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Biomedical subjects

F Grehn

Publications and source records attributed to F Grehn.

At least 19 recordsLinked to original sources
PubMed1992

Improved suture for fornix-based conjunctival flap in filtering surgery.

Major problems in the early postoperative phase in filtering surgery are hypotony, flattening of the anterior chamber and choroidal detachment. We describe a new suture technique for the closure of the conjunctiva in goniotrephination with a fornix-based conjunctival flap which is helpful in reducing these complications. After dissecting the conjunctiva from the limbus, a shallow groove is cut directly behind the former conjunctival insertion. At the end of the operation the conjunctiva is sutured into this groove using a running 10.0 nylon suture in a meander-like fashion. A very tight wound closure results. We used this technique in 104 consecutive goniotrephinations. We found a low incidence of only mild external fistulation, hypotony, flattening of the anterior chamber and choroidal detachment. Astigmatism induced by the operation was -1.2 +/- 1.2 D, usually with the rule.

Aged↗
PubMed1992

Sezolamide: additivity to timolol twice daily.

Sezolamide, a potent topical carbonic anhydrase inhibitor previously known as MK-417, was studied to determine its ocular hypotensive activity in patients with elevated intraocular pressure while on continuing therapy with topical timolol. This was a three-centre, double-masked, randomised, placebo-controlled, parallel study in 36 patients with bilateral primary open angle glaucoma or ocular hypertension on therapy receiving 0.5% timolol twice daily, with a morning intraocular pressure greater than or equal to 22 mmHg in both eyes 2-4 hours following an 8 a.m. dose of timolol. Sezolamide 1.8% or placebo twice daily was added to treatment with timolol on the evening of day 1 and continued for 2 weeks. Twelve-hour diurnal curves were performed before the study on day 1 (timolol alone) and on day 15. Intraocular pressure measurements were also taken on days 2 and 8 at 8 a.m. and 9 a.m. Patients who received timolol and sezolamide showed additional intraocular pressure reductions from day 1 (timolol alone) of 8.0 to 15.5%, which were significant at all times. At hours 1, 2, 4 and 8 the reductions in intraocular pressure observed in the group receiving sezolamide and timolol were significantly greater than those in the group receiving timolol and placebo.

Aged↗
PubMed1991

Comparative tolerability of topical carbonic anhydrase inhibitor MK-927 and its S-enantiomer MK-417.

A single-dose, randomised, double-masked, placebo-controlled, five-period cross-over comparative ocular tolerance study was undertaken with the topical carbonic anhydrase inhibitor (CAI) MK-927 (1% and 2% concentrations) and its S-enantiomer MK-417 (1% and 1.8% concentrations) in 20 healthy, normal volunteers. Subjects received one drop of placebo (common vehicle) or CAI in each eye on five different days that were separated by washout intervals of 1 week. The incidence of burning increased significantly after treatment with 2% MK-927 (P less than 0.01) and 1.8% MK-417 (P less than 0.05) as compared with placebo. The mean duration of burning following placebo was 16.8 s, somewhat less than that following CAI application (23-37.1 s). The duration of tearing following CAI treatment was also significantly prolonged (P less than 0.05). Pupil size was not changed by CAIs. No other side effects were observed. At 3 h after instillation, intraocular pressure (IOP) was found to be decreased following all four CAI treatments, significantly so with 1% and 1.8% MK-417. The reasonable single-dose tolerability of MK-927 and MK-417 in this sensitive normal-volunteer model supports their potential as topical glaucoma medications. This study suggests that MK-417 may possess greater IOP-lowering activity than MK-927 in man.

Administration, Topical↗
PubMed1991

[Additive effect of timolol and the local carbonic anhydrase inhibitor MK-417 (sezolamide)].

