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Biomedical subjects

B Svedbergh

Publications and source records attributed to B Svedbergh.

At least 19 recordsLinked to original sources
PubMed1999

Impact of intraocular pressure regulation on visual fields in open-angle glaucoma.

OBJECTIVE: To investigate the correlation of different parameters of intraocular pressure (IOP) to visual field decay in open-angle glaucoma. DESIGN: Analysis of visual field decay during a prospective, randomized clinical trial comparing primary laser trabeculoplasty with medication. PARTICIPANTS: Of a total of 82 included eyes in 82 patients with newly detected high-pressure open-angle glaucomas, 76 (55 capsular, 21 simple) fulfilled the 2-year follow-up with the stated number of reliable visual field examinations and were included in this analysis. INTERVENTION: Automated perimetry and a daytime IOP curve were taken every second month during the 2-year follow-up. MAIN OUTCOME MEASURES: Six IOP parameters were evaluated and correlated to visual field outcome. The subgroups with the two types of glaucoma (capsular and simple) were analyzed separately. RESULTS: Visual field decay showed greater correlation to IOP variation (range and peak) and mean IOP than IOP at start or degree of IOP reduction. The relation between mean IOP and visual field decay in the whole group was not quite linear, with more decay at higher IOP levels. The association between IOP regulation and visual field decay was most pronounced in capsular glaucoma, whereas the results in the small group of simple glaucomas were inconclusive. CONCLUSIONS: Visual field prognosis in high-pressure open-angle glaucoma, essentially capsular glaucoma, is better in patients with smaller IOP variation and poorer in patients with high mean IOP.

Aged↗
PubMed1995

Primary argon laser trabeculoplasty vs pilocarpine. III. Long-term effects on visual fields.

In a prospective randomized study on primary argon laser trabeculoplasty vs pilocarpine in 82 newly detected open-angle glaucoma patients, visual field changes were analysed for absolute changes over 2 years on automated threshold perimetry and manual Goldmann perimetry. Regression analysis was also performed using the threshold perimetry examinations taken every second month. Analyses based on automatic perimetry were corrected for eventual bias due to cataract and induced miosis. There was significantly less decay of visual field in the group treated with laser. This was even more pronounced for eyes with capsular glaucoma, especially in the early stage. For the smaller group with simple glaucoma no significant advantage of laser could be shown. Successful intraocular pressure reduction significantly improved the visual field outcome. Laser trabeculoplasty is therefore recommended as primary therapy in capsular glaucoma.

Aged↗
PubMed1995

Primary argon laser trabeculoplasty vs pilocarpine. IV. Long-term effects on optic nerve head.

In a prospective, randomized study on primary argon laser trabeculoplasty vs piloparpine in 82 newly detected open-angle glaucomas the progress of optic nerve head damage is presented. In 70 patients reliable stereo photographs could be analysed. In the laser treated group a progression of glaucoma damage after 24 months was seen in 6/37 eyes (16%) and in the pilocarpine-treated group 16/33 (49%) (p = 0.0048). There was a statistically significant favourable outcome if intraocular pressure was regulated in terms of peak and range of pressure, but not average pressure. This was even more pronounced in capsular glaucoma, but not significant for simple glaucoma. Pilocarpine increased the risk for further damage to the optic nerve head 6.4 times compared to laser trabeculoplasty. Thus, laser is recommended as the primary therapy in high tension glaucoma, especially in capsular glaucoma.

Aged↗
PubMed1994

Primary argon laser trabeculoplasty vs pilocarpine. II: Long-term effects on intraocular pressure and facility of outflow. Study design and additional therapy.

In a prospective study 82 patients recently diagnosed with simple or capsular glaucoma were randomized to receive primary argon laser trabeculoplasty or pilocarpine treatment. A 2-year follow-up showed a better success rate in the laser group, with less need for additional therapy. The average intraocular pressure and peak pressure was lower and the daytime pressure variation was significantly less in the laser group. The better increase in facility of outflow in the laser group was not statistically significant. In capsular glaucoma, laser treatment resulted in a significantly lower average pressure than with medication. In simple glaucoma the effect was about the same in the two treatment groups. Increase in facility of outflow was significantly better in simple glaucoma than in capsular glaucoma. High initial intraocular pressure gave a significantly lower success rate. Primary argon laser trabeculoplasty as a single glaucoma treatment seems advantageous in comparison to medication with pilocarpine for regulating intraocular pressure.

