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N F Schrage

Publications and source records attributed to N F Schrage.

32 records · Page 2Linked to original sources
PubMed1996

Electrolytes in the cornea: a therapeutic challenge.

BACKGROUND: Reported here are the results of electrolyte measurements in different layers of 70 apparently normal human corneas. METHODS: Samples were examined by energy-dispersive X-ray analysis under calibrated conditions in a scanning electron microscope. The method allows the simultaneous quantitative analysis of, among others, sodium (Na), chloride (Cl), phosphorus (P) and potassium (K). The results are related to the dry weight of the analyzed samples. Four distinct layers, subepithelium, middle stroma, posterior stroma and Descemet's membrane, were analysed in each cornea. RESULTS: In the middle stroma we found concentrations of: sodium 0.609 +/- 0.13, chloride 0.557 +/- 0.115, potassium 0.058 +/- 0.02 and phosphorus 0.038 +/- 0.01 (mol/kg dry weight) [corrected]. CONCLUSION: The collation of normal electrolyte concentrations provides reference values for future studies on changes of the corneal electrolyte composition in diseased or injured eyes. The electrolyte composition of rinsing fluids or eye drops should be adjusted to that of the corneal stroma. Phosphate buffer, for example, is not a good vehicle for topical eye treatments and should be replaced by organic buffering systems.

Adult↗
PubMed1996

Does the human cornea contain silicon?

BACKGROUND: Our study investigated the presence, type and quantity of silicon in the human cornea. We report the results of silicon measurements in the corneas of silicotic individuals, bricklayers and apparently normal human individuals and offer a hypothesis for the mechanism of silicon deposition in the human cornea. METHODS: We examined corneas from 13 decreased subjects who suffered from silicosis, 2 bricklayers and 6 apparently healthy subjects. Cornea samples were examined by energy-dispersive x-ray analysis (EDXA) under calibrated conditions in a scanning electron microscope (SEM). The EDXA detector was a silicon-free germanium crystal. Five distinct layers (epithelium, Bowman's membrane, central stroma. Descemet's membrane and endothelium) were analyzed in each cornea. The method allows simultaneous semiquantitative analysis of, among other elements, silicon, calcium and oxygen. We measured amorphous silicon and visible particles of silicon. RESULTS: We found amorphous silicon in low concentrations in 38% of the silicotic corneas and in very low concentrations in 29% of the healthy corneas. Bricklayers showed high concentrations of amorphous silicon. These accumulations of silicon were predominantly located in Descemet's membrane. Silicotic corneas showed significantly more silicon-containing particles than corneas of healthy controls (chi 2-test, P < 0.01). CONCLUSION: Normal corneas contain very low amounts of silicon. Longterm exposure to inhalative silicon dusts results in only very slightly increased levels of amorphous silicon in the cornea. However, silicon-containing particles accumulate in the cornea of silicotic individuals. Bricklayers incorporate more amorphous silicon into the cornea.

Aged↗
PubMed1995

Conjunctival tissue examination in severe eye burns: a study with scanning electron microscopy and energy-dispersive X-ray analysis.

BACKGROUND: Long-lasting inflammation is a major problem in treatment after severe eye burns and may find expression in an altered elemental composition of the conjunctiva. Particulate contamination of biological tissue induces such inflammatory processes. In the anterior eye segment, trauma or subsequent therapy may give rise to such contamination. Scanning electron microscopy and energy-dispersive X-ray analysis are able to detect traumatic residues of submicron size and changes of the elemental composition. METHODS: Conjunctival specimens from first-time peridectomy of three healthy and nine severely burnt-eyes were examined with scanning electron microscopy and energy-dispersive X-ray analysis. The samples were prepared as cryo- or paraffin sections, mounted on carbon blocks and coated with evaporated elemental carbon. RESULTS: The samples of healthy conjunctiva showed higher concentrations of Na, P and CI. These elements showed lower concentrations in conjunctival stroma of burnt eyes excised before the 20th day after trauma than in material obtained subsequently. In two burnt conjunctival specimens there was severe traumatic contamination with Ca in Ca(OH)2 and CaO burns, and in one case the traumatic substance was Si, in a peroxide plus silicone spray burn. In the remaining six cases, particulate contamination with Fe, Al, Ni, Zn, Cu, Ti and other substances was present in the burnt conjunctivas, while no contamination was detected in the specimens of healthy conjunctivas. CONCLUSIONS: The origin of the contaminant particles is assumed to be the trauma itself and the subsequent therapy. These investigations stress the importance, for clinical purposes, or early peridectomy and contamination-free therapy.

