Biomedical subjects

C Vass

Publications and source records attributed to C Vass.

13 recordsLinked to original sources

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↗

PubMed1997

[A case of ovarian struma causing symptoms of hyperthyroidism].

The authors report the case of a 46-year old woman, who went with diffuse complaints to the endocrinology department. The laboratory date showed hyperthyroidism. She had hypogastric complaints, therefore a gynecological consultation was carried out. An infant--head sized elastic formation was found on the left hand side next to a female fist sized myomatous uterus. On sonographic examination the growth proved to have a size of 12 x 14 cm. Besides the myomatous uterus the histology of the operative specimen confirmed a left sided ovarious teratoma, which was composed solely of usual thyroid tissue. After the operation it the patient's endocrine disorders became spontaneously regulated. Our attention to called the fact that especially in case of therapy resistant hyperthyroidism we should think of this infrequent clinical picture.

Female↗

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

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↗

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↗

PubMed1994

Computerized statistical analysis of corneal topography for the evaluation of changes in corneal shape after surgery.

We examined 20 patients for the effect of a 3-mm sutureless temporal clear corneal incision cataract operation on corneal topography, as recorded with the computer-assisted video-keratoscope TMS-1 (Computed Anatomy, Inc., New York, New York). Each topographic image was cut into 178 fields in eight concentric rings. The refractive values of these fields were stored in a database. The mean differences between the preoperative and one-month postoperative findings were calculated and transformed into color-coded maps as output for the statistical analysis. The patients operated on showed a mean flattening of 0.4 to 1.0 diopter in the temporal region. This was statistically significant by paired Wilcoxon signed-rank tests. There was no significant vertical steepening or nasal flattening, except in two isolated fields. For control purposes, we twice examined 20 age-matched volunteers who were not operated on. The paired Wilcoxon tests of this group did not show significant changes. When compared with Cravy's vector analysis, induced topographic change analysis is better at evaluating surgically induced corneal shape changes.

Aged↗

PubMed1991

Pattern electroretinogram and luminance electroretinogram in Alzheimer's disease.

Visual symptoms are often among the first complaints of patients suffering from Alzheimer's disease and several studies showed a delay in flash visual evoked potentials. Hinton et al. (1986) described optic nerve degenerations in patients with Alzheimer's disease and Sadun published a dropout of retinal ganglion cells that range from 30% to 60%. The reduction of neurotransmitters, especially of acetylcholine, found in the brain might also occur in the retina. Therefore we examined the retinal functions of patients suffering from Alzheimer's disease. In eight patients the pattern-electroretinograms and the scotopic and photopic luminance-electroretinograms were recorded and compared to an age-matched control group. We could not find any abnormalities in the pattern- and the luminance electroretinograms of patients with Alzheimer's disease. Although cholinergic cells have been found in the retina, our results did not reveal an involvement of retinal functions in Morbus Alzheimer.

Aged↗

PubMed1990

Effect of levodopa on the human luminance electroretinogram.

Scotopic and photopic electroretinograms (ERGs) were recorded in 12 healthy volunteers before and 90 and 180 min after administration of levodopa. After 90 min the drug significantly increased the scotopic ERG b-wave amplitude and implicit time. The dark-adapted oscillatory potentials (OPs) were selectively affected, while no changes were observed in the photopic ERG. Levodopa had no effect on the ERG after 180 min drug applications. As a control, the experimental procedure was repeated without drug administration, and no changes were observed.

Adult↗

PubMed1989

Effect of levodopa on the human pattern electroretinogram and pattern visual evoked potentials.

Pattern electroretinograms (P-ERGs) and pattern visual evoked potentials (P-VEPs) were recorded at three luminance levels and five different check sizes in a group of 16 control subjects before and after the oral administration of levodopa. At the lower luminance levels, significant decrease in P-ERG and P-VEP latencies were found. For P-VEPs the latency changes occurred only at small check sizes. No changes were observed in control experiments without levodopa administration. Our results show that levodopa-induced changes even occur at the retinal level and support a dopaminergic involvement in light and dark adaptation. Our observations are in agreement with a VEP delay found in Parkinson's disease and with a VEP latency increase in rats after dopamine depletion.

Administration, Oral↗

PubMedDate not supplied

Improved algorithm for statistical batch-by-batch analysis of corneal topographic data.

PURPOSE: To describe an improved algorithm for topographic batch-by-batch analysis and evaluate the effect of artifact correction on the reproducibility of topographic records. SETTING: University Eye Hospital Vienna, Austria. METHODS: We twice examined 22 eyes of 22 patients (volunteers) using the TMS-1 computer-assisted videokeratoscope (Computed Anatomy, Inc.). Entry criteria were age more than 60 years and lack of corneal pathology. A batch-by-batch analysis of the paired differences was performed. The software consisted of special macro functions for a programmable computer database to eliminate small local artifacts, as well as rotate data, produce mirror images, calculate averaged differences for an entire group, and reduce data to 225 areas in 7 concentric rings. The reduced set of data was used for statistical analysis and correction of defocus artifacts. Reproducibility was evaluated by calculating the absolute deviations between the areas of paired measurements. RESULTS: The absolute deviations were below 0.9 diopter (D) in over 50% of the areas in 90% of the patients with the uncorrected data; after correction for local artifacts, defocus artifacts, and both local and defocus artifacts, these values were 0.9 D, 0.8 D, and 0.5 D, respectively. Absolute deviations were above 1.0 D in 10% of the patients in 66, 40, 29, and 0 of 225 areas, respectively. CONCLUSION: Correction for both local and defocus artifacts yielded a two-fold improvement in the reproducibility of topographic records.

Aged↗

PubMedDate not supplied

Corneal topographic changes after frown and straight sclerocorneal incisions.

PURPOSE: To compare the corneal topographic changes following cataract surgery with two types of sclerocorneal tunnel incisions for implantation of 6.0 mm optic poly(methyl methacrylate) intraocular lenses. SETTING: University Eye Hospital, Vienna, Austria. METHODS: This prospective, unmasked, and unrandomized study comprised 48 otherwise healthy eyes scheduled for cataract surgery. A 4.5 mm sutureless frown incision was made in 22 eyes and a 6.0 mm straight sclerocorneal incision with a horizontal 10-0 nylon infinity suture in 26 eyes. Preoperatively and 1 week and 1 and 3 months postoperatively, corneal topography was recorded by the TMS-1 computer-assisted videokeratoscope (Computed Anatomy, Inc.). The data were evaluated by batch-by-batch analyses of the paired differences between the records. The significance of topographic changes was calculated by paired Wilcoxon tests; group comparisons were made using Wilcoxon tests. RESULTS: In both groups, horizontal steepening and lower corneal flattening were consistently 0.4 diopter (D). Upper peripheral corneal flattening at 1 week and 1 and 3 months postoperatively was 0.7, 0.7, and 0.7 D, respectively, in the straight-incision group and 0.7, 0.4, and 0.3 D, respectively, in the frown-incision group. Vertical flattening and horizontal steepening were significant in both groups (P < .01). Group comparisons revealed significant differences in only 15 of 225 areas (P < .05). CONCLUSION: There were no major differences between the two incision groups in surgically induced topographic changes.

Aged↗