. CONCLUSIONS: Detection of the infectious agent was more successful using PCR than using conventional microbiological tests, especially in the diagnosis of delayed endophthalmitis where the pathogen was detected in the aqueous humor in all eyes.

Acute Disease↗
PubMed1998

[Listeria monocytogenes-induced endogenous endophthalmitis in an otherwise healthy patient: PCR-assisted rapid diagnosis as the basis for successful therapy].

BACKGROUND: Listeria monocytogenes is a rare cause of endogenous endophthalmitis. Only 14 cases are published in the literature so far. All eyes showed similar clinical features and profound visual loss. PATIENTS AND METHODS: We report on a case of an otherwise healthy 73-year-old male. He was referred to our hospital because of acute hypopyoniritis with secondary glaucoma. Within a few hours the severity of the intraocular infection increased dramatically resulting in the clinical picture of an acute endophthalmitis. RESULTS AND CONCLUSION: Early identification of the causative pathogen in the aqueous humor after anterior chamber paracenthesis using polymerase chain reaction (PCR) and the initiation of a specific, systemic antibiotic medication resulted in a complete recovery of visual acuity.

Acute Disease↗
PubMed1998

[Eye injuries during a laser show].

BACKGROUND: Laser injuries are usually described in case reports concerning military personnel or scientists who had an accidental exposition to a laser. Today laser injuries to un-involved persons become more frequent. The potential danger for eye injuries was discussed by Birngruber and Gabel (2) in 1984. PATIENT: A patient presented 4 days after the accident with a monocular decline in vision and a scotoma after being hit by a ray of a discotheque laser. At the time of the accident the patient was standing on the dance floor watching a laser show. From that moment he reported a scotoma on the affected eye. The examination of the patient by an ophthalmologist 3 days later revealed a monocular decline in vision to 0.3 and a scotoma. Reading problems were reported. The fluorescence angiography confirmed the biomicroscopical barely visible line shaped defect next to the foveola which was according to our clinical experience caused by the ray of a laser. The vision defect and the scotoma remained stable during the follow up period. CONCLUSIONS: Before the first use of a show-laser unit it gets approved. Every change of the unit or the change of its position requires a new technical check by authorized institutions. At present many show lasers in use are not met with this requirement. Manipulations to the lasers are easy to perform and improve the intended show effect. The missing control practice provokes eye threatening situations for an enormous number of persons who are not aware of the danger.

Adult↗
PubMed1998

Regression after LASIK for the treatment of myopia: the role of the corneal epithelium.

Factors responsible for postoperative regression are still unknown but postoperative epithelial hyperplasia might play an important role. To evaluate the role of the corneal epithelium on regression after laser in situ keratomileusis (LASIK), the thickness of the epithelium was measured in 18 eyes preoperatively and at various postoperative intervals. Measurements of the epithelial thickness were taken using a high-frequency (50 MHz) ultrasound device and measurements were correlated with the postoperative refraction. In all eyes, preoperative epithelial thickness was between 34 and 44 microm. In contrast, after surgery, values were between 35 and 111 microm. In eyes with a refractive outcome of +/-1.0 diopter of that intended, there was an increase of the epithelial thickness of less than 5 microm postoperatively. In contrast, eyes with severe regression showed a significant increase in the thickness in the epithelium after LASIK. In our patient group, regression of the attempted correction was related to postoperative epithelial hyperplasia. Broadly speaking, an increase of 10 microm epithelial thickness resulted in a 1 diopter regression. Mechanical and/or pharmaceutical factors controlling postoperative epithelial hyperplasia would be beneficial.

Adult↗
PubMed1997

[Rapid diagnosis of infectious endophthalmitis using polymerase chain reaction (PCR): a supplement to conventional microbiological diagnostic methods].

BACKGROUND: Endophthalmitis is, although relatively rare, a serious intraocular infection, which could result in a loss of visual function. Therefore, the rapid diagnosis and initiation of the appropriate treatment is of critical importance. To date, approximately 60 percent of eyes with a clinical diagnosis of infectious endophthalmitis show a positive microscopic or culture result. By using the very sensitive polymerase chain reaction this number might increase. PATIENTS AND METHODS: In a series of 12 eyes with infectious endophthalmitis we have performed microscopic investigations, diagnostic culture and polymerase chain reaction in aqueous humor and vitreous in order to detect the infectious agent. RESULT: Microscopic investigations showed a positive result in the vitreous of 3 eyes. This number improved to 6 eyes using culture media. Significant less positive results were obtained in the aqueous humor. The infectious agent could be detected in the aqueous humor in all 12 eyes and in the vitreous in 9 eyes by PCR. Only in 2 eyes with a delayed endophthalmitis the vitreous was negative. CONCLUSIONS: The detection of the infectious agents was more successful using PCR compared to conventional microbiological tests. In particular, for the diagnosis of delayed endophthalmitis PCR proves to be very superior. In all cases of delayed endophthalmitis the pathogen could be detected in the aqueous humor.

