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Biomedical subjects

R Brancato

Publications and source records attributed to R Brancato.

At least 73 records · Page 4Linked to original sources
PubMed1996

Automatic centering of the microscope image for vitreoretinal surgery.

PURPOSE: The authors report on their device, the surgical image tracker, which provides automatic compensation for movements of the surgical image within the microscope field of view, during vitreoretinal procedures. METHODS: The authors developed a compact device acting as an automatic image tracker, based on video monitoring of the surgical image and translation of the operating microscope. Basic components are a standard color charge-coupled device camera and a specifically designed frame grabber for discrimination and tracking of the target image. Operation of the device is fully compatible with the usual pedal adjustments. RESULTS: Ready, fast, and correct automatic centering of the microscope field of view has been achieved successfully in all typical operating conditions. Video recording always is equally well centered. System operation also is effective with panoramic optics and diffuse illumination. CONCLUSION: The surgical image tracker appears to be a valuable tool to obtain well auto-centered surgical images, eliminating a bothersome task during vitreoretinal surgery.

Humans↗
PubMed1996

Value of ultrasound biomicroscopy for ciliodestructive procedures.

Ciliodestructive procedures are commonly performed by the transscleral approach because ciliary processes are seldom visible. Thus the ablative energy is directed toward an "invisible" target whose position can only be estimated on the basis of experimental data. Ultrasound biomicroscopy has been recently introduced in ophthalmologic practice. This high-frequency ultrasound B-scan method gives real-time images of the subsurface structures of the anterior portion of the living eye at microscopic resolution. Ultrasound biomicroscopy perfectly visualizes the ciliary body and its surrounding structures and is a promising complementary tool for ciliodestructive procedures. The system has been used to image early and late ciliary body alterations after transscleral cyclophotocoagulation, to establish the position of the ciliary body to ensure correct laser probe placement, to locate ciliary body residuals for retreatment, and to rule out scleral damage after the procedure. An apparatus has been designed for simultaneous contact cyclophotocoagulation and ultrasound biomicroscopy analysis. A prospective randomized clinical trial is now needed to clarify the influence of ultrasound biomicroscopy on the success rate of ciliodestructive procedures.

Animals↗
PubMed1996

Correlation of lens thickness with blood glucose control in diabetes mellitus.

The aim of this study was to verify if lens thickness in insulin-dependent diabetic patients is greater than in non-diabetics, and to establish which parameters affect the thickness of the lens age, diabetes duration, glycaemic control, insulin dose. Ultrasound biometry and blood glucose measurements were taken in 87 patients three times a day: fasting 2 and 4 h after lunch. The patient sample was divided into three groups: 30 with no retinopathy, 30 presented background retinopathy and 27 with proliferative retinopathy; 30 normal subjects with a similar age to the diabetic group, comprised the control group. No correlation was found between biometric values and blood glucose in the three groups (p < 0.05). A significant difference in lens thickness was found in the four groups, even after adjusting for age (p < 0.05). Significant differences in lens thickness were seen between proliferative retinopathy and the other groups, after adjusting for age and duration of diabetes (p < 0.05); lens thickness was shown to correlate with diabetes duration (p < 0.05).

Adult↗
PubMed1996

Quantitative comparison of direct antibody labeling and tumor pretargeting in uveal melanoma.

UNLABELLED: SPECT radioimmunoscintigraphy with 99mTc-labeled anti-melanoma monoclonal antibodies (MAbs) 225.28S is being used to detect uveal melanoma. Recently, pretargeting methods have been described to reduce background activity and perform imaging in a shorter time interval. METHODS: We compared the three-step pretargeting method with conventional radioimmunoscintigraphy in 15 patients with a clinical and laboratory diagnosis of uveal lesion. High-resolution SPECT radioimmunoscintigraphy was performed in all patients with directly labeled MAbs and, 1 wk later, with the three-step pretargeting technique. Eleven patients underwent eye enucleation and specimens of uveal melanoma were available for histology, whereas four patients underwent conservative therapy. The percent injected dose (%ID) delivered to the tumor and the tumor-to-background ratio were calculated. RESULTS: In all three-step radioimmunoscintigraphy studies, there was a reduction of nonspecific nasopharyngeal background. The three-step radioimmunoscintigraphy tumor-to-nontumor ratio was 3.1 +/- 1.3 versus 1.5 +/- 0.5 of conventional radioimmunoscintigraphy, while the percent injected dose on the tumor was similar for the two methods (4.4 +/- 3.0 versus 3.8 +/- 2.8) x 10(-3). CONCLUSION: Improved SPECT imaging with the three-step radioimmunoscintigraphy results from reduced background and from higher counting statistics due to reduction of time interval between radiotracer administration and imaging, whereas the absolute amount of tracer delivered to the tumor by the two methods is comparable.

