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Biomedical subjects

R Menapace

Publications and source records attributed to R Menapace.

At least 19 recordsLinked to original sources
PubMed1998

Reversal of endothelin-1-induced ocular hemodynamic effects by low-dose nifedipine in humans.

BACKGROUND AND PURPOSE: There is evidence that calcium channel blockers may be useful in patients with normal tension glaucoma and vasospastic reactions. We therefore hypothesized that calcium channel blockers may increase ocular blood flow and that there may be a functional antagonism between endothelin-1 (ET-1) and calcium channel blockers in the ocular vasculature. METHODS: This was a randomized, double-blind, three-way crossover study with respect to ET-1 infusions (placebo, 2 ng/kg/min ET-1, and 4 ng/kg/min ET-1) and a randomized double-blind study in two parallel groups with respect to nifedipine (placebo or 5 mg nifedipine). Ocular hemodynamics in the 12 healthy subjects participating in the study was assessed by laser interferometric measurement of fundus pulsation amplitude (FPA) in the optic disc and two-dimensional scanning laser Doppler flowmetry in the optic disc. RESULTS: ET-1 caused a dose-dependent decrease in FPA and flow. With a dose of 4 ng/kg/min a decrease of -18% +/- 5% (p < 0.001) and -17% +/- 5% (p = 0.023) on FPA and flow, respectively, were observed. This effect was completely reversed by nifedipine compared with placebo (FPA, p < 0.001; flow, p = 0.011). However, nifedipine did not affect ocular hemodynamics after placebo infusion. CONCLUSIONS: These results show that nifedipine does not increase optic nerve head blood flow during baseline conditions but reverses ET-1-induced constriction in ocular vasculature at doses that do not affect systemic hemodynamics. This supports the close relation of the therapeutic effect of calcium channel blockers in patients with normal tension glaucoma to the endothelin system. Moreover, the present study provides a strong rationale for a study of low dose nifedipine as a supplementary medication in glaucoma patients.

Adult↗
PubMed1998

Ultrastructure of clear corneal incisions. Part I: Effect of keratomes and incision width on corneal trauma after lens implantation.

PURPOSE: To examine the ultrastructure of clear corneal incisions (CCIs) performed with diamond keratomes and steel blades as well as the corneal trauma after implantation of a foldable intraocular lens (IOL) through two incision widths. SETTING: University Eye Clinic and Institute of Histology and Embryology II, University of Vienna, Austria. METHODS: Twenty-four human cadaver eyes without prior ocular surgery were obtained from the University Eye Bank, Vienna. Single-plane CCIs were performed with 3.0 and 3.2 mm Alcon steel blades and with a 3.0 mm Huco diamond keratome. The AMO PhacoFlex II lens was implanted with a Fine II folder. During the entire procedure, the eye pressure was kept between 26 and 30 mm Hg by infusing balanced salt solution into the anterior chamber. Specimens were prepared for light microscopy, transmission electron microscopy, and scanning electron microscopy according to standard procedures. RESULTS: The diamond keratome produced cleaner cuts than the steel blade. After IOL implantation, 3.0 mm steel blade incisions exhibited extensions at their lateral ends. Within these extensions, the collagen lamellae were displaced and torn. This was not true with 3.2 mm tunnels. Because of the thickness of a 3.0 mm diamond keratome, the extent of corneal trauma was between that found with 3.0 and 3.2 mm steel keratome tunnels. CONCLUSIONS: Implantation of the SI-30 through 3.0 mm CCIs produced by the steel blade led to more severe corneal trauma than implantation through 3.2 mm steel blade incisions or 3.0 mm diamond keratome incisions. Thus, IOL implantation through incisions that are too small intensifies corneal trauma.

Aged↗
PubMed1998

Ultrastructure of clear corneal incisions. Part II: Corneal trauma after lens implantation with the Microstaar injector system.

