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Biomedical subjects

G Trabucchi

Publications and source records attributed to G Trabucchi.

At least 19 recordsLinked to original sources
PubMed2000

ICGA-guided laser photocoagulation of occult choroidal neovascularization in age-related macular degeneration. Indocyanine green angiography.

PURPOSE: To evaluate the efficacy of indocyanine green angiography (ICGA)-guided laser photocoagulation in eyes with fluorescein angiographic evidence of occult choroidal neovascularization (O-CNV) in patients with age-related macular degeneration (ARMD) with or without pigment epithelium detachment (PED). METHODS: Eighty eyes of 79 consecutive patients with O-CNV underwent laser treatment of a clearly outlined extrafoveal ICGA hyperfluorescent area, presumed to be focal CNV. Four types of presumed CNV were treated: Group 1 (20 eyes), CNV beneath the PED; Group 2 (23 eyes), CNV at the margin of the PED; Group 3 (10 eyes), parapapillary CNV and PED; and Group 4 (27 eyes), macular CNV without PED. Median follow-up was 17.5 months (range, 6-24 months). RESULTS: After 1 year, 15% of the eyes in Group 1, 30% in Group 2, 100% in Group 3, and 52% in Group 4 had obliteration of the presumed CNV. After 1 year, visual acuity was stable or improved in 18% of Group 1, in 37.5% of Group 2, in 100% of Group 3, and in 73% of Group 4. The remaining eyes worsened. CONCLUSIONS: Indocyanine green angiography-guided laser treatment may improve or stabilize visual acuity in some eyes with O-CNV. The best outcome is seen in eyes with presumed parapapillary CNV, probably made up of choroidal telangiectases in many cases. The type and location of the presumed CNV influence prognosis after laser treatment considerably. A randomized, controlled clinical study appears necessary to investigate the efficacy of ICGA-guided laser treatment in different types of presumed CNV. The inclusion criteria for further trials need to be defined with precision, as data from patients with different choroidal vascular abnormalities have been pooled until now.

Aged↗
PubMed1999

Ultrasound biomicroscopic evaluation of ciliochoroidal effusion after laser treatment.

We evaluated ciliochoroidal effusion (CE) by ultrasound biomicroscopy (UBM) following diode endophotocoagulation at the end of the vitreoretinal surgery. The aim of our study was to assess any differences in the CE morphology following diode endophotocoagulation or transpupillary krypton photocoagulation, and to demonstrate the influence of diabetes and intravitreal surgery on CE formation. Sixty-six consecutive patients were divided in to four groups. Twenty-nine patients with proliferative retinopathy underwent transpupillary krypton photocoagulation; 11 diabetic patients underwent vitreoretinal surgery and diode endophotocoagulation; 18 nondiabetics underwent vitreoretinal surgery and diode endophotocoagulation; 8 consecutive nondiabetic patients were the control group and underwent vitreoretinal surgery, without laser treatment. UBM was performed in the four groups before and after laser treatment, if performed. We determined, by UBM, not only the presence, but also the thickness of CE. CE was present in all the patients treated by laser, diabetics and nondiabetics, and its thickness was not correlated with the number of laser spots (p = 0.28). CE was seen ultrasonically in all the patients undergoing transpupillary photocoagulation or endophotocoagulation, regardless of diabetes and surgical trauma.

Aged↗
PubMed1998

Indocyanine green angiography in enlarged blind spot syndrome.

PURPOSE: To report the indocyanine green angiography findings in a case of acute idiopathic blind spot enlargement syndrome. METHOD: The patient underwent ophthalmologic examination with fluorescein angiography and indocyanine green angiography. RESULTS: A monocular enlarged blind spot was found on automated perimetry; fluorescein angiography showed a hypofluorescent peripapillary atrophic area and indocyanine green angiography highlighted diffuse, small hypofluorescent spots scattered throughout the posterior pole. Visual field defects and indocyanine green angiography abnormalities resolved over 4 weeks. CONCLUSION: Indocyanine green angiography in acute idiopathic blind spot enlargement syndrome showed many lesions not visible with fluorescein angiography, indicating a choroidal involvement reaching not only the peripapillary area but the entire posterior pole.

Acute Disease↗
PubMed1998

Fluorescein and indocyanine green angiography in vascular chorioretinal diseases.

Fluorescein angiography allows visualization of blood flow in retinal and choroidal tissues, permitting diagnostic support in many ocular diseases. Particularly, fluorescein angiography has become a very important tool in the study and treatment of chorioretinal diseases. Because of the limitations of fluorescein angiography in imaging the choroidal circulation and associated pathologies, investigators have searched for alternative dyes to improve choroidal angiography, the most promising of which has been indocyanine green dye. The usefulness of indocyanine green angiography to aid in the diagnosis and treatment of a variety of chorioretinal diseases was reported during the last years. The goal of this article is to make an overview on the most frequent Fluorescein and ICGA patterns of vascular diseases of the chorioretina.

Choroid Diseases↗
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

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↗
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

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

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↗
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

Corneal nerve damage and regeneration after excimer laser photokeratectomy in rabbit eyes.

PURPOSE: To investigate corneal nerve damage and its subsequent regeneration after excimer laser photokeratectomy in rabbit eyes. METHODS: Corneal photokeratectomy was performed on the right eyes of 34 pigmented rabbits, while the left eyes were used as a control. A Summit UV 200 excimer laser (Summit Technology, Waltham, MA) was used to produce a 100 microns depth phototherapeutic keratectomy (4.5 mm diameter). The rabbits were killed at 0, 1, 2, 3, 4, 5, 7, 8, 10, 15, and 20 days and 1, 2, 3, and 4 months after treatment. Corneal nerve regeneration was investigated using a monoclonal antibody directed against a 150 kD subunit of neurofilaments, in combination with acetylcholinesterase staining. RESULTS: At time 0, the subepithelial plexus had disappeared completely from the photoablated area. One day after treatment, some regenerating nerves sprouting within the treated area were visualized by a monoclonal antibody directed against a 150 kD subunit of neurofilaments. Acetylcholinesterase staining was detectable 7 days later. One month after surgery the subepithelial plexus had already reappeared, but was morphologically disorganized. Four months after treatment, the newly formed subepithelial plexus had considerably thickened in comparison with that of the control eye. CONCLUSIONS: This study shows that corneal nerve regeneration after excimer laser photoablation in rabbit eyes, although more intense, is similar to that produced after other surgical procedures involving the epithelium and the anterior stroma or one of the two.

Acetylcholinesterase↗
PubMed1993

Diode versus argon-green laser panretinal photocoagulation in proliferative diabetic retinopathy: a randomized study in 44 eyes with a long follow-up time.

A clinical randomized study using argon-green (532 nm) and diode (810 nm) lasers was carried out on 44 eyes (34 patients) affected by proliferative diabetic retinopathy (PDR), with the aim of evaluating the long-term effects of diode panretinal photocoagulation. Of the total 44 eyes, 22 were randomized to argon laser treatment (ALT) and 22 to diode laser treatment (DLT). The mean follow-up time was 25 +/- 5 months in the ALT group versus 24 +/- 4 months in the DLT group. In the ALT group 20 eyes (91%) showed regression of PDR whereas 2 eyes (9%) deteriorated. In the DLT group regression of neovascularization was observed in 22 eyes (100%). These results show that the long-term efficacy of diode laser PRP in the treatment of PDR is similar to that of argon-green laser PRP.

Adult↗