Biomedical subjects

R Brancato

Publications and source records attributed to R Brancato.

At least 55 records · Page 3Linked to original sources

PubMed1997

Intraocular measurements of pressure transients induced by excimer laser ablation of the cornea.

BACKGROUND AND OBJECTIVE: The evolution of pressure waves induced by argon-fluoride laser ablation of the cornea in the typical operative conditions of clinical laser keratectomy has been studied experimentally and analyzed. MATERIALS AND METHODS: Freshly enucleated porcine eyes were irradiated at a laser fluence of 180 mJ/cm2 with various spot diameters in the range 1-6.5 mm. Pressure transients were detected by a fast rise time needle hydrophone inserted into the eyeball from the posterior pole and moved along the eye optical axis toward the cornea. RESULTS: Pressure peaks as high as 90 bar and 50 ns pulse duration (FWHM) were measured in the anterior chamber. Observation of the pulse shape evolution during propagation put in evidence the onset of a marked rarefaction phase following the compressional spike, with intense negative peaks (up to -40 bar) located at increasing distances from the corneal surface for increasing spot diameters. CONCLUSIONS: This behavior was explained by means of simplified models describing pressure pulse generation and diffraction effects occurring during its propagation. Implications to clinical procedures, as possible damages due to tissue stretching and cavitation formation, are also discussed.

Animals↗

PubMed1997

Hyperfluorescent plaque lesions in the late phases of indocyanine green angiography: a possible contraindication to the laser treatment of drusen.

PURPOSE: To highlight the possible role of indocyanine green angiography in predicting future exudative changes in eyes that are candidates for drusen laser treatment. METHODS: In a 56-year-old woman, fluorescein and indocyanine green angiography were performed before drusen laser treatment. RESULTS: The treated eye had a suspicious lesion at baseline indocyanine green angiography and a nonsuspicious fluoroangiographic pattern. Seven months after treatment, the patient developed choroidal neovascularization and pigment epithelial detachment in the treated eye. CONCLUSION: To decrease the risk of macular exudative changes that may be related to laser treatment, eyes that are candidates for drusen laser treatment should be examined before treatment, not only by fluorescein angiography, but also by indocyanine green angiography.

Angiography↗

PubMed1997

Laser photocoagulation of choroidal neovascularization in angioid streaks.

PURPOSE: To determine if laser photocoagulation of macular choroidal neovascularization in angioid streaks may be effective in preventing severe loss of vision. METHODS: Sixty-six consecutive eyes of 52 patients with extrafoveal, well-defined choroidal neovascularization secondary to angioid streaks who underwent direct laser photocoagulation were followed for 3-108 months (mean, 34.5 months; median, 20 months). RESULTS: Pretreatment mean visual acuity was 20/40 (range, 20/200-20/20), postlaser outcome was a visual acuity of 20/50 at 3 months, 20/50 at 6 months, 20/80 at 1 year, 20/80 at 2 years, 20/100 at 3 years, 20/125 at 4 years, 20/125 at 5 years, 20/100 at 6 years, and 20/80 at 7 years. During the first year after treatment there was a significant decrease in visual acuity (P < 0.01), but no significant change thereafter. Choroidal neovascularization recurred one or more times in 77% of the eyes, but by the final examination choroidal neovascularization had been eliminated completely in 31 eyes (47%). Fellow eyes with naturally progressed choroidal neovascularization were considered control eyes. Final visual acuity in treated eyes was definitely better than that in untreated eyes (P < 0.01). CONCLUSIONS: This is the largest series of eyes treated by laser photocoagulation for angioid streaks and choroidal neovascularization ever reported. Laser photocoagulation of choroidal neovascularization in angioid streaks may end the choroidal neovascularization and help stabilize visual acuity or slow down visual loss. Considering the very high frequency of recurrences (77% of the eyes studied), an intense clinical and fluorangiographic follow-up period is strongly recommended, mainly for the first 3 months after treatment.

Adult↗

PubMed1997

Clinical and ultrasound study of peripheral vitreoretinal adhesions.

