Biomedical subjects

M Halberstadt

Publications and source records attributed to M Halberstadt.

9 recordsLinked to original sources

PubMed2006

PVR recurrence and the timing of silicon oil removal.

BACKGROUND: Following vitrectomy for PVR-associated retinal detachment, placement of an encircling band, filling with silicone oil (SO) and successful retinal reattachment, a recurrence of PVR can develop. Retinal redetachment after SO removal is usually due to secondary or residual PVR. We wanted to ascertain whether the anatomical and functional outcomes of surgery in patients with a reattached retina and recurrent PVR can be improved by delaying the removal of SO. PATIENTS AND METHODS: 112 consecutive patients with PVR-associated retinal detachment who had undergone vitrectomy with SO filling, were monitored for at least 6 months after SO removal. Prior to SO removal, the retina posterior to the encircling band had to be completely reattached. Patients who developed PVR after SO filling were divided into two groups according to the duration of SO retention: 12 - 18 months (group 2: n = 48); > 18 months (group 3: n = 21). Individuals without PVR recurrence after SO filling and in whom the SO was consequently removed within 4 - 12 months served as control (group 1: n = 43). Anatomical success, intraocular pressure (IOP) and best-corrected visual acuity (BCVA) served as the primary clinical outcome parameters. RESULTS: Six months after SO removal, the anatomical success rates (86.3 %, 88.8 % and 84.6 %, in groups 1, 2 and 3, respectively; log rank = 0.794) and the BCVAs (p = 0.861) were comparable in the three groups. Mean IOP (p = 0.766), and the frequency of complications such as PVR recurrence (p = 0.936), bullous keratopathy (p = 0.981) and macular pucker (p = 0.943) were likewise similar. Patients in whom SO was retained for more than 18 months had the highest IOPs and required the heaviest dosage with anti-glaucoma drugs. CONCLUSIONS: In patients who develop a recurrence of PVR after vitrectomy and SO filling the surgeon can observe and treat retinal changes for up to 18 months without impairing the anatomical and functional outcomes. The retention of SO for more than 18 months does not improve the anatomical outcome. However, it can impair the functional outcome by precipitating the development of a persisting secondary glaucoma.

Comorbidity↗

PubMed2005

Toxic effects of indocyanine green, infracyanine green, and trypan blue on the human retinal pigmented epithelium.

BACKGROUND: Indocyanine green, infracyanine green, and trypan blue are frequently used as aids to visualize structures removed during vitreoretinal surgery. But they may have toxic effects on the retina. We therefore compared the acute and chronic toxicities of these stains on cultured human retinal pigmented epithelial (RPE) cells using clinically relevant concentrations and an identical experimental setup for each agent. METHODS: Monolayers of RPE cells were incubated with various concentrations of indocyanine green, infracyanine green (each at 0.005%, 0.05%, and 0.5%) or trypan blue (0.05%, 0.06%, 0.1%, 0.15%, and 0.5%) for 5 min (acute exposure) or 6 days (chronic exposure). Using the propidium iodide assay, acute cytotoxicity was monitored at 15-min intervals for up to 3 h. Chronic cytotoxicity was assessed by monitoring cell calcein esterase activity, cell proliferation, and cell morphology (viability) after 6 days of exposure. RESULTS: Indocyanine and infracyanine green induced acute and chronic toxicities at a concentration above 0.05%. Trypan blue evoked no acute toxicity, but it was chronically cytotoxic at all tested concentrations. CONCLUSIONS: Despite thorough rinsing after application, significant amounts of the not sufficiently water soluble indocyanine and infracyanine green are retained after surgery by the eye. Trypan blue, being more water-soluble than ICG, is probably retained to the least degree. This circumstance is fortunate given that trypan blue exhibits a chronic cytotoxicity comparable to ICG at all clinically relevant concentrations. During vitrectomy, surgeons should aim to expose retinal tissue to only low concentrations of these stains and for as short a period as possible.

Cell Proliferation↗

PubMed2005

Primary retinal reattachment surgery: anatomical and functional outcome in phakic and pseudophakic eyes.

AIM: To compare the anatomical and functional success of primary scleral buckling, performed either alone or in combination with vitrectomy, for primary retinal detachment (RD) in phakic eyes and in eyes had undergone uneventful phacoemulsification and had received posterior chamber lens implantations. METHODS: A total of 243 consecutive patients were included in this retrospective, nonrandomized comparative study. In all, 165 phakic and 78 pseudophakic individuals with primary RD underwent scleral buckling alone or in combination with vitrectomy and were followed up for 6 months. Pre-, intra- and postoperative findings including anatomical success, best-corrected visual acuity (BCVA), complications, and the development of proliferative vitreoretinopathy (PVR), macular pucker, or secondary cataracts were recorded. Cases requiring more than one surgical intervention were defined having failed, although further surgical intervention might have led to success. RESULTS: At 6 months after scleral buckling alone, the anatomical success was similar in phakic (88.98%) and pseudophakic (87.65%) eyes (log rank=0.310). The corresponding results after scleral buckling with vitrectomy were 82.13 and 77.63% for phakic and pseudophakic eyes, respectively (log rank=0.799). At 6 months after scleral buckling alone, BCVA was similar in phakic and pseudophakic eyes (0.62+/-0.30 vs 0.70+/-0.29; P=0.227). Likewise, after scleral buckling with vitrectomy, BCVA did not differ significantly (P=0.322) between phakic (0.34+/-0.32) and pseudophakic eyes (0.50+/-0.27). CONCLUSION: The anatomical and functional outcome of primary retinal reattachment surgery, involving scleral buckling alone or in combination with vitrectomy, is similar in phakic and pseudophakic eyes.