Aqueous Humor↗
PubMed1997

[Polymerase chain reaction (PCR) and its possible applications in diagnosis of infection in ophthalmology].

The polymerase chain reaction (PCR) is a relatively new molecular biology-based technique that allows the specific identification of small amounts of DNA or RNA. This technique offers significant advantages compared to conventional microbiological tests, such as microscopy or culture. Increasing numbers of immunosuppressed patients with intraocular infections and, improvements in antibiotic therapy for specific organisms require a more accurate diagnosis. PCR is capable of providing such requirements. This technique is evolving rapidly and in cooperation with clinicians and molecular biologists a number of applications are being developed, which contribute to the growing demands on microbiological testings. This article describes the basics, indications and the limitations of the polymerase chain reaction.

Diagnosis, Differential↗
PubMed1997

[Intraocular pressure in sections with 2 microkeratomes in vitro].

BACKGROUND: The rapid integration of new technology into ophthalmologic practice, e.g. LASIK (laser in situ keratomileusis), is associated with new complications. The limitations of the new technology cannot be precisely determined. During lamellar cuts with microkeratomes intraocular pressure (IOP) elevations occur. The IOP elevation during the lamellar cut cannot be determined by conventional tonometry. MATERIALS AND METHOD: We examined the IOP rise during the complete microkeratome treatment. Fresh enucleated porcine eyes were cannulated and direct IOP measurement with a Statham manometer was carried out. Thus we evaluated the IOP during the complete treatment for two differently constructed microkeratome systems. RESULTS: IOP elevations (mean values) between 77 mm Hg for the Corneal Shaper and 229 mm Hg for the Keratek during the vacuum phase and 140 mm Hg for the Corneal Shaper and 360 mm Hg for the Keratek during the lamellar cut were monitored. A sudden IOP decrease to-5 mm Hg was registered for the post-vacuum phase. CONCLUSIONS: In our opinion unphysiologic high IOP values could be dangerous for risk eyes.

Animals↗
PubMed1996

[Treatment of recurrent corneal erosion using phototherapeutic keratectomy with the excimer laser].

BACKGROUND: Recurrent corneal erosion is a common corneal disease and may be a difficult disorder to treat with a number of patients suffering persistent symptoms despite conventional therapy. PATIENTS AND METHODS: We present a series of 32 eyes who underwent Excimer-Laser phototherapeutic keratectomy (PTK) for recurrent corneal erosion. There were 11 eyes who were treated during an acute episode of recurrent erosion. All remaining patients were treated in a symptom-free interval. The affected area of epithelium was removed and a 25 pulse ablation was performed to Bowman's membrane. RESULTS: In 30 eyes there was a marked improvement in symptoms postoperatively with no recurrences. However, 2 eyes experienced a recurrent episode 6 days and 2 weeks after PTK, respectively. Postoperative refraction and corneal topography was unaltered in all cases. CONCLUSIONS: Excimer-Laser PTK appears to be a safe and promising procedure for recurrent corneal erosion in cases refractory to medical treatment.

Adult↗
PubMed1996

Excimer laser phototherapeutic keratectomy for recurrent erosions: a clinical study.

BACKGROUND AND OBJECTIVE: Recurrent corneal erosion is a common corneal disease. It may be difficult to treat, with a number of patients suffering persistent symptoms despite having had conventional therapy. The aim of this study was to evaluate the usefulness of the excimer laser for the treatment of recurrent corneal erosions. PATIENTS AND METHODS: The authors studied 31 eyes of 24 patients who underwent excimer laser phototherapeutic keratectomy (PTK) for recurrent corneal erosion. Three eyes were treated during an acute episode of recurrent erosion. The remaining eyes were treated during a symptom-free interval. The affected area of epithelium was removed and a 25 pulse ablation was performed to Bowman's membrane. RESULTS: In 30 eyes there was a marked improvement in symptoms postoperatively, with no recurrences. However, 1 eye had one recurrent episode 2 weeks after PTK. Postoperatively, refraction and corneal topography were unaltered in all cases. CONCLUSIONS: Excimer laser PTK appears to be a safe and promising procedure for cases of recurrent corneal erosion refractory to medical treatment.

