Biomedical subjects

H Mietz

Publications and source records attributed to H Mietz.

54 records · Page 3Linked to original sources

PubMed1995

Onset and recurrence of proliferative vitreoretinopathy in various vitreoretinal disease.

AIMS: This study aimed to evaluate both the mean time intervals between retinal disease and the development of proliferative vitreoretinopathy (PVR) and the time intervals at which recurrent PVR develops following various kinds of vitreoretinal disease and surgery. METHODS: One hundred and thirty six consecutive cases of PVR that were seen and operated on between 1991 and 1994 were evaluated retrospectively. Intervals between onset of disease and PVR or recurrent PVR were noted. Conditions leading to PVR, surgical procedures, and the final anatomical and functional results were evaluated. RESULTS: Before PVR was noted for the first time, an average of 1.06 vitreoretinal surgical procedures were performed (range 0 to 3). A mean of 1.99 surgeries were performed to control PVR or to reach an end stage where further surgery would have been unreasonable (range 0 to 5). The average (median) time interval between the onset of the retinal disease and PVR was 2.0 months (range 0.5 to 45 months). The median time intervals between surgery and recurrence for the second, third, or fourth times was also 2.0 months (range 0.5 to 34 months). CONCLUSIONS: PVR starts earliest at 2 weeks after an event and subsequently quietens down within a maximum of 45 months after treatment (median 2 months). PVR may recur more than once but the time course of the disease is likely to be the same for each recurrence.

Adolescent↗

PubMed1994

The effect of preservatives and antiglaucomatous medication on the histopathology of the conjunctiva.

BACKGROUND: Topical medication applied chronically for the treatment of glaucoma changes the cellular profile of the conjunctiva. We wanted to determine the role of preservatives, which are usually combined with the drugs, on this effect. METHODS: We applied metipranolol 0.3% and pilocarpine 2% with and without benzalkonium chloride 0.01% and cetrimonium chloride 0.004%, respectively. Twenty-four rabbits, divided into four groups, were treated for 3 months. The complete globes and the adherent bulbar conjunctiva were examined histopathologically and immunohistochemically. RESULTS: With special stains for collagen, a slight increase of the thickness of subepithelial collagen of the conjunctiva was present in both groups treated with medication and preservative compared with eyes treated with medication alone. This effect was also true for special antibodies for collagen type IV and alpha-smooth muscle actin in the eyes treated with pilocarpine, but not in the eyes treated with metipranolol. CONCLUSION: The results suggest that preservatives may have an additional adverse effect on the conjunctiva in addition to the effects of the medications alone.

Actins↗

PubMed1994

Visual outcome of secondary lens implantation after trauma or complicated retinal detachment surgery.

PURPOSE: Visual outcome of intraocular lens (IOL) implantation as a separate surgical procedure after severe trauma of the anterior or posterior segment or after vitreoretinal surgery for complicated retinal detachment resulting in aphakia was evaluated. METHODS: The charts of all patients undergoing secondary IOL implantation for the above reasons between 1988 and 1992 were retrospectively reviewed. A special transcleral suturing technique was developed for the posterior chamber lenses, where needles are primarily passed from the outside through the sclera to enhance correct positioning of the sutures. RESULTS: In all but one of the cases in group 1, visual acuity after surgery was equal to or better than before surgery. In the second group, visual acuity after surgery was equal to or better than before surgery in 9 of 12 cases. CONCLUSIONS: Secondary IOL implantation after severe trauma or vitreoretinal surgery for complicated retinal detachment is a fairly safe technique, with only few transient complications. Visual acuity did not deteriorate after surgery by more than two lines in any the cases discussed. Peripheral binocularity was restored in all cases. The suturing technique described here, in which the needles are primarily passed from the outside through the sclera, offers the advantage of exact positioning of the haptics in the ciliary sulcus.

Adolescent↗

PubMed1994

Histopathologic study of epiretinal proliferations after vitrectomy with daunomycin and silicone oil.

PURPOSE: The cellular composition of primary and recurrent periretinal proliferations has been widely described. The use of daunomycin, an antiproliferative antibiotic, has been recommended to reduce these proliferations. Two recurrent membranes after intraoperative application of daunomycin were examined. METHODS: Two epiretinal membranes, which were removed 5 months and 20 months after vitrectomy with daunomycin, were examined by light and electron microscopy to determine the structure and cellular composition of these membranes. RESULTS: The matrix of the membranes consisted of new collagen with fiber diameters between 20 and 22 nm. Fibrocytes and macrophages were present in both specimens. Retinal pigment epithelial cells and fibrous astrocytes were present in only one specimen. CONCLUSION: Retinal pigment epithelial cells, which are consistently present in primary periretinal membranes, were found in only one of the two specimens examined. Myofibroblasts, also normally present, were not found. The other cells found are typically seen in primary periretinal proliferations.

