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Biomedical subjects

M Millodot

Publications and source records attributed to M Millodot.

At least 55 records · Page 3Linked to original sources
PubMed1977

The influence of pregnancy on the sensitivity of the cornea.

Corneal touch thresholds (CTT) were measured in 30 non-pregnant women serving as a control group and 29 pregnant women at different times during and after pregnancy. The results show that CTT becomes significantly higher after 31 weeks of pregnancy. However, only 86% of the subjects showed a difference in CTT during and after pregnancy, while 52% reported having some swelling. The loss of sensitivity (CTT-1) is assumed to be related to the water retention occurring during pregnancy, a view which is supported by some measurements of corneal thickness. It is suggested that this study may have exposed a new, hitherto unknown, way of monitoring pregnant women.

Adult↗
PubMed1977

The influence of age onthe sensitivity of the cornea,.

Corneal touch threshold (CTT) was measured in 205 healthy people of different ages. It was found that CTT increased gradually throughout life, although more significantly after the fifth decade of life. The results are found to be in good accord with those of Boberg-Ans, thus refuting an earlier report asserting that corneal sensitivity (threshold-1) increased up to the fifth decade and declined thereafter,

Adolescent↗
PubMed1976

A possible change of refractive index with age and its relevance to chromatic aberration.

The Purkinje-Sanson images of the eyes were photographed in red and blue light in two groups of subjects, young (19-38 years) and old (52-63 years). Densitometric examination of the negatives showed a significant increase in the amount of red light and a significant decrease in the amount of blue light reflected from the anterior surface of the lens (third image) in the group of old subjects as compared to the group of young persons. There is also a significant decline in the blue light reflected from the posterior surface of the lens (fourth image) but no change in the red light in old versus young eyes. From these results it is suggested that the index of refraction of the lens increases for red (nC) and decreases for blue light (nF) in the aging eye and similarly the index of the vitreous varies differentially in blue and red light. These specific changes in the indices of the lens and vitreous are believed to account for the large decline of axial chromatic aberration of the aging eye. In addition, the examination of the first Purkinje-Sanson image tends to indicate that the index of refraction of the cornea does not vary with age.

Adult↗
PubMed1976

The influence of age on the chronatic aberration of the eye.

The axial chromatic aberration of the eye was measured in 58 persons varying from 10 to 80 years of age. It was found that the chromatic aberration diminished significantly after the onset of presbyopia. It is suggested that this decrease in axial chromatic aberration may be due to increase in the index of refraction of the vitreous thereby producing a negative optical surface in the eye which more or less cancels the chromatic aberration of the cornea and anterior surface of the lens. This supposition is supported by measurements of chromatic aberration made on 10 aphakic patients. It is also observed that at near, older eyes who exhibit very little chromatic aberration, cannot make use of this aberration to spare some of the required accommodation (simulated by ophthalmic lenses in older eyes) as is the case in younger eyes.

Accommodation, Ocular↗
PubMed1976

The state of accommodation during the measurement of axial chromatic aberration of the eye.

The axial chromatic aberration of the eye was determined as in previous studies by finding the lens required to eliminate or minimize blur of the fixation target when it is illuminated by a series of monochromatic sources. Objective measurement of the refraction of the eyes during this procedure showed that accommodation remained constant throughout. Hence, the conclusion that the accommodative state does not in this case respond automatically to changes in the vergence of light falling in the retinal plane. It is suggested that some other stimulus, perhaps perceived distance, predominates. Further, the least amount of plus lens required to blur a near target was about the same for white and red but much less for blue. This substantiates an earlier finding that the eye accommodates for near only sufficiently to place the blue end of the chromatic interval on the retina.

Accommodation, Ocular↗
PubMed1976

Effect of the length of wear of contact lenses on corneal sensitivity.

Corneal touch thresholds (CTT) were determined once in the morning before inserting contact lenses then after 4, 8 and 12 h of continuous wear. Two groups of subjects participated in this study; 12 persons wearing hard contact lenses and 15 wearing soft contact lenses. All subjects were perfectly adapted to their contact lenses and had worn them for not less than three months. It was found that hard contact lenses caused a progressive diminution of corneal sensitivity. After 12 h corneal sensitivity was, on average, 110% lower (that is an increase of the threshold) than in the morning. Soft lenses also caused a progressive reduction of corneal sensitivity which after 12 h wear was, on average, 45% lower than in the morning, although there were marked differences. Moreover, 9 of the hard contact lens subjects had been tested a year earlier and it was found that their CTT after 8 h wear had slightly but not significantly diminished which indicated that these subjects had not adapted significantly to their lenses in one year.

Adaptation, Physiological↗
PubMed1976

Corneal sensitivity in people with the same and with different iris color.

Corneal touch thresholds were determined for both eyes of 15 people with different colored irides (a condition known as heterochromia) and of 25 people with similar colored irides. It was found that corneal sensitivity is not significantly different in both eyes of either group. Therefore it is suggested that the fact previously demonstrated that corneal sensitivity is related to iris color is not of corneal origin.

Adolescent↗
PubMed1975

Effect of hard contact lenses on corneal sensitivity and thickness.

Corneal sensitivity and central corneal thickness were measured on 11 subjects before and after 8 hours of hard contact lens wear. Both factors were monitored for 30 min after removal. It was found that hard contact lenses affect both corneal sensitivity and thickness, significantly. After 8 hours the reduction of sensitivity was found to be, on average, 94% in the centre and 116% in the periphery, and the average increase increase in thickness was 6.9%. Thirty minutes after removal corneal sensitivity had recovered 82% and 100% in the centre and periphery, respectively, and corneal thickness had decreased by 6.3%. A high correlation was found between central and peripheral corneal sensitivity. This investigation shows that corneal sensitivity measurements offer an alternative method of assessing corneal integrity which is simple and precise.

Adult↗
PubMed1975

Variation of visual acuity with soft contact lenses: a function of luminance.

The relationship between visual acuity and luminance with soft contact lenses, compared with the same one obtained with glasses or the naked eye, shows that acuity decreases at the same rate as luminance is reduced. This result differs from what had previously been found in comparing acuity with hard contact lenses and glasses. In the present case, soft lenses conform to the aspherical curvature of the cornea, and therefore the eye wearing soft contact lenses is not affected by spherical aberration, as in the case of hard contact lenses. At the outset, soft lenses produce a somewhat lower visual acuity but with adaptation, acuity improves and becomes equal or better, as evinced by measurements made after three months of wear.

Adult↗