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Biomedical subjects

F Grehn

Publications and source records attributed to F Grehn.

At least 55 records · Page 3Linked to original sources
PubMed1994

Intraocular thymoxamine or acetylcholine for the reversal of mydriasis.

In a placebo-controlled prospective study, thymoxamine 0.02% or acetylcholine 1.0% or thymoxamine 0.01% plus acetylcholine 0.5% were used intraocularly to reverse mydriasis during cataract surgery. Prior to surgery, pupils were dilated with scopolamine 0.25%, tropicamide 1%, and phenylephrine 10%. At the end of surgery, 228 eyes were randomly assigned to 1 of 4 different treatments: 57 eyes each received intracamerally thymoxamine 0.02%, acetylcholine 1%, a combination of both drugs, or placebo. At 5 min posttreatment, there was a significant mean pupillary constriction of 1.86 +/- 0.67 mm following acetylcholine administration and 1.53 +/- 0.80 mm following thymoxamine application as compared with the placebo group, in which the pupillary diameter remained almost constant. For the combination of acetylcholine plus thymoxamine the effect was fully additive, with a pupillary constriction of 3.42 +/- 0.98 and 4.04 +/- 1.02 mm being observed at 5 and 10 min posttreatment, respectively. No drug-related side effect was detected. We conclude that thymoxamine can be useful during surgery as an intraocular miotic to reverse mydriasis and can considerably enhance miosis when given in combination with acetylcholine.

Acetylcholine↗
PubMed1994

[Color duplex ultrasound findings in patients with endocrine orbitopathy].

UNLABELLED: Color Doppler imaging makes it possible for the first time to assess the blood flow velocity of orbital vessels. Especially in Graves disease, with its increase of orbital contents, this technique allows detection of changes in the perfusion of retrobulbar arteries and veins. We examined 23 patients (19 female, 4 male, average age 47.9 years) with thyroid ophthalmopathy using color Doppler imaging. Central retinal artery and vein, posterior ciliary arteries, vortex veins, superior orbital vein and ophthalmic artery were located and their Doppler spectra analysed. Results were compared with observations recorded in a control group consisting of 105 healthy volunteers. The thicknesses of extraocular muscles were measured echographically. RESULTS: There was no significant difference in blood flow velocity in central retinal artery and vein, posterior ciliary arteries and vortex veins between patients with Graves disease and the control group. The maximal blood flow velocity in superior orbital vein was significantly decreased (P = 0.01 on right eye, P = 0.04 on left eye). There was a slight correlation between reduced venous outflow in the superior orbital vein and the severity of the disease (r = 0.52 on right eye, r = 0.5 on left eye). CONCLUSION: Color Doppler imaging is a new, noninvasive technique that could be used to examine patients with thyroid ophthalmopathy. Reduced venous outflow may contribute to exophthalmus by creating perivenous edema and consequent swelling of orbital fat.

Adult↗
PubMed1994

[Color duplex ultrasound. A new procedure in the study of orbital blood vessels in diabetic retinopathy].

Color Doppler imaging is a new noninvasive technique that allows the measurement of flow velocity in small orbital vessels (both arteries and veins). We compared 59 eyes with proliferative, 47 eyes with nonproliferative and 24 eyes with preproliferative diabetic fundus changes with a control group of non-diabetic patients. The central retinal artery, short ciliary artery and ophthalmic artery of each patient were examined. The systolic, diastolic and mean velocity was obtained for each vessel. Differences between the groups were most prominent in the central retinal artery. The perfusion velocity was significantly lower (P < 0.01) in proliferative eyes (Vsyst 5.7 +/- 1.9 cm/s) than in the control group (Vsyst 9.4 +/- 1.4 cm/s) or the nonproliferative eyes (Vsyst 8.3 +/- 1.9 cm/s). In the preproliferative group the velocity distribution varied widely. Consequently, no statistically significant difference could be deduced in relation to either the control group or the group with proliferative diabetic changes. In the ophthalmic artery and ciliary artery no group showed significant differences from normal. Our measurements indicate a definite correlation between the severity of diabetic retinopathy and a decreased flow velocity, particularly in the central retinal artery. Thus, color Doppler imaging may help to identify those diabetic patients who are at high risk of developing severe diabetic retinopathy so that early photocoagulation treatment can be initiated.

Adult↗
PubMed1993

[Postoperative follow-up after goniotrepanation with fornix-based conjunctival flap].

Goniotrephination with a fornix-based conjunctival flap was performed in 60 glaucomatous eyes. The postoperative course was monitored with special reference to intraocular pressure, anterior chamber depth, choroidal detachment and external fistulation. Some degree of choroidal detachment was observed in 1/3 of cases, extending centrally to the equator in only 11% and centrally to the vessel arcade in none. The anterior chamber was found to have become shallow in 16%, but this persisted longer than 3 days in only 6.7%. In 13.3% a external fistula arising from the conjunctival wound persisted for more than 1 day. The described technique with a fornix-based conjunctival flap and meander-like suture at the limbus further reduces the frequency and severity of complications in filtering surgery.

Choroid↗
PubMed1993

[5-fluorouracil in goniotrepanation with poor prognosis. Results of 1-year follow-up].

14 eyes of 14 patients with medically untreatable glaucoma and extremely bad surgical prognosis because of young age, secondary glaucomas or following previous surgery were treated by means of goniotrephination with a scleral flap and a fornix-based conjunctival flap. Postoperatively, all eyes received 5 mg 5-fluorouracil in 0.5 ml NaCl 0.9% subconjunctivally daily for 7 days and weekly for another 6 weeks. IOP was lowered in all eyes from 33.9 +/- 5.0 mmHg preoperatively to 15.6 +/- 8.4 mmHg 1 year postoperatively. 71% of eyes were IOP controlled without further therapy. Results were unfavourable in eyes with irido-corneo-endothelial syndrome. Local side effects were less frequent than described previously, possible due to the reduced but prolonged administration of 5-fluorouracil. Also, all eyes received corneal supportive therapy with hyaluronic acid and polyvinyl alcohol.

Adult↗
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↗