H. E. Völcker

Cryopreserved human amniotic membrane for ocular surface reconstruction

Abstract · Background: Amniotic membrane transplantation is used for the reconstruction of the ocular surface in the context of, for example, corneal ulcers or conjunctival scarring. The mechanisms by which preserved amniotic membrane grafts promote reepithelialization are unknown. As a first step the viability and proliferative capacity of amnion cells following cryopreservation of membranes in glycerol is investigated. · Methods: Fresh and cryopreserved (in 50% glycerol) amniotic membranes were investigated histologically and by vital stains. Following enzymatic digestion, amniotic cells were stained for viability and cultured in DMEM+10% FBS. In addition, explant cultures were established from fresh and cryopreserved membranes. · Results: Histologicacl examination showed no significant morphological alteration following cryopreservation. While fresh membranes contained predominantly vital cells, no such cells were detected following cryopreservation. Also, cells removed enzymatically from cryopreserved membranes were not viable and did not grow in culture. While both epithelial and fibroblastic cells grew from fresh membranes, no growth was seen from cryopreserved membranes. · Conclusion: The results suggest that the technique for preservation which is most widely used for ophthalmological amniotic membrane transplantation significantly impairs viability and proliferative capacity. This supports the clinical finding that neither immunological reactions nor signs of ingrowth of amniotic cells are observed in patients. Furthermore amniotic membrane grafts seem to function primarily as matrix and not by virtue of transplanted functional cells.

Effect of healon5 and 4 other viscoelastic substances on intraocular pressure and endothelium after cataract surgery

Purpose: To compare the ophthalmic viscoelastic device (OVD) Healon®5 (sodium hyaluronate 2.3%) with 4 other commonly used OVDs during phacoemulsification and intraocular lens implantation in terms of influence on intraocular pressure (IOP) postoperatively and endothelial cells preoperatively and postoperatively. Setting: Department of Ophthalmology, Ruprecht‐Karls‐University Heidelberg, Germany. Methods: This clinical randomized prospective study, in which patients and observer were masked, comprised 81 eyes. Seventy‐four eyes (mean patient age 71.2 years ± 7.8 [SD]) completed all preoperative and 5 postoperative examinations. The OVDs used were OcuCoat® and Celoftal® (hydroxypropyl methylcellulose 2.0%), Viscoat® (sodium hyaluronate 3.0%–chondroitin sulfate 4.0%), Healon GV® (sodium hyaluronate 1.4%), and Healon5 (sodium hyaluronate 2.3%). Intraocular pressure was measured by standard Goldmann applanation tonometry preoperatively and 4 to 6 and 24 hours and 7, 30, and 90 days postoperatively. Endothelial cell counts were done preoperatively and 90 days postoperatively using a Pro/Koester WFSCM contact endothelial microscope. Exclusion criteria were IOP greater than 21 mm Hg at the preoperative examination, age younger than 40 years, significant corneal pathology, and a history or presence of uveitis or pseudoexfoliation syndrome. Results: All groups had increased IOP 4 hours postoperatively. The Healon5 group had the highest mean pressure (24.9 mm Hg) followed by the Viscoat group (23.6 mm Hg). The mean IOP in the other OVD groups was less than 22.1 mm Hg. These differences were not significant. Twenty‐four hours postoperatively and at all subsequent examinations, mean IOP was below 20 mm Hg. The Healon5 group had the lowest mean endothelial cell loss (6.2%), significantly lower than in the other groups (P < .02). Conclusion: With all 5 OVDs, endothelial cell loss was found, with the lowest in the Healon5 group, and IOP was increased 4 to 6 hours postoperatively. After 24 hours, no significant increases in IOP were noted.

Topical application of methotrexate for inhibition of corneal angiogenesis

Abstract · Purpose: Methotrexate (MTX) is a folic acid antagonist used in chemotherapy regimens. Additional therapeutic applications have been suggested based on effect as an immuno-modulating drug in systemic rheumatoid disease and associated uveitis. Since chronic inflammatory disease is often associated with a neovascular response, we investigated the use of MTX for treatment of corneal angiogenesis.· Methods: Neovascularizations were induced by fibroblast growth factor in a corneal pocket model. Vessels were examined biomicroscopically. MTX was applied topically to rabbit corneas in a concentration of 0.2 mg/day. MTX level was measured in aqueous humor and plasma. · Results: On day 9 the vascularized area was 12.0±6.9 mm2 in control eyes and significantly smaller, 2.2±1.86 mm2, in treated eyes. Treated animals showed no local side effects such as epithelial defects. Although therapeutic levels were measured in the aqueous humor, MTX could not be detected in the serum of treated animals.· Conclusion: The antiangiogenic mechanism of MTX might be due to inhibition of both macrophage invasion during early angiogenesis and endothelial cell proliferation. The high levels in the aqueous humor indicate a possible application of topical MTX for inflammations of the anterior segment of the eye.

