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Dry eye and blink rate simulation with a pig eye model
Emily Pik Yin Choy1, Pauline Cho, Iris Frances Forster Benzie
1School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China. pychoy@gmail.com
Purpose:
To simulate medium level "dry eye" and investigate the effect of "blink" rates in "dry eye" condition using a novel porcine dry eye model (pDEM).
Methods:
In the first experiment, a 40 s "lacrimation/blink" interval (lacrimation occurring in conjunction with blink) was set in the pDEM to simulate a medium level of "dry eye" condition. In the second experiment, "lacrimation" interval was set at 60 s and three different "inter-blink" intervals of 6, 12, and 20 s were set in groups A, B, and C, respectively. The integrity of each cornea was assessed before and after experiments by slit-lamp microscopy with sodium fluorescein solution. The viability of corneal epithelial cells was assessed by the Trypan blue exclusion test after the experiment.
Results:
The amount of sodium fluorescein staining was significantly (p < 0.05) lower at the end of the experiment, when the "inter-blink" interval was set at 12 s. The medians of the final fluorescein grades of corneas in the pDEM were grade 1.5, 1.0, and 2.0 when the "inter-blink" intervals were set at 6, 12, and 20 s, respectively. There was no significant difference in the number of damaged cells between the central and peripheral corneas with different "inter-blink" intervals. Although in each case the peripheral area had a lower number of non-viable cells than the central area of the cornea, there was no significant change in the number of Trypan blue stained cells in either area with different "inter-blink" intervals.
Conclusion:
Different severity levels of "dry eye" can be simulated using the newly developed pDEM. Increased blink rate may protect the cornea against desiccation-induced damage; however, increased blink rate may also increase shear force between the cornea and conjunctiva and result in mechanical damage because of increased frictional force.
Insights
A novel porcine dry eye model (pDEM) was used to simulate dry eye conditions. A 12-second inter-blink interval showed the lowest corneal staining, suggesting increased blink rates may protect against desiccation, but could also cause mechanical damage.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Corneal Science
Background:
- Dry eye disease is a prevalent condition affecting millions worldwide.
- Current models for studying dry eye have limitations in accurately replicating human conditions.
- Understanding the impact of blinking on corneal health is crucial for developing effective treatments.
Purpose of the Study:
- To develop and validate a novel porcine dry eye model (pDEM).
- To investigate the effect of varying blink rates on simulated dry eye conditions.
- To assess corneal integrity and epithelial cell viability under different blink frequencies.
Main Methods:
- A porcine dry eye model (pDEM) was established to simulate medium-level dry eye.
- Experiments involved controlled lacrimation and inter-blink intervals (6, 12, and 20 seconds).
- Corneal integrity was assessed using slit-lamp microscopy with sodium fluorescein, and cell viability was evaluated via Trypan blue exclusion.
Main Results:
- The 12-second inter-blink interval demonstrated significantly lower sodium fluorescein staining compared to 6 and 20-second intervals (p < 0.05).
- Median fluorescein grades were 1.5, 1.0, and 2.0 for 6, 12, and 20-second intervals, respectively.
- No significant differences in corneal epithelial cell damage were observed across different inter-blink intervals.
Conclusions:
- The pDEM effectively simulates varying levels of dry eye.
- Increased blink rates may offer protection against desiccation-induced corneal damage.
- However, excessively frequent blinking could potentially lead to mechanical damage due to increased frictional forces.
