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Biomedical subjects

A Reibaldi

Publications and source records attributed to A Reibaldi.

At least 19 recordsLinked to original sources
PubMed2003

Diabetic patients and retinal proliferation: an evaluation of the role of vascular endothelial growth factor (VEGF).

Vascular endothelial growth factor (VEGF) has been shown to play a major role in intraocular neovascularisation in ischaemic retinal diseases. The aim of this study was to evaluate the concentration of VEGF in vitreous, aqueous and epiretinal membranes of diabetic and non-diabetic patients, with other pathological conditions requiring surgical intervention. Higher VEGF concentration were found in samples from the eyes of diabetic patients versus other pathologies as well as in epiretinal membranes versus the other eye compartments in diabetic patients. However, high VEGF levels were also found in retinal detachment and proliferative vitreoretinopathy of non-diabetic patients. We concluded that VEGF is produced locally and plays a fundamental, but not specific, role in diabetic retinal neovascularisation and proliferation.

Aqueous Humor↗
PubMed2003

Vitreous polyamines spermidine, putrescine, and spermine in human proliferative disorders of the retina.

BACKGROUND/AIMS: Many cytokines are involved in the pathogenesis of retinal proliferative diseases, but none has been shown to be related to a specific disorder. The aim of this study was to provide a selective marker of diabetes induced proliferative retinopathies. METHODS: 10 vitreous samples from 10 subjects affected by quiescent proliferative diabetic retinopathy (PDR), 20 vitreous samples from 20 subjects affected by active PDR, and 15 samples from 15 patients with proliferative vitreoretinopathy (PVR) were studied. Samples from 18 patients with a macular hole (n = 8) or pucker (n = 10) served as controls. Vitreous samples were obtained via pars plana vitrectomy. The polyamines spermidine, putrescine, and spermine, vascular endothelial growth factor (VEGF), interleukin 8 (IL-8), and transforming growth factor 1beta (TGF-1beta) were measured by high performance liquid chromatography (HPLC) and enzyme linked immunosorbent assay (ELISA), and the correlation coefficients between the vitreous polyamine content and VEGF, IL-8, and TGF-1beta levels were determined. RESULTS: Spermidine and putrescine were expressed in normal vitreous, but spermine was not detectable. In all the test groups spermidine was 3-4 times higher than in control vitreous and putrescine was similarly lower. The spermine content was up to 15 times higher only in vitreous from patients affected by PDR. Correlation coefficients showed that the spermidine and putrescine level variations correlated with the VEGF and IL-8 content in the active PDR and PVR groups, but not in those with quiescent PDR patients, while spermine was correlated to these cytokines in PDR, but not in PVR groups. CONCLUSIONS: These data suggest a significant role for spermidine and putrescine as markers of proliferative diseases of the retina. The increase in spermine, restricted to diabetic states, may indicate that this polyamine is a unique and specific index of PDR.

Adult↗
PubMed2001

Biocompatibility and biodegradation of intravitreal hyaluronan implants in rabbits.

To study the biocompatibility and the biodegradation rate in vivo of new intravitreal implants made with three different hyaluronic acid esters: Hyaff7, Hyaff11 and Hyaff11p75 (100% ethyl ester, 100 and 75% benzyl esters, respectively), the plugs were implanted through a sclerotomy at 3.5 mm from the limbus of rabbit eyes. In order to evaluate the in vivo biodegradation the shaft diameter of the plugs was measured by ultrasound biomicroscopy. Slit lamp microscopy, ophthalmoscopy and ERG were performed periodically. The effects of the implants on ocular tissues were also evaluated histologically. All the plugs showed a good biocompatibilitv. Plugs of both the total esters, Hyaff7 and Hyaff11, were found to undergo a slow dissolution process for 60 and 150 days, respectively. The partial benzyl ester, Hyaff11p75, was completely reabsorbed after 15 days. Analysis of variance showed a high correlation between biodegradation rate and the time of resorption (F = 90.5; p < 0.001). The biodegradation rate of each implant is related to the chemical structure of the three types of Hyaff (F = 4.51; p = 0.005). The present data suggest that intravitreal implants based on hyaluronic acid esters represent useful biocompatible and biodegradable devices for a potential drug delivery system in the treatment of posterior segment ocular diseases.

Animals↗
PubMed1999

Long-term visual results of bifocal intraocular lens implantation.

