By Sarah Guy
Continuous long-term overnight use of reverse geometry lenses results in a significantly increased presence of inflammatory mediators compared with wearing 30-night silicone-hydrogel (Si-H) contact lenses or wearing no lenses, show study results.
Specifically, interleukin (IL)-6 and IL-8, and matrix metalloproteinase-9 (MMP-9) were significantly increased after 12 months use of the corneal refractive therapy (CRT; reverse geometry) lenses, which induce temporary flattening in the central corneal curvature, compared with use of the other lens type or no lenses.
Users of either type of lens had significantly increased presence of epidermal growth factor (EGF), another inflammatory mediator, compared with non-lens users, show the findings.
"The evaluation of levels of inflammatory mediators at the ocular surface is... important to know if the cornea undergoing corneal refractive therapy could be compromised," suggest Javier González-Pérez (University of Santiago de Compostela, Spain) and co-investigators.
The team studied tear samples from 32 individuals who had used CRT lenses over a 12-month period, 28 individuals who had worn Si-H lenses over the same period, and 32 individuals who had never worn lenses (controls), to assess the presence of the inflammatory mediators that could indicate a wound healing response.
EGF concentration was significantly greater in tear samples collected from both groups of lens-wearers compared with non-wearers, at 2348 and 1536 pg/mL versus 698 pg/mL for CRT and Si-H users, respectively, versus controls.
Furthermore, IL-6, IL-8, and MMP-9 were each significantly greater in the tear samples collected from CRT users compared with Si-H users and controls, report the researchers.
The team also found an association between the magnitude of these markers in tear samples from lens users and the degree of myopia correction needed by the individual, as well as an association with the presence of fluorescein corneal staining.
This finding suggests that a compressive effect plus mechanical trauma could be the main causes of the inflammatory upregulation in CRT users' tears, write González-Pérez et al in the British Journal of Ophthalmology.
They suggest future studies should focus on the ocular implications for the inflammatory response revealed by their research.
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