PURPOSE: To examine the ultrastructure of clear corneal incisions (CCIs) after implantation of a plate-hepatic intraocular lens (IOL) with the Microstaar injector system through two incision widths. SETTING: University Eye Clinic and Institute of Histology and Embryology II, University of Vienna, Austria. METHODS: Fourteen human cadaver eyes without prior ocular surgery were obtained from the University Eye Bank, Vienna. Single-plane CCIs were performed with 3.0 and 3.2 mm steel keratomes. Using the Microstaar injector system, a foldable silicone plate-haptic IOL (23 diopters) was implanted in the anterior chamber. During the entire procedure, the eye pressure was kept between 26 and 30 mm Hg by infusing balanced salt solution into the anterior chamber. Specimens for light microscopy and scanning electron microscopy were prepared according to standard procedures. RESULTS: After IOL implantation, the 3.0 mm steel blade incisions exhibited distinct distensions at their lateral ends. Adjacent to these distensions, the collagen lamellae were pressed apart, displaced, and torn. In 3.2 mm tunnels, the corneal trauma at both lateral ends was considerably less severe. These incisions also showed a better primary adaptation of the wound lips after implantations. CONCLUSIONS: Implantation performed with the Microstaar injector system through 3.0 mm steel blade CCIs led to considerably more severe corneal trauma than implantation through 3.2 mm incisions.

Aged↗
PubMed1998

Phacotrabeculectomy with a small-optic PMMA implant: two-year functional and morphological results.

PURPOSE: Previous studies have documented good pressure control with combined cataract and filtering surgery. However, relatively high incidences of iridocapsular synechiae (ICS) and cell precipitates on the optic (CPO) were found. Corneal valve incisions preclude intraoperative chamber flattening and iris injury or prolapse. Rigid one-piece PMMA lenses with a small optic maintain a pronounced optic-iris clearance. In a prospective series, the effect of this approach was studied with special regard to the morphological results. METHODS: A temporary corneal lip was created in the clear cornea beneath the scleral flap to serve as a temporary valve during cataract extraction. The lip was then widened and a rigid one-piece 5-mm PMMA lens implanted. Lip and trabeculum were finally excised en bloc at a width of 3 mm. Two years' functional and morphological results were evaluated. RESULTS: Fifty-four eyes were available for evaluation. After the mean follow-up of 21 months, mean IOP had dropped from 21.6+/-3 mm Hg preoperatively to 13.9+/-2.4 mm Hg, with a mean pressure reduction of 7.7+/-3.4 mm Hg. IOP was 18 mm Hg or less in all cases. The mean medication index dropped from 2.7 to 1.0. Eyes with a preoperative IOP of 21 mm Hg or more showed a significantly greater IOP reduction than eyes with an IOP of 20 mm Hg or less (-9.2+/-3.0 vs. -6.1+/-2.9 mm Hg, p = 0.0003). Intraoperatively, the temporary valve effectively prevented chamber flattening and iris injury or prolapse. Postoperatively, 9 eyes or 6% showed hyphemas, 1 undergoing lavage. Two eyes developed a capsular hematoma, 1 requiring YAG capsulotomy. Ten eyes or 19% developed mild and 2 eyes severe but transient fibrin exudation following hypotony or iridoplasty. One eye showed grade I anterior chamber flattening, 1 developed a ciliolenticular block requiring surgery. Postoperative pressure spikes of 30-35 mm Hg were noted in 4 eyes. Three eyes showed prolonged hypotony associated with transient choroidal effusion. A pronounced optic-iris clearance was found in 87% of the eyes. Iris-optic touch developed in 1 eye with prolonged postoperative anterior chamber flattening and in 3 of the 4 eyes that had undergone intraoperative iridoplasty. Three of the latter developed extensive ICS followed by CPO. The mean optic-iris distance was 1.2 mm and the anterior chamber depth 4.2 mm. CONCLUSION: Apart from effectively lowering IOP, the surgical approach used significantly reduced the incidence of ICS and CPO.

Anterior Eye Segment↗
PubMed1998

Dose-dependent protection by azelastine eye drops against pollen-induced allergic conjunctivitis. A double-blind, placebo-controlled study.

