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Biomedical subjects

M Rolando

Publications and source records attributed to M Rolando.

At least 55 records · Page 3Linked to original sources
PubMed1991

Recovery time of the temporary threshold shift for delayed evoked otoacoustic emissions and tone bursts.

The recovery time of temporary threshold shift after 1-kHz tone bursts delayed evoked otoacoustic emissions (DEOE) after the same stimulus were studied after auditory fatigue (AF) with a pure tone (0.75 kHz, 10 min, 95 dB HL) in 20 normal-hearing subjects aged 19-23 years. Close similarities were observed in the two experimental conditions. Since DEOE are transmitted to the outer ear via structures independent of the fibers of the afferent acoustic pathway and their synapses, it may be supposed that changes in the motile activity of the outer hair cells caused by AF could be partly responsible for their production and could constitute an active intracochlear mechanism taking part in this phenomenon. It may also be supposed that the effects of this active mechanism could be superimposed on those produced by a passive intracochlear mechanism consisting of the traveling wave induced in the basilar membrane by the perilymph owing to the movements of the stapes.

Adolescent↗
PubMed1991

[Reversibility of visual field defects in primary open-angle glaucoma].

The course of the glaucomatous visual field seems to be best followed by computerized perimetry which allows threshold evaluation in a great number of locations and statistical analysis of the results. To determine the visual field defect reversibility, 16 patients (27 eyes) affected by uncontrolled open-angle glaucoma underwent visual field analysis before and after prescription of a new medical therapy. To avoid the "learning effect" and to decrease the influence of the heterogeneous component of long-term fluctuation, the visual field examination was repeated within 48 hours whenever a change in sensitivity was detected. In addition a total of 10 normal eyes in 10 patients were tested as a control group. A statistically significant threshold improvement was demonstrable after one week of therapy in 31.7% of the eyes.

Adult↗
PubMed1990

Conjunctival surface damage distribution in keratoconjunctivitis sicca. An impression cytology study.

Impression cytology was used to study the ocular surface of 32 eyes with keratoconjunctivitis sicca. Among these eyes, on the basis of the results of the Schirmer I test, two groups of eyes have been identified. The first group with Schirmer test less than 5.5 mm/5 min showed decreased concentration of goblet cells and increased cytoplasm/nucleus ratio on all the areas of the bulbar conjunctiva. The second group, with Schirmer test greater than 5.5 mm/5 min, showed similar changes to be localized in the interpalpebral bulbar conjunctiva only, while the eye surface protected by the lids was almost normal. These observations suggest a pathogenetic role of tear evaporation in eyes with tear film instability even in the presence of a 'theoretically' normal tear production.

Adult↗
PubMed1989

Are delayed evoked oto-acoustic emissions (DEOE) solely the outcome of an active intracochlear mechanism?

Post-mumps and post-measles hearing losses are a result of the destruction of Corti's organ. Both the basilar and the Reissner membranes are unimpaired. In 11 subjects with post-mumps (8 cases) and post-measles (3 cases) unilateral anacusis, DEOE with a mean amplitude lower than that of the contralateral normal ear with the same sensation level were observed with 0.5, 1 and 2 kHz tone-bursts and air conduction stimulation. These findings lend credit to the view that DEOE could in part be produced by a passive intracochlear mechanism, probably a consequence of the basilar membrane travelling wave induced by the displacement of the perilymph. In a normal ear, this passive mechanism could be superimposed by an active mechanism linked to the contractile activity of the outer hair cells (OHC) which modulates and increases the travelling wave depth.

Adolescent↗
PubMed1988

Tear mucus crystallization in children with cystic fibrosis.

Cystic fibrosis is characterized by an abnormally high electrolyte concentration in exocrine secretions. The authors performed the tear mucus ferning test in 26 eyes of children with cystic fibrosis and compared the results to those in an equal number of age-matched normals. The results suggest that the increased electrolyte concentration could be responsible for the increased hyperviscosity of mucus. The tear mucus ferning test appears to be a suitable diagnostic test for the assessment of cystic fibrosis.

