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Biomedical subjects

R De Natale

Publications and source records attributed to R De Natale.

14 recordsLinked to original sources
PubMed2000

Visual field defects and normal nerve fiber layer: may they coexist in primary open-angle glaucoma?

The retinal nerve fiber layer (RNFL) is the anatomical structure most sensitive to glaucoma injury. Before a functional loss such as a visual field defect is displayed, a large number of nerve fibers can be damaged. However, there are glaucoma patients in which an apparently normal RNFL coexists with evident visual field defects. A total of 54 eyes affected with primary open-angle glaucoma were studied. Visual field was examined with the Humphrey Field Analyzer (Zeiss) using program 30-2. The Nerve Fiber Analyzer II (Laser Diagnostic Technologies) was used to study the RNFL of these patients. Mean deviation of the visual field ranged from 6 to 31 dB in all eyes that were examined. The average thickness of the RNFL ranged from 20 to 90 microm. According to our previous experience 75 microm was fixed as the cutoff between normal and pathological values of RNFL thickness. We identified 5 eyes with a RNFL thickness over 75 microm and a visual field with a mean deviation over 6 dB; 9% of the studied eyes were found to have a visual field defect with no changes in RNFL. We conclude that not all subjects have the same number of fibers at birth and that it is therefore possible to underestimate the RNFL changes. Our study illustrates that the concept of normal and altered has to be considered as a relative one for all the aspects characterizing the glaucomatous disease.

Aged↗
PubMed2000

Visual acuity disturbances in chronic renal failure.

Patients affected by chronic renal failure often complain of blurred vision when submitted to hemodialysis. Refraction, visual acuity and lens transparency have been evaluated in 36 eyes of 18 patients who underwent hemodialysis, before and after the treatment. Student's t test did not prove any statistically significant difference between the considered parameters. However, a change in refraction was noted in 64% of the eyes, always in hyperopic mean. Corrective glasses had to be changed to ensure the same visual acuity as before the hemodialytic treatment. Particular care must be taken in lens prescription in those patients who could undergo dialysis for chronic renal failure.

Contrast Sensitivity↗
PubMed1997

Phacotrabeculectomy with or without punch: preliminary results comparing the two techniques.

The authors report their experience in the combined surgery, for glaucoma and cataract, by using the Crozafon-De Laage punch. 24 patients affected by open-angle glaucoma and cataract have been enrolled in the study. 12 underwent a combined operation of phacoemulsification and trabeculectomy according to Cairns, and 12 underwent phacoemulsification and protective filtering surgery executed with the Crozafon-De Laage punch. Comparing the two methods we noted as advantage of the punch its easiness of use, through the sclerocorneal tunnel of the phacoemulsification, to create a filtering fistula; this shortened the duration of surgery. As a disadvantage of punch use we noted a lower filtering gradability as opposed to Cairns' trabeculectomy.

Adult↗
PubMed1997

Does nerve fiber layer thickness correlate with visual field defects in glaucoma? A study with the nerve fiber analyzer.

The Nerve Fiber Analyzer, a confocal scanning laser ophthalmoscope, was used to measure the thickness of the retinal nerve fiber layer (NFL) in a glaucoma population. The authors studied the correlation between NFL thickness and the perimetric defects. The NFL was found to be statistically thinner in comparison to a normal control group of subjects. The correlation between the perimetric index MD and the NFA was statistically significant only for the lower quadrant of retinal NFL. The correspondence between thinner NFL and perimetric defects was investigated.

Glaucoma↗
PubMed1994

High-resolution perimetry of the central visual field.

The Octopus Program M1 was designed for the detection/follow-up of central or paracentral visual field defects in patients with neurological disorders or with macular or perimacular diseases. Within the central 25 degrees visual field, 59 test locations provide a resolution of < or = 1.4 degrees. The differential light sensitivity is measured with 'Octopus normal strategy', i.e. a 4/2/1 staircase procedure. The Program M2X has 81 test locations in the central 10 degrees, giving even higher resolution (< or = 0.7 degrees) of the central visual field. Both programs have 2 phases, the second being a re-test. Program M2X's phases are divided into 4 stages and allow interruption anytime.

