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Purpose Chemical burns with calcium containing corrosives as well as irrigation with phosphate buffer solutions after eye burns bear the risk of corneal calcification. The aim of this study was to evaluate the correlation between the occurrence of corneal calcification after chemical injuries and the usage of phosphate buffer containing local therapeutics. Methods We reviewed the data of 179 patients who have been treated in the University Eye Clinic Aachen, Germany, between 1941 and 2000. Only when the corrosive did not contain calcium and when the initial irrigating solution did not contain phosphate buffer, respectively, were patients included in the study. The cases were analyse, if the patient was treated with phosphate buffer containing eye drops/ointment during the first 7 days of hospitalization or as an out-patient, and if corneal calcification was visible by slit-lamp examination during the follow-up. Statistical analysis was performed using Fischer's exact test. Results 152 eyes were included. From 63 eyes treated with phosphate buffer containing eye drops, 31 eyes (49%) developed corneal calcification. From 89 eyes treated without phosphate buffer containing eye drops, only 23 eyes (26%) developed corneal calcification. The two-sided p-value of Fischer's exact test is 0.0036. Conclusion During follow-up after chemical eye burns, eye drops containing phosphate buffer double the risk of corneal calcification. We recommend avoiding these agents in order to prevent the burned cornea from additional opacity. Substances containing phosphate buffer are listed in this article.

Hintergrund Wahrend der Organkultur schwellen die Hornhaute stark an und mussen daher vor der Transplantation mit Hilfe eines Mediums wieder entquollen werden. Sowohl die Quellung als auch die Entquellung fuhren zu einem vermehrten Endothelzellverlust. Daruber hinaus ist das derzeit verwendete Dextran toxisch und wird in die Hornhaute aufgenommen. Ob HES als Dauerzusatz in der Organkultur vertraglich ist und hiermit auch dauerhaft der Quellung der Hornhaute entgegen gewirkt werden kann, soll in dieser Studie untersucht werden.

Purpose: To evaluate the effects of hypo-osmolar tap water and isotonic saline solution on the intracameral pH, intraocular pressure and histological changes in alkali burned rabbit eyes. Methods: Four groups of four rabbit corneas each were burned with 2 N sodium hydroxide, and then rinsed with 0.5 l or 1.5 l of saline solution or tap water, respectively. Changes in pH were monitored with an intracameral microelectrode. Intraocular pressure (IOP) was monitored by a transducer placed in the vitreous cavity. After enucleation, histology was performed. Results: The pH increased after 1.5 min following alkali application. Irrigation with different solutions affected the maximum pH levels reached. Following the tap water rinse, the maximum rise was significantly lower than after the saline solution rinse. The maximum rise following rinsing with 1.5 l of tap water showed a significant delay. The increase in IOP was 23 ± 10 mmHg without differences between the groups; the original pressure was recovered after 18 ± 9 min. Histology of the eyes revealed a significant oedema in all corneas. Other ocular structures appeared unchanged. Conclusions: The hypo-osmolarity of tap water led to remarkable corneal oedema. Enlargement of the diffusion barrier and intracorneal dilution inhibit elevated intracameral pH levels. The difference in maximum pH levels reached may influence the degree of subsequent intraocular structure injury. Therefore, the use of iso-osmolar saline solution proves to be less efficacious than tap water as an irrigation agent for ocular burns.

The 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.A 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.Calciferous burning agents and corneal calcification are correlated (P0.01). 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 (P0.005).Eye 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 Ca(2+) and PO(4) (-) 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.