Burns, Chemical↗
PubMed1994

The microtrephine. A new diagnostic tool for obtaining corneal biopsies.

We have developed a new tool for obtaining biopsies of the cornea in a manner which is less traumatic than former biopsy techniques. The new instrument consists of a drill with an aperture of 160 microns which functions as a trephine and is powered at 30,000 rpm. The instrument contains a 120 microns mandrel to remove the samples. In order to monitor electrolyte contents in alkali burnt corneas, 32 rabbit eyes underwent an alkali burn of one cornea (1 n NaOH for 30 sec) followed by a sequence of microtrephinations at different times. A total of 81 microtrephinations were performed. Fifty samples were obtained. One corneal perforation occurred. Forty-four puncture sites were examined by means of histology. Forty-eight biopsies were examined in a scanning electron microscope and identified as punctures of corneal tissue by way of an energy dispersive X-ray analysis. Human corneas had been punctured with this device.

Animals↗
PubMed1993

[Chemical and thermal eye burns in the residential area of RWTH Aachen. Analysis of accidents in 1 year using a new automated documentation of findings].

BACKGROUND: Until now there were no statistical data on the incidence and the prevalence of eye burns. Therefore we studied all patients coming to our hospital from the area of Aachen with eye burns during the time from September 1990 until August 1991. PATIENTS AND METHODS: All patients underwent a standardized examination including special history of the burning agent, industrial medical aspects and the employers liability insurance association. The documentation of the anterior eye segment pathology was scored separately for each eye encoded by location and special items. This documentation was worked up by the aid of a database (Filemaker II). 171 patients with eye burns were documented during one year. 65 patients had both eyes burned resulting in 236 documented records. RESULTS: The 171 accidents can be divided in 104 (61%) industrial accidents and 64 (37%) housework accidents. 3 accidents were of unknown origin. Classification of burns was scored according to Reim 1991. 208 (88%) eyes showed score I burns, 27 (11.5%) score II and only one patient showed a score III eye burn. We saw 121 (70%) male patients, 39 (23%) female patients and 11 children (7%). The main age group ranged from 16-45 years. 28% (n = 30) of all accidents happened in machine factories, which have thereby in our study the highest incidence of industrial accidents. CONCLUSION: By means of a one-year statistic we found that over 60% of all eye burns were industrial accidents, 28 in machine factories and 20% in service industries. 37% houseworks accidents are very difficult to prevent because of a deficit of safety rules.

Accidents, Home↗
PubMed1993

[Keratoplasty with 11-12 mm diameter for management of severely chemical-burned eyes].

Up to now 73 patients with 101 very severe eye burns have been operated on in our clinic. Thirty-nine patients were treated by a penetrating keratoplasty. More than 1 year after the accident 8 patients were treated with keratoplasties, 11-12 mm in diameter. These large diameters were necessary, because 6 patients developed widespread progressive corneal ulcerations, and in 2 patients the artificial epithelium failed to protect the denuded corneal stroma and sloughed off because of deep stromal defects. The long-term follow-up in these cases is now at least 1 year. Six grafts remained clear with a healthy epithelial layer. The resulting visual acuity in these cases ranged from 0.1 to 0.5. Five patients developed a cataract secondary to the application of steroids. Two grafts were rejected in a very early period 2-3 months after transplantation. In corneal melting processes including the limbal region, treatment with large keratoplasties seems to be a possibility for long-lasting healing and rehabilitation in very severe eye burns. Important for the prognosis of the graft obviously is the restoration of an intact limbal region.

Adolescent↗
PubMed1993

[Surgical therapy of pterygium. Incidence of recurrence after free conjunctival transplant and surgical techniques without transplantation].