Aged↗
PubMed1992

Primary argon laser trabeculoplasty vs. pilocarpine. Short-term effects.

This is a prospective study of 82 newly discovered patients with simplex or capsular glaucoma from two centres, collected between 1984 and 1989 and selected at random for primary treatment by either laser or pilocarpine. Preliminary two-year follow-up shows that primary laser treatment gives a significantly higher number of patients where the intraocular pressure is successfully controlled. Primary argon laser trabeculoplasty has been carried out in 40 patients. The first treatment was given to either the upper or to the lower half of the trabecular meshwork. In the second treatment after one month the other half was treated. In both groups the first treatment gave the highest pressure reduction. The somewhat higher pressure reduction after upper treatment versus lower was insignificant. The degree of trabecular pigmentation did not influence the two month follow-up result, neither did the type of glaucoma. Of the eyes treated with laser, peripheral anterior synechiae could be seen in 18%. Acute intraocular pressure rises greater than 5 mmHg occurred in 21% of the eyes after the first treatment and in 37% after the second treatment. Pressure rises greater than 10 mmHg occurred in 5% after the first and in 10% after the second treatment. No pressure-lowering substances were given. Considering that 16% of the eyes had an intraocular pressure that was higher than baseline pressure even 6 h after either first or second treatment, it is recommended that a pressure-lowering medication on the day of treatment should be administered.

Follow-Up Studies↗
PubMed1992

The IOP-IOL. A probe into the eye.

The intraocular lens (IOL) implant can be looked upon as a probe into the space of the eye. Adapting that view, it is logical to furnish the IOL-probe with biomedical sensors that would explore its environment. A sensor is presented for continuous monitoring of intraocular pressure (IOP), incorporated in the haptics of an IOL. The sensor consists of a capacitative spiral circuit, needing no energy, correlating its resonance frequency to the actual IOP. This resonance frequency is remotely and non-invasively detected by an external device located in a spectacle frame.

Biosensing Techniques↗
PubMed1986

Goniodysgenesis in elderly glaucoma and non-glaucoma patients. A masked slit-lamp and gonioscopy study.

The aim was to elucidate whether goniodysgenesis is more frequently observed in elderly patients with glaucoma, and furthermore, which signs of goniodysgenesis are of importance and most unanimously detected. Thus, 3 examiners evaluated 21 glaucoma patients and 19 non-glaucoma patients in a masked fashion. None of the patients had a first-degree heredity. Gonioscopy, slit-lamp examination and measurements of the corneal and pupillary diameter were performed, in all 26 variables. Significantly (P less than 0.05) more frequent in glaucoma were an increased corneal diameter, scleral overriding, hypoplasia of the pupillary seam, abnormal Schwalbe's line and an opaque pretrabecular membrane (one examiner). Less frequent were a peripupillary yellow pigment ring and pigment stars on the lens. Inter-observer variation was small regarding e.g. corneal diameter but rather large regarding e.g. the pretrabecular membrane.

Aged↗
PubMed1985

Argon laser trabeculoplasty in exfoliation syndrome.

A retrospective study of the effects of argon laser trabeculoplasty on a consecutive series of 44 phakic patients (55 eyes) with exfoliation syndrome glaucoma is reported. The follow-up was 12 to 23 months, mean 15 months. At an individual level laser trabeculoplasty was successful in 70% of the patients and 40% were able to reduce or stop their medication. Two patients showed 'late failure' at 15 months after initial control. An early rise of intraocular pressure was fairly common in the exfoliation group, and perhaps these patients need particularly careful monitoring during the initial hours following argon laser trabeculoplasty. A beneficial effect was noted on diurnal curve fluctuations and peak intraocular pressures.

Aged↗
PubMed1981

Immotile-cilia syndrome and the cilia of the eye.

Ten patients with the immotile-cilia syndrome were subjected to an extensive eye examination, which failed to demonstrate any consistent single abnormality. The tests of the retinal function and the aqueous humor dynamics were normal. However, different corneal abnormalities--mostly without clinical significance--were observed in 9 out of 10 patients, suggesting a developmental disturbance.

