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Biomedical subjects

P S Soni

Publications and source records attributed to P S Soni.

At least 19 recordsLinked to original sources
PubMed2000

Longitudinal changes in corneal asphericity in myopia.

PURPOSE: To report the change in shape of the peripheral cornea (asphericity, Q) as it relates to myopia progression in adolescence. METHODS: Forty-eight subjects with initial ages between 11 and 13 years of age were observed for 5 years. Each subject had participated in a variety of soft contact lens studies and all had worn daily wear soft contact lenses successfully for the 2 years before collection of the second data set. RESULTS: Myopia increased by an average of 1.46 D and was strongly correlated with a 0.56-mm increase in axial length. There was no contribution to the change in myopia from the change in central radius of the cornea. A significant (p < 0.01, one tail) correlation was found between Q and the progression of myopia. Principal axis analysis yielded a slope of -0.04 in Q per diopter of increase in myopia. CONCLUSION: These data show a shift to a more positive Q (in the oblate direction) with increased myopia.

Adolescent↗
PubMed1999

Myopia progression in adolescent wearers of soft contact lenses and spectacles.

The purpose of this 3-year, randomized clinical trial was to determine the difference in myopia progression in adolescents wearing soft contact lenses over a control group wearing spectacles. A total of 175 adolescents between the ages of 11 and 14 years were randomized into 2 groups, spectacle wearers and soft contact lens wearers. The main result was that the spherical equivalent change between the groups showed no clinical or statistically significant difference. However, when a power vector analysis was used, which uses all the refractive error data, a small but statistically significant (F test = 4.24, T2 = 17.35, p < 0.01) difference between the groups was found (i.e., the refractive error of the spectacle wearers had a slight increase in astigmatism). It can be concluded that soft contact lens wear does not lead to additional myopia progression in adolescents.

Adolescent↗
PubMed1997

Spectacles, contact lenses, and children's self-concepts: a longitudinal study.

The purpose of this study was to search for changes in children's self-concepts after the replacement of their spectacles with contact lenses. From a sample of 125 children 10- to 13-years-old who wore spectacles, 69 children were randomly designated to receive contact lenses. Over a 3-year span, self-concepts of the children who retained their spectacles and the children who switched to contact lenses were monitored for changes. Self-concept measures of the two groups did not change at significantly different rates, nor did rate of change vary with severity of myopia or how long glasses had been worn before the children entered the study, but boys' self-concepts changed more than girls' self-concepts. Theoretical and clinical implications of these results are discussed.

Adolescent↗
PubMed1996

Ocular response to lens care systems in adolescent soft contact lens wearers.

The purpose of this 3-year prospective study is to compare high school-aged subjects, randomized into wearing soft contact lenses and spectacles, in terms of ocular health, refractive status, and self-esteem. This report focuses on ocular response to the lens care systems used through the first 18 months of the investigation. Eighty-four subjects were randomly fitted with either CibaSoft Visitint or CibaSoft-Standard Visitint contact lenses. Three lens care systems, Ciba Vision AOSept Disinfection/Neutralization Solutions (AOSept), Opti-Free Rinsing, Disinfection, and Storage Solution (Opti-Free), and ReNu Multi-Purpose Solution (ReNu), were randomly prescribed to the subjects wearing contact lenses. Limbal congestion, conjunctival hyperemia, corneal staining with fluorescein, corneal edema, and corneal neovascularization were graded at dispensing and at 6-, 12-, and 18-month visits. There were no significant differences among the groups at baseline. At 6 months statistically significant difference (p = 0.0131, Kruksal-Wallis) was found for fluorescein staining of the cornea among the systems. At 12 months significant differences were found for corneal edema (p = 0.0404, Kruksal-Wallis) and neovascularization (p = 0.0315, Kruksal-Wallis) among the systems. At 18 months generalized conjunctival hyperemia was significantly different (p = 0.0234, Kruksal-Wallis) among the systems along with greater limbal congestion (p = 0.0015, Kruksal-Wallis) and neovascularization (p = 0.0238, Kruksal-Wallis). In conclusion, the cornea, limbal vessels and the conjunctiva respond differently to the lens care systems used in this study. Overall, patients using AOSept showed less corneal staining and inflammatory response than patients using ReNu and Opti-Free.

Adolescent↗
PubMed1995

Will young children comply and follow instructions to successfully wear soft contact lenses?

We fit eighty-five children between the ages of 11 years and 13 years, 11 months with soft contact lenses to study safety of soft contact lens wear in children. We report the results at 6 months of a 3 year longitudinal study. Contact lens care compliance, a critical factor in successful lens wear, was evaluated using a questionnaire. The questionnaire was completed by 74 subjects at dispensing and at 1-week and 6-months post-dipensing visits. Subjects found contact lens removal to be the easiest and lens insertion the most difficult procedures. After 6 months, 85% of the children correctly identified the purpose of lens care solutions, 90% knew that daily cleaning was necessary, 96% understood lens disinfection, and 99% expressed confidence in their ability to care for their lenses.