PURPOSE: To evaluate the frequency of peripheral vitreoretinal adhesions in the region of the vitreous base by ultrasound examination in relation to axial length of the eye and the age of the patient. Patient gender and the presence of visual symptoms also were considered. METHODS: A total of 228 consecutive patients (445 eyes) underwent biometry, ultrasound examination, and biomicroscopic fundus examination. Their medical history also was taken. The patients were divided into three groups according to axial length of the eye (< 24 mm, 24-26.5 mm, and > 26.5 mm) and into three age groups (20-40 years, 41-60 years, and > 60 years). RESULTS: No correlations was found between peripheral vitreoretinal adhesions and gender or between peripheral vitreoretinal adhesions and axial length of the eye. A significant correlation was found between peripheral vitreoretinal adhesions and age (P < 0.001). The proportion of adhesions increased with age (P < 0.001). The association between adhesions and presence of symptoms also was significant (P < 0.001). Multivariate analysis showed that only the presence of symptoms independently correlated with adhesions (relative risk, 1.71, 95%; confidence interval, 1.19, 2.46). CONCLUSION: Our study shows that peripheral vitreoretinal adhesions, detected by ultrasound, were always associated with the presence of symptoms.

Adolescent↗

PubMed1997

Third, fourth, and sixth cranial nerve palsies.

Clinical manifestations of ocular motor palsies may differ according to the type and the localization of the lesions involving the third, fourth, and sixth cranial nerves. Topical diagnosis of the third, fourth, and sixth nerve palsies is therefore required before imaging studies and workup are performed. The development of modern imaging techniques has significantly improved the diagnosis of the disorders affecting the ocular motor nerves. This review covers the most important aspects, in terms of clinical signs and symptoms and differential diagnoses, of these cranial nerve palsies. The more recently published articles have added new disorders to the differential diagnosis of ocular motor palsy. Moreover, magnetic resonance imaging (MRI) has been confirmed to be the most important diagnostic tool in most cases. Finally, recently developed MRI techniques were presented and demonstrated to be more sensitive than conventional MRI in several cases.

Abducens Nerve↗

PubMed1997

Congenital aphakia in Peters' anomaly syndrome. A case report.

The authors report a case of congenital bilateral corneal opacities in which one of the eyes was enucleated because of malignant glaucoma and corneal perforation. Corneal defects and iridocorneal adhesion were found, but aphakia was the major pathologic ocular finding. The clinical picture and pathology study indicated this case as a Peters' anomaly presenting congenital aphakia.

Anterior Eye Segment↗

PubMed1997

Indocyanine green angiography in angioid streaks.

PURPOSE: To define the indocyanine green angiographic aspects of angioid streaks, peau d'orange and choroidal new vessels. METHODS: Fifty-seven consecutive patients (112 eyes) with angioid streaks were evaluated by fluorescein angiography and indocyanine green angiography. RESULTS: Indocyanine green angiography showed angioid streaks in all eyes. We identified three different indocyanine green patterns of streaks (four groups): fluorescent (63%), hypofluorescent (8%), 'track-like' (19%) and mixed (10%). Angioid streaks were visualized better by indocyanine green angiography and red-free retinography than fluorescein angiography. Peau d'orange was seen better and found to be more widespread by indocyanine green angiography. Fluorescein angiography visualized choroidal neovascularization better, except for occult forms. CONCLUSIONS: Our findings show that angioid streaks have different indocyanine green angiography patterns. Considering that the hypofluorescent pattern was significantly observed in younger patients, indocyanine green angiography aspects might be correlated with different stages of the disease.

Adult↗

PubMed1997

A motorized hand piece for injectable lenses.

Foldable lenses represent a major breakthrough in the effort to achieve ever smaller incisions. The plate-haptic or "taco-style" lenses are folded and implanted by a device called an injector. Although customized for each manufacturer's lens, the injectors all have a common design principle: the intraocular lens (IOL) is folded within a funnel-like structure of the tip and is advanced by a plunger that pushes and delivers the lens. To maintain optimal hand stabilization and injector management, both hands are usually required. This does not leave a hand to help with IOL positioning. To improve handling, a simple, mechanized system has been created for a new injector system that allows the delivery of the plate-haptic lens with one hand, in a pen-like fashion.