MK-417 (sezolamide) is a topically active carbonic anhydrase inhibitor. The effect of additional treatment with sezolamide 1.8% twice daily to patient already receiving timolol 0.5% twice daily was investigated. For this purpose, 12-h diurnal curves were used in a double-masked, randomized, placebo-controlled, parallel study in 36 patients with bilateral primary open angle glaucoma or ocular hypertension who during beta blocker therapy had intraocular pressures (IOP) greater than or equal to 22 mmHg. For 15 days patients received sezolamide or placebo 10 min after 0.5% timolol given at 8 a.m. and 8 p.m. On treatment day 15, this addition of sezolamide twice daily induced a further mean decrease in IOP of approximately 4 mm Hg (about 15%) at 1, 2 and 4 h and of approximately 2-3 mm Hg at 0, 6, 8, 10 and 12 h after drug administration, thus demonstrating a partial additive effect of sezolamide and timolol. Thus, sezolamide may be a useful addition to the treatment of glaucoma in patients not adequately controlled by beta blocker therapy.

Aged↗
PubMed1990

[Computer-controlled analysis of the optic papilla with the Optic Nerve Head Analyzer: normal values and various age dependent papilla parameters].

The Rodenstock Optic Nerve Head Analyzer was used to study the disk parameters of 194 eyes of 122 healthy subjects. No age-related changes in the neuroretinal rim area or in the cup/disk ratio could be detected. Furthermore, no significant differences in the mean values of disk parameters were found when right eyes were compared with left eyes or when eyes of male and female subjects were compared. It was thus possible to base calculations of normal values for disk parameters on the entire sample of 194 eyes, irrespective of age and sex. It was also possible to determine the range of variation of these parameters. Statistical analysis of the data produced the following results: the smallest mean neuroretinal rim area is in the temporal disk quadrant; the largest is in the nasal disk quadrant. The mean neuroretinal rim area of the upper quadrant is almost as large as that of the lower quadrant. Consequently, the temporal quadrant has the largest cup/disk ratio, while the nasal quadrant has the smallest. The cup/disk ratios of the upper and lower quadrants are almost identical. The range of variation of all disk parameters was found to be considerable, i.e., the neuroretinal rim area of the whole disk, as well as that of each disk quadrant may be very small, not only in glaucomatous but even in normal eyes. Accordingly, the cup/disk ratio may be large even in normal eyes. Due to the broad range of interindividual variation of disk parameters, a single examination with the Optic Nerve Head Analyzer is not sufficient to distinguish normal from glaucomatous disks. Follow-up examinations are therefore required for early diagnosis of glaucoma, because the finding of a reduction in neuroretinal rim area during follow-up must be interpreted as an important sign of early glaucoma damage.

Adolescent↗
PubMed1990

A single dose of the topical carbonic anhydrase inhibitor MK-927 decreases IOP in patients.

MK-927 is a novel topical carbonic anhydrase inhibitor (CAI). We present the first single-dose clinical trial of MK-927 in 24 patients with bilateral primary open-angle glaucoma or ocular hypertension. This investigation was conducted as a two-centre, double-masked, randomised, placebo controlled study. Patients received one drop of 2% MK-927 in one eye and placebo in the other eye. Modified diurnal intraocular pressure (IOP) curves were performed before the study and on one treatment day. A single dose of 2% MK-927 induced a peak mean IOP decrease of 10.5 mmHg at 4.5 hours postdose. With compensation for diurnal variation, as determined by the prestudy diurnal pressure curve, the net peak mean reduction of IOP caused by MK-927 was 7.5 mmHg versus a corresponding net change of 1.4 mmHg in the contralateral placebo treated eye. Thus a single dose of MK-927 gave a clinically significant IOP reduction in patients.

Carbonic Anhydrase Inhibitors↗
PubMed1990

[Surgical therapy of glaucoma].