Adult↗
PubMed1992

Lens opacity: a population study.

Age-corrected normal values for the Opacity Lens Meter (OLM) 701 were established by measuring 1598 eyes of 799 healthy volunteers. This study revealed a remarkable age-relation for the normal values. The average readings of the OLM of the 30-year-old subjects were around 10 units whereas the average for the 65-year-olds was close to 20 units. The best fit of the opacity vs. age was a quadratic function. The interindividual variation was small in the young and quite large in the older population. The correlation between contralateral eyes was high (R = 0.93).

Adolescent↗
PubMed1992

Effectiveness of computer-assisted perimetry in the follow-up of patients with pituitary microadenoma responsive to medical treatment.

DESIGN: Patients were studied before and after 1 year of bromocriptine or 6 months of SMS 201-995 treatment, for prolactinomas or GH-secreting adenomas, respectively. PATIENTS: Seventeen patients with intrasellar pituitary tumour (ten prolactinomas, all females; seven GH-secreting adenomas, four males and three females) and the presence of relative or absolute scotomas, were examined. MEASUREMENTS: We used computed tomodensitometry, Goldman perimeter and computer-assisted perimetry. RESULTS: The patients were divided into three groups according to their response to medical treatment as proved by computed tomodensitometry which revealed the disappearance of the tumour in four prolactinomas (group 1), a reduction > 40% in three prolactinomas and in three acromegalics (group 2) and no significant variation in the diameter of the adenoma in three prolactinomas and in four acromegalics (group 3). Comparison by the paired t-test of the visual fields before and after treatment revealed a significant positive change (P < 0.01) for all patients in groups 1 and 2 and for one patient in group 3, with disappearance of the scotomas in all cases in group 1 and in two cases in group 2. Visual field defects were detected by means of the Goldman perimeter in only one patient with prolactinoma and in two acromegalics, although the computer-assisted perimetry showed that, in 15 out of 17 patients, visual impairment was unilateral and in all cases the presence of relative scotomas was concentrated in the upper temporal quadrant. The visual defects observed with computer-assisted perimetry and the pituitary tumour dimension evaluated with computed tomodensitometry did not show significative correlations (r = 0.059, P NS). CONCLUSIONS: Computer-assisted perimetry was most useful in the diagnosis and follow-up of patients with pituitary adenoma, especially in the evaluation of small masses without subjective symptoms of visual loss, when the Goldman perimeter does not usually allow us to recognize minimal chiasmatic involvements or the improvement of visual field as a result of the medical therapy.

Acromegaly↗
PubMed1992

Human lens transparence in high-myopic subjects.

The possibility of a relation between high myopia and lens opacity was studied. For this research, the Lens Opacity Meter 701 was used. The lens opacity values measured in 91 high-myopic eyes were compared with those measured in a control group of 106 emmetropic eyes. This comparison showed that myopic had always higher lens opacity values than emmetropic ones, and this result was statistically significant after the age of 20.

Adolescent↗
PubMed1990

The transparency of the lens: a comparison between diabetic and non-diabetic patients.

The transparency of the lens of 485 eyes of 266 healthy volunteers were compared with 143 eyes of 83 diabetic patients. All the patients had well controlled diabetes. The transparency of the lens was measured with the opacity lensmeter 701. The concept of the instrument is based on the measurement of scattered light. The result revealed a similar transparency of the lenses of diabetic patients in relation to the normal volunteers. There was only a slight, and statistically not significant trend in the older age group versus a greater opacity for diabetic patients.

Adolescent↗
PubMed1989

Effectiveness of computer-assisted perimetry in the diagnosis of pituitary adenomas.

