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Biomedical subjects

R Menapace

Publications and source records attributed to R Menapace.

At least 55 records · Page 3Linked to original sources
PubMed1998

Episcleral versus combined episcleral and intrascleral application of mitomycin-C in trabeculectomy.

BACKGROUND AND OBJECTIVE: To determine whether intrascleral exposure to mitomycin-C (MMC) improves the control of intraocular pressure (IOP), increases the incidence of complications, or both. PATIENTS AND METHODS: The authors retrospectively evaluated 38 eyes of 29 patients following the intraoperative application of MMC (0.2 mg/ml; 5 minutes). In 21 eyes the MMC-soaked sponge was applied to the intact episclera (episcleral group). In 17 eyes, two sponges, one episcleral and the other intrascleral (sandwich group), were applied. The median follow-up times were 19.0 (episcleral group) and 24.0 (sandwich group) months. Outcome measures were the IOP, the number of medications, success rates, and the incidence of complications. RESULTS: The only statistically significant difference between the two groups was the 2-week postoperative IOP, which was significantly lower in the episcleral group (P = .0314). CONCLUSION: Because there is no additional benefit, the authors recommend that the intrascleral application of MMC be avoided. However, they did not observe increased complication rates when MMC was applied in this way.

Adult↗
PubMed1998

Capsule-bending ring for the prevention of capsular opacification: a preliminary report.

BACKGROUND AND OBJECTIVE: To report the preliminary results of a study on the preventive effect of the capsule-bending ring on anterior and posterior capsule opacification (ACO and PCO, respectively). PATIENTS AND METHODS: The ring is an open, band-shaped, circular polymethylmethacrylate (PMMA) ring measuring 11 mm in diameter with pre-tension (13 mm in diameter when the ring is open), 0.2 mm in thickness, and 0.7 mm in width. To retain sharp edges, the ring is not polished. The sharp edges should create a sharp, discontinuous capsular bend in the fornix, which induces contact inhibition of migrating lens epithelial cells after cataract surgery. This capsule-bending ring is inserted into the capsular fornix following phacoemulsification, prior to the implantation of an intraocular lens (IOL). In a multicenter trial, 100 patients were scheduled to undergo phacoemulsification and IOL implantation in both eyes within 1 month. The procedure was performed with the ring in 1 eye and without the ring in the other eye of each patient. RESULTS: The anterior capsule was prevented from coming into contact with the IOL, and ACO was significantly reduced in the eyes with the ring, rendering the capsular opening larger 3 months after surgery. PCO was obviously reduced on slit-lamp examination in the follow-up period up to 6 months, but needs to be evaluated during a longer period. CONCLUSION: This band-shaped, sharp-edged capsule-bending ring may be useful for cases that need good fundus visualization for photocoagulation or expected vitreoretinal surgery and for the prevention of PCO.

Biocompatible Materials↗
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↗
PubMed1995

Suction fixation system for stereotactic radiosurgery of intraocular malignancies.

We designed a suction fixation system for the radiosurgical treatment of intraocular malignancies with the Leksell gamma unit (gamma knife). OUr device consists of a circular suction chamber and an adjustable unit to be fixed to the Leksell stereotactic head frame. All components are made of plastic materials in order to avoid artifacts in CT or MRT imaging. A permanent suction of 600 to 800 millibars is provided by a standard vacuum pump, powered by a portable battery. Suction times up to 40 minutes were well tolerated in all cases. In the gamma knife of the Neurosurgical Department at the University of Vienna, we successfully used this device. Up to January 1994 we have performed 19 radiosurgical treatments in 9 patients with large or extra-large uveal melanomas and in one patient suffering from a choroidal metastasis.

Aged↗
PubMed1995

Evaluation of 35 consecutive SI-30 PhacoFlex lenses with high-refractive silicone optic implanted in the capsulorhexis bag.

Thirty-five PhacoFlex foldable open-loop lenses with high-refractive silicone optics were evaluated. All lenses were implanted using a folding forceps and were fixated in the bag. Mean follow-up was 14 months. With adequate forceps, the lens may be inserted through a 3.2 mm incision, using a 3 mm long self-sealing sclerocorneal tunnel. With a well-centered 4 mm to 5 mm capsulorhexis opening, centration was very satisfactory. Moderate decentration occurred in two cases, one from a small, heavily shrinking capsulorhexis and the other from a poorly shaped capsulorhexis that captured the optic along its edge. Except in one case of combined cataract and filtering surgery, all optics were at a pronounced distance from the iris. Consequently, signs of iris chafing or iridocapsular synechias and cellular invasion were not seen. The optic typically exhibited a slight bluish tint and minute granular inclusions without clinical significance. Neither discoloration nor haze was present. Best visual acuity was 20/25 or better in all cases. The small wound required for insertion makes the PhacoFlex especially appropriate for clear corneal incision surgery. Attempts are being made to minimize the grainy appearance of the optic. Increasing the rigidity of the loops may be advantageous.

Aged↗
PubMed1995

Delayed iris prolapse with unsutured 5.1 mm clear corneal incisions.

I describe two cases of iris prolapse after sutureless 5.1 mm clear corneal incision cataract surgery with implantation of a 5 mm poly(methyl methacrylate) lens. Both patients reported having exerted localized digital pressure on the globe peripheral to the temporally located incision. Following resection of the prolapse, the pupil was reconstructed in situ using a translimbal transfixation technique. The prolapse and other observed complications (e.g., transient pupillary capture, delayed endophthalmitis) indicate that 5.1 mm clear corneal incisions do not provide adequate stability if localized pressure is exerted peripheral to the wound. Thus, securing the incisions with a radial 10-0 nylon suture is strongly advocated to provide sufficient wound stability against deformation.

Aged↗