研究目的
To develop a safe, noninvasive, noncontact, continuous in vivo method to measure the dehydration rate of the precorneal tear film and to compare the effectiveness of a viscoelastic agent in maintaining the precorneal tear film to that of a balanced salt solution.
研究成果
The shape and surface area of the corneal reflection are strongly correlated with tear film state, and the method provides an unbiased, noninvasive assessment. Viscoelastic significantly increases tear film stability, maintaining hydration over 9 times longer than BSS+ in rabbits, suggesting potential benefits for reducing irrigation frequency in ophthalmic surgery. Further human studies are needed to confirm these findings.
研究不足
The subjective nature of the surgeon's decision for reapplication may have introduced bias, as they were not masked to the agents. Extrapolation for viscoelastic duration showed inconsistency, possibly due to over-application. The study was conducted on rabbits, and results may not directly apply to humans. Real-time use of the software with cutoff values could improve objectivity in future studies.
1：Experimental Design and Method Selection:
The study used a rabbit model to compare tear film stability between a viscoelastic agent and BSS+. Software was designed to analyze corneal reflections from an operating microscope's coaxial illumination, fitting an ellipse to quantify distortion as the tear film evaporates.
2：Sample Selection and Data Sources:
20 eyes from 10 New Zealand white rabbits were used, with each rabbit receiving viscoelastic on one eye and BSS+ on the contralateral eye in a randomized order to eliminate bias.
3：List of Experimental Equipment and Materials:
Operating microscope (OPMI), lid speculum, viscoelastic fluid (2% hydroxypropylmethylcellulose, Cornea Protect, Croma-Pharma GmbH), BSS+ irrigating solution (Alcon, Inc.), LabView software (National Instruments Corp.), digital single-lens reflex camera, video recording equipment, Origin 7 software (Origin Lab).
4：Experimental Procedures and Operational Workflow:
Rabbits were anesthetized; a lid speculum was inserted, and test agents were applied. Eyes were monitored for 20 minutes via the operating microscope, with video and images captured every 5 seconds. The surgeon subjectively decided when to reapply agents based on corneal hydration.
5：Data Analysis Methods:
Post-processing with LabView software to analyze reflection shape by fitting an ellipse and calculating axes ratio. Evaporation rates were determined using linear regression in Origin 7 software, with statistical analysis for significance.
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