Adolescent↗
PubMed1988

Delayed oto-acoustic emissions evoked by bone-conduction stimulation: experimental data on their origin, characteristics and transfer to the external ear in man.

1) BCEOE have been obtained in subjects with normal hearing by 1 kHz tone-bursts; 2) the morphology of BCEOE varies from one subject to another, and is stable over the course of time. BCEOE do not display a linear relation between their amplitude and the intensity of the stimulus, whose spectral composition is the same as theirs; 3) by contrast with ACEOE, whose mean threshold is the same as that of the subjective tonal threshold for the same stimulus presented by the same stimulation modality, BCEOE threshold, on overage, is about 10 dB HTL higher; 4) this difference in threshold is not due to interference on the part of the controlateral ear, via the efferent fibres, since it is also observed in persons with unilateral anacusis. It is probably the outcome of unilateral competitive inhibition between two stimuli presented to the same ear at the same time. By bone-conduction stimulation in fact, when the meatus is occluded by the probe, as in our experimental situations, Corti's organ is reached by a supplementary contingent of mechanical energy generated by the vibration of the bony part of the meatus and transmitted by air conduction; 5) ACEOE cannot be obtained in otosclerotic subjects whereas they appear after surgery. BCEOE are obtained before surgery and increase in amplitude post-operatively; 6) the findings mentioned in point 5) clearly demonstrate that the ossicular chain plays an important, but not an essential role in the transfer of EOE from the inner to the external ear.

Acoustic Stimulation↗
PubMed1987

Eye parameters influencing the results of argon laser trabeculoplasty in primary open-angle glaucoma.

Argon laser trabeculoplasty (ALT) was performed on 173 eyes of 126 patients affected by uncontrolled primary open-angle glaucoma. All subjects were phakic. An overall decrease of intraocular pressure (IOP) from baseline of 19.1 (+/- 18) were observed. With linear regression analysis, a positive correlation was found between baseline IOP and percentage IOP fall. The effect of ALT in myopes, hyperopes, younger and older patients was also analyzed. Although a less pronounced IOP fall was observed in the subgroups of higher myopes and of younger patients, no direct relationship could be established between amount of IOP change and age or refraction. In subjects treated bilaterally, a significant correspondence of effect was found between the two eyes.

Aging↗
PubMed1985

Relationships between acoustic reflex patterns elicited by unfiltered white noise and narrow band white noise stimuli of different duration but of the same intensity.

For the purpose of this study, acoustic signals were generated by an Amplaid MK VI. An Amplaid 702 impedence meter was connected to its averaging section and to its computer. The stimuli were bursts of unfiltered white noise (UWN) and of narrow band white noise (NBWN; 30 db./oct/slope; central frequencies 1,000, 2,000, 4,000 Hz.) lasting 3-1,000 msec., at intensity of 105 db. SPL p.e. The following parameters were evaluated: stapedius contraction latency, amplitude, duration and recruitment time. It was found that latency was independent of the spectrum of the stimulus and its duration. Amplitude and recruitment time, on the other hand, were related to spectrum and duration, while duration of contraction was directly related to the duration of the stimulus only.

Adult↗
PubMed1985

Tear water evaporation and eye surface diseases.

The water evaporation rate from the tear film of eyes with anterior surface pathology (corneal and/or conjunctival scars, meibomitis) was tested by means of the "Rolando-Refojo tear evaporimeter', which allows noninvasive and reproducible test conditions. These eyes show a statistically significant increase in tear evaporation rate compared to normal eyes. The clinical implications of this finding are discussed.

Adult↗
PubMed1983

Increased tear evaporation in eyes with keratoconjunctivitis sicca.

