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Maud Gorbet, Doerte Luensmann, Lyndon Jones; The response of tear film neutrophils to occasional overnight lens wear. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2069.
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During sleep, in the closed-environment, an influx of polymorphonuclear neutrophils (PMNs) occurs, which typically returns to normal levels a few hours after waking. This clinical study was conducted to investigate the response of tear film PMNs to occasional overnight lens wear.
Adapted lotrafilcon A lens wearers and non-lens wearers were included (n=20 per group). Lenses were worn on a daily basis for 30 days and two nights, one at the beginning and one at the end of the lens wear cycle (Day1 & Day30). After each of these two nights, ocular surface cells were collected immediately upon waking using an eye-wash technique. Cells were also collected from the contact lenses. Cells were incubated with fluorescently labeled antibodies against ICAM-1, Mac-1, CD66b and CD33 (degranulation membrane markers) and CD45 (pan leukocyte-marker) with and without Lipopolysaccharide. Flow cytometry was used to determine the level of expression and the ratio between unstimulated and stimulated PMNs was calculated.
After 8hrs of sleep, leukocyte cell count collected from the ocular surface ranged from 60,000 to 2 million. There was no significant difference in the total number and leukocyte type collected from lens wearers and non-lens wearers (p>0.05). Cells collected from the lenses represented 9.4 ± 8.2 % of the total PMN count. Cell samples collected from the contact lenses were only included for flow cytometry analysis if > 500 PMNs events were observed (n=7). Eye-wash collected PMNs showed a similar expression and ratio between the two groups for Mac-1 and ICAM-1 (p>0.05). Significant lower levels of expression of CD66b and CD33 were found in the lens wearers (p<0.05 for both), while the ratio LPS stimulated/unstimulated was similar to the non-lens wearers suggesting that cells were able to appropriately respond to stimuli. The tear film PMNs collected from the contact lenses had significantly lower CD66b expression and higher ICAM-1 expression when compared to the PMNs collected from the ocular surface of the lens wearers (p=0.03).
Occasional overnight lens wear may have an effect on the degranulation profile of tear film PMNs, particularly for PMNs that remain in direct contact with the contact lens. Changes in PMN phenotype could play a role in the development of ocular inflammatory events; however, further research is needed to better understand this mechanism.
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