Adult↗

PubMed1994

A scleral shield for the application of mitomycin C during trabeculectomy: a rabbit model.

The use of mitomycin C during trabeculectomy is associated with a significant degree of persistent hypotony. To address this problem, we designed a scleral shield with a dry sponge glued on it for use in applying mitomycin C that reduces the penetration of the substance through the sclera. The effectiveness of the shield was tested in a rabbit model using regular sponges and sponges with the attached shield. Histopathologic examination of the eyes after 1 month revealed toxic changes in the eyes in which only a regular sponge had been used, but not in those in which the sponges with the attached scleral shield had been used. The scleral shield may help reduce the incidence of hypotony in eyes undergoing trabeculectomy with adjunctive mitomycin C.

Animals↗

PubMed1994

Extraocular application of mitomycin C in a rabbit model: cytotoxic effects on the ciliary body and epithelium.

Since prolonged postoperative hypotony has been a frequent complication of glaucomatous filtration surgery in which mitomycin C (MMC) was used, it is important to determine the intraocular toxic effects of the drug. We placed MMC, in concentrations of 0.05, 0.2, and 1.0 mg/mL on the intact sclera of rabbits and obtained the eyes after 1, 7, and 28 days. Examination of the ciliary epithelium by transmission electron microscopy revealed an electron-dense material near the endoplasmic reticulum. Large intracellular vacuoles were present, and the mitochondria appeared swollen. These findings suggest a toxic effect of MMC on the ciliary epithelium in rabbits after extraocular application, possibly decreasing aqueous production.

Animals↗

PubMed1994

Mitomycin C for trabeculectomy in complicated glaucoma: preliminary results after 6 months.

Mitomycin C (MMC) was used as a perioperative adjunct during trabeculectomy for 51 consecutive cases of complicated glaucoma. The concentration applied was 0.5 mg/ml, and the sponge positioned upon the intact sclera was left in place for 3-5 min. At a follow-up of 6 months, information on 49 eyes was obtained. Following treatment with antiglaucomatous medication, the average intraocular pressure decreased from 31.5 to 13.1 mmHg. The number of different medications required was 0.25 after 6 months as compared with 2.6 before surgery. In 16 of the 49 eyes (33%), the intraocular pressure was below 10 mmHg at follow-up. Complications included severe prolonged hypotony (n = 9), conjunctival dehiscence (n = 4), and scarring (n = 1). Vision was reduced in 5 cases by more than 2 Snellen lines. We consider MMC to be a substance that can be used in trabeculectomies where early scarring of the conjunctiva is anticipated.

Adolescent↗

PubMed1994

Anterior proliferative vitreoretinopathy in trauma and complicated retinal detachment. A histopathologic study.

Anterior vitreoretinal proliferations are frequent sequelae of retinal detachment repair and severe trauma. Cellular proliferations can form membranes extending anteriorly from the peripheral retina. These membranes have the capability to contract and may lead to detachment of both the peripheral retina and, in more advanced stages, the ciliary body. Because the vitreous base and vitreous remnants are leading structures for cellular proliferation, complete removal of the anterior vitreous base in particular is important in cases of severe trauma or complicated retinal detachment. In 11 cases of anterior proliferative vitreoretinopathy examined histopathologically, we found overlying membranes and cellular infiltration of the vitreous in close correlation with the amounts of vitreous remnants present. Visualization of the peripheral retina and pars plana can rarely be accomplished in the presence of the crystalline lens or pseudophakia. Therefore, the removal of the anterior vitreous is often incomplete. To achieve complete dissection of the anterior vitreous, we remove even a clear lens during the first surgical intervention in selected cases.

Adult↗

PubMed1993

Detection of HIV in human vitreous.

Assay of human vitreous specimens obtained postmortem for HIV antibodies, or HIV p24 antigen, is reported to be a reliable technique to demonstrate HIV infection in possible cornea donors from whom serum could not be obtained. We tested three vitreous samples obtained during vitrectomy from two HIV-positive patients. One patient exhibited the clinical AIDS syndrome. HIV antigen and antibody tests were negative in all specimens. HIV proviral DNA was detected by PCR only in the vitreous of the patient with AIDS. Therefore, testing only vitreous samples is insufficient to exclude HIV infection in potential cornea donors.

