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Biomedical subjects

F Grehn

Publications and source records attributed to F Grehn.

At least 73 records · Page 4Linked to original sources
PubMed1989

Limbus-based versus Fornix-based conjunctival flap in filtering surgery. A randomized prospective study.

A randomized prospective study was performed to compare the results of filtering surgery using a Limbus-based versus a Fornix-based conjunctival flap. The wound closure of the Fornix-based flap was performed using a running 10/0 nylon suture at the limbus. No statistical significant difference of IOP regulation was found between the two groups. There was a tendency of reduced occurrence of shallow anterior chamber and of less vascularized filtering blebs in the Fornix-based technique.

Conjunctiva↗
PubMed1989

Correlation between neuroretinal rim area and age in normal subjects.

The Rodenstock Optic Nerve Head Analyzer was used to study the age distribution of the neuroretinal rim area in 194 eyes of 122 normal subjects aged 7-84 years. No significant linear correlation was found between neuroretinal rim area and age. Linear regression analysis of the neuroretinal rim area in the temporal disc quadrant as a function of age led to the following equation: y = 0.00029x + 0.245; r = 0.052. Linear regression analysis of the neuroretinal rim area in the total disc as a function of age led to the following equation: y = 0.001x + 1.314; r = 0.0053. The 99% confidence limits of the regression slope ranged from -0.0025 to + 0.0045 (temporal disc quadrant) and from -0.00077 to + 0.0013 (total disc), respectively. A nonlinear correlation between neuroretinal rim area and age is very unlikely. Using the Mann-Whitney U-test, no statistically significant difference between the smallest (group of subjects aged 7-19 years) and the largest mean neuroretinal rim area (group of subjects aged 30-39 years) was detectable. From our data we conclude that there are no age-related changes in the neuroretinal rim area as measured with the Optic Nerve Head Analyzer. Changes in the neuroretinal rim area during follow-up examinations of glaucoma suspects may therefore be interpreted as an important sign of early glaucomatous damage. This confirms our previous suggestion that follow-up examinations of the optic disc structure with the Rodenstock Optic Nerve Head Analyzer are useful to confirm the diagnosis of glaucoma, even at a stage where a visual field loss cannot yet be detected by routine perimetry.

Adolescent↗
PubMed1989

[Treatment of glaucoma chronicum simplex with a combination of 0.5 percent timolol with 0.5 percent adrenaline plus 0.3 percent guanethidine].

The effect on the intraocular pressure of patients with primary open-angle glaucoma of a combination of timolol 0.5% with epinephrine 0.5% plus guanethidine 3% was studied and compared with the effects of timolol alone, of epinephrine 0.5% plus guanethidine 3%, and of other glaucoma drugs. The combination of timolol 0.5% with epinephrine 0.5% plus guanethidine 3% had a stronger effect on intraocular pressure (reduction 10.9 +/- 1.1 mm Hg) than epinephrine 0.5% plus guanethidine 3% (7.6 +/- 0.9 mm Hg) or timolol alone (5.8 +/- 1.1 mm Hg) or other glaucoma drugs. However, when the three substances are administered in combination therapy may show an addition of both pressure-lowering and side effects.

Clinical Trials as Topic↗
PubMed1989

[Changes in the temporal neuroretinal border area of the papilla following pressure-reducing surgery].

The Optic Nerve Head Analyzer (Rodenstock München, FRG) was used to investigate the optic disc structure of 9 eyes before and after surgical reduction of intraocular pressure (IOP). Four out of 9 eyes showed a marked increase of their temporal neuroretinal rim area after surgery (between 140% and 400%). The observed increase of neuroretinal rim area was still present after more than one year, although it was less pronounced. Five eyes did not show changes of the neuroretinal rim area of their optic discs. A further evaluation regarding IOP and visual field of the 9 eyes examined lead to the following results: 1) There is no correlation between increase of neuroretinal rim area and extent of IOP reduction, i.e. some eyes showed an increase of neuroretinal rim area with only slight IOP reduction whereas others with more pronounced IOP reduction did not show an increase of neuroretinal rim area. 2) All eyes showing an increase of neuroretinal rim area after surgical IOP reduction had normal visual fields an a mean sensitivity of more than 24.5 dB within the central part of the G 1-program of the Octopus perimeter. 3) All eyes without increase of the neuroretinal rim area after surgical IOP reduction had visual field defects and a mean sensitivity of less than 19 dB within the central part of the G 1-program. According to these data we suppose that occurrance of increase of neuroretinal rim area after glaucoma surgery depends mainly on the stage of glaucoma (as determined by visual field testing) and that it is not clearly correlated to the amount of IOP reduction.

Follow-Up Studies↗
PubMed1988

Neuroretinal rim area and visual field in glaucoma.