Adult↗

PubMed2002

[Implantation of toric intraocular lenses for correction of high post-keratoplasty astigmatism].

BACKGROUND: High postkeratoplasty astigmatism remains a challenge for the surgeon. First experiences after implantation of a toric PMMA IOL in three eyes from patients with cataracts are reported. MATERIALS AND METHODS: After routine phacoemulsification we implanted an individually manufactured toric PMMA posterior chamber IOL via a sclerocorneal 6-mm tunnel incision in three postkeratoplasty eyes with high, topographically relatively regular astigmatism. One eye with the intraoperative aspect of circular zonular instability also received a capsular tension ring. A complete standard ocular examination was performed pre- and postoperatively including corneal topography, evaluation of anterior chamber depth, ultrasonic biomicroscopy and perimetry. RESULTS: Implantation and intraoperative alignment of the toric IOL were uneventful. The refractive astigmatisms of 5.0, 6.0 and 7.5 cyl D preoperatively, were reduced to 2.0, 1.75 and 3.0 cyl D, 10 and 12 months postoperation, respectively. The eye with the capsular tension ring showed no morphological or refractive changes during follow-up. In the other two eyes we observed IOL rotation of 20 and 30, respectively after 6 months. There were no posterior capsule opacification or capsular folds in the optical centre. CONCLUSION: Toric IOL technology allows enhancement of IOL surgery with improved refractive outcome. Simultaneous implantation of a capsular tension ring may improve long-term stability.

Aged↗

PubMed2002

The outcome of corneal grafting in patients with stromal keratitis of herpetic and non-herpetic origin.

AIM: To evaluate the outcome of corneal grafting in patients with stromal keratitis of herpetic (HSK) and non-herpetic origin, using predefined diagnostic criteria and standardised postoperative therapeutic strategies. METHODS: 384 adult immunocompetent recipients of a corneal graft for herpetic (n = 186) or non-herpetic (n = 198) keratitis were followed up prospectively for up to 5 years. RESULTS: The herpetic group displayed significantly more corneal vascularisation (p = 0.013), more epithelial defects (p = 0.049), lower corneal sensitivity (p <0.001), more graft rejection episodes (p = 0.002), and required larger grafts (p<0.001). However, the postoperative course of visual acuity, endothelial cell numerical density, and rate of graft failures were similar in both groups. After 5 years, cumulative probability of graft survival in HSK patients (40.85%) was similar to that observed in individuals with non-herpetic keratitis (50.15%; log rank = 0.874; relative risk: 1.04). CONCLUSION: Despite a markedly higher preoperative risk profile in herpetic eyes, the functional outcomes of grafts in individuals with keratitis of herpetic or non-herpetic origin were similar. Probably the most important contribution is a consequent close follow up and a therapeutic strategy including systemic prophylaxis of viral recurrence and of graft rejection by well adopted local steroid therapy.

Adult↗

PubMed2001

Corneal cryopreservation with dextran.

Different methods of corneal cryopreservation have been introduced, those employing intracellular cryoprotectants such as Me2SO or glycerol being the most widely favored. We investigated the influence of several freeze-thaw trauma variables on the survival of porcine endothelial monolayers when employing the extracellular cryoprotective agent dextran. We first examined the effects of various dextran concentrations and then, having ascertained the optimal concentration, further investigated the influence of fetal calf serum (FCS) concentration in the cryopreservation medium, the cooling rate, the thawing temperature, and the length of the preincubation in the freezing medium prior to cryopreservation. The numerical densities of endothelial cells were determined at dissection in hypoosmotic balanced salt solution and after organ culture by staining with alizarin red S and trypan blue. Morphological evaluation was not performed directly after thawing but after a subsequent organ culture at 37 degrees C to detect latent cell damage after freeze-thaw trauma. Our data revealed that corneas cryopreserved in minimal essential medium containing 10% dextran but lacking FCS, preincubated for 3 h, frozen at a cooling rate of 1 degrees C/min, and thawed at 37 degrees C incurred the lowest cell losses (22.4%, SD +/- 3.8). We conclude that dextran is an effective cryoprotectant for freezing of porcine corneas. However, variations between species in the results of cryopreservation require further investigation of an in vivo animal model and studies with human corneas before its clinical use can be recommended.

