Table 3.
Studies on the effects of external forces on the corneal epithelium.
| Author(s) | Methods | Results |
|---|---|---|
| Lin et al., 1999 | Measurement of tear layer by optical pachometry after application of soft contact lenses. | Showed the use of optical pachometry as a method to measure tear film thickness between eye and contact lens. Further investigation required to determine if post lens tear thickness is affected by lens wear. |
| Ladage et al., 2003 | One rabbit eye assigned to wear either silicone hydrogel or disposable contact lenses or eyelid suturing or no intervention. Cell proliferation using BrdU staining performed after 24hrs and 1 week. | Decrease in cell proliferation in all test groups at day 2. After 1 week of suturing or silicon hydrogel lens wear there was a significant increase in proliferation. Limbal staining for BrdU in all groups not significantly different from control. |
| Nichols and King-Smith, 2003 | Use of interferometric method to measure tear film thickness pre and post lens application. | Superior method of measuring tear film thickness after lens use compared to pachymetric method. |
| Wang et al., 2003 | Measurement of tear film thickness pre- and post-lens using optical coherence tomography (OCT). | Tear film thickness increased after lens fitting. Post-lens tear film is thicker than pre-lens tear film with soft contact lenses. Thickness independent of lens types. |
| McMonnies et al., 2010 | Eye rubbing of live subjects followed by measurement of epithelial thickness. | Reduction in epithelial thickness observed after rubbing. |
| Liu et al., 2011 | Measurement of corneal hysteresis, corneal resistance factor, corneal compensated IOP (IOPcc) and Goldman equivalent IOP (IOPg) in 40 subjects before and after 2 episodes of eye rubbing and breath holding. | Corneal hysteresis, corneal resistance factor and IOPg significantly lower after eye rubbing. This was not the case for IOPcc. Breath holding made no difference in any of the measurements. |
| Prakasam et al., 2012 | Eye rubbing over closed eyelids of live subjects followed by spectral domain OCT. | Eye rubbing in a circular motion over closed eyelids did not affect total corneal, epithelial and bowman's membrane thickness. |
| Balasubramanian et al., 2013 | Tear collection before and after 60 s of eye rubbing followed by measurement of tear collagenase activity and inflammatory molecules. | Increased level of MMP-13, IL-6 and TNFα but no significant alteration in collagenase activity. |
| Takatori et al., 2013 | Use of micro-polarographic Clark electrode to measure in situ corneal oxygen uptake during soft contact lens wear. | 12 different lenses varied oxygen uptake from low to high permeability depending on the lens. High oxygen permeable lenses have high oxygen uptake rates similar to a no lens eye. |
| Elkins et al., 2014 | Live cell rheometer to quantify cell adhesion to contact lenses in vitro with shear stress | Lens deposited tear film proteins that affect corneal epithelial cell adhesion |