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Biomedical subjects

G Ravalico

Publications and source records attributed to G Ravalico.

At least 55 records · Page 3Linked to original sources
PubMed1995

Foveal avascular zone in macular branch retinal vein occlusion.

The mean area of the foveal avascular zone (FAZ) in normal subjects was reported as 0.231 mm2 to 0.405 mm2, using fluorescein angiography. The FAZ enlarges in vaso-occlusive diseases, especially diabetic retinopathy, sickle cell retinopathy, talc retinopathy and branch retinal vein occlusion. In the present study the FAZ of 20 patients affected by macular branch retinal vein occlusion (MBRVO) was compared with the FAZ of 41 control subjects. The FAZ mean area was 0.56 +/- 0.34 mm2 SD in the MBRVO group, while 0.26 +/- 0.07 mm2 SD in the control group, with a statistically significant difference (p < 0.001). The FAZ mean perimeter was 4.77 +/- 1.90 mm SD in the MBRVO group, and 2.36 +/- 0.32 mm SD in the control group, with a statistically significant difference (p < 0.001). Taking into account the MBRVO group, a statistical correlation was found between visual acuity impairment and FAZ enlargement (p = 0.02), but not between visual acuity impairment and macular edema (p = 0.41). In 14 cases (70%) secondary avascular microzones located in the macular sector correspondent to MBRVO were also evident. MBRVO causes an irregular enlargement of the FAZ which seems to represent the most important feature related to visual acuity impairment.

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PubMed1995

Primary empty sella syndrome and central retinal vein occlusion.

Empty sella syndrome (ESS) is a peculiar disease that may involve systemic, neurological or ophthalmological symptoms. Our report presents a case of primary ESS complicated with central retinal vein occlusion. In an attempt to explain the pathogenesis of the retinal venous stasis, it may be hypothesized that the compression of the optic nerve may produce a slowing of axoplasmic flow, with a consequent optic nerve head swelling. Thus the central retinal vein gets compressed with the clinical result of a retinal venous stasis.

Empty Sella Syndrome↗
PubMed1995

Oscillatory potentials in subjects with treated hypertension.

Oscillatory potentials of the ERG proved to be a sensitive indicator even in mild disturbances of retinal circulation, such as the first stage of hypertensive retinopathy (WHO classification). Oscillatory indexes (OIs) and blood pressure levels of 24 hypertensive patients in stage 1 of the WHO classification, who underwent an antihypertensive therapy for the first time, were considered. The patients were retested after a mean period 8 months. a strict inverse correlation was found between OIs and blood pressure levels.

Adult↗
PubMed1995

Capillary macroaneurysms in central retinal vein occlusion.

The occurrence of macroaneurysms as a consequence of central retinal vein occlusion was previously reported in one study only with the appearance of a single capillary macroaneurysm. We report a case of central retinal vein occlusion presenting several capillary macroaneurysms. It may be supposed that retinal ischemia plays an important role in the pathogenesis of capillary macroaneurysms, in association with the pressure increase in the capillary network due to venous obstruction.

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PubMed1995

Oscillatory potentials of the electroretinogram in hypertensive patients.

Because alteration of oscillatory potentials of the electroretinogram has been described in diabetic patients without signs of diabetic retinopathy as an early marker of changes in microcirculation, we studied the behavior of these potentials in patients with early-onset hypertension. Electroretinograms were recorded in 24 subjects with essential hypertension (blood pressure > 140/90 mm Hg) and in 9 age-matched normotensive control subjects (blood pressure < 140/90 mm Hg). Diabetes and ocular diseases were considered exclusion criteria. Sitting blood pressure was measured by a single investigator with a mercury sphygmomanometer after each subject had been at rest for 10 minutes. Funduscopic changes in all subjects did not exceed stage I World Health Organization classification. The oscillatory index was calculated by adding waves O1, O2, and O3 within the b wave of the electroretinogram. Statistical analysis was performed with Student's t test for paired and unpaired data and linear regression. The oscillatory index was significantly reduced in hypertensive patients compared with normotensive subjects. An inverse relationship was observed when systolic and diastolic blood pressures were plotted against the oscillatory index. In conclusion, our data demonstrate that the electrical activity of the retina is altered early in the course of hypertension and that the influence of systolic pressure on the oscillatory index is greater than that of diastolic pressure.

Adult↗
PubMed1994

Visual and blood flow responses in low-tension glaucoma.

Low or normal-tension glaucoma (NTG) is a rare clinical condition characterized by a glaucomatous cupping of the optic disk associated with the appearance of typical visual field defects, without ocular hypertension. According to several authors, NTG accounts for 5-15% of primary open angle glaucomas (POAG). In our open study we obtained a complete documentation of clinical and instrumental data-tonometric curve, computerized perimetry, pattern electroretinogram, pulsatile ocular blood flow (POBF) and retinography--on 10 consecutive patients (18 eyes) affected by NTG. We found that the NTG patients were similar to the controls as regards arterial systemic pressure and heart rate, but that POBF values were lower in the NTG patients.

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PubMed1994

Heparin-surface-modified intraocular lens implantation in eyes with pseudoexfoliation syndrome.