Animals↗

PubMed2000

Impact of transportation on short-term preserved corneas preserved in Optisol-GS, Likorol, Likorol-DX, and MK-medium.

PURPOSE: To investigate the impact of transportation, simulated under laboratory conditions, on the corneal endothelium preserved by Optisol-GS, Likorol-DX, Likorol, and MK-Medium. METHODS: Three hundred twenty corneas from freshly slaughtered pigs were stored in Optisol-GS. Likorol-DX, Likorol. and MK-Medium for 1, 3, 6, or 10 days. After short-term preservation, the transportation was simulated on a laboratory shaker at 4 degrees C with an acceleration of 0-100 km/h in 16 seconds for 5 hours. Mate corneas served as the control. Corneal endothelial cell density was determined at the time of dissection, directly before the experiment, and after subsequent organ culture. RESULTS: A significant cell loss induced by transportation simulation was not observed in any experimental group. Preservation in MK-Medium starting at 3 days of short-term preservation resulted in a significant cell loss. Storage for up to 6 days in Optisol-GS, Likorol-DX, and Likorol did not result in a significant decrease in cell density. CONCLUSION: Short-term preserved corneas can be routinely distributed without a reevaluation, if the tissue is preserved for a shorter time as recommended by the manufacturers.

Animals↗

PubMed1996

[Hydroxyethyl starch for reversing edema in short-term culture media for donor corneas].

PURPOSE: To investigate the feasibility to use hydroxyethylstarch as an alternative deswelling additive in short-term preservation media. MATERIALS AND METHODS: Corneoscleral discs were prepared from pairs of eye balls of freshly slaughtered pigs. Corneas were stored in MEM-medium containing either 10% or 20% hydroxyethylstarch 450 000 at 4 degrees C in a refrigerator. Subsequently, the tissue was stored for 24 hours in organ culture at 37 degrees C in MEM-medium containing 10% fetal calf serum to detect latent endothelial cell damage. Mate corneas were treated the same except for being stored in Optisol GS during 4 degrees C storage. We determined corneal endothelial cell density, stromal thickness, and glucose concentration in the medium directly after preparation, after short-term storage at 4 degrees C, and after subsequent organ culture at 37 degrees C. Scanning electron microscopy of corneal endothelium was performed at each step during the experimental course. RESULTS: We did not observe any significant differences in endothelial-cell density between experimental groups and control groups. No decrease in endothelial-cell density was observed during the course of experiments. No increase in stromal thickness was determined in any group after short-term storage at 4 degrees C. Corneas stored in medium containing 20% hydroxyethylstarch showed a decrease in stromal thickness after short-term storage. After subsequent organ culture all corneas displayed a uniform stromal swelling. Glucose concentrations in the media decreased in all groups during the experiment. In scanning-electron microscopy we observed a reversible degeneration of cell borders after storage at 4 degrees C. Additionally, corneas stored in Optisol GS showed a reversible cobblestone appearance at this stage of the experiments. CONCLUSION: Hydroxyethylstarch appears to be an alternative to the use of dextran and chondroitin sulfate as a deswelling additive in corneal preservation media.

Animals↗

PubMedDate not supplied

The diagnostic yield of vitrectomy specimen analysis in chronic idiopathic endogenous uveitis.

PURPOSE: The low diagnostic yield of vitrectomy specimen analysis in chronic idiopathic uveitis (CIU) has been related to the complex nature of the underlying disease and to methodologic and tissue immanent factors in older studies. In an attempt to evaluate the impact of recently acquired analytic methods, the authors assessed the current diagnostic yield in CIU. METHODS: Retrospective analysis of consecutive vitrectomy specimens from patients with chronic endogenous uveitis (n = 56) in whom extensive systemic workup had not revealed a specific diagnosis (idiopathic) and medical treatment had not resulted in a satisfying clinical situation. Patients with acute postoperative endophthalmitis served a basis for methodologic comparison (Group 2; n = 21). RESULTS: In CIU, a specific diagnosis provided in 17.9% and a specific diagnosis excluded in 21.4%. In 60.7% the laboratory investigations were inconclusive. In postoperative endophthalmitis, microbiological culture established the infectious agent in 47.6%. In six of eight randomly selected cases, eubacterial PCR identified bacterial DNA confirming the culture results in three, remaining negative in two with a positive culture and being positive in three no growth specimens. A double negative result never occurred, suggesting a very high detection rate, when both tests were applied. CONCLUSIONS: The diagnostic yield of vitrectomy specimen analysis has not been improved by currently routinely applied methods in recent years in contrast to the significantly improved sensitivity of combined standardized culture and PCR analysis in endophthalmitis. Consequently, the low diagnostic yield in CIU has to be attributed to insufficient understanding of the underlying pathophysiologic mechanisms.

Adolescent↗