Computer-assisted perimetry (CP) is a new method which quantifies the differential light sensitivity threshold and allows the statistical analysis of the data. It offers advantages as compared with manual methods. This study has been carried out in 27 patients with pituitary adenomas (four males and 23 females; 13 with prolactinomas; six with acromegaly, four with Cushing's disease and four with non-secreting adenomas). A skull X-ray and a computed tomodensitometry (CT), a manual Goldman perimeter and a computer assisted visual field examination were performed in all cases. The presence of a pituitary tumour was suggested by the X-ray and by the CT in 12 and 23 patients respectively out of the 27: the CT scan revealed a suprasellar extension in seven cases. Visual field defects were detected by means of the Goldman perimeter in six patients and by means of the computer-assisted technique in 25/27. The effectiveness of this new technique was proved by the concordance with the CT scan results in 21 cases and by the histological examination of the four adenomas which were not apparent at CT scan. A significant difference was found for both eyes (right eye, chi squared = 258, P less than 0.001; left eye, chi squared = 295.0, P less than 0.001) between patients and controls. No correlation existed between visual defects and the pituitary size apparent at CT scan. Six patients were evaluated with the CT and CP after 1 year of bromocriptine treatment; a slight reduction of size was documented with the CT in four cases, whereas a significant positive change in visual acuity was observed in five patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1988

Influence of age on the transparency of the lens in normals: a population study with help of the Lens Opacity Meter 701.

The Lens Opacity Meter 701 measures the lens density quantifying the back light scatter of the lens. The instrument emits a modulated dark-red beam which runs along the optic axis of the lens. The stray light is converted into an electrical impulse which is displayed and printed using a numerical scale. The lens density in a normal population was investigated with this instrument in order to study the influence of age on the opacification process.

Adolescent↗
PubMed1985

[Specificity of suprathreshold test methods in automated perimetry].

The specificity of suprathreshold automated perimetry of the central visual field was investigated comparatively with the Fieldmaster Model 225 computer perimeter, utilizing five different test strategies. The clinical study comprised 30 eyes of 30 healthy subjects. The test strategies were: (1) threshold-related supraluminosity of 5 dB with constant supraluminosity between 0 degrees and 30 degrees eccentricity; (2) threshold-related supraluminosity of 5 dB, increasing the luminosity according to the sensitivity gradient of the retina at 15 degrees eccentricity; (3) threshold-related supraluminosity of 5 dB and stepwise increase of luminosity every 5 degrees of eccentricity; (4) threshold-related supraluminosity of 3 dB and stepwise increase of luminosity every 5 degrees of eccentricity; (5) central stimuli luminosity of 200 asb and stepwise increase of luminosity every 5 degrees of eccentricity. The highest specificity of the visual field examination was obtained with test strategy 3, followed by 5, 4 and 2. The lowest specificity was obtained with test strategy 1.

Computers↗
PubMedDate not supplied

Collagen shields delivery of netilmicin: a study of ocular pharmacokinetics.

Collagen shields have been used as therapeutic contact lenses to promote corneal epithelial healing and to deliver hydrosoluble drugs. In albino rabbits, we studied the ocular pharmacokinetics of netilmicin, an aminoglycoside antibiotic, released by a 24-hour collagen shield immersed for 10 min in commercially available eye solution of netilmicin, at the standard concentration of 3 mg/ml. The animals were sacrificed after 0.5, 1, 6 and 18 h. The antibiotic concentrations were measured by the microbiological method. The drug levels remained above the MIC for the usual pathogens for 18 h in the cornea and for 6 h in the aqueous humor. In the iris and ciliary body the peak concentration was reached 1 h after shield application, netilmicin concentration decreased thereafter rapidly. The lens and the vitreous did not appear to be permeated by the drug. In the conjunctiva, drug concentrations were low, showing a negligible lateral diffusion of netilmicin released by shields. In conclusion, our findings show, that if the collagen shields are used as delivery systems, a very concentrated drug solution is not required to obtain high and persistent levels of netilmicin in cornea.

Animals↗