The efficacy and tolerability of azelastine (CAS 58581-89-8) eye drops at three different doses (0.025%, 0.05% and 0.1%) were investigated in a double-blind, randomized, placebo-controlled, crossover study in 24 subjects with a history of allergic conjunctivitis/rhinoconjunctivitis, who were challenged, out of season, by airbone allergen in the "Vienna Challenge Chamber" (VCC). Subjects received a single dose of azelastine eye drops 60 min before the start of a 4 h challenge in the VCC. Additional local challenge, mimicking a gust of wind, was administered 15 min before the end of the session. Each of the 4 study days was separated by a 2 week washout period. Azelastine eye drops showed a dose-dependent inhibition of the development of itching of the eyes. The effect was most pronounced 15 min after the additional local challenge. A maximal effect was achieved at a dose of 0.05%. Similar effects were observed on lacrimation. Azelastine eye drops also dose-dependently inhibited the degree of conjunctival redness, measured by digital imaging, and tended to reduce the low incidence of chemosis observed. Ranking of the results of all symptoms for each treatment group confirmed the optimal effect at a dose of 0.05%. Azelastine eye drops had no effect on nasal and bronchial symptoms or on measurements of airways function (FEV1). No adverse effects of the treatments were reported. The data support the use of 0.05% azelastine eye drops in the treatment of allergic conjunctivitis/rhinoconjunctivitis.

Adult↗
PubMed1997

Capsular bag shrinkage after implantation of an open-loop silicone lens and a poly(methyl methacrylate) capsule tension ring.

PURPOSE: To quantify the dynamics of capsular bag shrinkage after cataract surgery. SETTING: University Eye Hospital, Vienna, Austria. METHODS: Nineteen eyes in 13 patients had clear corneal cataract surgery with implantation of a foldable, open-loop, silicone posterior chamber intraocular lens (IOL) (AMO SI-30). At the same time, an open, poly(methyl methacrylate) capsule tension ring (Morcher type 14 or 14A) was inserted to allow measurement of capsular bag circumference and diameter. After surgery, capsular bag shrinkage was quantified by measuring anterior chamber depth (ACD), iris-lens distance (ILD), and distance between the eyelets of the capsule tension ring using optical methods. Capsular bag circumference (CBC) was deduced from these measurements, which were taken 1 day (baseline), 1 week, and 1 and 3 months postoperatively. RESULTS: Between 1 day and 3 months, all three parameters decreased significantly. During the first postoperative week, ACD and ILD did not change, while both parameters decreased between 1 week and 1 month. After 1 month, ACD did not decrease further; ILD continued to decrease. The CBC decreased during the entire postoperative period. CONCLUSION: Besides ACD and ILD, CBC significantly decreased during the first 3 months after cataract surgery with in-the-bag posterior chamber IOL implantation. The CBC can be calculated from the distance between the ends of the capsule tension ring, which can be measured gonioscopically. From this, the diameter of the capsular bag can be calculated in the living eye. The influence of the capsule tension ring itself on capsular bag shrinkage remains to be established.

Anterior Chamber↗
PubMed1997

Topical anesthesia with pH-adjusted versus standard lidocaine 4% for clear corneal cataract surgery.

PURPOSE: To evaluate and compare the efficacy of a sodium-bicarbonate-adjusted preparation of lidocaine 4% (pH = 7.2) and standard lidocaine (pH = 5.2) for topical anesthesia in clear corneal cataract surgery. SETTING: Department of Ophthalmology, University of Vienna, Austria. METHODS: In a prospective, randomized, double-blind clinical trial, clear corneal cataract surgery was performed under topical anesthesia in 44 eyes of 34 patients. In 22 eyes, pH-adjusted lidocaine 4% was administered; in the other 22, standard lidocaine 4%. Aqueous and serum concentrations of lidocaine were measured by high-performance liquid chromatography and ultraviolet detection. Subjective pain was assessed using a visual analog scale of no pain (0%) to worst imaginable pain (100%). On the first postoperative day, visual acuity, intraocular pressure, and corneal staining with fluorescein were examined. RESULTS: In the pH-adjusted lidocaine group, significantly higher lidocaine concentrations were found in the aqueous humor (15.06 microg/mL +/- 8.2 [SD] versus 4.75 +/- 3.5 microg/mL; P < .0001). In all samples (n = 8), serum lidocaine concentrations were below a minimum detectable level of 0.02 microg/mL. Subjective pain ratings were similar in the pH-adjusted and standard lidocaine groups (mean 9.73 +/- 10.4% and 10.0 +/- 15.4%, respectively). There was no significant between-group difference in intraoperative and postoperative outcomes. CONCLUSIONS: In this study, pH-adjusted lidocaine 4% was a safe, effective topical anesthetic for clear corneal surgery and had minimal local and systemic toxicity. Administration of pH-adjusted lidocaine 4% resulted in significantly higher aqueous humor lidocaine concentrations than administration of standard lidocaine 4%.