Development of the standard reference plane for the Heidelberg retina tomograph.

Abstract Background: Topometry of the optic disc is the quantitative assessment of the structure of the optic nerve head by means of three- dimensional parameters. The parameter values depend on definitions of intraocular reference planes. Purpose: To describe the development of intraocular reference planes in laser scanning tomography for the Heidelberg Retina Tomograph (HRT) using image intrinsic data with a fixed offset reference plane (320 µm) and to present a contour-line-based ”flexible” standard reference plane (”SRP”) for calculation of intrapapillary stereometric parameters taking the interindividual variability of optic disc topography into account.Methods: Ten-degree triple images were obtained by laser scanning tomography from 99 glaucoma eyes and 180 normal eyes. The images were evaluated to assess the variability of height measurements of an optic disc border contour-line segment (6° width) corresponding to the site of the papillo-macular bundle as indicated by the average optic disc surface inclination angle. Results: The average optic disc surface inclination angle was –7°±3° below the horizontal meridian (0°). The 6° wide contour-line segment for the SRP was chosen according to the average surface inclination angle (–10° to –4°). The reproducibility of the SRP-segment height measurements was 16.0±10.8 µm for normal eyes and 23.4±18.0 µm for glaucoma eyes. To ensure that the automatic reference level determination for intrapapillary parameters remained below the disc border height, we defined the SRP level at a 50 µm offset (>2 SD of average segment height reproducibility in glaucoma) added to the individual height position of the 6° contour line segment. Conclusion: The flexible standard reference plane allows for automatic determination of intrapapillary variables once a disc border contour line is interactively defined. In contrast to a fixed offset reference plane (e.g. 320 µm below the mean retina height), the interindividual variability of optic disc topography (oblique insertion, glaucomatous surface flattening) is respected at the cost of the need for an accurate optic disc border outline.

Inhibition of posterior capsule opacification by an intraocular-lens-bound sustained drug delivery system: An experimental animal study and literature review

Purpose: To find a way to prevent or significantly reduce posterior capsule opacification (PCO) with modern phacoemulsification and in‐the‐bag intraocular lens (IOL) implantation. Setting: Department of Ophthalmology and Institute for Pharmaceutical Technology and Biopharmacy, Ruprecht‐Karls‐University of Heidelberg, Germany. Methods: We evaluated the effects of an IOL‐bound sustained drug delivery system (SDDS) consisting of the carrier substance poly‐DL‐lactid and the drug daunorubicin or indomethacin. The system was applied to the IOL surface and implanted in rabbit eyes. At 8 weeks postoperatively, PCO wet mass was determined. Toxic and inflammatory effects were documented by histopathology. Results: The average PCO wet mass was 54.6 mg in the control group, 28.6 mg with daunorubicin, and 64.1 mg with indomethacin. Statistical analysis showed a significant reduction of PCO with daunorubicin (Mann‐Whitney U‐test, P = .025) and no PCO‐reducing effect with indomethacin. Light microscopy of the specimens revealed mild inflammation, especially at the limbus, and some endothelial cell loss in the daunorubicin group and iris and ciliary body inflammation in the indomethacin group. Conclusion: In the rabbit eye, slow release of daunorubicin reduced PCO formation by approximately 50%. It must be determined whether the endothelial side effects are specific to the rabbit species or whether the human cornea is as sensitive. The principle of the IOL‐bound SDDS and the evaluation procedure can be standardized and used for systematic tests in the future.

Static fundus perimetry using the scanning laser ophthalmoscope with an automated threshold strategy

Abstract• Purpose: The purpose of this study was to develop software that allows the performance of routine static threshold perimetry using the scanning laser ophthalmoscope (SLO) and the comparison of the results with conventional computerized cupola perimetry. The original software does not allow performance of static threshold perimetry within a reasonable examination time. • Methods: Static perimetry was performed in random order on 50 healthy eyes using our SLO staircase threshold perimetry technique and the Octopus 500 (program 38). We compared the relative sensitivities for each of 25 corresponding visual field locations. • Results: Mean sensitivity in the SLO perimetry amounted to 32.7 dB (range 25–37 dB) while it was 28.7 dB in the Octopus. For all test locations the SLO showed higher dB values on average. The mean difference between both methods was 3.7±0.8 dB (range 1.4–5.8 dB) when the test locations at the blind spot were excluded (linear regression between the two methods: r=0.843, P<0.0001). The mean time interval between two stimulus presentations was 2.5 s with the SLO perimetry. • Conclusion: With the Heidelberg software, automated static threshold perimetry using the SLO is possible within reasonably short examination times. The mean time interval between two test point presentations is about one tenth of that necessary using the original Rodenstock software. There is a systematic difference between SLO and Octopus fields of about 4 dB which was not very much influenced by the stimulus locations.

