Sirpa Kompa

Comparison of emergency eye-wash products in burned porcine eyes

Abstract.Background: The long-term prognosis of patients with chemical eye burns depends on immediately rinsing the eye after the trauma. The chemical properties and tolerance of currently used rinsing solutions were examined. Methods: NaCl 0.9%, Ringer lactate, balanced salt solution (Aqsia), phosphate buffer, tap water, and Previn were analyzed. The buffer capacities were determined by titration with HCl and NaOH. The osmolarity of the solutions and the osmolarity of 100 healthy and 100 alkali burned porcine corneas were determined by means of freezing point depression. 56 enucleated porcine eyes were burned and rinsed with NaCl solutions of different osmolarities (0–1200 mosmol/l), Previn, NaCl 0.9% or phosphate buffer, respectively. The different swelling behaviors were determined by pachymetric measurements, and the resulting corneal osmolarity after irrigation was assessed. The effect of Previn as a hyperosmolar solution in comparison with isoosmolar phosphate buffer was examined on 10 healthy human eyes. Results: Only phosphate buffer and Previn show high buffer capacities. The osmolarity of the healthy/burned porcine corneas was 329±61/1203±289 mosmol/kg. Except for Previn (862±3 mosmol/l), all solutions are hypo- or almost isoosmolar in comparison with the healthy cornea. Rinsing of the burned corneas causes swelling in all groups in inverse proportion to the osmolarity of the solution. Thus, the lower the solutions osmolarity, the stronger the swelling reaction of the cornea. The resulting corneal osmolarity following rinsing behaves proportionally to the osmolarity of the rinsing solution. Therefore, a high osmolarity of the rinsing solution correlates with a high corneal osmolarity. No long-term effects in healthy eyes were observed after rinsing with Previn or phosphate buffer. Conclusion: Corneal thickness and osmolarity are significantly correlated to the osmolarity of the rinsing solution. Corneal edema dilutes the agent in the stroma. Therefore, we recommend solutions with low osmolarity (tap water) or high buffer capacity (Previn) for the initial post-trauma irrigation.

Use of an amphoteric lavage solution for emergency treatment of eye burns: First animal type experimental clinical considerations

PURPOSE Severe eye burns occur rarely, but are related to a poor prognosis in rehabilitation. As emergency treatment has been identified as decisive factor for the prognosis of eye burns, new first aid rinsing solutions should be considered carefully in their clinical action. In a first approach, the new drug Diphoterine was subjected to a comparison with saline solution to evaluate the effects in a model of severe eye burns. METHODS In a double-masked experiment 16 rabbits underwent a severe eye burn of one cornea followed by immediate rinsing with 0.9% sodium-chlorine solution (n=8) or Diphoterine (n=8). During 16 days after burn, an irrigation therapy with 0.9% saline solution three times daily 160 ml was applied in both groups following the recommendation of prolonged irrigation therapy performed in our clinic. In a similar setup, 16 eyes were subjected alkali burns with measurements of aqueous humor pH within 30s after burn and after a period of 5 min rinsing with 500 ml saline 0.9% or Diphoterine, respectively. RESULTS The result of the severe eye burn with an opaque cornea was similar in both groups. During rinsing no fibrin precipitates occurred in the Diphoterine rinsed group whereas this was detectable in all eyes rinsed with saline solution. After 16 days there was no difference between both groups indicating no harmful effect of Diphoterine as emergency treatment compared to saline 0.9%. After 30s of burn with 1N NaOH and rinsing with 500 ml of the specified solutions the anterior chamber pH was 10+/-0 in the saline group and 9.35+/-0.3 in the Diphoterine group showing efficacy of the buffering capacity of Diphoterine. CONCLUSION Diphoterine proves to be efficient in the primary treatment of burns. The anterior chamber pH could be lowered by 5min of rinsing. No harmful effects of Diphoterine could be observed compared to rinsing with saline solution in the course of an severe alkali burn of the cornea.

Relationship of eye burns with calcifications of the cornea

IntroductionThe clinical pattern of corneal calcification has been considered to be a part of chronic eye diseases, such as uveitis, severe glaucoma, keratitis and eye burns. Since, in some cases of eye burns, we have found corneal calcifications to be related to the initial calciferous caustic agents and to the use of phosphate-buffer-containing fluids, we have reviewed our files of clinical eye burns for the incidence and appearance of corneal calcification.MethodsA total of 176 burnt eyes of 98 patients suffering from severe eye burns were retrospectively reviewed. The following data set was acquired: the type of caustic agent, the time of the burns, the delay and type of immediate treatment and the time and type of first aid, the subsequent medication, the clinical grading and the later results.ResultsCalciferous burning agents and corneal calcification are correlated (P<0.01). Initial single rinsing with phosphate does not produce corneal calcification (P=0.134). There is evidence that corneal calcifications are correlated with chronically administered phosphate-buffered eye drops (P<0.005).DiscussionEye burns followed by calcifications follow two different major patterns: the corrosive substance contained calcium or the continued therapy was applied with phosphate-buffered eye drops. We present case reports of three different types of eye burns and later therapy resulting in corneal calcification. Corneal calcifications are presumably related to longer-lasting phosphate application. One suspicious mechanism is the low content of calcium ion stabilizing proteins such as hyaluronate or fetuin in treatments for severe eye burns. The exceeding of the solubility product of Ca2+ and PO4− results in the precipitation of calcium phosphates. In cases of chronic corneal disturbance, we recommend the elimination of phosphate-buffered medications to prevent corneal calcification.

