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Biomedical subjects

G Ravalico

Publications and source records attributed to G Ravalico.

At least 37 records · Page 2Linked to original sources
PubMed1999

Visual representation of space in congenital and acquired strabismus.

The aim of the present work was to readdress the problem of altered spatial localization in strabismic subjects and to assess whether and how spatial representation is affected by the degree of plasticity of the brain. We therefore compared targeting performance in adult subjects affected by acquired strabismus versus children affected by congenital strabismus. Our data confirm the correlation between deviation of the eye and targeting errors, but they also show that this correlation is not present when strabismus occurs early in life. We suggest that the neuronal machinery involved in the building of an internal representation of space reaches its full maturity several years after birth and that this might explain the limited differences observed in targeting errors between normal and strabismic children.

Adult↗
PubMed1999

Effect of astigmatism on multifocal intraocular lenses.

PURPOSE: To study the effect of astigmatism on multifocal intraocular lens (MIOL) function. SETTING: Laser Laboratory, Department of Electronics, Electrotechnics and Informatics, University of Trieste, Italy. METHODS: Using an experimental optical system, this study compared the division of a laser beam in the focal spots of 1 monofocal IOL (Pharmacia 722A), 1 bifocal IOL (Pharmacia 811E), and 2 MIOLs (AMO Array MPC25NB and Domilens Progress 1). The model consists of a helium-neon laser and an optical system: a triangular optical bench with a precision collimator, a micropositionable immersion stage to support the IOL, and a digital image-processing system. Astigmatism was induced by interposing a +1.0 diopter (D) cylinder lens between the IOL and the television camera. Astigmatism was corrected by adding a -1.0 D cylinder lens in front of the IOL on the same axis. RESULTS: Astigmatism creates pairs of focal lines, 1 for each focal spot in the IOL. In the multifocal IOL, the posterior focal line of the nearest focus interfered with the anterior line of the next focus. Correcting the astigmatism led to a significant reduction (mean 20%) in light intensity. CONCLUSIONS: Astigmatically neutral surgery or surgical correction of pre-existing astigmatism is essential in MIOL implantation to minimize the decrease in contrast sensitivity.

Astigmatism↗
PubMed1999

Spontaneous dislocation into the vitreous of a poly(methyl methacrylate) disc lens 9 years after surgery.

A 76-year-old woman had sudden visual loss 9 years after an extracapsular cataract extraction with implantation of a poly(methyl methacrylate) disc intraocular lens (IOL) in the capsular bag. Slitlamp examination showed the disc IOL had luxated into the vitreous through a linear inferior opening in the capsular bag; the IOL lay on the retinal surface. A pars plana vitrectomy was performed. The vitreous cavity was filled with perfluorocarbon liquid, floating the IOL to behind the iris. The IOL was removed through a limbal incision, then another type of IOL was implanted in the ciliary sulcus using transscleral fixation. Thirty days after surgery, best corrected visual acuity (BCVA) was 20/20. At 2 months, total retinal detachment appeared with a large superior retinal dialysis. Another pars plana vitrectomy was performed and the scleral-fixated IOL removed through a limbal incision. Internal gas tamponade was used. The eye was left aphakic. Final BCVA was 20/25.

Aged↗
PubMed1999

Grid laser treatment of macular edema in macular branch retinal vein occlusion.

AIM: Macular branch retinal vein occlusion (MBRVO) is a subgroup of branch retinal vein occlusion in which the occlusion is limited to a small venous vessel draining a sector of the macular region. The present study aims to evaluate the efficacy of grid laser treatment for macular edema in MBRVO. METHODS: 77 Patients with MBRVO of recent onset were prospectively studied during a 24 month period. Eyes were randomly assigned to a grid laser treatment group and to a control group. Clinical parameters such as visual acuity, presence of macular edema and angiographic features were recorded during the follow-up period. RESULTS: Visual acuity increased significantly in both groups after 3 months of follow-up (p<0.001) and after 1 year of follow-up (p<0.005). No additional improvement was noted at the two year control. There was no statistical difference between the two groups. CONCLUSIONS: The visual prognosis of MBRVO is not improved after grid laser treatment of macular edema. This suggests that sudden ischemic damage to central photoreceptors rather than macular edema is the main factor for permanent visual acuity reduction.

Aged↗
PubMed1999

Antihypertensive drugs and the nervous system: ACE-inhibitors restore oscillatory potentials in hypertensives.

