• Conference proceedings Dutch Contact Lens Conference 2014.
• Subject: Extended wear tear film secrets page 87.
• Several small studies show a diurnal change in tear film composition. There appears to be a substantial increase in secretory immunoglobulin A concentration after a night’s sleep. Additionally, activated complement has been reported. These findings have led to the hypothesis of a physiological nocturnal inflammatory state of the tear film. Contact lens extended or closed eye wear gained popularity due to the introduction of silicone hydrogel materials and orthokeratology. Unfortunately, we still don’t understand the pathways that lead to deposition and the role of deposition in inflammatory processes. Therefore I strongly recommend further research in this area.
Protein Extraction Effectiveness
Method Protein extracted from Lotrafilcon B (µg/lens)
TFA/ACN 8.04 ± 3.75
Urea 3.29 ± 2.32
Acetone 2.06 ± 1.15
TCA 0.31 ± 0.23
Powell et al., Lipophilic versus hydrodynamic modes of uptake and release by contact lenses of active entities used in multipurpose solutions, CLAE, 2009
Extraction efficiency of TFA/ACN
Extraction efficiency in % for TFA/ACN for Albumin
Lens Material
73.5 ± 5.6 Lotrafilcon B
91.5 ± 3.4 Galyfilcon A
81.5 ± 5.8 Balafilcon A
Subbaraman et al., Efficacy of an Extraction Solvent used to Quantify Albumin deposition on Hydrogel Contact Lens Materials, Eye & Contact Lens, 2009
Protein (µg/lens)
0
5
10
15
20
25
30
35
1.5 ml 50:500.2% TFA/ACN
1.5 ml 50:500.02% TFA/ACN
4M urea
lotrafilcon Alotrafilcon BBalafilcon AGalyfilcon ASenofilcon A
Dr Barr’s Hypothesis (1989)
• Not the amount of protein, but the state of the protein elicits inflammatory responses.
Barr et al., Protein and Elemental Analysis of Contact Lenses of Patients with SLK or GPC, Optometry and Vision Science, 1989
Lysozyme activity
Active protein Reference
Etafilcon >94% Subbaraman et al., Protein Deposition and Symptoms with Daily Wear Etafilcon Lenses, OVS, 2012
Balafilcon A approximate 50%
Luensmann & Jones, Protein deposition on contact lenses CLAE, 2012
Lotrafilcon A+B ≤25% Luensmann & Jones, Protein deposition on contact lenses CLAE, 2012
Lipids on Silicone Hydrogels
Problem:
Wide variety of extraction chemicals and methodology.
Pucker et al., In Vitro Lipid Deposition on Hydrogel and Silicone Hydrogel Contact Lenses, IOVS, 2010
Hatou et al., Biochemical analyses of lipids deposited on silicone hydrogel lenses, Journal of Optometry, 2010
Lipids on Silicone HydrogelsKey Points:•Majority cholesterol deposits•Little bit polar phospholipids•Care systems might play a role•Deposit formation pathways remain unknown
Hatou et al., Biochemical analyses of lipids deposited on silicone hydrogel lenses, Journal of Optometry, 2010
Heynen et al., Quantification of Non-Polar Lipid Deposits in Senofilcon A Contact Lenses, OVS, 2011
Closed eye sub inflammatory?
Increase in IgA concentration
(closed eye)
BUT
N=6
No p-value
Sack et al., IOVS, 1992
Immunoglubulin or Antibody
• Soluble proteins secreted by activated B cells or by plasma cells in response to an antigen.
• Recognises antigen & initiates complement fixation and opsonisation.
Closed eye sub inflammatory?
Higher presence of complement C3 and Factor B (closed eye)
BUT
N=8
No p-value
Willcox et al., IOVS, 1997
Closed eye sub inflammatory?
Increase in IgA concentration upon waking by 9-fold ANOVA p=0.005
Increase in albumin concentration upon waking by 9-fold ANOVA p=0.006
BUT
N=9
Pooled R+L eye samples
Markoulli et al., OVS 2012
Conclusions
• SiHy’s might have relatively more deposited denatured proteins than traditional hydrogels.
• Deposits might elicit inflammation, but its pathways remain unclear.
• The closed eye tear film may have a sub inflammatory state.
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