Die Augenspulung ist nach Augenveratzungen eine anerkannte Erste-Hilfe-Masnahme. Hierbei soll das atzende Agens entfernt, verdunnt und am besten auch neutralisiert werden. Im Vergleich zu den herkommlichen schon lange klinisch angewendeten Augenspulmedien (Wasser, NaCl 0,9%, Ringer-Lactat und Phosphatpuffer) soll hier die relativ neue Substanz Previn® in Bezug auf Vertraglichkeit und Wirksamkeit gestestet werden. Die erste Studie (I) befasst sich mit dem Unschadlichkeitsnachweis von Previn® an 10 gesunden Probanden nach Spulung mit 500 ml im Vergleich zur Augenspulung mit Phosphatpuffer, die mithilfe von konfokaler- und Spaltlampenmikroskopie ausgewertet wurde. In einem zweiten Ansatz (II) wurde a) die Pufferkapazitat unterschiedlicher Augenspullosungen in vitro und b) ihre unterschiedliche Wirkung auf Hornhautoberflachen- und Vorderkammer-pH bei Kaninchen nach 30 s Veratzung mit 1 N NaOH getestet. (I) Es konnten keine negativen Auswirkungen von Previn® auf das gesunde menschliche Auge gefunden werden. Es besteht in der Vertraglichkeit kein Unterschied zwischen Previn® und Phosphatpuffer. (IIa) Pufferkapazitatsmessungen in vitro ergaben eine etwas bessere Pufferkapazitat fur Previn® im Vergleich zu Phosphatpuffer oder Ringer-Lactat sowohl im sauren als auch im basischen Bereich. (IIb) Die In-vivo-Messungen ergaben einen vergleichbaren Puffereffekt von Previn® und Phosphatpuffer. Die o. g. Studien haben gezeigt, dass Previn® im Vergleich zu den herkommlichen Spulmedien vertraglich ist und in der Pufferkapazitat eine vergleichbare Wirkung hat wie Phosphatpuffer. Phosphatpuffer und Previn® sollten nur in der Erste-Hilfe Therapie und nicht zur prolongierten Augenspulung verwendet werden.

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 30 s 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 30 s 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 5 min 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. © 2002 Elsevier Science Ltd and ISBI. All rights reserved.

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.

Purpose: Corneal biopsies are important in diagnosing multiple corneal diseases. They were previously performed by way of keratectomy, a method that causes corneal opacity and topographic changes due to scarring. Microbiopsy is a new way to perform corneal biopsies. Before microbiopsy may be performed on human corneas, the safety of this procedure has to be proved concerning clinical development, histological changes and topographic changes after multiple biopsies. Methods: The healthy right cornea of 24 rabbits was punctured. 12 microtrephinations in 4 different symmetric patterns were performed. The clinical development of the bioptic sites as well as the topographic changes were observed over 5 months. After enucleation, serial sections of the corneas were analysed histologically. Results: Out of 294 performed biopsies, 291 samples could be collected. 4 perforations occurred. The initial epithelial defect closed within 3 days. A pale stromal scar remained. The histological analysis of these scars showed a facette underlined by a dense hypocellular fibrous layer and a typical star-shaped figure consisting of a loose hypercellular stromal tissue. Only dioptric power of corneas with circle-pattern showed a statistically significant decrease. Conclusion: Micropuncture is a safe and efficient bioptic procedure. Even 12 micropunctures do not lead to significant changes of dioptric power in most patterns. Further studies are necessary to evaluate the reproducibility of refractive changes by circle patterns and corrections of astigmatisms.

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.

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.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.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.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.

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.

To evaluate the effects of hypo-osmolar tap water and isotonic saline solution on the intracameral pH, intraocular pressure and histological changes in alkali burned rabbit eyes.Four groups of four rabbit corneas each were burned with 2 N sodium hydroxide, and then rinsed with 0.5 l or 1.5 l of saline solution or tap water, respectively. Changes in pH were monitored with an intracameral microelectrode. Intraocular pressure (IOP) was monitored by a transducer placed in the vitreous cavity. After enucleation, histology was performed.The pH increased after 1.5 min following alkali application. Irrigation with different solutions affected the maximum pH levels reached. Following the tap water rinse, the maximum rise was significantly lower than after the saline solution rinse. The maximum rise following rinsing with 1.5 l of tap water showed a significant delay. The increase in IOP was 23 +/- 10 mmHg without differences between the groups; the original pressure was recovered after 18 +/- 9 min. Histology of the eyes revealed a significant oedema in all corneas. Other ocular structures appeared unchanged.The hypo-osmolarity of tap water led to remarkable corneal oedema. Enlargement of the diffusion barrier and intracorneal dilution inhibit elevated intracameral pH levels. The difference in maximum pH levels reached may influence the degree of subsequent intraocular structure injury. Therefore, the use of iso-osmolar saline solution proves to be less efficacious than tap water as an irrigation agent for ocular burns.

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.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.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.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.

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.

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 device's 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.