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Measurement of ocular surface protection under natural blink conditions.

Abelson R, Lane KJ, Angjeli E, Johnston P, Ousler G, Montgomery D - Clin Ophthalmol (2011)

Bottom Line: The traditional methodology (Forced-Stare [FS]) measures TFBUT and IBI separately.TFBUT (P = 0.034) and BUA/IBI (P = 0.001) were able to distinguish the treatment effect of artificial tears in dry-eye subjects.The VCMA methodology provides a clinically relevant analysis of tear film stability measured in the context of a natural blink pattern.

View Article: PubMed Central - PubMed

Affiliation: Arizona State University, Tempe, AZ, USA. rabelson@sdcclinical.com

ABSTRACT

Purpose: To evaluate a new method of measuring ocular exposure in the context of a natural blink pattern through analysis of the variables tear film breakup time (TFBUT), interblink interval (IBI), and tear film breakup area (BUA).

Methods: The traditional methodology (Forced-Stare [FS]) measures TFBUT and IBI separately. TFBUT is measured under forced-stare conditions by an examiner using a stopwatch, while IBI is measured as the subject watches television. The new methodology (video capture manual analysis [VCMA]) involves retrospective analysis of video data of fluorescein-stained eyes taken through a slit lamp while the subject watches television, and provides TFBUT and BUA for each IBI during the 1-minute video under natural blink conditions. The FS and VCMA methods were directly compared in the same set of dry-eye subjects. The VCMA method was evaluated for the ability to discriminate between dry-eye subjects and normal subjects. The VCMA method was further evaluated in the dry eye subjects for the ability to detect a treatment effect before, and 10 minutes after, bilateral instillation of an artificial tear solution.

Results: Ten normal subjects and 17 dry-eye subjects were studied. In the dry-eye subjects, the two methods differed with respect to mean TFBUTs (5.82 seconds, FS; 3.98 seconds, VCMA; P = 0.002). The FS variables alone (TFBUT, IBI) were not able to successfully distinguish between the dry-eye and normal subjects, whereas the additional VCMA variables, both derived and observed (BUA, BUA/IBI, breakup rate), were able to successfully distinguish between the dry-eye and normal subjects in a statistically significant fashion. TFBUT (P = 0.034) and BUA/IBI (P = 0.001) were able to distinguish the treatment effect of artificial tears in dry-eye subjects.

Conclusion: The VCMA methodology provides a clinically relevant analysis of tear film stability measured in the context of a natural blink pattern.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of % corneal area exposed versus time during a single interblink interval.Abbreviation: TFBUT, tear film breakup time.
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f2-opth-5-1349: Schematic diagram of % corneal area exposed versus time during a single interblink interval.Abbreviation: TFBUT, tear film breakup time.

Mentions: Figure 2 shows an example schematic diagram of the percentage of corneal exposure versus time during a single IBI used to calculate BUA. In this example, the IBI is assumed to follow a partial blink, potentially leaving tear film defects, with the consequence that the initial percentage of area exposed is nonzero as depicted by the diagonal cross hatch area in Figure 2. At some point during the IBI, the BUA begins to increase, and this defines the TFBUT. The rate of increase between TFBUT and end of the IBI is represented by the slope of the triangular area at the right of Figure 2. The manual analysis of the video data provided measurements of the percentage cornea exposed at time 0 (immediately following a blink), at the point of increasing BUA (TFBUT), and of the maximum level of tear film breakup at the end of the IBI. Sequences of these three measurements form sequences of schematic diagrams such as that shown in Figure 2. From each diagram, BUA was calculated, and these were averaged to give mean values for the 1-minute observation period. The units of BUA are (% cornea exposed). The IBI minus the TFBUT represents the “time-exposed interval”, which can be expressed as a fraction of the IBI. The steepness of the increase in BUA after the TFBUT allows analysis of tear film breakup rates.


Measurement of ocular surface protection under natural blink conditions.