A retrospective examination was conducted on 104 patients who had undergone operations for a pterygium over a time period of 2-73 months. Thirty-one patients were operated on with a free autologous conjunctival transplant; in 40 cases a conjunctival suture was performed and in 33 cases the bare sclera technique was used. The pterygium and any recurrences were scored clinically from 0 to 4. Small recurrences with a score less than 3 and a small conjunctival corpus were called "calm" recurrences. A bigger corpus and a head with a score > or = 3 and parallel vessels were called "active" recurrences. The recurrence rates were taken as the total calm and active recurrences. Autologous conjunctival transplant had a recurrence rate of 32.3%, excision with conjunctival suture 58.5%, and the bare sclera technique had a recurrence rate of 66.7%. Excision techniques cause high rates of recurrences, severe conjunctival scarification and irritation for a long time. A free autologous conjunctival transplant from the same or other eye to the place of excision improves the rate of recurrences even when the condition is more severe initially. Even though more complicated operation methods decrease the rate of recurrence, but 20-35% recurrence rates are still not satisfactory.

Conjunctiva↗
PubMed1993

A simple empirical calibration of energy dispersive X-ray analysis (EDXA) on the cornea.

Monitoring of the corneal electrolyte content is important for the study of chemical eye burns. This paper describes quantitative measurements on gelatin standards, corneas and a cornea homogenate with an energy dispersive X-ray analyzer (EDX) in the scanning electron microscope (SEM). Ten micrometers thick cryosections were freeze-dried and mounted on solid carbon supports. The applied quantification procedure was a local peak background analysis with a specifically designed computer program. Similar chemical and physical properties of gelatin, cornea homogenate, and cornea were proven by EDX-analysis and wet chemical analysis. Gelatin standards with known concentrations of different added salts showed linear correlations with a correlation coefficient higher than 0.95 for all considered elements. The local background generation on carbon supports was the same for gelatin standards and corneal tissue. The results demonstrate that quantitative EDX analysis of semi-thin samples, mounted on neutral carbon supports, can be reliably used for the assessment of the corneal mineral composition.

Animals↗
PubMed1991

[Silver nitrate burn after Credé's preventive treatment. A roentgen analytic and scanning electron microscopy study].

Following Credé's prophylaxis with silver-nitrate, the cornea of a newborn presented greyish-brown, lime-like plaques on the nasal part of the right eye. A paracentral ulcerating stromal opacification undermined these appositions, when the patient was admitted to the eye-clinic at Aachen. In the material taken in a lamellar keratectomy scanning electron microscopical examination was able to prove the existence of granules, previously described in light-microscopy. These granules measured 100 to 300 nm in diameter and were placed up to 110 microns deep into the corneal stroma of the specimen. An earlier chemical analysis of necrotic material showed no silver specific reaction. By means of EDX-Analysis these granules could be identified as silver-containing. This was once reassured by a newly developed modification of van-Kossa's-staining-method. The fact that the granular deposits contained mainly silver proves that the onset of a sodium-chloride-irrigation did not promote an intended therapeutic silver-chloride-precipitation and therefore had no effects on the silver-nitrate's penetration abilities. Injuries by silver-nitrate-solutions used for Credé's prophylaxis are seldom but still reported. The mechanism of injury in this case of a child, born by sectio remains unknown. Neither the use of an unusual silvernitrate solution, that was taken from a disposable ampoule (Mova-Nitrat) was reported, nor any corneal injury during sectio mentioned.(ABSTRACT TRUNCATED AT 250 WORDS)

Burns, Chemical↗
PubMed1990

Particulate matter contamination in the corneal stroma of severe eye burns in humans.

Corneal buttons obtained from keratoplasty were examined by energy dispersive x-ray analysis (EDXA) combined with scanning electron microscopy (SEM). This method enables to assay the mineral composition of minute parts of tissue samples identified in SEM images. Samples were cut from paraffin embedded corneae, deparaffinized in xylol, dried in aceton, critical-point desiccated, covered by evaporating with a thin layer of carbon and examined by SEM. In healthy human donor eyes, only some iron particles had been found. In the 22 patients samples high amounts of different particles were identified, materials from rubber stoppers, chromesteel, titanium pigments, talcum, barium and glass. Furthermore a lot of different metal particles containing varying amounts of Na, Mg, Al, Si, P, S, Cl, K, Ca, Fe, Cu, Cr, Zn, La and Ce were detected. Some particles may be caused by the initial trauma, others by therapy. Such contaminations might have supported leucocyte and fibrocyte invasion increasing the inflammatory reaction in the burnt cornea.