Adult↗
PubMed1981

Vascular damage in the anterior uvea induced by intravitreal autogenous blood.

The effects of vitreous hemorrhages on anterior uveal vessels were studied. Albino rabbits were injected intravitreally with autogenous blood, plasma, RBCs, iron-dextrin, or Ringer's solution. The vascular permeability was assessed by fluorescein iris angiography, carbon labeling and penetration of peroxidase. Following one injection of blood, aqueous flare and fluorescein leakage from the iris were observed for 40 days. Intense vascular carbon labeling in iridial and ciliary processes was present for 1-40 days and weak-to-moderate labeling in the iris for 9-40 days. Repeated blood injections aggravated the vascular response, showing extravasation of peroxidase and carbon labeling of iridial vessels for 92 days. The most severe vascular damage ensued from iron-dextrin and RBCs. Plasma an Ringer's solution gave no reaction. The authors suggest that the iron-containing degradation products of RBCs induce vascular damage in anterior uvea and disruption of blood-aqueous barriers.

Animals↗
PubMed1980

Transcellular aqueous humor outflow: a theoretical and experimental study.

When the aqueous humor passed through the transcellular channels of the inner wall endothelium of Schlemm's canal the flow was estimated to be very slow and viscous (Reynolds' number about 10(-3)). It was found to be accurate to treat this extreme flow situation with conventional hydrodynamic formulae without specific corrections. Four different principal configurations of the transcellular channels were investigated. The theoretical calculations yielded results in good agreement with those obtained from the experimental model studies. Where deviations occurred they were probably explained by a radial flow component, which was not incorporated in the theoretical formulae applied. A spherical channel configuration was considered most similar to the in vivo situation and this yielded experimental resistance values half those of previously applied theoretical methods. Using previous morphological data the present results indicated that less than 5% of the total resistance to aqueous humor outflow was located in the inner wall endothelium in normal human eyes, and about 10% in cynomolgus monkey eyes at normal intraocular pressures.

Animals↗
PubMed1980

Effects of intracameral Na2EDTA and EGTA on aqueous outflow routes in the monkey eye.

Intracameral perfusion with 4 to 6 mM Na2EDTA or 4 mM EGTA for 40 to 80 min caused a very large increase in gross outflow facility. This effect was partly reversible when followed by perfusion with mock aqueous humor. Eyes perfused with Na2EDTA were studied morphologically. In the trabecular meshwork the cells separated due to a splitting of the cell junctions. A distention of the cribriform meshwork, a wash-out of extracellular material , and a disintegration of the denuded trabecular cores were also noticed. The inner wall of Schlemm's canal protruded in a "balloonlike" manner into the lumen of the canal and showed frank ruptures, especially after prolonged perfusion times. The conventional outflow pathways beyond Schlemm's canal showed no abnormalities. In the uveoscleral outflow routes the anterior and middle part of the ciliary muscle demonstrated very wide intermuscular clefts and many degenerated muscle fibers. The posterior third of the muscle was normal. So were the ciliary epithelium, the choroid, and the retina. The pupillary sphincter also showed degeneration. The corneal endothelial cells separated, starting at the apical junctional complex.

Animals↗
PubMed1978

Goniodysgenesis in exfoliation glaucoma.

According to our material the exfoliation glaucoma can be regarded as the result of an interplay of at least two different pathologic conditions: a primary genetic goniodysgenesis creating a relative block to the outflow, and a probable vasculopathy in the iris. Subsequent degeneration of the iris will lead to a liberation of pigment and debris, i.e., the exfoliation syndrome, eventually causing obliteration of the outflow pathways.

Aged↗
PubMed1976

Protrusions of the inner wall of Schlemm's canal.

Large specific protrusions of the trabecular meshwork into Schlemm's canal (hernias) have been suggested to be the main drainage routes for aqueous humor, similar to the function of the arachnoid villi in draining the cerebrospinal fluid. My quantitative study in cynomolgus monkeys does not support such a hypothesis. The drainage routes of the aqueous humor, evaluated from the number and sizes of the pores observed by scanning electron microscopy, were as common through the hernias as through other parts of the inner wall of Schlemm's canal at different levels of intraocular pressure. The total surface of the hernias was a small percentage of the total surface of the inner wall.

Animals↗