The authors have previously reported that oscillatory potentials (O.P.) of the electroretinogram are impaired in essential hypertensive patients before the appearance of funduscopic changes. They can therefore be considered an early marker of the nervous damage induced by hypertension. Aim of this study was to evaluate whether an antihypertensive regimen could influence the progression of this damage. O.P. were recorded in 35 essential hypertensives before antihypertensive treatment and after one-year treatment. The patients were randomly allocated into 4 treatment groups: 1) beta-blockers 2) ACE-Inhibitors 3) calcium antagonists 4) no pharmacological treatment. At the end of the study, blood pressure was significantly decreased in all but group 4. O.P., similar in the 4 groups at the beginning, were significantly higher at the end of the study only in patients treated with ACE-inhibitors. The results of this study suggest that although all hypotensive agents reduced blood pressure only ACE-I showed a protective effect on the retinal electric electrophysiology in hypertensive patients.

Adrenergic beta-Antagonists↗
PubMed1998

Spatial resolution threshold in pseudophakic patients with monofocal and multifocal intraocular lenses.

PURPOSE: To compare the spatial resolution threshold in the central visual field of pseudophakic patients with monofocal and multifocal intraocular lenses (IOLs). SETTING: Eye Clinic, University of Trieste, Italy. METHODS: Twenty phakic normal subjects and four groups of 20 pseudophakic patients each, implanted with refractive and diffractive multifocal IOLs (Domilens Progress 1, AMO Array MPC25NB, or Pharmacia 811X) or with monofocal IOLs (Allergan PC43NB), were studied. The spatial resolution threshold in the central visual field was assessed using high-pass resolution perimetry. Measurements were performed adding spherical correction to test the different foci of the IOL. RESULTS: No significant differences between phakic subjects and pseudophakic patients with monofocal IOLs were found. In distance vision, no significant differences between patients with refractive multifocal IOLs and those with monofocal IOLs were found. The group with the diffractive multifocal IOL showed a significantly higher spatial resolution threshold (P = .003). In intermediate vision, the AMO Array group showed a significantly lower spatial resolution threshold than the other groups (P < .01). The best performance at near distance was in the diffractive group, which was statistically significantly different from the other groups (P < .001). CONCLUSION: In the diffractive group, the high spatial resolution threshold in distance vision could be explained by the lower brightness of the principal focus, related to a different light energy division between the foci. In the Domilens group, the high spatial resolution threshold in near vision could be related to the light energy scattered in a large number of foci.

Aged↗
PubMed1998

Analysis of light energy distribution by multifocal intraocular lenses through an experimental optical model.

PURPOSE: To analyze and compare the light energy distribution generated by multifocal intraocular lenses (IOLs). SETTING: Laser Laboratory of the Department of Electronics, Electrotechnics and Informatics, University of Trieste, Italy. METHODS: An optic system to examine the division of a laser beam in the various focal spots of multifocal IOLs was developed. The model consists of a helium-neon laser and an optical system: a triangular optical bench with a precision collimator, a micropositionable immersion stage supporting the IOL to be measured, and a digital image-processing system. Four bifocal and three multifocal IOLs were studied. This system is able to expand the distance between foci, leading to a sharper separation of the focal spots. The resolution of the images makes it possible to analyze the distribution of total light energy among the foci. RESULTS: Results showed the variation in light intensity of the focal spots of multifocal and bifocal IOLs, as well as their disposition in the dioptric range. CONCLUSION: Light distribution among various focal distances corresponded to the foci provided by monofocal, bifocal, and multifocal IOLs. The percentage of light energy distribution was related to the importance of each focus.

Lenses, Intraocular↗
PubMed1998

Iris arteriovenous communication: clinical and angiographic features.

BACKGROUND: Iris arteriovenous communication (IAVC) represents a quite rare congenital anomaly, consisting of abnormal vascular connection bypassing the iris capillary bed. The aim of the present study is to describe clinical and angiographic pattern of IAVC on iris fluorescein angiography (IFA) and on indocyanine green videoangiography (IICGV). METHODS: During a mean follow-up period of 33.5 months, eight patients affected by IAVC underwent at least three ophthalmological examinations completed by IFA and IICGV. RESULTS: IFA allows the detection of IAVC vascular structures, evidencing afferent and efferent branches, which show a rapid filling, without any evidence of leakage or iris hypoperfusion. IICGV shows more precisely the entire vascular pattern of IAVC, revealing also the presence of iris hypoperfusion in the sector in which the IAVC lay. One patient underwent cataract surgery; three months later, two neovascular tufts appeared in the hypoperfused area related to IAVC. In all other patients, periodical examinations did not reveal any clinical or angiographic changes. CONCLUSION: In IAVC, the clinical picture appears stable throughout the follow-up; both angiographic techniques seem able to precisely delineate the vascular pattern. Nevertheless, IICGV is superior in showing iris hypoperfusion surrounding the vascular abnormality. Particular care must be drawn to patients affected by IAVC who need cataract surgery.