Corneal Stroma↗
PubMed1990

Corneal silver deposits following Crede's prophylaxis an examination with electron dispersive x-ray analysis (EDX-analysis) and scanning electron microscope (SEM).

In a case of silver nitrate injury after Credé's prophylaxis, the cornea of a newborn presented yellow-brown, lime-like plaques on the nasal part of the right eye. A paracentral ulcerating stromal opacification undermined these appositions, when the patient was admitted to the eye-clinic at Aachen. In the material obtained by a lamellar keratectomy scanning electron microscopical examination was able to prove the existence of granules, previously described in light-microscopy. These granules measured 100 to 300 nm in diameter. An earlier chemical analysis of necrotic material showed no silver specific reaction. By means of EDX-analysis these granules could be identified as silver-containing. Injuries by silver nitrate solutions used for Credé's prophylaxis are seldom but still reported. The mechanism of injury in this case of a child, born by sectio remains unknown. Neither the use of an unusual silver nitrate solution, that was taken from a disposable ampoule (Mova-Nitrat R) was reported, nor any corneal injury during sectio mentioned. Nevertheless the method of EDX-analysis and SEM proved the diagnosis of corneal silver deposits, so that the origin of the granullar opacification of the cornea could be determined.

Cornea↗
PubMedDate not supplied

[The microtrephine: experimental experiences, initial clinical application].

INTRODUCTION: In some diseases of the cornea, histopathological or microbiological evaluation of a stromal samples is essential. On the other hand one of the main aims in the therapy is to keep the cornea clear and without scars. Until now bioptic techniques were not suitable for both aims, getting a sample with minimal damage of the cornea. There was a lack of a method for corneal biopsy which is clinically easily applicable. MATERIAL: We developed a new instrument for taking corneal biopsies. It is a microtrephine with 160 microns diameter rotating with 30,000 Rpm. It takes biopsies of corneal epithelium and stroma as solid cylinders. The biopsy is non traumatic, safe and repeatable. Biopsies were taken until now on 32 alkali burnt rabbit corneas, 8 enucleated human corneas and 5 patients. RESULTS: 157 biopsies were taken until now. In 75% a sample could be gained. The perforation rate was 0.63% in rabbits. No perforation occurred until now in human corneas. Preparations of light-, scanning- and transmission electron microscopy are presented in this paper for demonstrating examples of application. Microbiological preparations of corneal infiltrates were sterile up to now, representing sterile technique with this new instrument. Herpes simplex PCR was positive in one out of six stromal biopsies from one cornea in supposed herpes keratitis. CONCLUSION: With the microtrephine samples of the corneal stroma can be taken with high precision. A wide variety of routine diagnostics including repeated measurements on stromal samples of a single cornea are possible now. Early bioptic diagnostics of corneal diseases can be achieved now.

Animals↗
PubMedDate not supplied

Interactions between ocular surface fluid and cornea related to contact lenses.

PURPOSE: To improve the quantification of damage to the ocular surface, metabolite levels, electrolyte concentrations, and enzyme activities were assayed in corneal epithelium, stroma and tears. METHODS: In rabbits, rinsing or contact lenses were used to induce microtrauma. For more severe trauma, experimental injuries were induced with 1 N NaOH. Human accidents included epithelial lesions and mild chemical burns. Enzymatic test systems and electron dispersive X-ray analyses (EDXA) were employed. Corneal hydration was assessed by wet and dry weights. Interleukins were analysed with ELISA. RESULTS: In contrast to normal eyes, in ocular surface trauma the interaction between tear fluid and cornea played an important part. After wearing contact lenses or rinsing, glucose and lactate levels in the cornea and in tears increased, and ATP and glycogen in the cornea decreased. After epithelial lesions, N-acetylglucose aminidase (NAcGA, E.C.3.2.1.50) was released into the tears. Epithelial defects alone and--much more--rinsing the denuded stromal surface produced an increase of lactate and glucose in tears and a dramatic fall in Na, Cl, and S levels in the stroma. Rinsing with phosphate induced corneal calcification. IL-1 and IL-6 were increased in human corneal buttons from patients with trauma and inflammation. CONCLUSIONS: Biochemical analyses may be useful to quantify trauma to the ocular surface.

Acetylglucosaminidase↗