The terms dry eye and keratoconjunctivitis sicca (KCS) imply a condition of highly reduced or absent tear film that often is not clinically demonstrable despite the presence of other signs and symptoms. In 52 patients with KCS symptoms, either with or without tear volume reduction as measured by Schirmer's basic secretion test, we found a statistically significant increase in water evaporation rate from the tear film when compared with normal subjects. Such an increased evaporation rate might account for the tear hypertonicity known to be associated with KCS and postulated to be responsible for ocular surface damage. Thus, we propose to identify this group of paradoxically wet "dry eyes" as a "syndrome of increased tear evaporation", which better describes the pathogenesis of the ocular condition.

Adult↗
PubMed1983

Tear evaporimeter for measuring water evaporation rate from the tear film under controlled conditions in humans.

The rate of water evaporation from the tear film depends on the conditions under which it is determined. If measured in a controlled and easily reproducible setting, tear evaporation rate could serve as a useful diagnostic and research tool. We have developed a tear evaporimeter that provides a non-invasive method for evaluating water evaporation rate in eyes with normal or pathologic tear films. The subject is fitted with a pair of swimmer's goggles modified so that the air over the test eye is conditioned to a desired baseline of relative humidity (29.5%) and temperature (23 +/- 1 degree C). To eliminate other sources of water, the lids and skin under the goggles are covered with petroleum jelly. The subject is asked to keep his/her eye open and to avoid blinking during the 1-min test. The increase in relative humidity due to water evaporation from the tears is then determined. The surface area of the eye exposed to evaporation is calculated from the lid aperture. We measured the water evaporation rate in 52 normal eyes (average = 4.07 X 10(-7) +/- 0.40 X 10(-7) g/cm2/sec) and compared the results with values obtained in 52 eyes with various tear-film abnormalities (average = 8.17 X 10(-7) +/- 2.65 X 10(-7) g/cm2/sec). The difference between the two groups is statistically significant (P less than 0.01). In normal eyes, after the instillation of one drop of 0.5% proparacaine, the increase in evaporation rate was statistically significant.

Adult↗
PubMedDate not supplied

Morphometric analysis of the optic disc surface. The level of smoothness as a diagnostic parameter for glaucoma.

PURPOSE: Since the glaucomatous loss of nerve fibers changes the appearance of the optic disc, we evaluated the morphology of the surface of the optic disc in normal and glaucomatous eyes by using a computerized system to provide the reciprocal position of a large number of points placed on its surface in order to study the clinical significance of differences in the 'smoothness' of optic disc surface. METHODS: The morphology of the optic disc surface was evaluated by means of simultaneous stereoscopic videographic pictures (IMAGEnet X Rev-3.51b-Topcon Europe, The Netherlands): the reciprocal distribution of a large number of points located on the surface of one eye of 100 subjects randomly chosen (45 normal and 55 glaucoma patients) was studied. In order to define the level of 'smoothness' of the optic disc surface, the differences of the relative position of each surface point were studied by measuring the standard deviation (SD) from the average heights of the points (n. ranging from 623 to 1916 depending on the size of the disc area) that identify the optic disc surface. RESULTS: The coefficient of variation of the reciprocal location of the points, placed on the optic disc surface at the different measurements performed by a single operator was 10.4%. The differences in Optic Disc Surface Smoothness (ODSS) between glaucoma and normal group were statistically significant (p < 0.0001 using Mann-Whitney U test). No correlation was detectable between age and standard deviation. The best threshold value, calculated using ROC methodology, able to separate the two groups was: normal group: SD < or = 17.79 (-1 x 10(-2) mm); glaucoma group: SD > -17.79 (-1 x 10(-2) mm). Such threshold value had a sensitivity of 82.1%, a specificity of 92.2% and a diagnostic precision (DP) of 86.5% in dividing the glaucoma group from the normal group. CONCLUSION: ODSS is a global index of optic disc conditions based on quantitative measurements of the morphology of the optic disc surface. As such it does not provide information about the location and the characteristics of optic disc damage. Nevertheless, ODSS measurement is able to separate normal from glaucomatous optic disc with a rather interesting sensitivity, specificity and diagnostic precision (DP). As such it could be useful both for research and clinical applications.

Female↗