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Biomedical subjects

P Cho

Publications and source records attributed to P Cho.

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

The relation between invasive and noninvasive tear break-up time.

TBUT and NITBUT (tear break-up time and noninvasive tear break-up time, respectively) were measured on four groups of subjects from different countries (two groups of Caucasians, two groups of Chinese). No significant difference was found in either TBUT or NITBUT values among the four groups of subjects. Gender of the subjects was not a factor affecting the TBUT or NITBUT values. The distributions of both NITBUT and TBUT were non-Gaussian and the median value of either parameter was lower than those previously reported. The NITBUT values were significantly higher than the TBUT values in both Caucasian and Chinese subjects. An investigation into the extent of agreement between the TBUT and NITBUT methods of assessing tear stability indicated that these methods do not agree sufficiently closely (that is, tear stability values measured with the NITBUT technique do not agree with those measured with the TBUT technique); short average tear break-up values are associated with small differences between the measures, whereas long average tear break-up values are associated with large differences between the measures.

Adolescent↗
PubMed1995

The effect of benoxinate on the tear stability of Hong Kong-Chinese.

We conducted a series of experiments to examine the effect of local anaesthetic instillation on tear stability measurements. All experiments were conducted with the examiner masked with respect to treatments. We measured tear break-up time (TDUT) and non-invasive tear break-up time (NITBUT) 30s after instillation of benoxinate (0.4%) in a single masked experiment and found that NITBUT was significantly increased while TBUT was unaffected. In separate experiments tear stability was assessed 5 min after instillation of benoxinate and there was no significant effect on either TBUT or NITBUT measurements. In a control experiment to examine the effect of instilling a drop of liquid into the eye, neither TBUT nor NITBUT were affected 30s after the instillation of saline. No corneal staining was observed in any of the subjects after instillation of benoxinate. The results suggest that benoxinate does not affect the stability of the precorneal tear film, and that tear stability can be assessed after the instillation of unpreserved benoxinate.

Adult↗
PubMed1993

Review of the tear break-up time and a closer look at the tear break-up time of Hong Kong Chinese.

The technique of assessing tear stability using the fluorescein instillation technique has been widely used in the clinical diagnosis of "dry eye" and in the screening of potential contact lens wearers. Various inconsistencies in the application of the tear break-up time (TBUT) techniques and the results obtained were noted in the literature and this review summarizes the differences and the conclusions of various investigators. The reliability of this technique using two different methods of observation was examined and the mean TBUT of Hong Kong Chinese subjects (HK-Chinese) was determined. We conclude that the TBUT can be measured reliably using either the scanning or full beam method in most patients. The mean TBUT of HK-Chinese is approximately 8 s and about 70% of HK-Chinese have TBUT's less than 10 s.

Adolescent↗
PubMed1993

Schirmer test. I. A review.

Since its introduction by Schirmer in 1903, the Schirmer test has been widely used for the assessment of the adequacy of tear production. Although the faults of the Schirmer test have been well documented, it is nevertheless still being used to assess tear production, especially in the diagnosis of keratoconjunctivitis sicca (KCS) and for screening potential contact lens wearers. We summarize the findings and conclusions of some of the previous studies.

Contact Lenses↗
PubMed1993

Schirmer test. II. A clinical study of its repeatability.

In most parts of the world, the Schirmer test (ST) is still the main test used by optometrists for the assessment of tear adequacy in the screening of potential contact lens wearers and as an aid in the diagnosis of "dry" eye. We tested the reliability of a 1-min ST in nine normal Hong Kong-Chinese (HK-Chinese) subjects during five to seven visits over a period of 2 weeks. For 4 of the subjects, the test consistently measured 0 mm/1 min, and 68% of the test results were less than 6 mm/1 min, a value suggested as the lower limit for normal asymptomatic eyes. The results obtained were inconsistent and it is concluded that the ST is unreliable and of little clinical value in this population.

Adult↗
PubMed1993

The cotton thread test: a brief review and a clinical study of its reliability on Hong Kong-Chinese.

Fifty-four asymptomatic Hong Kong-Chinese subjects were recruited and their lacrimation was assessed using a modified cotton thread test (CTT). The CTT was performed once on each subject and, for seven subjects, the test was repeated seven times on different days over a period of 2 weeks to test the reliability of the CTT. The mean (+/- SD) CTT value (length of wetting of thread in millimeters for a 1-min testing period) of this group of subjects was 22.8 (+/- 9.4) mm/min. Repeated measures analysis of variance revealed no significant difference in the CTT values made on different days. The CTT was found to be superior to the conventional Schirmer test in terms of comfort and consistency of results obtained. A brief review of some studies and results reported by previous investigators using the CTT is also presented for comparison.

Adolescent↗
PubMed1993

Age, gender, and tear break-up time.

We investigated the effect of age and gender on the tear break-up time (TBUT) of 2 groups of normal, asymptomatic subjects [92 Hong Kong-Chinese (HK-Chinese) and 76 Singapore-Chinese (S-Chinese)] using the conventional fluorescein-instillation technique. The mean TBUT (+/- SD) is 6.5 (+/- 4.0) s for the S-Chinese and 7.8 (+/- 2.4) s for the HK-Chinese. The mode was 7.0 s for HK-Chinese and 5.0 s for S-Chinese. About 80% of the subjects of each group have TBUT less than 10 s. The TBUT of both groups of Chinese decreases with age. It was found that TBUT was significantly different between the two sexes in the S-Chinese but no equivalent effect was observed in the HK-Chinese.

Adolescent↗
PubMed1993

Reliability of a portable noninvasive tear break-up time test on Hong Kong-Chinese.

Seven normal asymptomatic Hong Kong-Chinese (HK-Chinese) were recruited and their noninvasive tear break-up time (NITBUT) was measured. Measurements were performed eight times over a period of 8 weeks to test the reliability of the NITBUT test over time. The distribution of NITBUT data was positively skewed. The mean (+/- SD) NITBUT was 16.0 (+/- 9.4) s and the mode was 17.5 s. Friedman two-way analysis of variance revealed no significant difference in the NITBUT taken on different days. For the clinical estimate of the NITBUT, we recommend taking five measures of NITBUT and average the three closest measures and use this as a representative value of tear stability for the subject.

Adult↗
PubMed1993

Mechanical manipulation of the lids and tear break-up time measurements in Hong Kong Chinese.

We measured tear break-up time (TBUT) after lid-rubbing in a single masked experiment, and found that TBUT was unaltered. A further single masked experiment in which non-invasive tear break-up time (NITBUT) was measured after the lids were raised as if to apply fluorescein also showed no effect of this interference with the lids. An experiment in which fluorescein was applied either with the lid raised or not raised during fluorescein application, again with the experimenter masked with respect to treatment, also produced no significant difference in TBUT. When we measured TBUT with the lid raised so that it was not in contact with the cornea, there was no difference in TBUT for the group between the 'lifted' and 'non-lifted' eye; some subjects showed substantially shorter TBUT values, while others showed substantially longer TBUT values. These findings are surprising in view of the concerns expressed in the literature regarding the sensitivity of the tear film to mechanical interference, and suggest that the tear film is more resistant to disruption than has previously been thought.

Adult↗