The correlation between visual field and neuroretinal rim area of the optic disc was studied in 70 eyes of 44 patients with suspected or definite glaucoma. Visual field analysis was performed by automated perimetry with the Octopus 2000R, using the program G1; the neuroretinal rim area of the disc was measured by the "Optic Nerve Head Analyzer." All eyes with a glaucomatous loss within the central sector of the visual field showed a significantly reduced neuroretinal rim area in the corresponding, i.e., the temporal quadrant of the disc. The reverse conclusion, however, was not valid: If there is a significantly reduced neuroretinal rim area in the temporal quadrant of the optic disc, one cannot predict the presence or absence of visual field loss. Actually, both high and low values are found in the neuroretinal rim area even if no visual field loss is detectable by the Octopus G1 program. There are two clinical consequences based on this result: (1) follow-up examinations of the disc structure that show increasing loss of the neuroretinal rim area may establish the diagnosis of glaucoma even at a stage where no visual field loss can be detected. Therefore, analysis of the disc structure may be more sensitive than analysis of the visual field, especially in patients who only show elevated intraocular pressure and no other signs of glaucoma. (2) If there is already a definite visual field loss due to glaucoma, the effect of antiglaucomatous therapy should be monitored by visual field analysis rather than by analysis of the optic nerve head.

Evaluation Studies as Topic↗
PubMed1988

[Procedures for the quantitative follow-up control of computerized perimetric findings in glaucoma].

A statistical model for long-term follow-up of glaucomatous visual fields is described. Using an analysis of individual testpoints, a statistical evaluation of visual field change is done by the Bowker symmetry test. Eccentricity of test points in the visual field, density of scotomas and number of defective test points were used as parameters. The authors demonstrate that evaluation with this method is superior to methods using total sensitivity loss or mean sensitivity of the visual field. This model is currently being used in a retrospective and a prospective glaucoma study.

Follow-Up Studies↗
PubMed1987

[Laser trabeculoplasty or goniotrepanation. A prospective comparative study].

In a consecutive series of glaucoma patients, laser trabeculoplasty was performed in 115 eyes and goniotrephination in 44 eyes. Follow-up time ranged from 3 to 29 months. In the group treated by laser trabeculoplasty, intraocular pressure was reduced by at least 20% and was below 25 mm Hg at the end of the study in 50% of the eyes. On the basis of these criteria, intraocular pressure was controlled in 91% of the eyes in the goniotrephination group. A significant pressure elevation occurred in 9% of the eyes in the trabeculoplasty group, but in none of the eyes in the goniotrephination group. At the end of the study the mean pressure reduction in the laser trabeculoplasty group was 5 mm Hg (19% of the initial value), whereas in the goniotrephination group it was 13.6 mm Hg (46% of the initial value). When tested with the Octopus perimeter, there was no change in the mean sensitivity of the visual fields during the study in the eyes treated by laser trabeculoplasty. In the eyes treated by goniotrephination, the mean sensitivity improved, probably due to a postoperative increase in pupillary diameter. There were two cases of acute cataract formation caused by a flat anterior chamber in the goniotrephination group. The incidence of reduction of visual acuity in the goniotrephination group was 14%, as compared to 6% in the laser trabeculoplasty group. From the results of this study the authors conclude that in cases in which a considerable pressure reduction is called for because of extensive field loss or high intraocular pressure, goniotrephination is to be preferred.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-Up Studies↗
PubMed1986

Thymoxamine: a miotic for intraocular use.

Thymoxamine hydrochloride can be used intraocularly to reverse phenylephrine or epinephrine mydriasis during intraocular surgery (0.2-0.5 ml of 0.01% or 0.02% solutions proved to be effective). No endothelial damage was found up to a dose of 1 ml of 0.02% thymoxamine in animal experiments using a physiologically buffered solution. Since stability is low in the buffered state, the final concentration has to be prepared at the time of surgery using a 0.5% solution and a phosphate buffer. Intracameral thymoxamine is a potent miotic during operations and can be helpful in extracapsular cataract surgery, keratoplasty, and repair of perforating injuries.

Animals↗
PubMed1985

[Surgical indications in glaucoma].

A number of aspects of glaucoma surgery are discussed. Complete drainage of the aqueous via the subconjunctival space results in underperfusion of the trabecular meshwork, leading to significant impairment of the trabecular function. In certain cases, therefore, we prefer trabeculotomy, even though its pressure-lowering effect is inferior to that of fistulizing surgery: trabeculotomy preserves the unaffected trabecular meshwork. Laser trabeculoplasty has the advantage of increasing the outflow facility. In angle-closure glaucoma, iridectomy is performed as an initial procedure in every case in order to eliminate pupillary block. The transcorneal approach ensures watertight wound closure and preserves the conjunctiva for fistulizing surgery if necessary. Glaucoma surgery can usually be performed in lid akinesia and subconjunctival infiltration. This alternative helps to avoid retrobulbar injection when the optic nerve is already severely damaged by glaucoma.

Anesthesia, Local↗