Eyes with pseudoexfoliation syndrome have a greater risk of intraoperative and postoperative complications. Clinical and histopathological studies indicate that heparin-surface-modified intraocular lenses (HSM IOLs) can reduce postoperative anterior segment inflammation. Our study evaluated the blood-aqueous barrier permeability in eyes with pseudoexfoliation syndrome and implanted with an HSM IOL. We examined two groups of 20 patients, one comprising patients with pseudoexfoliation syndrome and one a sex- and age-matched control group with senile cataracts. Each group was divided into two subgroups of ten patients each. In one subgroup, an HSM IOL was implanted; in the other, a conventional poly(methyl methacrylate) IOL. We performed a complete ophthalmologic examination and iris angiography preoperatively and at 30, 90, and 180 days after surgery. Fluorophotometry was performed at the 90-day and 180-day postoperative examinations. The patients with pseudoexfoliation syndrome had a higher blood-aqueous barrier permeability than did the control group. Permeability decreased significantly three and six months after surgery, especially in the HSM IOL group.

Aged↗
PubMed1994

Corneal endothelial function in diabetes: a fluorophotometric study.

The corneal endothelium in diabetics is particularly susceptible to surgical trauma. This is related to the presence of morphological alterations of endothelial cells and to a supposedly concomitant functional failure of the endothelium in these patients. The aim of our study was to evaluate the corneal endothelial function in diabetics. A fluorophotometric study was performed on 3 groups of diabetic subjects without retinopathy, with nonproliferative retinopathy and with proliferative retinopathy compared with an age-matched control group. We evidenced a significant increase in corneal thickness and in passive corneal permeability in diabetics with severe retinal involvement. These findings are not related with a proportional significant increase in endothelial pump function. We suggest an altered regulation in corneal hydration in diabetic patients depending on the functional failure of endothelial cells that is likely to be connected with corneal biochemical modifications caused by an altered glucidic metabolism.

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PubMed1994

[Functional evaluation of a new type of intraocular lens: Domilens type PROGRESS 1].

This study presents the first clinical and functional results on the implantation of a new multifocal IOL model, the Domilens type PROGRESS 1. A group of 20 patients underwent extracapsular extraction of cataract with continuous circular capsulorhexis and IOL implantation in the capsular bag. In 65% of the cases, final visual acuity from a far distance proved to be greater than or equal to 8/10 without correction, while visual acuity from a short distance was J2 without the need of additional lenses. BAT identified a decrease in visual acuity of 0.01 Snellen lines at a medium lighting level and 0.05 at the maximum level. The perimetric results obtained with the C 30-2 threshold programme of the Humphrey field analyzer showed a foveal sensitivity threshold of 32.5 dB +/- 9.25 dB and a mean defect of -2.22 dB +/- 2.90 dB. The Vistech VCTS 6500 underlined a decrease in the sensitivity to space frequency contrast of 6.0 c/d versus a control group of patients with monofocal IOL (P < 0.05). This reduction involved a wider range of space frequencies (3.0, 6.0, 12.0 c/d) in comparison with a group of phakic subjects (P < 0.05). With the on-off PEV patterns, a slight decrease in contrast sensitivity threshold was found versus patients with monofocal IOL statistically non significant (P > 0.05). At a medium space frequency of 2.33 c/d, a decrease in contrast sensitivity versus phakic subjects (P < 0.05) was observed. Depth of focus went from infinite to 19 cm. from the eye.

Aged↗
PubMed1993

Contrast sensitivity in multifocal intraocular lenses.

Contrast sensitivity was measured in two groups of 20 patients each implanted with refractive and diffractive multifocal intraocular lenses and in two control groups of 20 patients each--the first group implanted with a monofocal IOL and the second phakic subjects. All cases had a postoperative follow-up of at least one year and a corrected visual acuity of 20/20- or better. We used two psychophysical tests, Pelli Robson test chart and Vistech 6500 test chart, and an objective test, visual evoked potentials (VEPs). There were no statistically significant differences in contrast sensitivity in the psychophysical tests between the two groups implanted with multifocal IOLs. The situation was different, however, when they were compared with the control group with monofocal IOLs and the group with phakic eyes: the Pelli-Robson test results were not significantly different, but the Vistech 6500 test showed a significant reduction in contrast sensitivity in both groups. The pattern VEPs objective test confirmed these results: no differences were noted between the two different multifocal IOLs, while there was a drop in contrast sensitivity when their results were compared with those of the control groups; the intermediate frequencies were particularly affected by this phenomenon. The contrast sensitivity in patients with multifocal IOLs is reduced despite high visual acuity and this can affect the quality of vision.

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PubMed1993

Long-term results with Iogel IOLs.