Equipment Design↗

PubMed1997

A disposable needle for frontalis suspension surgery in congenital ptosis.

In six patients affected by congenital ptosis, a disposable epidural anesthesia needle was used instead of a Wright needle for frontalis suspension surgery. For each of the patients in this study, the use of a disposable needle permitted smaller supra-brow area incisions with a minimal scar. The needle also created a smaller breach in the plane of levator aponeurosis and preaponeurotic fat, causing less tissue edema and bleeding than with a Wright needle.

Anesthesia, Local↗

PubMed1997

Excimer laser correction of astigmatism using erodible masks.

PURPOSE: The latest development in the erodible mask technology is an excimer laser containing the mask in the laser optical pathway. This paper reports the results of the first human series of consecutive treatments performed for the correction of compound myopic astigmatism. METHODS: We have treated 83 eyes. Spherical equivalent attempted correction ranged between -1.75 and -11.75 D (mean -7.07 +/- 2.45 D), astigmatic attempted correction ranged between -1.00 and -5.00 D (mean -2.42 +/- 1.02 D). The sphere correction was made by diaphragm using a multi-zone software with three ablation zones: 100% of the total attempted correction for the central 5.0 mm zone, 70% for the second 6.0 mm zone, 30% for the outer 6.5 mm zone. Cylinder correction was made sequentially after myopic correction using the appropriate mask. RESULTS: One month after treatment, mean refractive error was +1.07 +/- 1.24 D (range +4.50/-1.75 D) for spherical equivalent, and -0.49 +/- 0.57 D (range +0.75/-2.00 D) for astigmatism. Forty-eight eyes (57.8%) had uncorrected visual acuity of 20/40 or better. At six months, mean refractive error was +0.42 +/- 0.97 D (range +3.75/-1.00 D) for spherical equivalent, and -0.44 +/- 0.51 D (range +0.25/-3.00 D) for astigmatism. Vector analysis showed that 57 eyes (68.7%) had 5 or less degrees rotation. Seventy-two (86.7%) and 54 eyes (65.1%) had uncorrected visual acuity equal or better than 20.40 and 20/25 respectively. One eye (1.2%) showed a best corrected visual acuity loss of more than one line, but 8 eyes (9.6%) had a gain of more than one line. One-year results on a smaller series (33 eyes) overlap the six-month results. CONCLUSIONS: The mask in-the-rail excimer laser delivery system appears to be effective and predictable in the correction of compound myopic astigmatism. We observed no significant regression of the astigmatic correction over time. Longer follow-up on larger series is necessary to draw final conclusions.

Adolescent↗

PubMed1996

Study of photoablation of rabbit corneas by Er:YAG laser.

BACKGROUND AND OBJECTIVE: This work studied the ablation mechanisms of rabbit corneas by the Erbium:YAG laser. The occurrence of thermal and mechanical damages in the tissue as a function of the laser fluence was also investigated. STUDY DESIGN/MATERIALS AND METHODS: The experiments were performed both on enucleated eyes and in vivo. An ultrafast imaging technique was used to investigate the dynamic evolution of the ablation. The treated samples underwent histological and ultrastructural study. RESULTS: A single high fluence laser shot led to the complete removal of the epithelium by a photomechanical effect. In eyes whose epithelium was manually removed, high fluence pulses resulted in evident tears in the stroma, whereas low fluence pulses led to few microns deep incisions, characterized by limited mechanical and thermal damages. CONCLUSION: The photomechanical action plays a significant role in the ablation of the cornea by Erbium laser. Precise control of the fluence is required to avoid cracking phenomena in the stroma.

Aluminum Silicates↗

PubMed1996

Double-frequency Nd:YAG laser vs. argon-green laser in the treatment of proliferative diabetic retinopathy: randomized study with long-term follow-up.