Measurement method for the determination of rotation and decentration of intraocular lenses

PURPOSE In the past 50 years the IOL has been improved. Nowadays it is possible to exactly calculate the necessary IOL power and correct toric refractive errors. In this study we developed methods for measuring rotation and decentration using the example of a hydrophilic acrylic IOL. METHODS Following cataract surgery, the first retroilluminated photograph was taken. The position of the IOL was determined with the image analysis program Adobe Photoshop. RESULTS Measurement of a rotational movement or of a decentration of an IOL can be done accurately and rapidly. Evaluation of the stability of rotation of the hydrophilic acrylic IOL measured here showed an average rotation of the IOL of 5.3+/-1.4 degrees after 6 months compared to the position directly after implantation. CONCLUSION The measurement methods presented here are easy to use and provide reliable results. Examiners must have basic knowledge of the computer programs used. Also, these methods depend on good quality of the retroilluminated photographs.

Messmethode zur Bestimmung der Rotation und der Dezentrierung von Intraokularlinsen

PURPOSE In the past 50 years the IOL has been improved. Nowadays it is possible to exactly calculate the necessary IOL power and correct toric refractive errors. In this study we developed methods for measuring rotation and decentration using the example of a hydrophilic acrylic IOL. METHODS Following cataract surgery, the first retroilluminated photograph was taken. The position of the IOL was determined with the image analysis program Adobe Photoshop. RESULTS Measurement of a rotational movement or of a decentration of an IOL can be done accurately and rapidly. Evaluation of the stability of rotation of the hydrophilic acrylic IOL measured here showed an average rotation of the IOL of 5.3+/-1.4 degrees after 6 months compared to the position directly after implantation. CONCLUSION The measurement methods presented here are easy to use and provide reliable results. Examiners must have basic knowledge of the computer programs used. Also, these methods depend on good quality of the retroilluminated photographs.

Severe Arthrographis kalrae keratomycosis in an immunocompetent patient.

Purpose: To describe a severe case of keratomycosis caused by Arthrographis kalrae requiring repeated keratoplasty. Methods: A 42-year-old otherwise healthy soft contact lens wearer developed a unilateral central corneal ulcer. Treatment with topical and systemic voriconazole is described. Results: Repeated microbiological testing of ocular swabs (culture) initially yielded Candida albicans. Under treatment with topical clotrimazole, the ulcer progressed, and a corneal perforation required a keratoplasty à chaud. For prophylaxis, the patient received fluconazole systemically and continuous topical clotrimazole. However, in 2 weeks time, the mycotic infiltrates penetrated the corneal transplant and led to a second keratoplasty only 1 month after the first one. In the meantime, the microbiological analysis of the first keratoplasty revealed A. kalrae, which was sensitive to voriconazole. High-dose serum level-controlled systemic voriconazole and topical voriconazole were able to stabilize, but not eliminate the infection. About 1 year after the start of the voriconazole therapy, treatment had to be discontinued because of side effects. Mycotic infiltrates increased, and even an intracameral voriconazole injection could not prevent a third and a fourth keratoplasty. Conclusions: Ocular infection with A. kalrae is very rare. The microbiological differentiation of A. kalrae can be difficult. Because a broad spectrum of fungi is sensitive to voriconazole, the early topical and possibly systemic treatment is a reasonable therapeutic option when a mycotic infection of the eye is suspected, even before the causative fungus is identified.

[Radial optic neurotomy for central retinal vein occlusion -- how deep should it be?].

PURPOSE Most of the studies on radial optic neurotomy (RON) have not defined the depth of the incision. Complications following a deeper incision have been described. This histological study was performed to evaluate the required depth for RON. METHODS Serial sections of the area of the optic nerve head were performed in 19 eye bank eyes. The distance between the inner surface of the optic disc and the outer limit of the cribriform plate was measured. Ten additional eye bank eyes underwent 2 mm deep experimental RON using the Spaide CRVO Knife (DORC, Netherlands). The cutting depth was assessed histologically by serial cuts. RESULTS The distance between the inner surface of the disc and the outer limit of the cribriform plate measured 1.35+/-0.3 mm (shrinkage-revised value: 1.45 mm). The experimental RON showed cutting depths of 1.53+/-0.3 mm (shrinkage-revised value: 1.65 mm). CONCLUSION Based on normal eyes, a cutting depth of 1.45 mm is sufficient to cut through the cribriform plate. This might change during central retinal vein occlusion because possible papillary edema due to central retinal vein occlusion has to be considered. Even under controlled experimental conditions RON leads to great variation in incision depths. The development of a knife with a fixed penetration depth would be helpful.