Adolescent↗
PubMed1994

Technegas versus krypton-81m gas as an inhalation agent. Comparison of pulmonary distribution at total lung capacity.

Exactly how the pulmonary distribution of inhaled radioactive gas and Technegas, or ultra-small aerosol particulates, differs from each other, is still uncertain. The authors compared the distribution of inhaled Kr-81 m gas and Technegas in the lungs at total lung capacity in 13 control subjects with no clinical conditions and 13 patients with various chest diseases. In normal lungs, there was no difference in the distribution ratios in the right and left lungs between inhaled Kr-81m gas and Technegas. However, there was a significant difference in the lungs of patients with pulmonary disease. Technegas tended to deposit more in the lung bases than did Kr-81m gas. Despite these statistical differences, they were visually, or qualitatively, similar. From a practical and clinical standpoint, Technegas seems to be useful as an inhalation agent, unless quantitative analyses are required.

Administration, Inhalation↗
PubMed1994

Proteinuria in essential hypertension.

Porteinuria was quantitatively measured in twenty-five controls and eighty-one newly detected patients of essential hypertension without renal insufficiency. Hypertension was treated with enalapril, enalapril and nifedepine and nifedepine alone. Mean proteinuria was more in patients of hypertension as compared to controls (P < .001). Proteinuria decreased significantly (P < .001) after six weeks of control of hypertension. Patients treated with enalapril alone had maximum reduction in proteinuria than those with enalapril and nifedepine, and nifedepine alone.

Adult↗
PubMed1993

Effects of target distance and pupil size on letter contrast sensitivity with simultaneous vision bifocal contact lenses.

Using simulated presbyopia we measured the effects of target vergence and pupil size on letter contrast sensitivity while subjects wore accurately centered simultaneous vision bifocal contact lenses. These experiments examined the increase in depth of focus provided by two bifocal contact lenses, and the effects of pupil size on near and distance vision. Monocular contrast sensitivity was assessed with three different designs of soft contact lenses. First, as a single vision control, we measured contrast sensitivity with a Bausch & Lomb, Optima 38 lens corrected for distance. We then measured contrast sensitivity with an Allergan Optical, Hydron Echelon, which is a diffractive simultaneous bifocal and a CIBA Vision, Spectrum, which is a concentric design, center-near, two-zone simultaneous vision bifocal. In general both bifocal contact lenses improved contrast sensitivity at near but decreased contrast sensitivity at distance (when compared to the single vision lens). With a fixed 3.5-mm artificial pupil, the Echelon lens had two clear peaks of sensitivity, one at distance (0.00 D) and one at near (-2.00 D), but the Spectrum lens had no clear peaks. Performance of the Spectrum lens depended on its center zone size. Near (-2.00 D) and distance (0.00 D) contrast sensitivity was measured with pupil sizes that ranged from 1 to 6 mm. The results showed that visual performance with a diffractive lens was almost independent of pupil diameter up to 3 to 4 mm but, as predicted, performance with the two-zone lens depended critically on pupil size.

Contact Lenses, Hydrophilic↗
PubMed1991

Reliability and validity of videokeratoscopic measurements.

When a test surface or a cornea is carefully and properly positioned with respect to the Corneal Modeling System (CMS) videokeratoscope, measurements are highly repeatable, but the accuracy of the measurements is dependent on the shape of the surface. For spherical and toroidal surfaces, the CMS provides suitably accurate descriptions of the topography of the surface. For aspheric surfaces the CMS renders less accurate, but still clinically acceptable, topographic descriptions.

Cornea↗
PubMed1991

The management of keratoconus using the corneal modeling system and a piggyback system of contact lenses.

The purpose of this report is to describe the use of the Corneal Modeling System (CMS) in the quantitative evaluation of the front surface of a soft contact lens on a keratoconic cornea. The management of one eye of a single case is presented as an example. A keratoconic patient fitted with an RGP lens presented with the signs and symptoms of discomfort, reduced wearing time and recurrent corneal erosions. Corneal topography was evaluated utilizing the CMS. The patient was then fitted with a soft contact lens. Next the entire front surface of the contact lens-fitted eye was measured with the CMS. Utilizing those data a piggyback lens was designed. As a result of this fitting technique corneal integrity improved, wearability increased and discomfort dissipated.

Adult↗
PubMed1990

Gastroesophageal reflux scintigraphy with radioactive capsules--a new technique for detection and quantitation of reflux.