Administration, Topical↗
PubMed1997

Surgically induced astigmatism following a 4.0 mm sclerocorneal valve incision.

PURPOSE: To determine whether sutureless small incision cataract surgery reduces induced astigmatism over the long term. SETTING: University Eye Hospital, Vienna, Austria. METHODS: In a prospective study, we investigated surgically induced astigmatism in 63 cases of no-stitch, small incision cataract surgery with a 4.0 mm square sclerocorneal tunnel and implantation of a flexible intraocular lens. Follow-up was 4 to 5 years. Keratometry was measured with a Zeiss keratometer preoperatively and after 1 day, 1 week, 1, 3, and 9 months, and a median of 4.4 years. In 21 nonoperated eyes, we investigated the natural course of astigmatism over 5 years. RESULTS: The mean keratometric cylinder stabilized at 0.8 diopter (D) after 1 week and slightly decreased to 1.0 D after 4 to 5 years. Cravy's vector analysis showed an immediate against-the-rule (ATR) shift of -0.2 D that remained relatively stable until 9 months. Between 9 months and 4.4 years postoperatively, there was a statistically significant increase in ATR induced astigmatism from -0.2 to -0.5 D. The natural course of astigmatism in the nonoperated eyes showed an ATR shift of -0.1 D for the same period. CONCLUSION: The result show a small, though statistically significant amount of postoperatively induced astigmatism 4 to 5 years after no-stitch, small incision cataract surgery.

Aged↗
PubMed1997

Effects of changes in intraocular pressure on human ocular haemodynamics.

PURPOSE: Myogenic autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. Ocular perfusion pressure is defined as the difference between ocular arterial pressure and ocular venous pressure, the latter dependent on intraocular pressure (IOP). The aim of the present study was to investigate the effect of moderate increases in IOP on ocular haemodynamics. METHODS: Changes in IOP (+ 10 mmHg, +20 mmHg) were induced by a suction cup in 10 healthy subjects. Ocular fundus pulsations in the macula and the optic disc were measured by laser interferometry; blood flow velocities in the central retinal artery (CRA) and in the ophthalmic artery (OA) were measured by Doppler sonography. RESULTS: Changes in IOP caused a significant reduction in fundus pulsations, which was more pronounced in the macula (at +10 mmHg: -9 +/- 2%, p < 0.01; at +20 mmHg: -19 +/- 3%, p < 0.001) than in the optic disc (at +10 mmHg: -5 +/- 2% (ns); at +20 mmHg: -9 +/- 3%, p < 0.01). Mean flow velocity in the CRA was reduced by -5 +/- 3% at +10 mmHg (ns) and by -14 +/- 5% at +20 mmHg (p < 0.005), resistive index was increased by +4 +/- 1% at +10 mmHg (p < 0.05) and by +6 +/- 2% at +20 mmHg (p < 0.01). In contrast, a rise in IOP did not affect blood flow parameters in the OA. CONCLUSIONS: Our results from fundus pulsation measurements indicate that choroidal blood flow decreases when IOP is increased. The Doppler sonographic findings in the CRA indicate reduced blood flow velocity in this artery during raised IOP.

Adult↗
PubMed1997

Reproducibility and sensitivity of scanning laser Doppler flowmetry during graded changes in PO2.