PURPOSE: To evaluate the long-term visual results and variability in contrast sensitivity in patients with heparin-surface-modified (HSM) diffractive bifocal intraocular lenses (IOLs). SETTING: Institute of Ophthalmology, University of Catania, Italy. METHODS: In this prospective study, visual acuity (distance and near) and contrast sensitivity were measured in 35 patients who had phacoemulsification with bifocal diffractive IOL (model 811E, Pharmacia) implantation. Patient satisfaction was also evaluated using a questionnaire. Mean follow-up was 20 months (range 18 to 24 months). RESULTS: At the last examination, mean distance visual acuity was 0.79 +/- 0.2 (SD) without correction and 1.0 +/- 0.15 with best correction. Mean uncorrected near visual acuity was J1.6 +/- J0.77 and with best distance correction, J1.19 +/- J0.49. No statistically significant changes in visual acuity were evident at the last follow-up (Student t test). No changes were found in contrast sensitivity reduction over time, nor were late postoperative complications noted. Overall patient satisfaction was rated as good by 94.3% of patients with best distance correction. CONCLUSIONS: The diffractive bifocal HSM IOL provided good visual performance for distance and near over time. In relation to the low rate of postoperative complications, the slight contrast sensitivity reduction was stable during follow-up.

Adult↗
PubMed1998

[Evaluation of the filtering bleb using ultrasound biomicroscopy].

BACKGROUND: Sometimes in glaucomatous patients treated with trabeculectomy there is not a correlation between bleb shape and intraocular pressure. So we studied the functional anatomy of the filtering bleb by a ultrasound biomicroscope, using high frequency (50 Mhz) probe, which provides high resolution images of filtering blebs. MATERIALS AND METHODS: A total of 46 filtering blebs of 46 patients after trabeculectomy were analyzed by ultrasound biomicroscopy (50 Mhz). Dimensions, shapes and structure of blebs were evaluated in 2 groups of patients. RESULTS: It was possible to obtain longitudinal or transverse images of filtering blebs, to measure the height, to evaluate the reflectivity inside and to follow the route under the scleral flap. Blebs with lower reflectivity and a visible route under the scleral flap had a lower intraocular pressure while the height was not important for a good intraocular pressure. CONCLUSIONS: So ultrasound biomicroscopy can be a useful method to study filtering blebs and also to explain the mechanisms of filtering structures in patients who underwent trabeculectomy.

Aged↗
PubMed1998

Keratoconus staging with ultrasound biomicroscopy.

The diagnosis of keratoconus is based on slip-lamp and keratometric findings, and its classification includes 4 different stages. In this study, we compare the ultrasound biomicroscopy (UBM) findings and the keratoconus index (KI) determined using UBM with the severity of the disease. By means of UBM (Humphrey Instruments system model 840) using a 50-MHz probe, we studied 49 eyes affected with different forms of keratoconus. Using a method previously described, we calculated the KI and compared these data with the findings obtained using videokeratography. The mean thickness at the corneal apex in keratoconic eyes was 0.369 mm, while the mean peripheral corneal thickness was 0.568 mm. The mean KI was 1.449 in keratoconic eyes. The KI increased according to the severity of the disease. The mean central keratometry power was 56.95, while the mean amount of steepening of the inferior cornea compared with that of the superior cornea was 8.16. UBM can be considered a useful tool in the study of keratoconus. Using high-frequency ultrasound, it is also possible to obtain reliable measurements of corneal thickness related to the severity of the disease determined by videokeratography.

Cornea↗
PubMed1998

Corneal oedemas: diagnosis and surgical planning with ultrasound biomicroscopy.

We used the Humphrey Ultrasound Biomicroscope (UBM System 840 by Zeiss-Humprey Instruments, San Leandro, Calif. USA) to study various corneal oedemas and leucomas. This UBM system, using a high-resolution probe of 50 Mhz, has an axial and lateral resolution of about 50 micrometer. We analysed 36 eyes divided into two groups, 27 (group A) affected by corneal oedema caused by traumatic-mechanic or phlogistic-toxic lesions, 9 (group B) affected by postsurgery oedema. Thanks to its high-resolution power, we could study their pathogenesis and their clinical evolution and so arrange a suitable therapy and perform an accurate follow-up of these pathologies.

Burns, Chemical↗
PubMed1998

Ultrasound-biomicroscopic evaluation of filtering blebs after laser suture lysis trabeculectomy.