Adult↗

PubMed1993

Agenesis of Bowman's layer. A histopathological study of four cases.

Congenital absence of Bowman's layer has been described in Peters' anomaly, sclerocornea, and osteogenesis imperfecta type II. More commonly, Bowman's layer is absent secondary to inflammatory or degenerative processes of the cornea. We present three cases of bilateral absence of Bowman's layer in otherwise unremarkable corneas that were unassociated with other ocular or systemic abnormalities. In a fourth case, similar absence of Bowman's layer was present in a patient with osteogenesis imperfecta type III. In all four cases, the absence of Bowman's layer was unassociated with any evidence of scarring or inflammation. By electron microscopy, the stroma was composed of regularly arranged collagen fibers with a uniform fiber diameter throughout. In the case of osteogenesis imperfecta type III, there was mild irregularity of the anteriormost stroma. The lack of inflammation or scarring in these four cases lead us to conclude that they represent a true congenital absence, or agenesis, of Bowman's layer.

Adolescent↗

PubMed1992

Foveal hypoplasia in complete oculocutaneous albinism. A histopathologic study.

Histopathologic and ultrastructural findings in an eye from a patient with complete oculocutaneous albinism are reported. Examination revealed posterior embryotoxon, high myopia, no foveal differentiation, and absence of melanin pigment in all ocular structures. A few nonmembrane-bound electron-dense granules of lipofuscin were present in the iris and retinal pigment epithelial cells.

Aged↗

PubMed1991

[A modification for reducing measurement value spread with the Hertel exophthalmometer].

The concave part of Hertel's exophthalmometer which contacts the orbita functions like an inclined plane. Therefore, the measurement is sensitive against tilting and changing of the basic distance. We modified this contact surface into a right angle. The tangents at the contact points form a common line at right angles to the measurement direction. Reproducibility of measurements was studied on 10 patients who were measured by 5 to 12 different examiners with both instruments. Accuracy improved significantly by 57%.

Equipment Design↗

PubMedDate not supplied

Fibrosis adjacent to the anterior lens capsule after extracapsular cataract extraction.

Fibrosis, contraction and opacification of the posterior lens capsule after extracapsular cataract extraction, is a frequent complication following cataract surgery. In these cases, cellular proliferation occurs along an intact posterior capsule. We report a case of fibrosis adjacent to the anterior lens capsule, where cellular proliferations and collagen production completely sealed the anterior capsulotomy three months after a routine extracapsular cataract extraction with implantation of a posterior chamber lens. The fibrosis led to contraction of the remainder of the anterior capsule, significantly reducing vision. Examination of the excised material by light and electron microscopy, and immunohistochemistry, revealed cells with features compatible with fibrocytes that did not stain positive for cytokeratin. The cells were situated in a dense collagen matrix. An anterior capsulotomy that is too small prevents sufficient removal of lens epithelium, and may be a risk factor for this complication.

Aged↗

PubMedDate not supplied

Immunohistochemistry of anterior proliferative vitreoretinopathy. Report of 11 cases.

Anterior proliferative vitreoretinopathy is characterized by epiretinal proliferation that extends anteriorly over the vitreous base, and may, in addition to the cells usually contributing to proliferative vitreoretinopathy, also contain cells of ocular structures located in that area. We examined 11 complete globes with aPVR that were enucleated after previous severe trauma or perforating injuries (n = 8) and complicated retinal detachment (n = 3) by a panel of immunohistochemical markers. We found presence of RPE, glial cells, macrophages and fibrocytes, as consistently reported in PVR membranes. In addition, T-cell lymphocytes were present in 6 of the cases, and cells expressing the common leucocyte antigen on 8 cases. Cells staining positive for the intracytoplasmic contractile filament alpha-smooth muscle actin were present in 5 cases and cells staining for desmin in one case. Collagen type IV was part of most of the membranes, and vessels with leakage of plasma factors were present in more than half of the cases.

Adult↗

PubMedDate not supplied

Immunohistochemistry of cellular proliferation in eyes with longstanding retinal detachment.