Arteriovenous Malformations↗
PubMed1998

Fluorescein angiography and indocyanine green videoangiography in the iris of pseudoexfoliation syndrome.

The precise evaluation of iris vascular pattern in pseudoexfoliation syndrome (PXS) may be difficult on iris fluorescein angiography (IFA) because of the frequent presence of a heavily pigmented iris and late conspicuous leakage. Thanks to its special characteristics, iris indocyanine green videoangiography (IICGV) is able precisely to visualize details of the iris vascular pattern. The aim of the study is to analyze the feasibility of IICGV in detecting microvascular changes in PXS and compare these findings with those of IFA. Twenty-eight patients affected in both eyes by PXS underwent an ophthalmologic examination including IFA and IICGV. IICGV was performed using IMAGEnet system H1024. A better visualization of iris hypoperfusion and anastomotic vessels was obtained on IICGV, whereas iris microneovascularization was far more clearly visible on IFA. Moreover, iris pigment epithelium defects were detectable on IICGV. IICGV may be considered a useful tool in the evaluation of the iris vascular pattern in PXS. Iris hypoperfusion could not play a contributory role in the development of iris microvascular changes.

Aged↗
PubMed1997

Postoperative cellular reaction on various intraocular lens materials.

PURPOSE: The presence of cellular deposits on the surface of intraocular lenses (IOLs) is a manifestation of: (1) the breakdown of the blood-aqueous barrier produced by surgery; and (2) foreign body reaction induced by lens implantation. The purpose of this study was to assess the presence of cellular deposits on the surfaces of various IOL materials. METHODS: Fifty patients scheduled for cataract surgery were randomized into five groups of ten patients each and received IOLs of the following materials: conventional polymethylmethacrylate (PMMA), surface-passivated PMMA, heparin-surface modified PMMA, poly-hydroxyethylmethacrylate (HEMA) hydrogel and silicone. Patients were examined at 7 days, 30 days, 90 days, and 180 days after surgery. All eyes were observed first via slit-lamp and then using a contact specular microscope for photographic documentation. RESULTS: Small, spindle-shaped cells were observed on all IOLs in the early postoperative period. Epithelioid cells appeared approximately 30 days after surgery on all PMMA IOLs, but most particularly on conventional PMMA IOLs. No cells were observed on poly-HEMA and silicone IOLs. CONCLUSIONS: The decreased number of epithelioid cells discovered in the early postoperative period may indicate a reduction in the inflammatory process induced by surgery. The permanence of epithelioid cells on IOL surfaces may be a sign of foreign body reaction. The results of this study indicated that poly-HEMA and silicone IOLs showed fewer cellular deposits than PMMA IOLs, suggesting that they may be better tolerated than PMMA IOLs.

Biofilms↗
PubMed1997

Corneal endothelial function after extracapsular cataract extraction and phacoemulsification.

PURPOSE: To compare the morphology and function of the corneal endothelium in the early postoperative period after extracapsular cataract extraction (ECCE) and phacoemulsification. SETTING: University Eye Clinic of Trieste, Italy. METHODS: In this prospective, randomized study of patients scheduled for cataract surgery, 40 patients were divided into two groups of 20 patients each. Group 1 had ECCE and Group 2, phacoemulsification; both had capsular bag intraocular lens (IOL) implantation. Preoperatively and 7 and 30 days postoperatively, a complete ophthalmological examination, endothelial specular microscopy, ultrasonic pachymetry, and anterior segment fluorophotometry were done. Visual acuity, endothelial cell density, cell size variation coefficient, corneal thickness, endothelial permeability coefficient, and endothelial pump function were studied. RESULTS: Visual acuity was better 7 days after phacoemulsification than after ECCE, but no differences were observed after 30 days. No significant differences in postoperative loss of endothelial cells were found between the two groups. Coefficient of variation in size, corneal thickness, and endothelial permeability significantly increased in both groups 7 days postoperatively, but only in the ECCE group 30 days postoperatively; the differences between the two groups were statistically significant. Endothelial pump function significantly increased after 7 days in only the phacoemulsification group. CONCLUSIONS: Functional endothelial failure occurred in the early period after ECCE. Phacoemulsification seemed to minimize postoperative functional damage to the endothelium.

