The affinity of atropine for muscarine receptors in human sphincter pupillae.

Concentration-dependent contractions in response to carbachol were determined on isolated pieces of human iris. Atropine competivtively antagonized the effect of carbachol. An apparent dissociation equilibrium constant of 0.4--0.7 nM was estimated for the muscarine receptor-atropine complex.

Inotropic and electrophysiological actions of verapamil and D 600 in mammalian myocardium. I. Pattern of inotropic effects of the racemic compounds.

A pattern analysis of inotropic actions was carried out on isotonically chortening cat papillary muscles exposed to (+/-)-verapamil and (+/-)-D 600 and compared to other Ca-antagonistic interventions. 1. (+/-)-Verapamil (1--5mug/ml) leaves contraction amplitudes nearly unchanged at 6/min, whereas at 60/min more than 90% depression (5 mug/ml) occurs. (+/-)-D 600 is about twice as effective as (+/-)-berapamil. 2. An increase of [Ca2+]O in the presence of (+/-)-verapamil or (+/-)-D 600 does not restitute the normal amplitude-frequency relationship. There is only a shift toward higher contraction amplitudes. 3. (+/-)-Verapamil and (+/-)-D 600 lead to typical biphasic inotropic transients after step changes of the friving rhythm. First a fast and (at higher frequencies) very pronounced negative staircase occurs, followed by a rather slowly developing positive staircase. 4. These drug effects contrast to the effects of lowering [Ca2+]O or of adding Ni2+ or La3+, which all produce a rather uniform depression of contraction amplitudes at all frequencies and do not elicit staircase phenomena such as seen under the influence of (+/-)-verapamil or (+/-)-D 600. 5. In contrast to the action of Ni2+, La3+ or low [Ca2+]O, (+/-)-verapamil slows down the restitution kinetics of Ca-reavailability from internal stores as determined by the amplitude of test contractions elicited after various periods of rest. 6. Drug-induced changes in the time course of the transmembrane action potential as depending on frequency may partially but not fully explain the contractile phenomena. 7. Possible interpretations as to the sites where (+/-)-verapamil or (+/-)-D 600 interferes with cardiac excitation-contraction coupling are given by the aid of a multicompartment model. This model describes excitation-contraction coupling in terms of transmembrane and intracellular Ca-movements.

Holmium:YAG laser thermokeratoplasty for correction of astigmatism.

The effect of astigmatic Holmium:YAG laser thermokeratoplasty in three eyes with previous surgery (extracapsular cataract extraction, penetrating keratoplasty and failed extracapsular cataract extractionntric photorefractive keratectomy 1 to 7 years previously) was evaluated. In the extracapsular cataract extraction eye the effect of a four-spot laser thermokeratoplasty regressed to almost zero within 1 week. In the penetrating keratoplasty and photorefractive keratectomy eyes an eight-spot laser thermokeratoplasty produced an enormous overshoot in astigmatic power of about 15.00 diopters (D), decreasing within 5 months to almost zero in the eye with penetrating keratoplasty and to 4.00 to 5.00 D corneal astigmatic power in the photorefractive keratectomy eye after 8 months of observation.

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.

A high-stability, one-stitch W incision for cataract surgery.

We describe a technique to create a highly stable, one-stitch incision for use with rigid posterior chamber intraocular lenses (IOLs). Inverse U and W incisions are compared in 203 consecutive eyes with 3 months follow-up. A scleral groove resembling an inverted W is dissected away from the limbus, and the anterior chamber is entered by a conventional tunnel technique that resembles a frown incision but has an additional triangular, central scleral flap. When the incision is closed, a single stitch is placed through the flap, away from the limbus. Advantages of the W incision include reduction and control of astigmatism, improved self-sealing, reduced postoperative leakage, no special suture-material requirements, high mechanical stability, easy extendability for extracapsular cataract extraction or trabeculectomy, and intraoperative sealing of a leaking irrigation/aspiration opening by inverting the flap. The W incision offers high stability and multiple advantages over the frown incision and is suitable for use with rigid posterior chamber IOLs.

Asymmetric L-shaped corneal no-stitch tunnel incisions for cataract surgery.