The Type II Aachen-Keratoprosthesis in humans: case report of the first prolonged application.

Purpose To improve the prognosis of corneal grafts in silicone-oil filled eyes of patients with severe ocular trauma by a prolonged application of the Type II Aachen-Keratoprosthesis (KPro). This application endeavors to improve post-keratoplasty prognosis by avoiding corneal endothelial dystrophy in the aphakic eye due to contact with silicone oil. Patient and Procedures The Aachen-Keratoprosthesis’ haptic was modified to allow tight contact with cells. The Type II Aachen-Keratoprosthesis was then implanted in an 18-year-old male, with previous management of bilateral corneal rupture. Rather than utilize the device as a temporary intraoperative tool, we extended the devices lifespan in the eye. Main Findings Following implantation, the patient could see hand movements up to 0.1 with best correction. After 8 weeks, vision decreased and a retroprosthetic membrane proliferated. Upon conjunctival retraction, 3 months after the initial surgery, we excised the prosthesis and performed a re-vitrectomy and corneal grafting. The silicone oil was removed. After eighteen postoperative months, the graft remained clear, the retina was completely attached, and the vision was stable: 0.1 best corrected. Conclusion This case reports the prolonged implantation and prospect of the Type II Aachen-Keratoprosthesis to be utilized as a permanent device to restore vision in the near future.

Aachen keratoprosthesis as temporary implant for combined vitreoretinal surgery and keratoplasty: report on 10 clinical applications.

Abstract A new keratoprosthesis was used during pars plana vitrectomy in order to test the optical quality, watertightness, short-term biocompatibility and handling of the new device. The implantability was also tested, given that this keratoprosthesis might in future be left in place for several months. This Aachen keratoprosthesis (Aachen-KPro) is developed to be used as permanent implant to restore vision in corneal blind patients. Patient and methods: The Aachen-KPro was used during pars plana vitrectomy in 10 patients with opaque corneas. In four cases, trauma precipitated the ocular disease. Eye burn was the cause of corneal and retinal disorders in another four cases. One patient had a history of congenital glaucoma with myopia, and one of uveitis with corneal dystrophy. After trephination of 6.5 mm in diameter, the Aachen-KPro, composed of soft silicone rubber, was temporarily placed in the trephination hole. After completion of the vitrectomy, the Aachen-KPro was replaced by a 7 mm corneal graft. Results: Intraoperative use of the Aachen-KPro allowed uncomplicated intraoperative handling, smooth adaptation to the corneal rim in the trephination hole, and an undistorted view of the central and peripheral retina. Leakage, even during scleral depression, could be avoided by individual suturing of the scleral rim. After a follow-up period of 1–10 months, the retina was still attached in all cases. The corneal graft was clear after surgery in four eyes, and edema was found in three cases. Amnion or conjunctiva was placed over three patients’ transplants. Conclusion: We report the first temporary implantations of a new keratoprosthesis in 10 patients. Its flexibility and good optical qualities allowed control of intraoperative procedures. The outcome and prognosis of the vitreoretinal surgery and keratoplasty were related to the primary diagnosis. The Aachen-KPro has shown advantages, especially in eyes where the anterior eye segment is severely damaged by eye burn or previous surgical interventions. In the future, prolonged use of the Aachen-KPro is planned for selected eyes.

Corneal biopsy in keratitis performed with the microtrephine

Abstract · Background: The aetiology of most cases of keratitis remains unclear because the causative agents respond to broad-spectrum antibiotics. Problems occur when they become resistant to local therapies. Further diagnostic measures such as corneal scrapings or biopsies are then necessary. In order to ensure early and gentle biopsy followed by effective diagnosis within 24 h, corneal biopsy specimens were obtained with a microtrephine. · Patients and methods: Microbiopsies were obtained from 28 patients suffering from corneal infiltrates or ulcerative keratitis. Different stainings were used to identify the pathogens. Photographs of the clinical healing process were taken immediately after biopsy and during the follow-up. · Results: One hundred and ten microbiopsies were performed. One hundred and eighteen specimens could be obtained. No perforation occurred. In 5 of 10 cases in which herpetic keratitis was predicted, herpes DNA could be confirmed. The other five cases were found to be caused by other microbes. In 15 of 18 cases, the bacterial pathogen could be confirmed by Gram’s stain diagnosis after microtrephination. Corneal smear was positive in only 7 of these cases. In 2 of 6 cases, predicted to be caused by fungi, lactophenol-blue staining of the microbiopsies showed positive results. Corneal smear was positive in only 1 of these 2 fungal cases. No intraoperative or postoperative complications occurred. No worsening of the disease as a result of treatment could be observed. · Conclusions: The confirmation of microbial cause of keratitis is more effective using microbiopsy than with corneal smears. As a result of the effective treatment after biopsy diagnosis, the majority of cases of keratitis healed. Local therapy seems to have been optimised due to the unroofing of infection during biopsy as well. Therefore microbiopsy in combination with laboratory diagnosis may prove to be a very useful diagnostic and possibly therapeutic method in the clinical routine.