Adult↗
PubMed1996

The importance of the corneal epithelium in excimer-laser photorefractive keratectomy.

To evaluate the importance of the epithelium for postoperative regression we undertook excimer-laser photoreactive keratectomy (PRK) in six rabbits. After the epithelium had been removed mechanically, two rabbits underwent a -3.0 D procedure; two rabbits, a -6.0 D procedure; and two rabbits, a -9.0 D procedure. Refraction was monitored pre- and postoperatively using streak retinoscopy. Rabbits were killed at 3 weeks after PRK and the thickness of the corneal epithelium in the centre of the ablation zone and in an untreated area just outside the treatment zone was measured using light microscopy. At the time of killing, no stromal haze was visible on slit-lamp biomicroscopy. In all rabbits the thickness of the corneal epithelium over the untreated area was between 31.4 and 36.7 microns. In contrast, the thickness of the epithelium in the centre of the ablation zone in rabbits treated with a -3.0 D procedure was only slightly increased, and retinoscopy showed a change in refraction of around 3 D. All other rabbits showed a significant increase in epithelial thickness, whereas the amount of thickness correlated with the amount of myopic regression. One rabbit in the -6.0 D group showed an increase in epithelial thickness of 18.4 microns and a myopic regression of 1.5 D. In both rabbits in the -9.0 D group the amount of corneal tissue removed by the laser was nearly completely substituted by epithelial hyperplasia. Postoperative retinoscopy showed nearly the same refraction as had been obtained preoperatively. In summary, the postoperative control of epithelial thickness seems to be an important factor for the success of excimer-laser PRK and, in particular, for high degrees of myopia.

Animals↗
PubMed1995

The effects of ablation diameter on the outcome of excimer laser photorefractive keratectomy. A prospective, randomized, double-blind study.

OBJECTIVE: To determine the effects of the ablation diameter on the outcome of excimer laser photorefractive keratectomy. DESIGN: Eighty patients were randomized to either a 5.00-mm or a 6.00-mm treatment group and within these groups underwent either a -3.00-diopter (D) or a -6.00-D correction based on their preoperative refraction. A Summit Omnimed excimer laser was used throughout the study. RESULTS: In eyes treated with a 6.00-mm-diameter ablation, the initial hyperopic shift was reduced, with significant differences at 1 week with -3.00-D corrections and at 1 and 4 weeks with -6.00-D corrections (P < .01). At 6 months, the refractive changes were greater and closer to that intended with 6.00-mm-diameter ablations. The predictability of photorefractive keratectomy was significantly improved with 6.00-mm zones, with a reduction in variance of the refractive changes at all stages postoperatively (P < .05 to P < .001). With -3.00-D corrections, objective measurements showed significantly less anterior stromal haze in eyes treated with 6.00-mm zones at 6 months (P < .05). With -6.00-D corrections, haze was significantly reduced at 1, 3, and 6 months in the eyes treated with 6.00-mm zones (P < .05). Five eyes treated with 5.00-mm zones experienced severe regression of the correction, with marked corneal haze and a reduction of 3 or more lines of best corrected Snellen visual acuity at 6 months. No eyes treated with 6.00-mm zones were similarly affected. Computerized measurements of "night" halo were significantly lower in the 6.00-mm treatment groups at 1 week and at 1 and 6 months in the eyes with -3.00-D corrections and at 1 week and at 1 month in the eyes with -6.00-D corrections (P < .05). At 6 months, seven patients treated with 5.00-mm zones complained of severe disturbances of night vision. No eyes in the 6.00-mm group were similarly affected. CONCLUSIONS: Treatment with 6.00-mm ablation diameters precipitated less initial overcorrection, greatly improved the predictability of photorefractive keratectomy, and was associated with a reduction in complications impairing postoperative visual performance.

Adult↗
PubMed1995

[ProTon--a new portable tonometer. Initial experimental and clinical results].

To determine the accuracy of a new portable tonometer using the Mackay Marg principle (ProTon, Tomey) we measured three cadaver eyes in vitro and 196 eyes of 98 patients in vivo. The 325 manometric determined IOP values were compared to ProTon measurements in three enucleated, canulated human eyes. The correlation was r = 0.99. In a clinical study 196 eyes were measured with both the Goldmann and the ProTon tonometer. The results showed good correspondence with a correlation of r = 0.95. The statistical significance (paired t-test) was P < 0.001.

Equipment Design↗