Antibodies, Monoclonal↗
PubMed1996

Evaluation of three different approaches to perform excimer laser photorefractive keratectomy for myopia.

BACKGROUND AND OBJECTIVE: The aim of this study was to evaluate the results of myopic excimer laser photorefractive keratectomy (PRK) performed using three different ablation approaches. PATIENTS AND METHODS: Using the Apex excimer laser (Summit Technology, Inc., Waltham MA), we have treated 75 eyes. Twenty-five of them were treated by a single ablation zone (SA, 6.5 mm diameter) to correct myopia of -4.50 +/- 2.10 D (mean +/- SD); 25 eyes underwent PRK for the correction of myopia of -4.98 +/- 2.17 D using a multipass multizone technique (MP, 3 zones); and 25 eyes were corrected for myopia of -5.03 +/- 1.98 D using new software which enables the creation of three ablation zones in a single-pass fashion (MZ). RESULTS: Mean refractive error (+/-SD) at the first post-operative month was +1.34 +/- 1.00 D for SA, +1.78 +/- 1.49 D for MP, and +0.90 +/- 0.75 D for MZ. Eyes treated by MZ had significantly better uncorrected visual acuity than those treated by SA (P=0.04). Corneal topography revealed a central island in 14 eyes (56%) of those treated by SA and 2 eyes (8%) of those treated by MZ, but in no eyes treated by MP. Six months after treatment, mean refractive error was +0.28 +/- 0.75 D for SA, +0.36 +/- 0.92 D for MP, and - 0.07 +/- 0.77 D for MZ. CONCLUSION: MZ ablation induced less hyperopic shift at 1 month, thus leading to a faster visual recovery and better uncorrected visual acuity. MP and MZ ablations proved effective in preventing central island formation, thus inducing less visual disturbances than SA ablations. These results suggest that MZ ablation may be preferable to the other techniques in performing myopic PRK.

Adult↗
PubMed1995

Central retinal vein and branch artery occlusion associated with inherited plasminogen deficiency and high lipoprotein(a) levels: a case report.

We describe a case of central retinal vein and branch artery occlusion associated with inherited type I plasminogen deficiency (68%) and permanent elevation of Lp(a) (460 mg/l, S2 phenotype) in a 45 year old white woman with no associated local or systemic risk factors. Pedigree analysis revealed inheritance of plasminogen deficiency from the deceased father and of high Lp(a) levels from the mother. Both the patient's sons had plasminogen deficiency, but they had normal Lp(a) levels. In a series of 40 consecutive patients with central retinal vein occlusion we previously reported the observation of high Lp(a) levels--consistently associated with the S2 phenotype--in 30% of the patients as compared to a 10% incidence in controls. This case emphasizes the importance of screening patients with occlusion of the retinal vessels and no associated risk factors for coagulation abnormalities predisposing to thrombosis.

Female↗
PubMed1995

Quantitative analysis of optic disc cupping in compressive optic neuropathy.

PURPOSE: Cupping of the optic disc, a characteristic sign of glaucoma, has been anecdotally described in association with compressive optic neuropathy. The aim of this study is to perform a masked, controlled, and quantitative measurement of the optic disc cup to determine if compressive lesions of the afferent visual pathway were associated with increased cupping. METHODS: The ratio of cup area:disc area of 29 patients with intracranial lesions impinging on the optic nerves and the chiasm (14 with pituitary adenomas, 7 with meningiomas, 6 with craniopharyngiomas, and 2 with aneurysms) was compared with those of 20 age-matched control subjects. The areal ratios were derived planimetrically from hand-drawn images of magnified stereophotographs. Patients were divided into three groups based on the degree of laterality of visual compromise. Uninvolved eyes served as an internal control for patients with unilateral disease. RESULTS: The median ratio of cup area:disc area was 0.37 for all eyes with visual compromise (n = 51) and 0.10 for control eyes, which was statistically significant (P = 0.0001). The median intereye difference in the ratio of cup area:disc area was 0.13 for patients with unilateral lesions and 0.04 for control subjects. This difference also was statistically significant (P = 0.0001). CONCLUSIONS: The finding of intereye asymmetry in patients with unilateral optic nerve compression is convincing evidence that the enlarged cup is an acquired feature. Several types of compressive lesions of the anterior visual pathway can be associated with increased cupping of the optic disc in the absence of increased intraocular pressure.

Adolescent↗
PubMed1995

Bovine factor VIII derivative in the treatment of non-proliferative diabetic retinopathy.