UNLABELLED: Sometimes in glaucomatous patients treated with trabeculectomy there is no correlation between bleb shape and intra-ocular pressure (IOP). In this study we evaluated the ultrasound biomicroscopy (UBM) features of filtering blebs after laser suture lysis (LSL) trabeculectomy in order to analyse whether its ultrasound-biomicroscopic image can predict the function (IOP). METHODS: The Humphrey ultrasound biomicroscope, using a high-frequency (50-Mhz) probe, provides high-resolution images of filtering blebs. A total of 103 filtering blebs after LSL trabeculectomy were analysed by UBM. Taking into account the characteristics of internal reflectivity and scleral flap, we classified the blebs into three groups (good, fair, poor) that indicate the bleb function and correlated this UBM pattern with the IOP control (good, borderline, failure). RESULTS: There was a statistically significant corelation between the UBM classification of function and the IOP control level. Both well-functioning and failed trabeculectomies could be identified by UBM. The UBM images of eyes with good IOP control are characterized by better visibility of the route under the scleral flap and a low reflectivity inside the bleb. CONCLUSIONS: In accordance with previous studies, we believe that UBM can be a useful method to study and explain the mechanisms of filtering structures and, together with IOP control, to evaluate the bleb function.

Adult↗
PubMed1997

Evaluation of central and peripheral corneal thickness with ultrasound biomicroscopy in normal and keratoconic eyes.

PURPOSE: Our study was designed to calculate central and peripheral corneal thickness in patients affected with early stages of keratoconus and in normal subjects using ultrasound biomicroscopy (UBM). To obtain an objective and reliable assessment of the corneal thinning in affected eyes, we developed a keratoconus index (KI) by means of the UBM measurements. METHODS: By means of the commercial version of the ultrasound biomicroscope (system model 840; Zeiss-Humphrey Instruments, San Leandro, CA, USA) using a 50-MHz probe, we studied 30 normal and affected eyes. In keratoconic eyes, we measured the thinnest corneal thickness (TCT) at the apex of the conus and at four peripheral sites at a distance of 2.5 mm from the central site (peripheral corneal thickness: PCT). The same procedure was performed in the normal eyes. To obtain an objective and reliable assessment of the corneal thinning, we calculated the ratio between the mean PCT and the mean TCT (Keratoconus Index: KI = PCT/TCT), in keratoconic eyes. In normal eyes, the KI was calculated on the basis of the ratio between the mean PCT and the mean central corneal thickness (CCT). RESULTS: In keratoconic eyes, the mean corneal thickness at the thinnest part of the conus was significantly different from the CCT in normal patients (Student's t test, p < 0.001). The peripheral measurements were not significantly different from keratoconic and normal eyes. The mean KI was 1.482 (SD, 0.095) in the keratoconic eyes, whereas it was 1.189 (SD, 0.086) in the normal subjects. The statistical analysis of the KI calculated on the basis of the UBM measurements showed that the KI values are significantly different from healthy subjects and from keratoconic patients (Student's t test, p < 0.001). CONCLUSIONS: UBM can be considered a useful tool in the study of keratoconus. We believe that calculation of the KI by means of UBM gives the possibility of obtaining an objective assessment of corneal thinning. Therefore this parameter can be useful in the staging and in the follow-up of these patients.

Adolescent↗
PubMed1994

[Controlled trabeculectomy and incidence of postoperative choroidal detachment].

In this study the authors report their experience with titrated trabeculectomy. It is performed as follows: tight scleral flap trabeculectomy, five or more 10/0 nylon sutures, argon laser lysis of one or more sutures (depending on the eye's postoperative condition) by means of the Hoskins lens. The aim of this technique, performed by the authors for 3 years, is to decrease atalamia and choroidal detachment. Results obtained in 70 eyes of 62 patients with chronic open-angle glaucoma are compared by means of statistical analysis with those in 70 eyes of 66 patients operated on by means of the traditional technique. The incidence of choroidal detachment is significantly reduced (P < 0.001). There is no important difference in ocular pressure and visual acuity. In conclusion, this technique is very useful in controlling and titrating the filtration rate, avoiding an excessive lowering of IOP after trabeculectomy and decreasing the complications.

Adult↗
PubMed1994

[Experiences with sclerostomy with the Holmium laser].