BACKGROUND AND OBJECTIVE: A randomized clinical trial using the argon-green (514 nm) and the double-frequency Nd:YAG (532 nm) lasers was carried out on 42 eyes with proliferative diabetic retinopathy (PDR), with the aim of assessing the long-term effects of double-frequency Nd:YAG panretinal photocoagulation (PRP). MATERIALS AND METHODS: Twenty-one eyes were randomized to argon laser treatment (ALT) and 21 to double-frequency Nd:YAG laser treatment (NdLT). The mean follow-up was 28.90 months (+/- 6.13) in the ALT group and 29.57 months (+/- 5.17) in the NdLT group. RESULTS: In the ALT group, 20 eyes (95.2%) showed regression of PDR and one eye (4.8%) enlargement of pre-existing new vessels. In the NdLT group, neovascularization regressed in 20 eyes (95.2%) and increased in one (4.8%). CONCLUSIONS: The long-term efficacy of double-frequency Nd: YAG laser PRP in the treatment of PDR thus appears to be similar to that of argon-green.

Adult↗

PubMed1996

New semiconductor laser for vitreoretinal surgery.

BACKGROUND AND OBJECTIVE: We investigated the potential application in vitreoretinal surgery of a CW diode laser with cutting capabilities. STUDY DESIGN/MATERIALS AND METHODS: A semiconductor CW laser emitting 300 mW optical power at 1.94 microns wavelength was used to perform retinotomies and membrane cutting on rabbit eyes. The device was integrated into a dedicated controller. The laser radiation was delivered through a low attenuation fused silica optical fiber of 200 microns core size, terminating into a 20-gauge endo-ocular handpiece. Histological aspects of threshold lesions obtained on the rabbits' chorioretina were evaluated by light microscopy. RESULTS: We obtained circular and linear full-thickness retinotomies with contact and noncontact procedures using energy of 120 mJ (240 mW x 0.5 s). Using a non-contact procedure, a larger peripheral coagulation halo around the retinotomies was observed, as compared to the contact method. The adjacent zone of thermal damage ranged from 50 to 200 microns. Lower efficacy was obtained on experimentally induced epiretinal membranes, where only superficial ablation was achieved. CONCLUSION: The CW 2 microns diode laser will have a promising future in vitreoretinal surgery when a higher output irradiance is available.

Animals↗

PubMed1996

Vitreous laser absorption following fluorescein angiography in diabetic patients.

BACKGROUND: Sodium fluorescein staining of the vitreous following fluorescein angiography may interact with laser photocoagulation. METHODS: We evaluated the laser absorption by fluorescein in the vitreous when photocoagulation is performed following fluorescein angiography in 15 eyes of nine diabetic patients. Axial fluorescein concentration in the vitreous was measured by a scanning vitreal fluorophotometer. The amount of light absorbed by the fluorescein within the vitreous was calculated according to the Lambert-Beer law. RESULTS: The mean fluorescein concentration ranged from 2.93 ng cm-3 to 105.16 ng cm-3 at 1 h after injection of fluorescein and from 8.03 to 188.56 ng cm-3 after 4 h. Maximum laser absorption at 488 nm ranged from 6.79% (after 1 h) to 14.53% (after 4 h); at 514.5 nm it ranged from 0.96% to 2.14%; at 532 nm it ranged from 0.03% to 0.07%. At lambda > 550 nm, laser absorption was found to be negligible. CONCLUSIONS: In order to optimize the effect of photocoagulation, especially during long photocoagulation sessions, argon blue laser (488 nm) should be avoided following fluorescein angiography. Argon green laser (514.5 nm) should be used within 1 h after fluorescein injection. Frequency-doubled Nd:YAG laser (532 nm), krypton laser (647 nm) or semiconductor diode laser (810 nm) may be used at any time.

Absorption↗

PubMed1996

Indocyanine green and fluorescein angiography of surgically excised macular choroidal neovascularizations: correlations with histopathologic and ultrastructural findings.

