Biomedical subjects

Barbara Cvenkel

Publications and source records attributed to Barbara Cvenkel.

4 recordsLinked to original sources

PubMed2004

Retinal thickness at the posterior pole in glaucoma and ocular hypertension.

PURPOSE: Ganglion cells with nerve fibre layer contribute a substantial fraction to the retinal thickness (RT). In contrast to the analysis of papillary and peripapillary area, which have shown large variability in normal eyes, the variation of retinal cell density in the perifoveal region is reported to be less than 10%. By measuring RT at the posterior pole we wanted to detect retinal changes due to glaucoma and determine their correspondence with visual field (VF) changes. METHODS: The Retinal Thickness Analyzer (RTA) was used to obtain RT maps in 21 normal eyes, 20 eyes with ocular hypertension and 22 eyes with glaucoma. A green laser slit (540 nm) of the RTA was focused on the retina at an angle and its intersection with the retina was imaged. The distance between the reflections from the vitreo-retinal and retina-retinal pigment interface is directly proportional to the RT. Five locations covering the central 20 degrees were scanned, generating 10 optical cross sections that were transformed into colour-coded RTA maps. Numerical data were presented for the perifoveal and posterior pole region. RESULTS: In glaucomatous eyes significant localised thinning of the retina was present, identified as the increased number of clusters including at least four points that are 2 standard deviations below normal. The minimum retinal thickness was decreased in glaucoma eyes and the perifoveal temporal modulation and perifoveal temporal/nasal asymmetry--indicators of greater RT loss in the temporal and the nasal quadrant, respectively--were higher in eyes with glaucoma, but with overlapping global indices between the groups. In 16 of 22 eyes with glaucoma there was good agreement of RT changes with VF defects. In two eyes with typical glaucomatous damage at the optic disc but without VF defects localised changes of RT were detected. CONCLUSIONS: The RTA enables objective noninvasive evaluation of the posterior pole and could become helpful in diagnosis of glaucoma before the onset of functional damage. However, at present its clinical usefulness is limited by overlapping values of retinal thickness between normal and glaucomatous populations.

Adult↗

PubMed2003

Acute ultrastructural changes of the trabecular meshwork after selective laser trabeculoplasty and low power argon laser trabeculoplasty.

BACKGROUND AND OBJECTIVES: To compare the histopathological changes in the human trabecular meshwork after low power argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT) with a Q-switched, frequency-doubled, neodymium:yttrium-aluminium-garnet (Nd:YAG) laser. STUDY DESIGN/MATERIALS AND METHODS: In gonioscopically normal trabecular meshwork of three patients awaiting enucleation due to malignant melanoma of the choroid, SLT and ALT were performed 1-5 days prior to enucleation. In each eye, the lower half of trabecular meshwork received SLT, one quadrant low power (460 mW) ALT and one quadrant was left untreated. Specimens were evaluated with light and transmission electron microscopy. RESULTS: A sharp demarcation line was visible between the laser treated and untreated intact trabecular meshwork after ALT and SLT. Both lasers caused disruption of trabecular beams, but the extent of the damage was smaller after SLT. The collagen component of trabecular beams was mostly amorphous, the long-spacing collagen was scanty after ALT, but more abundant after SLT. In the intertrabecular spaces fragmented cells and tissue debris with only a few pigmented cells were observed. Some endothelial cells were desquamated, but appeared slightly better preserved after SLT than ALT. CONCLUSIONS: Our ultrastructural comparison of the morphological changes after low power ALT and SLT in patients demonstrated that both lasers caused splitting and fragmentation of the trabecular beams of the trabecular meshwork, but the extent of the damage was smaller and the preservation of long-spacing collagen better after SLT than after ALT.

Argon↗

PubMedDate not supplied

Ocular surface changes induced by topical antiglaucoma monotherapy.

PURPOSE: To investigate the expression of inflammatory markers HLA-DR in impression cytology specimens from patients receiving topical antiglaucoma monotherapy. METHODS: Impression cytology specimens were obtained from patients taking no topical medication (n = 13) and from primary open-angle glaucoma or ocular hypertensive patients taking one topical medication for at least 3 months (latanoprost n = 14; betaxolol n = 12; timolol n = 14). None of the patients had any signs of ocular surface inflammation as detected by slit-lamp examination, a normal Schirmer's test and tear breakup time. The expression of HLA-DR on epithelial cells and T lymphocytes was analysed by flow cytometry. RESULTS: A significant increase in HLA-DR on epithelial cells in patients on monotherapy was detected (latanoprost p < 0.05; betaxolol p < 0.01; timolol p < 0.01). Although the duration of treatment differed significantly between individual groups, there was no significant correlation between the length of monotherapy and the expression of inflammatory markers by epithelial cells and T lymphocytes. In the latanoprost group, the increased expression of HLA-DR was associated with a shorter duration of treatment. CONCLUSIONS: The flow-cytometric results indicate that administration of a single topical medication preserved with benzalkonium chloride, irrespective of type, for 3 months or more induced a significant degree of subclinical inflammation detected as increased expression of HLA-DR on conjunctival epithelial cells.

Administration, Topical↗

PubMedDate not supplied

One-year follow-up of selective laser trabeculoplasty in open-angle glaucoma.

BACKGROUND: Selective laser trabeculoplasty (SLT) targets the pigmented trabecular meshwork (TM) cells without damage to the adjacent non-pigmented tissue. A study was conducted to evaluate the efficacy and safety of SLT in the treatment of uncontrolled open-angle glaucoma. METHODS: In a prospective non-randomized study 44 eyes of 31 patients with uncontrolled open-angle glaucoma were treated with a frequency-doubled, Q-switched Nd:YAG laser. A total of approximately 50 spots were placed over 180 degrees of the TM at energy levels ranging from 0.7 to 0.9 mJ. Intraocular pressure (IOP) was measured 1, 2, and 24 h, 1 and 2 weeks and 1, 2, 3, 6, 9, and 12 months after treatment. RESULTS: The average pre-operative IOP was 25.6 (SD 2.6) mm Hg (range 22-34). The mean IOP reduction from baseline at 24 h, 3, 6 and 12 months was 7.1 mm Hg (SD 3.5) or 27.6%; 4.2 mm Hg (SD 3.5) or 16.4%; 4.7 mm Hg (SD 4.2) or 18.6%, and 4.4 mm Hg (SD 3.8) or 17.1%, respectively. The percent of eyes with IOP reduction of 3 mm Hg or more at 3, 6 and 12 months was 66, 78 and 62%. A pressure spike of 8 mm Hg or more was detected in 4 eyes (9.1%). Anterior chamber reaction was seen 1 h after SLT and was mild to moderate in 16 eyes (40.4%) and marked in 3 eyes (6.8%). CONCLUSIONS: SLT has shown reasonable efficacy in lowering IOP over 1-year follow-up, but there was a tendency for IOP to increase with a longer follow-up. Long-term follow-up studies with a large sample size are needed to determine whether the IOP lowering effect is sustained over time, and to assess the efficacy of repeated SLT.

Aged↗