AIMS/BACKGROUND: Recently a commercially available scanning laser Doppler flowmeter has been produced, which provides two dimensional maps of the retinal perfusion. The aim of the present study was to investigate the reproducibility and the sensitivity of these measurements. METHODS: 16 healthy subjects were randomised to inhale different gas mixtures of oxygen and nitrogen in a double blind crossover study. The following gas mixtures of oxygen and nitrogen were administered: 100% oxygen + 0% nitrogen, 80% oxygen + 20% nitrogen, 60% oxygen + 40% nitrogen, 40% oxygen + 60% nitrogen, 30% oxygen + 70% nitrogen, 20% oxygen + 80% nitrogen, 15% oxygen + 85% nitrogen, and 10% oxygen + 90% nitrogen. Retinal haemodynamic variables and systemic haemodynamics were measured during all inhalation periods. Recordings under resting conditions were performed three times to calculate intraclass coefficients. RESULTS: In two subjects we did not obtain technically adequate results. A dose dependent change in retinal blood flow during graded oxygen breathing was observed (p < 0.001). During 100% oxygen breathing blood flow decrease was between 29% and 33%, whereas blood flow increase was between 28% and 33% during inhalation of 10% oxygen + 90% nitrogen. CONCLUSIONS: Scanning laser Doppler flowmetry has an acceptable reproducibility and is appropriate for description of the effect of graded changes in PO2 on retinal haemodynamics. The main problems with the system are the large zero offset, the fixation during retinal scanning, and the neglect of blood flow changes during the cardiac cycle.

Adult↗
PubMed1996

Quantification of conjunctival vascular reaction by digital imaging.

BACKGROUND: No objective evaluation of the conjunctival provocation test (CPT) was possible until now. OBJECTIVE: The aim of this study was to develop a tool that would enable us to monitor conjunctival allergic inflammation by objective measurements. METHODS: Twenty-four patients allergic to grass pollen were challenged by a CPT with grass pollen and genuine grass pollen in the "Vienna Challenge Chamber." Patients were randomized to treatment with placebo or topical application of an H1-receptor antagonist (azelastine). Vascular reaction of the conjunctiva was repeatedly monitored by special video equipment. The signal was sent to a digital frame grabber, and digital image analysis was done with the aid of the WCUE-3 program (Olympus Optical Co., Hamburg, Germany). RESULTS: The CPT led to an immediate increase of the red density. This extension was linear within the first 15 minutes. During the long-term challenge, the increasing vascular effect lasted 2 hours. During active treatment a consistent reaction pattern was obvious; however, the corresponding levels were statistically lower (p = 0.022). CONCLUSION: The calculation of red density of the conjunctiva by digital analysis proved to be a sensitive tool for measuring the conjunctival allergic reaction. It is possible to overcome the insufficient subjective evaluation of the CPT by objective measurements of the vascular reaction.

Adult↗
PubMed1996

Topical versus peribulbar anesthesia in clear corneal cataract surgery.

PURPOSE: To evaluate the efficacy of topical anesthesia as an alternative to peribulbar anesthesia in clear corneal cataract surgery. SETTING: Department of Ophthalmology, University of Vienna, Austria. METHODS: In this prospective, double-blind clinical trial, 36 patients had bilateral cataract surgeries performed from 1 to 3 months apart. Half of the patients had topical anesthesia for the first surgery and peribulbar anesthesia for the second surgery. The other half had peribulbar first and then topical. All surgery was done using a temporal clear corneal approach and bimanual phacoemulsification followed by in-the-bag intraocular lens implantation. Subjective pain was assessed using a visual analog scale of no pain (0%) to worst pain imaginable (100%) and intraoperative motility using a rank scale of adverse motility (-5) to ideal patient cooperation (+5). RESULTS: Subjective pain was comparable whether topical or peribulbar anesthesia was used (mean 10.75 versus 10.97%; P > .6). Patient cooperation (motility) was significantly better when topical anesthesia was used (+2.16 versus +1.11; P = .03). There were no significant differences in complications. A peribulbar block was given in addition to the topical anesthesia in two cases. CONCLUSIONS: Topical anesthesia is a safe, effective alternative to peribulbar anesthesia in clear corneal cataract surgery.

Administration, Topical↗
PubMed1996

Posterior capsule opacification and capsulotomy rates with taco-style hydrogel intraocular lenses.