During recent years, glaucoma surgery has been modified by the introduction of new antiglaucoma drugs and by laser therapy. Various glaucoma operations have, however, retained their value in the treatment of severe glaucoma cases. Acute angle-closure glaucoma is best treated by iridectomy. When a clear cornea is present, laser iridectomy can be performed. Prophylactic treatment of the contralateral eye is mandatory. In chronic open-angle glaucoma, filtration surgery with a scleral flap is usually performed (goniotrephination or trabeculectomy). Modifications in the conjunctival incision and the use of antifibroblastic drugs may reduce the failure rate for difficult cases in the future. Individual adjustment of postoperative treatment is of great importance for the development of functioning filtering blebs. Reoperations retain their high incidence of subconjunctival scarring. In congenital glaucoma, the success rate of trabeculotomy equals the success rate of goniotomy. Trabeculotomy has advantages when the cornea is cloudy, but may be more difficult to perform in eyes with a stretched anterior segment or in secondary congenital glaucomas. In neovascular glaucoma, cryotherapy of the peripheral retina often normalizes the intraocular pressure by reduction of neovascularization. Cyclocryotherapy of the anterior pars plicata often results in cataract and phthisis bulbi and is only rarely used. In non-neovascular secondary glaucoma or numerous reoperations for primary glaucoma, the implantation of a Molteno or Schocket implant may be helpful. Cyclodialysis is seldom used because its outcome is extremely variable. It is mostly replaced by modified filtering surgery, including ciliary tendon disinsertion (Watson trabeculectomy). If the IOP is high in coexisting glaucoma and cataract, two separate procedures are normally performed successively: when the filtering surgery has been successfully performed and settled, a separate extracapsular cataract operation is performed via a clear corneal incision. Simultaneous procedures, if necessary, can be performed with a trabeculotomy or with a filtering operation. If the IOP is borderline, an extracapsular cataract operation is normally sufficient to lower the IOP for some mmHg. Cataract formation after filtering surgery has become a less severe complication, as posterior chamber lens implantation is also possible in glaucomatous eyes. Therefore, filtering surgery nowadays seems indicated at earlier stages of glaucoma.

Cataract Extraction↗
PubMed1990

[Local carbonic anhydrase inhibitors MK-927 and Mk-417. Effect and tolerance].

A comparative ocular tolerance study was undertaken with the topical carbonic anhydrase inhibitor (CAI) MK-927 (1% and 2%) and its S-enantiomer MK-417 (1% and 1.8%) in 20 healthy normal volunteers. In this randomized, double-blind cross over study, placebos were used for control over five periods. The subjects received one drop of placebo (common vehicle) or CAI in each eye in successive periods separated by a washout period of 1 week. Three hours after the dose, the IOP was found to be decreased by 5.3% to 9.1%, depending on the dose, with all four CAI treatments and significantly so with MK-417. Pupil-size and central vision were unchanged by CAIs. External and anterior segment examination revealed no changes following any of the treatments. The incidence of burning was significantly increased by 2% MK-927 (p less than 0.01) and 1.8% MK-417 (p less than 0.05) compared to placebo. The mean duration of burning placebo was 16.8 s, but it was significantly longer (23 to 37.1 s) following CAI application. Duration of tearing following CAI application was also significantly prolonged (p less than 0.05).

Adult↗
PubMed1990

[Histologic comparison of a functioning and non-functioning filtration membrane with the Molteno implant].

In two patients with a Molteno implant, the filtration membrane was excised 2 and 21 months postoperatively because of uncontrolled elevation of intraocular pressure. This tissue was examined by light and electron microscopy and the findings compared with those of a third functioning Molteno filtration membrane obtained from an enucleation specimen. The most conspicuous differences were the high density and cellularity of the connective tissue of the non-functioning membranes and the frequent cell pyknosis and necrosis in the functioning membrane. In addition, one of the non-functioning membranes showed a condensed cellular layer on the inner surface. There were no inflammatory cell infiltrates in any of the three specimens. We conclude that the variable results of Molteno implants are related to the quantities of tissue components of the filtration membrane.

Adult↗
PubMed1990

[Decrease in intraocular pressure following administration of the local carbonic anhydrase inhibitor (MK-927)--comparison of the effect with pilocarpine].