130 single piece hydrogel Iogel intraocular lenses (IOL) were implanted in the capsular bag after planned extracapsular cataract extraction. Anterior capsulotomy was performed by capsulorhexis in 59 patients while the envelope technique was used in 71 cases. The mean follow-up was 22 months and the average visual acuity was more than 8/10 in 78.5% of cases. In the capsulorhexis group a higher percentage of IOL was placed right into the capsular bag. No significant inflammatory and noninflammatory postoperative complications occurred. Lens decentration, observed in 5 cases, was due to asymmetric lens placement with one flange in the bag and the other in the ciliary sulcus. In both groups endothelial cell loss was about 7%. Results of the study indicate the safety and the efficacy of the Iogel lens as an intraocular implant. To prevent postoperative decentration and deformation of the IOL unnecessary intraocular manipulation and 'in-out' positioning should be avoided.

Aged↗
PubMed1992

Refractive bifocal intraocular lens and pupillary diameter.

To assess the relationship between pupillary diameter and focusing for distance and near vision with the refractive bifocal intraocular lens (IOL), we studied visual acuity for far and near distance, near point, and depth of focus with normal pupillary movements and after pharmacological miosis and mydriasis (pilocarpine 2% and phenylephrine 10% eyedrops, respectively) in 20 patients implanted with an IOLAB refractive bifocal IOL. Pharmacological miosis and mydriasis did not change far and near visual acuity values from the values with normal pupillary diameter. After pharmacological miosis, the near point position and the width of the depth of focus were unchanged. After pharmacological mydriasis, near point distance was unchanged but depth of focus dropped in a statistically significant manner (P < .01). We concluded that the pupillary diameter alone cannot produce distance or near vision focusing. The choice depends on the brain's preference. Pupillary diameter increases the quality of vision through the blur circles mechanism.

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PubMed1992

Exudative retinal detachment subsequent to retinal vein occlusion.

Previous studies have shown the possible development of exudative retinal detachment (ERD) as a complication of retinal vein occlusion (RVO). Considering 473 consecutive cases of RVO, only 3 cases of ERD with peculiar clinical aspects were discovered. In the first case, the ERD followed a branch RVO, but it developed in the opposite quadrant, with a late occurrence of venous retinal collaterals. In the second case, the ERD developed after a central RVO, having a retinoschisis aspect, with the subsequent occurrence of optic disk collateral vessels. In the third case, the ERD was secondary to a hemicentral RVO and involved the entire macular area. The pathogenesis of the ERD subsequent to RVO is still debated. Our experience seems to indicate that the ERD pathogenesis is linked not only to an inability of the draining vascular system, but also to an impairment in the function of the retinal pigment epithelium.

Acetazolamide↗
PubMed1992

Hemicentral and hemispheric retinal vein occlusions.

Since some authors have considered useless a differentiation between hemicentral retinal vein occlusion (HCRVO) and hemispheric retinal vein occlusion (HSRVO), we have conducted a prospective research in order to evaluate the clinical and prognostic features of these diseases. We have followed prospectively 26 cases of HCRVO and 25 cases of HSRVO. The most important risk factors were hypertension, diabetes mellitus and glaucoma in HCRVO, and hypertension in HSRVO. In the HCRVO group 20 cases (76.9%) were of the non-ischemic type and six cases (23.1%) were ischemic-type, whereas in the HSRVO seven (28%) were non-ischemic type and 18 cases (72%) were ischemic-type. Our results demonstrate that the two retinal vein occlusions are quite different with regards to pathogenesis, clinical evolution and visual outcome and point out the necessity to achieve a precise diagnosis.

Adult↗
PubMed1991

Cup/disk ratio in branch retinal vein occlusion.

Recent reports have been attempted to evaluate, without obtaining a positive result, whether the reduction in size of the optic disc may influence the pathogenesis of central retinal vein occlusion. Cup/disc ratios in the fellow eye of 67 patients with branch retinal vein occlusion were compared with the ratios of 67 controls matched to cases for age, sex and refractive defect. There was no significant difference between cup/disc ratios of the two groups. These results suggest that the anatomical features of the optic disc are of no importance in the development of branch retinal vein occlusion.

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PubMed1990

Apparent accommodation in pseudophakic eyes.

The so-called apparent accommodation has been measured in patients implanted with anterior chamber, iris support and posterior chamber IOLs. The data have been related to pupillary diameter and anterior chamber depth in order to explain the actual possibility of a near vision with optical correction only for distance.

Accommodation, Ocular↗
PubMed1990

Optic nerve head drusen: histopathological considerations--clinical features.

The histopathological features made on 18 autopsies have proved that the optic nerve head drusen are calcified formations situated within the margins of the optic nerve head. It has been supposed that not only an aberrant axoplasmic transport, but also the presence of local factors, partly depending on the Bruch's membrane, can play a determining role in the pathogenesis of the optic disc drusen. A spongiotic edema gives us the histopathological equivalent of the clinical aspect of the optic disc with indistinct margins and lack of the central cup and furthermore gives us an explanation about the perimetric alterations pathogenesis. Clinical observations confirm that the optic nerve head drusen are prevalently asymptomatic and that visual acuity remains unchanged. The threshold tests are able to quantify exactly the entity and the depth of the visual field defects and its possible changing within a certain period of time. As regards the diagnosis, the retinal fluoroangiography is of great importance allowing to distinguish clearly a pseudo-papillary edema from a papillary edema.

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