To further characterize the content and nature of cyclitic membranes (n = 4), ringschwielen (n = 3) and a subretinal strand on sections of complete globes with long-standing retinal detachment after trauma (n = 7) or retinal reattachment surgery (n = 1), we applied a panel of cellular and extracellular antibodies using the APAAP (alkaline phosphatase and monoclonal anti-alkaline phosphatase) technique. Only one cyclitic membrane from an eye that was enucleated two months after trauma was positive for glial fibrillary acidic protein, demonstrating the presence of glial cells. All cyclitic membranes contained macrophages and expressed intracellular contractile proteins. Ringschwielen stained consistently for cells of epithelial origin (RPE) with cytokeratin and for macrophages. The subretinal strand stained for cytokeratin, macrophages and alpha-smooth muscle actin, supporting cellular contraction in the genesis of this form of proliferative vitreoretinopathy.

Adult↗

PubMedDate not supplied

Conjunctival fibrosis after application of mitomycin C: an animal experimental study.

Mitomycin C (MMC) is widely used as an antimetabolite to minimize scarring of filtering blebs. Its effectiveness has been demonstrated in several clinical studies. The drug's mechanism of action is attributed to its antiproliferative effect on the subconjunctival cells, reducing the wound healing response. We placed sponges soaked with various concentrations of MMC, from 0.05 to 1.0 mg/ml, under the conjunctiva of 18 rabbits. Four weeks later, there was marked concentration-dependent scarring of the substantia proppria of the conjunctiva. Macrophages were more numerous in treated eyes, as determined by immunohistochemistry. The reason for MMC-related fibrosis in this animal model is not clear but may be related to the substances toxic effects. Whether it is only present in rabbits remains to be clarified.

Animals↗

PubMedDate not supplied

Suramin to enhance glaucoma filtering procedures: a clinical comparison with mitomycin.

BACKGROUND AND OBJECTIVE: Trabeculectomies performed with mitomycin are more likely to be successful, but have an increased rate of complications. We performed a novel approach to enhance the outcome of trabeculectomies using suramin, a substance that inhibits the action of growth factors. MATERIALS AND METHODS: Trabeculectomies were performed in 10 eyes of 10 patients with advanced stages of complicated glaucoma and/or poor visual prognosis in a prospective, consecutive study. For comparison, an equal number of matched controls were selected from surgical cases using mitomycin and another 20 cases without mitomycin. Pre- and post-operative data were evaluated as well as complications and the need for further surgeries. RESULTS: The follow up was 18 months for the eyes in all groups. Average IOP values decreased from 32.7 mm Hg and 29.5 mm Hg to 19.7 mm Hg and 19.3 mm Hg in the suramin and mitomycin groups. The average number of medications decreased from 2.6 and 2.5 (P <0.86, t-test) to 1.3 and 0.4 (P <0.027) in the suramin- and mitomycin-treated eyes at the last visit. Hypotony following trabeculectomy occurred in 2/10 cases in suramin-treated eyes and 5/10 cases in mitomycin-treated eyes (P <0.18). Hypotony lasting for more than three months occurred in 0/10 suramin-treated eyes and 5/10 mitomycin-treated eyes. Conjunctival dehiscence (2/10), choroidal detachment (4/10), hypotony maculopathy (1/10), and endophthalmitis (1/10) were only noted in mitomycin-treated eyes. Without mitomycin 60% of surgeries performed failed. CONCLUSIONS: In this first study using suramin to inhibit fibrosis following trabeculectomy for complicated cases of glaucoma, it appears that the use of suramin is associated with fewer cases of severe hypotony, choroidal detachment, and severe visual loss as compared to mitomycin, while the success rates seem to be similar.

Adult↗

PubMedDate not supplied

Morphology of the trabecular meshwork three years after Erbium:YAG laser trabecular ablation.

Laser trabecular ablation (LTA) is an abinterno approach with the purpose to improve outflow facility by removing trabecular tissue and open Schlemm's canal. In a blind eye with secondary glaucoma following silicone oil surgery, Erbium:YAG LTA had been performed applying 12 neighboring single laser pulses (5-7 mJ pulse energy, 200 micros pulse duration) to the trabecular meshwork. Enucleation was performed three years after the procedure that did not achieve pressure control. Light-microscopy revealed neither marked scarring nor endothelial proliferation in the treated trabecular meshwork. However, most of the recognizable ablation craters failed to open Schlemm's canal. Although limited scar formation within the trabecular meshwork after LTA is a promising aspect, the present technique of Er:YAG LTA still needs technical and surgical improvements to guarantee reliable and reproducible openings of Schlemm's canal.

Eye Enucleation↗