The THC-YAG laser (holmium laser) war used to perform ab externo sclerostomies in patients affected by various types of glaucoma. This approach was employed in 48 eyes with diagnoses of medically uncontrolled chronic open angle glaucoma, plateau iris or neovascular glaucoma. Post-operatively, 5-FU was injected. At the tend of the follow-up (mean 10.22 +/- 3.4 months), in 25 eyes (52.1%) the IOP was under control without medical therapy. In 12 eyes (25.0%) it was necessary to use antiglaucomatous topical therapy, and in 11 eyes (22.9%) the IOP was uncontrolled despite therapy. The authors stress the importance of a correct pharmacological protocol before and after operation and describe the surgical technique. They confirm the validity of this approach, owing to its minical invasiveness, the possibility of repeating the procedure, and the low complication rate.

Aged↗
PubMed1994

[Determination of contrast sensitivity in patients with silicone oil tamponade].

UNLABELLED: The issue of whether silicone oil has a toxic effect on the retina is still being debated. In order to verify possible retinotoxic effects, the authors studied the variations of retinal function by means of computerized perimetry on patients who had undergone a vitreoretinal operation with injection of silicone oil in the vitreous cavity. Silicone oil remained in the eyes for a period of 120 days +/- 15. PATIENTS AND METHODS: 14 patients under treatment for vitreoretinal pathologies sparing the macula underwent five examinations (Macular Threshold Test of the Humphrey Field analyzer): two examination during the period silicone oil was in the vitreous cavity (30 days after injection and 10 days before removal) and three examinations after its removal (at 30, 90, and 180 days). RESULTS: When the paired t-test and ANOVA test were applied to our results, there were no significant differences in the light-difference sensitivity. CONCLUSIONS: These data do not indicate that silicone oil a retinotoxic effect (revealed by means of computerized perimetry) when it is removed within 4 months.

Adult↗
PubMed1993

MRI and intraocular tamponade media.

Thirteen patients who underwent surgery for retinal detachment and injection of intraocular tamponade media (silicone oil, fluorosilicone oil, or perfluorocarbon liquid) underwent magnetic resonance imaging (MRI), using spin-echo T1- and T2-weighted images. The ophthalmic tamponade media showed different signal intensity, according to their chemical structure. Unlike ophthalmoscopy or ultrasonography, MRI showed no oil-related artefact, making possible recognition of recurrent retinal detachment.

Humans↗
PubMed1992

Surgical management of closed angle glaucoma: our experience.

In this paper we present our experience of the last three years in the surgical treatment of eyes with closed angle glaucoma. We have performed an extracapsular lens extraction and posterior chamber intraocular lens implantation on 34 eyes of 34 patients. All of them were affected by closed angle glaucoma with variable control after a Yag laser iridotomy: 6 eyes had high I.O.P. notwithstanding maximal therapy, 11 eyes had I.O.P. under control (less than 21 mmHg) without therapy, 9 with I.O.P. controlled with topical therapy, 8 with I.O.P. controlled with maximal therapy (C.A.I. included). The cases with well controlled glaucoma were operated on because of the presence of a more or less significant lens opacities. After a follow-up of up to 40 months (mean = 20.3, range = 1-40), all eyes show satisfactory intraocular pressure and no eye needed a filtering procedure. The results of our studies are as follows (values are mean +/- SD). In the group of 6 eyes with high I.O.P., the mean pre-operative intraocular pressure was 29.7 +/- 5.6 mmHg and the mean post-operative I.O.P. was 15.1 +/- 1.4 mmHg. The mean reduction was 14.5 +/- 6.6 mmHg (p < 0.005). In the 28 eyes with pre-operative I.O.P. under control (17.5 +/- 1.6), the mean post-operative I.O.P. was 14.4 +/- 2.3 mmHg, with a mean reduction of 3.1 +/- 3.1 mmHg (p < 0.005). Before the E.C.C.E., 11 eyes had I.O.P. less than 21 mmHg without anti-glaucoma medication, whereas after the E.C.C.E. 28 eyes did not need such a medication.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[A new surgical procedure in angle block glaucoma].

Authors show the results obtained in 29 eyes of 29 patients with closed angle glaucoma operated with ECCE plus posterior chamber IOL implantation. After a follow up varying from 1 to 35 months (mean = 20.7) all eyes are under good control (25 without therapy, 4 with topical therapy) of I.O.P. Authors report on the "rationale" of their surgical approach: particular anatomo-functional features of the eyes affected by closed angle glaucoma. Pre-op. and post-op. biometrical and gonioscopical findings are described and discussed.

Aged↗