The complexity of the pathogenesis of diabetic retinopathy (DR) makes it difficult to produce effective drugs for its treatment. Among the active principles recently suggested, the peptide fraction of bovine factor VIII of the clotting cascade deserves particular attention. Bovine factor VIII derivatives (vascular factor, VF) have been shown to have significant effects on the capillary basement membrane and on vascular endothelium and they are able to stabilise vessel walls. The aim of this study was to assess the effectiveness of VF in diabetic patients with non-proliferative DR. Nineteen consecutive patients (37 eyes) affected by non-proliferative DR were included in the study and randomly assigned to VF or placebo. An ophthalmological examination, colour photographies and a retinal fluorescein angiography were carried out before as well as 3 and 6 months after inclusion. Every eye in the study was classified in accordance with the ETDRS criteria. While the progress of macular oedema and visual acuity was very similar in the two groups (VF and placebo), there was no deterioration, i.e., no change to a worse classification than that at the start, in any of the eyes in the group treated with VF, but deterioration was seen in 19% of the eyes treated with the placebo. On the basis of these results, VF may ensure some protection of the blood-retinal barrier against the harmful influence of diabetic microangiopathy.

Administration, Oral↗
PubMed1994

The corneal endothelium after myopic excimer laser photorefractive keratectomy.

OBJECTIVE: To investigate whether 193-nm excimer laser photorefractive keratectomy for the correction of myopia can determine in vivo changes in the human corneal endothelium 3 and 12 months after surgery. METHODS: Contact wide-field specular biomicroscopy of the central corneal endothelium was performed on 76 eyes of 61 patients (aged 20 to 49 years; mean, 29.7 years) who underwent photorefractive keratectomy for the correction of myopia ranging between -1.75 and -13.50 diopters (mean, -6.60 D). The maximum estimated central depth of the photoablation was 113 microns. Photomicrographs of the endothelium taken before surgery were processed by means of computer-assisted morphometric analysis and compared with those obtained 3 and 12 months after surgery. RESULTS: The mean (+/- SD) cell density was 2657 +/- 298 cells/mm2 preoperatively, 2672 +/- 286 cells/mm2 after 3 months (P = .670), and 2656 +/- 289 cells/mm2 after 1 year (P = .982). The mean (+/- SD) coefficient of cell area variation was 30.27% +/- 5.99% preoperatively, 28.25% +/- 5.21% after 3 months (P = .032), and 26.35% +/- 5.29% after 1 year (P = .001). The mean (+/- SD) percentage of hexagonal cells was 63.82% +/- 9.94% preoperatively, 64.02% +/- 10.53% after 3 months (P = .806), and 67.19% +/- 9.14% after 1 year (P = .025). CONCLUSIONS: Photorefractive keratectomy caused no damage to the corneal endothelium. Postoperative improvements of the coefficient cell area variation and the percentage of hexagonal cell values may be related to corneal metabolic modifications or discontinuance of contact lens use after surgery.

Adult↗
PubMed1994

Biomicroscopy and fluorescein angiography of pigmented iris tumors. A retrospective study on 44 cases.

The classification of pigmented iris tumors is a difficult clinical problem. Based on the retrospective observation of colour photographs and iris angiograms of 44 pigmented iris tumors observed over 19 years, the authors present an original grading scheme with scores depending on both the biomicroscopical and the fluoroiridographic patterns of the tumors. The biomicroscopical parameters considered were: thickening of the iris in the area of tumor, pupillary distortion and/or ectropion uveae and uneven pigment density. The fluoroiridographic parameters were: early visibility of the anomalous tumoral network, hyperfluorescence inside or around the tumor, and dye leakage at sites remote from the mass. Based on the score of each tumor, the 44 cases were divided into 3 groups with the different degrees of malignancy confirmed by either histological examination or by follow-up behaviour. The authors suggest that routine use of biomicroscopic-fluoroiridographic classification of pigmented iris tumors would be useful.

Female↗
PubMed1994

Endophotocoagulation through perfluorodecalin in rabbit eyes.

Retinal laser endophotocoagulation through perfluorodecalin was studied in six eyes of three Dutch-belted rabbits after vitrectomy. Both the energy density threshold (EDT/50) and the energy threshold necessary to obtain a therapeutic lesion were evaluated. Both argon and semiconductor diode laser endophotocoagulators were used. The amount of laser power energy and the histology of chorioretinal lesions were similar when photocoagulating through perfluorodecalin, compared to photocoagulation through balanced salt citrate-buffered solution. This experimental study indicates that no extra care is necessary when retinal endophotocoagulation is performed through perfluorodecalin, as long as circular spots are obtained and energy is delivered symmetrically to the target site.

Animals↗
PubMed1994

Electroretinographic findings in congenital oculomotor apraxia (Cogan's syndrome).