PURPOSE: To assess whether a unilateral asymmetric radial enlargement of a corneal tunnel incision for implantation of foldable intraocular lenses yields advantages over conventional linear enlargements. SETTING: Department of Ophthalmology, University of Brussels, VUB, Belgium. METHODS: Asymmetric corneal tunnel incisions with an L-shaped entrance and a concave exit were compared with equivalent conventional linear incisions in patients and in postmortem eyes. RESULTS: The asymmetric no-stitch L-designs scored consistently better than the symmetric linear designs in induced astigmatism, postoperative astigmatic shift, complications, and pressure resistance. CONCLUSION: An asymmetric corneal L-incision is superior to a conventional symmetric linear incision.

Alteration of the visual evoked potential and the electroretinogram in lead-treated monkeys.

Rhesus monkeys were pre- and postnatally exposed to either 0, 350, or 600 ppm lead acetate in lab chow. At the age of 7-7 1/4 years visual evoked potentials (VEP) and electroretinograms (ERG) were recorded. Flashes were used as stimuli. The VEP was taken under two background illuminance conditions. Lead-related decreases in amplitudes and increases in latencies were observed. Effects on amplitudes were more pronounced under the dark condition while latencies were more affected at the bright background level. The ERG was studied during the course of dark adaptation. The increase in amplitudes of the b-wave during the adaptation period was more prominent in lead-exposed subjects than in controls. Oscillatory potentials were not altered by lead. The findings are discussed in terms of the physiological mechanisms underlying these different potentials.

Sulcus fixated posterior chamber lenses with and without suture in cases lacking capsular support.

In a prospective study ten commercially available anterior chamber lenses with S-shaped haptics and multipoint support were implanted into the posterior chamber in cases of secondary lens implantation after intracapsular cataract operation. The lenses were trans-sclerally fixed by two sutures through the ciliary sulcus. They showed more immediate stability than ten C-loop posterior chamber lenses of a control group and remained firmly fixed without complications during a follow-up of up to 54 months. To overcome the disadvantages of suture fixation a sutureless sulcus self-fixation PCL was developed and implanted into six eyes with special indications. After more than one year of follow-up no late adverse reaction was noted.

[Asymmetric corneal tunnel incision for routine phacoemulsification and lens implantation]. / Asymmetrische korneale Tunnelinzision für die Routine-phakoemulsifikation und -linsenimplantation.

UNLABELLED: This study was designed to investigate whether it is possible to improve wound stability and reduce induced astigmatism of a linear corneal tunnel incision for the implantation of foldable intraocular lenses by radializing wound components. MATERIALS AND METHODS: A 4.1-mm linear and a 2.5 x 2.5-mm L-shaped corneal tunnel incision were compared in 60 and 59 patients, respectively. RESULTS: Complications and induced astigmatism (vector analysis) were significantly less in the L-shaped incision group than in the linear incision group (0.62 +/- 0.53 D vs. 0.84 +/- 0.75 D after 3 months). CONCLUSION: An L-shaped incision seems to be superior to the conventional linear type.

Astigmatic change after myopic spherical excimer PRK.

85 Patients who underwent a spherical PRK with an average of 6.08 dptr. and who could be followed over a period of 1 year were evaluated. After 1 year an average induced astigmatism of 0.58 dptr. was found. There seems to be a correlation between induced astigmatism and depth of PRK but not between induced astigmatism and pre-existent astigmatism. In cases of decentrated PRK a spontaneous regression of laser-induced astigmatism could be observed.

The use of hyaluronic acid of different viscosities in preventing postoperative hypotony after trabeculectomy.

Using hyaluronic acid (Healon) at the end of a trabeculectomy to fill the anterior chamber reduces postoperative hypotonia, while hyaluronic acid of higher viscosity (Healon GV) can provoke a pseudomalignant glaucoma.

Various indications for artificial aqueous drainage systems (Molteno implant).

In reoperations the draining effect of a Molteno Implant can be enhanced by a "sandwich" arrangement or a "bleb to bleb" anastomosis. Molteno implants can also be inserted via a pars plana trepanation and can control juvenile glaucoma. They are also compatible with anterior chamber lenses and corneal transplants.

Implantation of posterior chamber lenses of more than 30 dptr.

Posterior chamber lenses of more than 30 dptr. are supposed to correct preexisting high hyperopia. With high diopters, however, problems emerge which are not to be found in eyes requiring lower lens powers. These problems are neurosensory disorders, residual accommodation, difficulties in power calculation, unavailability of appropriate lenses and thick lens optics. These difficulties and possible solutions are addressed referring to cases of IOL powers between 46 and 53 dptr.