Functionally adapted surfaces on a silicone keratoprosthesis.

Background Silicone intraocular lenses as well as silicone sponges and encircling bands on the bulbar surface are widely used and are well tolerated. The aim of this project is a new one-piece silicone keratoprosthesis with enhanced cell adhesion in the haptic region to optimize the keratoprosthesis stability. These investigations show how enhanced profileration of conjunctival fibroblasts and, therefore, improved tissue compatibility can be achieved by hydrophilizing and by protein immobilisation on a hydrophobic silicone surface. This allows a combination of desired chemical and mechanical properties of the silicone bulk material with surfaces of improved tissue compatibility. Methods Silicone foils with surface modifications of different kinds were tested. Experiments were done using cell cultures with murine fibroblasts L-929 and human conjuctival fibroblasts. Cytotoxicity assays were carried out with cells grown on the material in direct contact, as well as in indirect contact, with extracts (EN 30993-5). Viability stains by means of fluoresceindiacetate and ethidiumbromide together with morphology analyses by hemalaun-staining were performed. Results For the unmodified and modified foils themselves and their extracts any negative influence on cell cultures of murine and human cells could be excluded. There was a gradual improvement of cell morphology, spreading and proliferation dependent on the degree of surface modification. Covalently immobilised fibronectin showed the best results in contrast to adsorptive binding. Conclusions Silicone surfaces can be modified chemically with bioactive proteins. These modifications are cell compatible and do not result in toxic reactions. The degree and type of silicone hydrophilization results in improved development of cell morphology, spreading and proliferation. Even better results are obtained after covalent binding of bioactive proteins like fibronectin. Improved biocompatibility with enhanced cellular overgrowth has been demonstrated in vitro for the modified silicone of the haptic region. We believe that this type of modification will help in reducing extrusion problems observed with former keratoprostheses.

The Aachen-keratoprosthesis--a flexible KPro that permits intraocular pressure measurement.

Purpose Postoperative glaucoma is one of the major complications observed in patients with keratoprostheses (KPro). The optical components of the majority of KPros are rigid and inflexible, which prevents indirect tonometry by common methods. This study confirms that the Aachen-KPro allows measurements of intraocular pressure (IOP) due to its flexible optical part with a modified Schiotz tonometer. Methods The Aachen-KPro was placed in a special chamber where pressure can be generated and monitored by a transducer. Measurements were taken by common ophthalmologic methods. The results were compared to the initial pressure values in the chamber. Results With the Goldmann tonometer, the Tono-Pen and the topography system (Technomed), no significant pressure changes could be observed. The results of the Schiotz tonometer were promising. It was slightly modified and standard curves with different weights could be obtained. Conclusions With a modified Schiotz tonometer, it is possible to detect elevated IOPs. Modifying this common instrument is inexpensive and can be easily performed. This advantage of the Aachen-KPro permits early management of postoperative high tension glaucoma.

Aachen-Keratoprosthesis as temporary implant. Case report on first clinical application.

Background The Aachen-Keratoprosthesis was designed to serve as a permanent keratoprosthesis, modeling natural corneal physical properties as closely as possible. Prior to permanent application in patients, keratoprostheses are commonly tested in animal models to assess biochemical and biomechanical compatibility. However, immune and inflammatory responses acquired through animal experimentation are difficult to extrapolate in order to develop a predictable and generalized outcome in humans. Therefore, this preliminary report includes results following a temporary implantation of the Aachen-Keratoprosthesis in a patient during vitreoretinal surgery to assess the long-term prospect of application as a permanent artificial cornea. Patient and Methods A 43 year old man presented with a ruptured right eye resulting in an opaque cornea and retinal detachment. A soft silicone rubber keratoprosthesis, the Aachen-Keratoprosthesis, was temporarily implanted. Subretinal membranes were removed and the total retinal detachment was reattached. Liquid perfluorocarbon and silicone oil were used. The temporary keratoprosthesis was replaced by a 7 mm corneal graft after completion of surgery. Results The Aachen-Keratoprosthesis was securely positioned into the trephined hole. It allowed complete visualisation of vitreous, retina and thus controlled manipulations in the vitreous cavity up to the extreme periphery. Leakage across the trephination-prosthesis interface was minimal. Conclusion: We report the first temporary application of an innovative keratoprosthesis. Its flexibility and good optical qualities allow visualisation and control of intraoperative procedures. This temporary pilot study of the Aachen KPro encourages further investigation of the Aachen KPro as a permanent replacement for a diseased cornea.