PURPOSE: To evaluate posterior capsule opacification (PCO) formation and neodymium: YAG (Nd:YAG) laser capsulotomy results in eyes with an logel intraocular lens (IOL). SETTING: First University Hospital, Vienna, Austria. METHODS: A retrospective study was done of 108 eyes with one of three types of an logel IOL that had decreased vision from PCO and required posterior capsule discission. RESULTS: In general, in eyes with sulcus-placed IOLs, a Soemmering's ring formed and the capsulorhexis rim tightly adhered to the posterior capsule, sealing the capsular bag periphery. Elschnig pearls had broken the barrier, invading the retrolental space. In eyes with bag-placed IOLs, there was a gap between the IOL and posterior capsule in which Elschnig pearls had accumulated. This gap frequently extended beneath the flanges to the periphery of the capsular bag, allowing residual lens epithelial cells to proliferate and migrate centrally. CONCLUSION: The logel lenses led to a high incidence of regeneratory PCO within the gap between the lens and capsule that might be the result of the properties of the lens' hydrogel material rather than its design.

Cataract↗
PubMed1996

In vivo study of cell reactions on poly(methyl methacrylate) intraocular lenses with different surface properties.

PURPOSE: To evaluate the biocompatibility of three poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) with different surface properties. SETTING: University Eye Clinic, Vienna, Austria. METHODS: Cell reactions on the surfaces of unmodified, heparin-surface-modified (HSM), and surface-passivated (SP) PMMA IOLs were documented in vivo using a Zeiss specular microscope. Risk factors for such reactions were also determined. RESULTS: During the first postoperative days, small round and spindle-shaped cells were found on all IOLs. Cell density was higher in eyes with increased postoperative inflammation. After several days, epithelioid and foreign-body giant cells were seen on some IOLs. Cells appeared significantly less often on the IOLs with hydrophilic surfaces (HSM) than on those with hydrophobic surfaces (unmodified, SP). CONCLUSION: The significantly lower incidence of foreign-body reactions on hydrophilic than on hydrophobic IOL surfaces is consistent with the results of previous studies on hydrogel and silicone IOLs.

Aged↗
PubMed1996

Straight-entrance, sclerocorneal valve incision with horizontal sutures for poly(methyl methacrylate) intraocular lenses.

Self-sealing sclerocorneal tunnel incisions with an external frown entry are widely used for implantation of poly(methyl methacrylate) intraocular lenses. Although safe and effective, these incisions have certain drawbacks. We developed a wound construction in which a straight external incision is used in conjunction with a tension-free, infinity-type suture. Out of 100 consecutive cases, only two did not seal satisfactorily at the conclusion of surgery but were tight upon placement of re-enforcing sutures. Postoperatively, the valve remained tight in all cases; there were no cases of hypotony, filtering bleb, flat chamber, or pupil capture or endophthalmitis indicating transient leakage. Flattening in the vertical and steepening in the horizontal meridian were minor and nonprogressive.

Cornea↗
PubMed1996

Batch-by-batch analysis of topographic changes induced by sutured and sutureless clear corneal incisions.

PURPOSE: To evaluate the effect of a suture on surgically induced corneal topographic changes in 5.0 mm clear corneal incisions. SETTING: University Eye Hospital, Vienna, Austria. METHODS: Thirty-seven eyes that had cataract surgery were included in the prospective study. A 5.0 mm long and 0.3 mm deep precut was followed by preparation of a corneal tunnel. After phacoemulsification and intraocular lens implantation, the self-sealing wound was left unsutured in 19 eyes; one radial 11-0 nylon suture was applied in 18 eyes. Using a TMS-1 videokeratoscope, corneal topography was measured preoperatively and at 1 week and 1 and 3 months postoperatively. The topographic data were evaluated by statistical batch-by-batch analysis. Each topographic image was cut into 178 fields in eight concentric rings. The refractive values of these fields were stored in a database. Differences between the four readings of each patient were calculated and the mean differences of the 178 fields in each group were transformed into color-coded maps. The significance of topographical changes and group comparisons of induced changes were computed by Wilcoxon tests. RESULTS: Both groups exhibited significant temporal flattening and vertical steepening. The unsutured eyes also displayed significant nasal flattening. Sutureless 5.0 mm clear corneal incisions induced significantly more vertical steepening and nasal flattening than sutured incisions. CONCLUSION: Application of one radial 11-0 nylon suture in 5.0 mm temporal clear corneal incisions significantly reduced shape changes in the nasal corneal region.

Aged↗