BACKGROUND: Informations are expected from the histopathological study of surgically excised choroidal neovascular membranes (CNMs), particularly in relation to the angiographic aspects of vascular architecture. METHODS: Fluorescein and indocyanine green (ICG) angiograms were studied together with the histopathological features of 12 surgically excised subfoveal CNMs in eyes affected by age-related macular degeneration (ARMD). RESULTS: Instead of the early and delayed diffuse hyperfluorescence secondary to CNMs observed on fluorescein angiography (seven were well defined, five scar evolved), ICG revealed (a) very early hypofluorescence of the membrane bulk over the fluorescence of the outer choroidal vascular bed and (b) late hyperfluorescence gradually increasing and partially defining the border of membranes. CNMs with well-defined hyperfluorescent aspects were characterized by fibrovascular bulk lined on one side by retinal pigment epithelium. Fibrosis reaction predominated over the vascular components in scar-evolved membranes. CONCLUSIONS: Fluorescein and ICG angiographic differences in the appearance of CNMs could depend on (a) the morphological structure and size of the CNM (b) its location within the chorioretinal layers and (c) different molecular characteristics of the dyes used.

Aged↗

PubMed1996

Atlantoaxial dislocation related to instilling eyedrops in a patient with Down's syndrome.

PURPOSE: To alert ophthalmologists of the risk of hyperextending the neck of patients with Down's syndrome while holding them to instill eyedrops. METHOD: We describe a case of atlantoaxial dislocation related to instilling eyedrops in a 6-year-old girl with Down's syndrome. RESULT: Early recognition of the problem allowed prompt treatment and partial recovery of the patient. CONCLUSION: Examination and clinical maneuvers in a child with Down's syndrome require gentleness and avoidance of hyperextension of the neck to prevent spinal cord injury.

Atlanto-Axial Joint↗

PubMed1996

Spontaneous regression of neovascularization at the disk and elsewhere in diabetic retinopathy.

PURPOSE: To report three cases of spontaneous regression of new vessels of the disk and elsewhere in proliferative diabetic retinopathy. METHODS: We retrospectively examined the clinical records of three young women (27, 26, and 19 years old) with insulin-dependent diabetes mellitus (for 16, eight, and 17 years, respectively) associated with other systemic diseases and referred to us for treatment of retinopathy. Complete general and ophthalmologic findings, visual field, and angiographic and electroretinographic examinations were available for each patient. RESULTS: All the patients showed marked, spontaneous improvement of their proliferative retinopathy, with regression of new vessels. Assessment of metabolic control did not bring to light any noteworthy change during the period when the new vessels disappeared. Regression of new vessels was associated with a marked improvement in blood-retinal barrier breakdown as detected on fluorescein angiograms. CONCLUSIONS: Although very unusual, spontaneous regression of neovascularizations in proliferative diabetic retinopathy can happen. We can offer no explanation for the regression of the new vessels and retinovascular hyperpermeability.

Adult↗

PubMed1996

Glucose metabolism and pathological findings in uveal melanoma: preliminary results.

The aims of this study were to assess the sensitivity of positron emission tomography (PET) using [18F]fluorodeoxyglucose (18F-FDG) in the detection of uveal melanoma, and to establish the relationship between pre-operative 18F-FDG uptake and a number of pathological features of uveal melanoma. Twenty consecutive patients with a clinical diagnosis of uveal melanoma were enrolled in the study. 18F-FDG uptake was assessed in all subjects and the following parameters were assessed in 11 enucleated subjects: the mitotic index, the MIB-1 proliferating cell index, number of epithelioid cells, largest tumour diameter, tumoral necrosis and inflammatory infiltration. Tumours with a diameter less than 7.5 mm were not detected by PET, possibly because of limited spatial resolution, and only 7 of 12 tumours with a diameter greater than 7.5 mm were detected. With tumours greater than 7.5 mm in diameter, PET and 18F-FDG allow two subgroups to be distinguished: those with high and those with low glucose consumption. Apart from tumour size, 18F-FDG uptake was not related to the pathological features examined. We hypothesize that 18F-FDG uptake may be related to the ratio of viable to non-viable cells, or to the hypoxic cell fraction within the tumour.

Adult↗