Posterior chamber lens implantation in children and infants.

Today the implantation of posterior chamber lenses in children and infants is still controversial. We report on the results of posterior chamber lens (PCL) implantation in a series of children with unilateral cataract, aged between 6 months and 14 years.

Transsclerally fixed posterior chamber lens in absence of posterior lens capsule support.

If an anterior chamber lens is contra-indicated in case of a (secondary) lens implantation with absence of a posterior capsule support, a posterior chamber lens (PCL) can be implanted fixing the haptics by sutures. The fixation is best achieved by directly suturing the haptics transsclerally into the sulcus, or indirectly by means of an iris flap created from an iridectomy. Complications are rare and not severe and long-term stability is rather good, provided an appropriate technique is applied including small incision, anterior vitrectomy and the use of viscoelastics. Forty-eight cases are reported with a follow-up of more than 5 years.

Long-term results of wagon wheel packed acrylic intra-ocular lenses (AcrySof).

To evaluate long-term results of Wagon Wheel packed AcrySof intraocular lenses (IOLs), 88 and 39 patients (115 and 55 eyes respectively) were examined at 14 and 28 months respectively. Visual acuity increased from an average of 0.324 preoperatively to about 0.722 one week post-operatively. A YAG capsulotomy had to be performed in two eyes only. Vacuoles, as described with the Acry Pak system, were also detectable in our Wagon Wheel packed lenses. They increased significantly in incidence and number with time.

Medium term results of HEMA intraocular lenses (Hydroview).

A group of 232 eyes that received a HEMA IOL (Hydroview, Storz Inc.) was followed over a period of six months. Mean visual acuity increased from 0.41 preoperatively to 0.79 post-operatively. During the follow-up period, the visual acuity remained stable in 175 eyes and decreased in 57 eyes, mainly due to progression of ARMD and posterior capsule opacification (PCO). Nine eyes required YAG-laser capsulotomy. Cell migration on the anterior surface of the Hydroview IOL was observed in 100% of the cases after a period of 3 months.

Cyclocryotherapy as an alternative treatment for primary glaucoma.

Cyclocryotherapy was used as an alternative treatment for primary glaucoma in a series of 56 patients, both with narrow and open angle. In this prospective study treatment was successful in 87.7% of the cases (Peak I.O.P. < or = 20 mm Hg) with a mean follow up period of 10.1 months. Mean intraocular tension decreased from 29.7 mm Hg preoperatively down to 17.25 mm Hg postoperatively. About 60% of the eyes, however, needed an additional local treatment. Postoperative complications were rare and mild. A conjunctival congestion, and a mild self limiting iridocyclitis, were the most frequent ones. Long term efficacy was evaluated retrospectively (21 eyes with primary glaucoma; mean follow up period: 51 months). 58.3% were still controlled today, the majority of them requiring local medication. A further deterioration of visual field, however, had been noticed in 26.6% of these "obviously normotensive eyes". Because of its good efficacy and its lack of severe complications as opposed to trabeculectomy cyclocryotherapy is suggested as a first choice treatment in primary glaucoma.

Are bifocal intraocular posterior chamber lenses superior to monofocals?

Twenty-eight eyes of 26 patients underwent a phacoemulsification with implantation of a bifocal posterior chamber lens (Storz-True Vista). The mean visual acuity increased from 0.28 to 0.74. To obtain best visual acuity for near, 19 eyes needed additional reading addition. A subgroup of 14 patients underwent also a phacoemulsification with implantation of a monofocal posterior chamber lens into the other eye. The mean visual acuity increased from 0.25 to 0.84. All monofocal eyes obtained an optimal near vision with a reading addition of 3 diopters. In this subgroup 9 patients preferred their monofocal eye for distance vision and 10 for near vision. Not a single patient preferred the bifocal eye.

W incision for combined cataract and glaucoma surgery.

The W incision can be regarded as a self sealing incision with an additional posterior flap. For cataract surgery, the flap can be used to add further stability to the incision whilst for combined glaucoma surgery it can also be used to "cover" a trabeculectomy located underneath. Up to now, 14 eyes underwent a combined cataract and glaucoma surgery using the W incision. In this article the short term postoperative results and advantages of this new technique in combined cataract and glaucoma surgery are discussed.