A new technique for performing quantitative gastroesophageal scintigraphy has been described. The method involves administration of radioactivity in capsule form into the stomach; the isotope is released after dissolution of the capsule. The mean time of onset of capsule breakage was 3.3 min (range 2-5 min) and complete dissolution occurred by 6.0 min (range 5-8 min). The appearance of isotope activity in the oesophagus by means of cine scintigraphy was quantified by PDP 11/34 computer (Gamma-11) in terms of percentage of gastroesophageal reflux (GER). In 15 healthy subjects, the percentage of reflux (mean +/- S.D.) in the lower, middle and upper oesophagus was found to be 1.25 +/- 0.67, 0.26 +/- 0.23 and 0.02 +/- 0.04 respectively. We have studied 52 patients using this technique, and results are encouraging.

Capsules↗
PubMed1988

Density and radioactivity distribution of respirable range human serum albumin aerosol.

Dry human serum albumin (HSA) aerosol in the respirable size range was generated using the BARC nebulizer. The aerosol was sampled using Lovelace Aerosol Particle Separator (LAPS) and the density of HSA was determined. Labelling of HSA with 99mTcO4- was done, both in HSA solution and with dry denatured HSA particles, to study the distribution of radioactivity in both cases. The results are discussed in the paper.

Isotope Labeling↗
PubMed1988

Extended wear contact lens movement under swimming pool conditions.

On site swimming pool studies have indicated that soft contact lenses adhere to the cornea when exposed to swimming pool water. It was the aim of this investigation to study, under controlled laboratory conditions, both the adherence of hydrophilic extended wear lenses and any changes in lens movement with exposure to swimming pool water. Normal saline and a hypotonic solution having a pH and osmolality identical to the pool water served as controls. Exposure to both swimming pool water and the hypotonic solution promptly caused both lenses to stop moving and adhere to the cornea. Notably, the instillation of normal saline also caused a dramatic decrease in lens movement for some subjects.

Adolescent↗
PubMed1988

Complications reported with hydrogel extended wear contact lenses.

We conducted a survey to evaluate the incidence of various complications associated with extended wear (EW) contact lenses. Of the 137 surveys sent out, 44 responded, 15 with data. The analysis indicates: (1) EW contact lens patients receive nonuniform care, evident from the fact that the EW follow-up to EW dispensing ratio varied between 1.6 and 16.75; (2) the incidence of epithelial microcysts, striae, and giant papillary conjunctivitis (GPC) was found to be considerably lower than that reported previously; (3) the incidence of "red-eye" response and corneal ulcers was calculated to be within the lower end of the range of previously reported research; and (4) there may be a seasonal variation in the incidence of GPC and red-eye response as indicated by an increase in both conditions during the month of March as compared to February.

Conjunctivitis, Allergic↗
PubMed1986

Feasibility of extended wear lens use in chlorinated swimming pools.

A group of 14 active swimmers was studied to evaluate corneal and conjunctival health immediately after extended wear contact lenses were worn in a chlorinated swimming pool. Two different lenses, a high (70%) and a low (38%) water content, were used for each subject in order to compare the corneal response to the high and low water content lenses. No significant difference in corneal and conjunctival response was found between the two lenses. Statistically significant differences were seen in corneal thickness and halo size between swimming with and without contact lenses. Corneal superficial erosion was of greater concern under both the control and test conditions, but this is believed to be due to unforeseen experimental design errors. The frequency of contact lens loss in this study was 3.57%. Hence, the conclusion that the rate of loss of hydrophilic lenses in a swimming situation is not the only concern in regard to lens wear during swimming, but there are other important factors such as lens adherence to the cornea and bacterial contamination of the lenses that need to be studied further.

Chlorine↗
PubMed1980

Peripheral curve design and the tear pump mechanism of soft contact lenses.

The role of the peripheral curve of a soft lens in the supply of oxygen to the cornea via the tear pump mechanism is considered. A group of 18 patients was optimally fitted with spherical DuraSoft lenses with and without peripheral curves; the absence of the peripheral curve was not found to affect adversely the physiological response of the cornea as determined by pachometric changes in central corneal thickness.

Contact Lenses, Hydrophilic↗
PubMed1980

Effects of oral contraceptive steroids on the thickness of human cornea.

Twenty-three women of childbearing age were monitored for a period of 3 months to evaluate the effect of oral contraceptive steroids on central corneal thickness. Eight of these women acted as the control group and 15 were first-time users of oral contraceptive steroids. Two males were also studied to investigate the possible existence of cyclic change of corneal thickness in females vs males. The results obtained from the control group of females indicated a definite cyclic variation in corneal thickness, females showing minimum thickness just before ovulation. The cornea seemed to be thickest either at the beginning or the end of the menstrual cycle. The males showed no specific pattern. The variation seen in females is hypothesized to be related to the ovarian and gonadotropin hormones. Of the experimental group, the females who were using the higher progesterone concentration pill showed stabilization starting almost immediately and by the 3rd month their corneal thickness showed very little variation during the cycle. The women on lower dosage pills also stabilized but took longer to do so.

Adolescent↗