Aged↗
PubMed1997

Corneal endothelial protection by different viscoelastics during phacoemulsification.

PURPOSE: To evaluate corneal endothelium morphology and function after phacoemulsification using different viscoelastics. SETTING: Eye Clinic, University of Trieste, Italy. METHODS: This prospective, randomized study included results of preoperative and postoperative (7, 30, and 90 days) examinations of 66 patients scheduled for phacoemulsification without ocular pathology; 8 patients were excluded. Patients were randomly assigned to one of four groups based on type of viscoelastic used: 1% sodium hyaluronate (Healon); 1.4% sodium hyaluronate (Healon GV); 4% sodium chondroitin sulfate-3% sodium hyaluronate (Viscoat); 2% hydroxypropyl methylcellulose (Hymecel). Mean cell density and cell size variation coefficient were determined by specular microscopy; central corneal thickness, by ultrasonic pachymetry; and endothelial permeability coefficient and active pump function, by anterior segment fluorophotometry. RESULTS: There were no significant differences in postoperative mean cell loss among the groups. The cell size variation coefficient was altered in all groups 7 days after surgery and was still impaired at 30 days in the Hymecel group. A significant increase in mean corneal thickness, endothelial permeability, and active pump function occurred in the Healon and Hymecel groups 7 days after surgery. These parameters were still altered 30 days after surgery in the Hymecel group. Endothelial functional alterations did not occur in the Healon GV or Viscoat group. CONCLUSION: Viscoat and Healon GV are effective in minimizing functional damage of endothelial structure in the early medium-term postoperative period.

Aged↗
PubMed1997

Branch retinal vein occlusion and macroaneurysms.

BACKGROUND: Macroaneurysms can represent common consequences of branch retinal vein occlusion (BRVO). The aim of the present study is to evaluate the clinical and angiographic aspects of 31 cases of branch retinal vein occlusions (BRVO) in which retinal macroaneurysms developed, in an attempt to analyze their pathogenic features. METHODS: One hundred and sixty-one consecutive patients affected by BRVO were considered. Each patient underwent an opthalmological examination including fluorescein angiography, at an average interval of two months (range: 1-4 months) from the onset of the disease, with a mean follow-up of 43 months (range: 32-56 months). The macroaneurysms were subdivided according to size into small (from 100 to 149 microns), medium (from 150 to 249 microns), and large (greater than 250 microns), and according to origin into arterial, venous, capillary and collateral-associated. RESULTS: Thirty-one patients (19.3%) developed retinal macroaneurysms. The total number of detected macroaneurysms was 51; ten (19.6%) were large, 21 (41.2%) were of medium-size and 20 (39.2%) were small in dimension. Three lesions were of arterial origin, 22 were capillary and 26 were from collateral vessels. In 27 patients (87.1%) the lesions were located outside the macular region, and in 4 patients (12.9%) in the macular region. Patients with retinal macroaneurysms did not show a different prevalence of capillary non-perfusion when compared with others. With regard to the number of retinal venous collaterals patients with macroaneurysms developed fewer than other patients, and the difference was statistically significant (p < 0.001). CONCLUSION: The insufficient number of retinal venous collaterals can be considered the most contributory factor in the development of macroaneurysms secondary to BRVO.

Aged↗
PubMed1997

Pulsatile ocular blood flow variations with axial length and refractive error.

Ocular pulse amplitude (PA) and pulsatile ocular blood flow (POBF) were studied in 80 eyes from 80 subjects with a refractive error between +3.00 and -28.00 dpt using the Langham Ocular Blood Flow System. PA and POBF were correlated with axial length and refractive error using linear regression analysis. A significant correlation (p < 0.001) was found between PA and axial length (r = -0.787), PA and refractive error (r = 0.775), POBF and axial length (r = -0.655) and POBF and refractive error (r = 0.650). Myopic eyes were further divided into subgroups according to axial length, refractive error and fundus oculi characteristics. Each subgroup exhibited a significant reduction in PA (p < 0.001) compared to the control group. POBF reduction was significant in every subgroup except the subgroup with a refractive error lower than 6 dpt and the subgroup with an axial length shorter than 26 mm.