We studied the effect of a single dose of the local carbonic anhydrase inhibitor, MK-927, on lowering IOP in 24 patients with bilateral primary open-angle glaucoma or ocular hypertension and compared it with the effect of pilocarpin in 9 patients. Following a washout of any glaucoma medication of 3 to 14 days, a diurnal IOP curve was performed. Two to seven days later one eye received a single drop of 2% MK-927 while the other eye received placebo and the diurnal IOP curve was repeated. MK-927 treated eyes showed a peak mean IOP change of 10.5 mmHg (33.1%) occurring at 4.5 h postmedication. In nine eyes treated with pilocarpin 1% q.d., the mean reduction of the mean IOP was 7.0 mmHg (22.1%) compared to no treatment. The same eyes showed a mean reduction of mean IOP of 6.1 mmHg (18.9%) following a single dose of MK-927. In contrast, the mean reduction of the maximal IOP treated with pilocarpin was 7.3 mmHg (25.8%) and 10.2 mmHg (34.2%) following MK-927. Considering the IOP lowering of MK-927 shown here, the possibility of a topically effective glaucoma therapy by local carbonic anhydrase inhibitor seems to be established. The IOP lowering effect of MK-927 appears to be similar to that of pilocarpin 1%.

Carbonic Anhydrase Inhibitors↗
PubMed1990

[Normal values of various papillary parameters and correlation to papillary size].

The Optic Nerve Head Analyzer was used to study the disc parameters--neuroretinal rim area and cup/disc ratio--in 194 eyes of 122 healthy subjects. Both neuroretinal rim area (1.35 +/- 0.35 mm2) and cup/disc ratio (0.5 +/- 0.18) showed a large interindividual variability, i.e., very small values for the neuroretinal rim and very large values in the cup/disc ratio are not only found in glaucomatous but even in healthy eyes. Due to the great variability of disc parameters, a single examination using the Optic Nerve Head Analyzer will presumably not be sufficient to decide whether an individual disc is glaucomatous or normal. Early recognition of glaucoma by means of computerized disc analysis will therefore require follow-up examinations. In accordance with other investigators, we found a highly significant correlation between the neuroretinal rim area and the corresponding disc size (p less than 0.001), i.e., a large disc normally has a large neuroretinal rim. In addition, we also found a significant correlation between the cup/disc ratio and the corresponding disc size (p less than 0.001), i.e., even the relative value of the cup/disc ratio is not independent of disc size. A large disc normally has a large cup/disc ratio. Correlation studies between disc parameters and disc size cannot determine whether the neuroretinal rim area or the cup/disc ratio gives more information about an optic disc. Both parameters, neuroretinal rim area and cup/disc ratio, however, are of equal value concerning the recognition of glaucoma by means of computerized disc analysis, because early diagnosis of glaucoma with this new technique presupposes intraindividual follow-up examinations.

Adolescent↗
PubMed1990

[Long-term results following preventive iridectomy. A retrospective study].

The frequency of complications after surgical iridectomy in angle-closure glaucoma is normally considered low. In order to estimate the influence of the surgical intervention independent from other factors (such as ischemia caused by angle-closure, progression of glaucomatous disease, medical treatment), 35 eyes that had undergone a prophylactic iridectomy because of acute angle closure of the contralateral eye were investigated retrospectively. The mean follow-up time of the 35 eyes was 6.1 years. None of the prophylactically iridectomized eyes developed angle-closure during follow-up. No significant change in visual acuity was present in the group of patients less than 65 years of age (n = 12). This group had a preoperative visual acuity of 0.85 +/- 0.18 and a visual acuity of 0.81 +/- 0.20 at the last visit. A considerable decrease in visual acuity, however, was found in the group of patients more than 65 years of age (n = 23). This group had a preoperative visual acuity of 0.64 +/- 0.24 and a visual acuity of 0.36 +/- 0.23 at the last visit. Biomicroscopically, one eye (8%) in the age group less than 65 years developed further lens opacity, whereas 15 eyes (65%) in the age group more than 65 years developed further lens opacity. In 2 eyes in the older group a cataract operation was performed. Five eyes developed posterior synechiae; in all of these eyes cataract formation increased. The results indicate that cataract progresses more rapidly after iridectomy if the patients are older.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
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↗