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Biomedical subjects

F Grehn

Publications and source records attributed to F Grehn.

At least 37 records · Page 2Linked to original sources
PubMed1995

The value of trabeculotomy in glaucoma surgery.

Trabeculotomy has received increasing interest as a glaucoma procedure not only in congenital glaucoma but also in adult-onset open-angle glaucoma. In this review, the development, surgical technique, mechanism of action, and results after trabeculotomy in different types of glaucoma are described. Combined trabeculotomy and trabeculectomy and combined cataract and trabeculotomy techniques are discussed. Some remarks are given on laser trabeculotomy ab interno and other developments of trabecular surgery.

Cataract Extraction↗
PubMed1995

[Ultrasound biomicroscopy findings in various forms of glaucoma].

Ultrasound biomicroscopy is a new imaging technology that uses high-frequency ultrasound and thus allows depiction of the anterior portion of the globe in microscopic resolution. It is independent on the clarity of the optical media and allows, for the first time, a non-invasive demonstration of the structures of the posterior chamber and their relationship to each other. Therefore, it is especially suitable for diagnosis and research on the various forms of glaucoma. Our examinations were performed with an ultrasound biomicroscope (UBM Humphrey Model 840) with a 50 MHz transducer. This allows resolution of structures up to 50 microns. Thirty-nine patients with different forms of glaucoma were examined: POAG, pigmentary glaucoma, pseudoexfoliation glaucoma, pupillary block, plateau iris syndrome, ciliolenticular block, congenital glaucoma, traumatic glaucoma and situations after glaucoma surgery. The following findings could be demonstrated: configuration of the anterior chamber angle region, iris curvature, ciliary body and lens position, differentiation between solid and cystic tumors, traumatic changes and trabeculectomy openings. With this information ultrasound biomicroscopy offers additional details for the differential diagnosis and treatment of various forms of glaucoma.

Anterior Chamber↗
PubMed1995

[The Müller-ectomy in endocrine orbitopathy].

Thyroid ophthalmopathy frequently causes significant upper- and lower-eyelid retraction. This is not only cosmetically disfiguring, but also causes the cornea to be exposed so that a lid-correcting procedure becomes necessary. We used the Mueller ectomy technique with mechanical disinsertion of the levator muscle of the upper eyelid, as described by Putterman et al. in 1972, and operated on ten patients with thyroid ophthalmopathy. By means of the Mueller ectomy and mechanical disinsertion of the levator muscle of the upper eyelid, the eyelid was lowered by 5.0 mm compared with the preoperative findings (measured as the distance between the edge of the upper eyelid and the center of the pupil). In 3 cases the postoperative result was a temporal upper eyelid flare that required operative correction in one case; in one case a ptosis resulted postoperatively. Transconjunctival Mueller ectomy with mechanical disinsertion of the levator muscle of the upper eyelid gives good cosmetic and functional results in patients with significant upper-eyelid retraction. The transconjunctival approach avoids external scar formation and leaves the external lid structures intact so that a revision can be performed by an external lid incision.

Adult↗
PubMed1995

Color Doppler imaging: a new technique to assess orbital blood flow in patients with diabetic retinopathy.

PURPOSE: Color Doppler imaging is a new noninvasive technique that enables measuring blood flow velocity in small orbital vessels, arteries as well as veins. Because hemodynamic changes are seen in patients with diabetic retinopathy by other techniques, the authors compared 61 eyes with proliferative, 59 eyes with nonproliferative, and 26 eyes with preproliferative diabetic fundus changes with a matched control group of 70 patients without diabetes (128 eyes). METHODS: The central retinal artery (CRA), short posterior ciliary artery (PCA), and ophthalmic artery (OA) of all patients were examined, and the systolic, diastolic, and mean velocities were measured for each vessel. RESULTS: Differences between the groups were most prominent in the CRA. The perfusion velocity was significantly lower (P < 0.001) in proliferative eyes (Vsystolic 5.7 +/- 1.8 cm/sec) than in the control group (Vsystolic 9.4 +/- 1.2 cm/sec) or in nonproliferative eyes (Vsystolic 8.4 +/- 1.8 cm/sec). In the preproliferative group, there was greater variability in velocity distribution. Consequently, no statistically significant difference could be deduced, either in the group with background retinopathy or in the group with proliferative diabetes. In the OA and PCA, neither group showed significant differences from normal. CONCLUSIONS: Measurements indicate a correlation between severity of diabetic retinopathy and decreased flow velocity in the CRA.

Adult↗
PubMed1995

Cataract extraction combined with trabeculotomy.

Eyes with glaucomatous damage as well as eyes showing a clear elevation of intraocular pressure (IOP) to levels above normal frequently develop a permanent elevation of IOP after phacoemulsification or extracapsular cataract extraction, whereas the pressure in normal eyes usually decreases. In eyes with glaucomatous damage, we therefore combined cataract extraction with an antiglaucomatous operation, especially if a moderate pressure elevation was present: trabeculotomy and cataract extraction were performed in the same procedure. A corneal incision was used for phacoemulsification or extracapsular cataract extraction. The effects of the operation on the IOP and the visual acuity as well as the incidence of postoperative complications were investigated. In 44 operated eyes, the combination of cataract extraction and trabeculotomy proved to result in few complications and had a sufficient pressure-decreasing effect that continued throughout the 18 months of postoperative follow-up.

Aged↗
PubMed1995

Prophylactic Nd:YAG-laser iridotomy versus surgical iridectomy: a randomized, prospective study.

Both surgical iridectomy and YAG-laser iridotomy have been shown to prevent angle-closure glaucoma. However, it remains unknown as to which procedure is superior. We therefore conducted a prospective randomized study, which compared the effect of the two methods on visual acuity, intraocular pressure, endothelial cell density, depth of the anterior chamber, and iris configuration as well as acceptance by the patients. A total of 30 patients, who were treated for acute angle-closure glaucoma in one eye, were subjected to either surgical iridectomy or Nd:YAG-laser iridotomy in the other eye according to a randomized protocol. All patients were followed for 12 months by examination at the 1st, 6th, and 12th month post treatment. No significant difference between the two treatments was found regarding visual acuity or intraocular pressure. The peripheral anterior chamber increased in depth following both methods, whereas the central depth of the anterior chamber was unaffected. A better gonioscopic visibility of the trabecular meshwork resulted from the increased width of the chamber angle. Whereas the number of endothelial cells remained constant in the patients treated with laser iridotomy, a small decrease was observed in the group of patients who underwent iridectomy (-7.2% after 12 months; difference not significant). The subjective acceptance by the patients was better in the group treated with laser iridotomy. We conclude that the two methods are equivalent with regard to intraocular pressure and visual acuity. The constant number of endothelial cells and the better acceptance by the patients suggest Nd:YAG-laser iridotomy to be the preferable method for prophylaxis of acute angle-closure glaucoma.

Acute Disease↗
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↗