Adult↗
PubMed1996

Adult-onset foveomacular vitelliform dystrophy and indocyanine green videoangiography.

BACKGROUND: Adult-onset foveomacular vitelliform dystrophy (AOFVD) represents a heterogeneous group of disorders with different clinical, angiographic, and histopathological features. The most common form is characterized by a yellow, round to oval subretinal macular lesion with or without central pigmented spot. METHODS: Eight patients affected by typical AOFVD underwent fluorescein angiography and indocyanine green videoangiography (ICGV). RESULTS: Fluorescein angiography showed a central hypofluorescent spot surrounded by an irregular hyperfluorescent ring. ICGV demonstrated a foveal nonfluorescent spot, visible during the entire examination, and a hyperfluorescent area surrounding the central spot, which became evident soon after the beginning of the examination. CONCLUSIONS: In light of previous histopathological studies, the central nonfluorescent spot may be interpreted as a masking effect of a pigment clump, whereas the hyper-fluorescent area may represent dye pooling or staining of the subretinal pigment epithelial material.

Adult↗
PubMed1996

Iris indocyanine green videoangiography in diabetic iridopathy.

AIMS/BACKGROUND: Iris fluorescein angiography (IFA) is not commonly used in clinical practice, although its value has been demonstrated especially in cases of diabetic disease. IFA is able to show neovascular tufts in order to guide the laser treatment, and it is highly recommended in diabetic patients who need cataract surgery or vitrectomy. Nevertheless, IFA fails to demonstrate the iris vascular pattern in heavily pigmented iris and conspicuous leakage cases. The aim of the study was to evaluate the feasibility of iris indocyanine green videoangiography (IICGV) and to correlate its findings with those of IFA in diabetic iridopathy. METHODS: Thirty six patients affected in varying degrees by diabetic retinopathy underwent an ophthalmic examination including retinal fluorescein angiography, IFA, and IICGV. IICGV was performed using IMAGEnet System H1024. RESULTS: The results demonstrated that IICGV allows precise visualisation of the iris vascular pattern, also in cases of heavily pigmented iris. CONCLUSIONS: Three main findings seemed to be evident: firstly, iris neovascularisations are detected with IFA far more easily than IICGV; secondly, capillary dilatations and iris hypoperfusion are identified far more clearly using IICGV; thirdly, there is no evident relation between capillary dilatation or iris hypoperfusion, and degree of diabetic retinopathy.

Aged↗
PubMed1996

Age-related ocular blood flow changes.

PURPOSE: Pulsatile ocular blood flow (POBF is influenced by well-known parameters, such as intraocular pressure (IOP), heart rate, scleral rigidity, blood pressure, and posture. Age is also likely to influence POBF strongly. The purpose of this study was to evaluate POBF in relation to age in normal subjects. METHODS: Relevant data were collected from a sample of 105 normal subjects, ranging in age from 10 to 80 years. To measure the effect of age on POBF, the subjects were divided into seven groups of 15 subjects each; the age range of each group spanned one decade, beginning with age 10. POBF and pulse amplitude (PA) were measured in sitting and supine positions and after suction cup application. RESULTS: Using linear regression analysis, there was a significant correlation between PA and age in the supine position (P = 0.012) and after suction cup application (P = 0.002); in the sitting position, there was a borderline level of statistical significance (P = 0.053). In the sitting position, POBF was 819 +/- 212 microliters/minute in the second decade and 630 +/- 194 microliters/minute in the eighth decade. In the sitting position and after suction cup application, but not in the supine position, a statistically significant correlation between POBF decrease and age was found with linear regression analysis (P < 0.001 and P = 0.004, respectively). Using multiple regression analysis, POBF values revealed a significant correlation with age (P < 0.001), but not with systolic and diastolic brachial pressure. Considering all the subjects, analysis of variance for repeated measures highlighted a significant decrease of POBF from the sitting to the supine position and associated with an IOP increase (P < 0.001) without significant changes of PA. After suction cup application, there was a significant reduction of both PA and POBF (P < 0.001). CONCLUSIONS: The data revealed that as age increased, PA decreased in all three series of measurements. POBF decreased with age, and in subjects older than 50 years, the decrease was more evident. These findings are especially noticeable after IOP increase with suction cup. It must be considered that the age-related value of POBF is a fundamental parameter to evaluate correctly the hemodynamic aspects of the pathologies affecting the eye.

Adolescent↗