Abelson R, Lane KJ, Angjeli E, Johnston P, Ousler G, Montgomery D - Clin Ophthalmol (2011)

Schematic diagram of % corneal area exposed versus time during a single interblink interval.Abbreviation: TFBUT, tear film breakup time.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198408&req=5

f2-opth-5-1349: Schematic diagram of % corneal area exposed versus time during a single interblink interval.Abbreviation: TFBUT, tear film breakup time.
Mentions: Figure 2 shows an example schematic diagram of the percentage of corneal exposure versus time during a single IBI used to calculate BUA. In this example, the IBI is assumed to follow a partial blink, potentially leaving tear film defects, with the consequence that the initial percentage of area exposed is nonzero as depicted by the diagonal cross hatch area in Figure 2. At some point during the IBI, the BUA begins to increase, and this defines the TFBUT. The rate of increase between TFBUT and end of the IBI is represented by the slope of the triangular area at the right of Figure 2. The manual analysis of the video data provided measurements of the percentage cornea exposed at time 0 (immediately following a blink), at the point of increasing BUA (TFBUT), and of the maximum level of tear film breakup at the end of the IBI. Sequences of these three measurements form sequences of schematic diagrams such as that shown in Figure 2. From each diagram, BUA was calculated, and these were averaged to give mean values for the 1-minute observation period. The units of BUA are (% cornea exposed). The IBI minus the TFBUT represents the “time-exposed interval”, which can be expressed as a fraction of the IBI. The steepness of the increase in BUA after the TFBUT allows analysis of tear film breakup rates.

Bottom Line: The traditional methodology (Forced-Stare [FS]) measures TFBUT and IBI separately.TFBUT (P = 0.034) and BUA/IBI (P = 0.001) were able to distinguish the treatment effect of artificial tears in dry-eye subjects.The VCMA methodology provides a clinically relevant analysis of tear film stability measured in the context of a natural blink pattern.

View Article: PubMed Central - PubMed

Affiliation: Arizona State University, Tempe, AZ, USA. rabelson@sdcclinical.com

ABSTRACT

Purpose: To evaluate a new method of measuring ocular exposure in the context of a natural blink pattern through analysis of the variables tear film breakup time (TFBUT), interblink interval (IBI), and tear film breakup area (BUA).

Methods: The traditional methodology (Forced-Stare [FS]) measures TFBUT and IBI separately. TFBUT is measured under forced-stare conditions by an examiner using a stopwatch, while IBI is measured as the subject watches television. The new methodology (video capture manual analysis [VCMA]) involves retrospective analysis of video data of fluorescein-stained eyes taken through a slit lamp while the subject watches television, and provides TFBUT and BUA for each IBI during the 1-minute video under natural blink conditions. The FS and VCMA methods were directly compared in the same set of dry-eye subjects. The VCMA method was evaluated for the ability to discriminate between dry-eye subjects and normal subjects. The VCMA method was further evaluated in the dry eye subjects for the ability to detect a treatment effect before, and 10 minutes after, bilateral instillation of an artificial tear solution.

Results: Ten normal subjects and 17 dry-eye subjects were studied. In the dry-eye subjects, the two methods differed with respect to mean TFBUTs (5.82 seconds, FS; 3.98 seconds, VCMA; P = 0.002). The FS variables alone (TFBUT, IBI) were not able to successfully distinguish between the dry-eye and normal subjects, whereas the additional VCMA variables, both derived and observed (BUA, BUA/IBI, breakup rate), were able to successfully distinguish between the dry-eye and normal subjects in a statistically significant fashion. TFBUT (P = 0.034) and BUA/IBI (P = 0.001) were able to distinguish the treatment effect of artificial tears in dry-eye subjects.

Conclusion: The VCMA methodology provides a clinically relevant analysis of tear film stability measured in the context of a natural blink pattern.

No MeSH data available.


Related in: MedlinePlus