We performed visual evoked potential testing and electroretinography in five patients with Cogan's oculomotor apraxia. The visual evoked potentials were normal, confirming previously reported data. Electroretinograms were abnormal in two of the five patients examined. A previous study showed normal electroretinogram responses bilaterally in one patient. Our findings suggest the existence of two variants of the syndrome; the one with electroretinogram anomalies has a worse visual prognosis.

Apraxias↗
PubMed1994

Single-sweep analysis using an autoregressive with exogenous input (ARX) model.

Single-sweep visual evoked potential analysis would be useful in clinical electrophysiology practice because it would make possible the evaluation of transient phenomena, but recording single-sweep visual evoked potentials is difficult because of the low signal-noise ratio. To increase this ratio we used a filter based on an autoregressive with exogenous input model. We studied a group of 12 diabetic patients matched with a control group of 14 normal subjects. The model, in most cases, allowed us to extrapolate the P100 component from each single sweep of visual evoked potential. The visual evoked potential values obtained by means of averaging were not significantly different in the groups studied, but single-sweep analysis showed different distribution of the P100 component amplitude. The preliminary results of our study evidenced differences in the amplitude and latency distribution of normal and diabetic subjects, thus confirming the power of this new technique and its ability to obtain some information that is masked by the averaging method.

Adult↗
PubMed1994

Indications, results, and complications of refractive corneal surgery with lasers.

The applications of the current laser technology in refractive surgery have developed during the past year. Several techniques to correct ametropia with various laser sources have been proposed and investigated. To date, using the myopic photorefractive keratectomy excimer laser is the most common technique; it has already been performed on more than 100,000 eyes worldwide. Refractive results on large series of patients with long-term follow-up indicate that the technique is safe, effective, and highly predictable in the correction of low to moderate myopia. Concerns about the treatment of high myopia still arise, especially regarding regression toward myopia and stability of achieved refraction; multizone treatments have been proposed to reach better results. The correction of compound myopic astigmatism with the excimer laser seems to be promising, although long-term results on large series are still pending. Among the patients treated, very few complications occurred. We believe that laser technology will play the most important role in refractive surgery in the future.

Contraindications↗
PubMed1994

Immunoscintigraphy with three step monoclonal pretargeting technique in diagnosis of uveal melanoma: preliminary results.

Several problems still limit the full use of the diagnostic potential of immunoscintigraphy (IS) with technetium-99m labelled monoclonal antibodies (MoAbs) 225-28S directed to high molecular weight melanoma associated antigen (HMW-MAA). The principal problem is the unfavourable ratio of tumour to non-tumour activity (T/nT), due to the poor tumour uptake and the high aspecific uptake of the tissue surrounding the tumour. Recently, it was demonstrated that using the tumour pretargeting technique based on the injection of monoclonal antibody and the avidin/biotin system (three step immunoscintigraphy), an improvement in the T/nT ratio can be obtained in patients with carcinoembryonic antigen secreting tumours. The aim of this study was to compare the diagnostic sensitivity of traditional immunoscintigraphy with that of three step immunoscintigraphy in seven patients with uveal melanoma. All the patients underwent immunoscintigraphy with MoAb 225.28S radiolabelled with technetium-99m, and a three step immunoscintigraphy 1 week later. No patients demonstrated immediate toxic effects after receiving the reagents, no matter which of the two methods was used. The traditional immunoscintigraphy had a diagnostic sensitivity of 71.4%, diagnosing five out of seven melanomas tested. The three step study detected all the melanomas examined (7/7) with a diagnostic sensitivity of 100% and showed a drastic reduction in background. The preliminary results confirm the feasibility of visualising the uveal melanoma and show that the three step immunoscintigraphy is more diagnostically sensitive than traditional immunoscintigraphy, particularly in small lesions.

Aged↗
PubMed1994

Relation between iridopathy and retinopathy in diabetes.

In order to assess the relation between diabetic iridopathy (DI) and retinopathy (DR), 225 eyes of 117 diabetics with clear media were evaluated. Each patient underwent iris and retinal fluorescein angiography, which was used to classify DI and DR. DI was classified as: absence of DI; non-proliferative DI; proliferative DI; neovascular glaucoma. DR was classified as: absence of DR; background DR; pre-proliferative DR; proliferative DR. The sensitivity of iris fluorescein angiography in assessing DR was 44.5%, the specificity 88%, the positive predictive value 92.8%, and the negative value 31.2%. In pre-proliferative and proliferative DR, fluoroiridographic detection of iris neovessels gave a sensitivity of 56% and a specificity of 100%. The positive predictive value was 100% and the negative value 65%. In conclusion, iris fluorescein angiography yields valuable information on DR and is a helpful basis for avoiding complications when scheduling eyes with dioptric media opacities for surgery.

Diabetic Retinopathy↗