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Snyder C. Solution Interaction with the Ocular Surface: The Significance in Making the Grade. Clinical & Refractive Optometry, 2005; 16:5, 134-140. Copyright Mediconcept 2005.

Bergmanson J. Interpretation of Corneal Staining on your Patient and in the Literature. Nordic Vision 6, 2006, 8

Carnt NT et al. Corneal Staining: The IER Matrix Study. Contact Lens Spectrum, September 2007

Morgan P. Contact Lens Compliance and Reducing the Risk of Keratitis. Optician, 2007

Clinical significance
More significant staining beyond the low grade physiological levels may indicate a disrupted or compromised corneal surface as a result of one of six causes: mechanical, exposure, metabolic, toxic, allergic and infectious.1 It is therefore essential that eye care practitioners prescribing contact lenses recognise and understand the many factors that can cause corneal staining.2

The importance of routine evaluation
Being rarely manifested through symptoms it is important to routinely assess patients for corneal staining, as 50% to 80% of symptom-free contact lens wearers are expected to demonstrate at least some degree of low level staining.3

Routine corneal fluorescein staining evaluation is strongly recommended to help the practitioner familiarise themselves with the incidence of low level staining commonly found in healthy patients (contact lens wearers and non contact lens wearers) to become familiar with what is normal and what is abnormal staining1,3 Familiarity with grading schemes, scales and standards for acceptable levels of corneal staining and definitions of significance are also important for practitioners to ascertain appropriate patient management and assist them in not believing that something must be significant on the occasion that they do see some level of staining in symptom-free and otherwise successful contact lens wearers.1 Therefore to reduce the variability in the grading of staining between examiners, training is critical, not only for day-to-day practice but also to ensure consistency across clinical studies.2


The implications


Clinically significant corneal staining is generally asymptomatic and reversible with correct clinical management and compliance. However, theories implicating corneal staining (of any grade) as one of five contributory factors to corneal infection (keratitis) has been put into question by various researchers and clinical studies.

The Institute for Eye Research showed that 419 contact lens wearers with corneal inflammatory events showed no significant difference in the degree of corneal staining or predisposition to microbial keratitis compared to the control group3
  • "no evidence has yet appeared to establish any such association (with microbial keratitis) for any type of staining, whether solution related or not"1
  • Professor Holden stated "we are disturbed that some have drawn conclusions between solution induced corneal staining and microbial keratitis."3

 

References

  1. Snyder C. Solution Interaction with the Ocular Surface: The Significance in Making the Grade. Clinical & Refractive Optometry, 2005; 16:5, 134-140. Copyright Mediconcept 2005.
  2. Ward K. Superficial Punctate Fluorescein Staining of the Ocular Surface. Optometry and Vision Science; 2008; 85:1, 8-16
  3. Carnt NT et al. Corneal Staining: The IER Matrix Study. Contact Lens Spectrum, September 2007


Compliance

Understanding the factors associated with corneal staining is essential in helping the practitioner treat contact lens wearers with clinically significant corneal staining. Research shows a direct and significant correlation between non-compliance with lens care systems and moderate-to-severe corneal staining (p <0.01). Results showed that 58% of compliant contact lens wearers were less likely to show moderate-to-severe corneal staining than non-compliant contact lens wearers.1

References
  1. Nichols K. et al. Corneal Staining in Hydrogel Lens Wearers. Optometry and Vision Science, 2002; 79,1; 20-30
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