Trip Answers

Question answered:13/09/07 Warning! this question is over two years old.

We searched the NLH Specialist Library for Eyes and Vision,TRIP and Medline databases plus the Royal College of Opthalmologists and BNF websites but found no list of indications for use of preservative-free eye drops.

 

However, the CKS (formerly PRODIGY) guideline on blepharitis states:

 

“Use preservative-free preparations if more than 6 applications per day are necessary: the more frequently drops containing benzalkonium chloride are used, the greater the risk of ocular irritation.

 

Soft lenses: eye drops containing preservatives should not be used with soft lenses. (Some preservatives, particularly benzalkonium chloride, accumulate in soft contact lenses and cause irritation.) Preservative-free drops should be used instead.” [1]

 

Similar recommendations are made in the CKS guideline on dry eye syndrome:

 

“Artificial tears limit damage and control discomfort. Hypromellose is effective. Use preservative-free drops where severe symptoms require regular daily 30 minute interval applications. Decrease frequency with symptom control.

 

Use preservative-free preparations if more than 6 applications per day are necessary: the more frequently drops containing benzalkonium chloride are used, the greater the risk of ocular irritation…

 

 

Soft lenses: eye drops containing preservatives should not be used with soft lenses. (Some preservatives, particularly benzalkonium chloride, accumulate in soft contact lenses and cause irritation.) Preservative-free drops should be used instead.” [2]

 

The recommendation concerning use preservative-free eye drops for patients wearing soft contact lenses is also made in the CKS guidelines on allergic conjunctivitis, and superficial corneal injury. [3 & 4]

 

An American guideline on treating herpes zoster notes in the section on HZ Ophthalmicus and VZV Retinitis:

 

“Therapy for chronic problems includes the following: (1) lubricating, preservative-free artificial tear gels or tears administered 4 times daily…” [5]

 

In addition, a study undertaken by Pisella et al found preservative-free eye drops used in glaucoma patients lead to fewer ocular side-effects than those using preserved eye drops. The Medline abstract to this study reads:

 

“METHODS: A prospective epidemiological survey was carried out in 1999 by 249 ophthalmologists on 4107 patients. Ocular symptoms, conjunctiva, cornea, and eyelids were assessed. A chi(2) test was used for differences between preserved eye drops (P) and preservative free eye drops (PF). RESULTS: 84% patients used P, 13% received PF, and 3% a combination of P and PF eye drops. All symptoms were more prevalent with P than with PF drops (p<0.001): discomfort upon instillation (43% versus 17%), and symptoms between instillations such as burning-stinging (40% versus 22%), foreign body sensation (31% versus 14%), dry eye sensation (23% versus 14%), tearing (21% versus 14%), and eyelid itching (18% versus 10%). An increased incidence (>2 times) of ocular signs was seen with P eye drops. The prevalence of signs and symptoms was dose dependent, increasing with the number of P drops. A reduction in the symptoms and signs was observed when patients changed from P to PF eye drops (p<0.001). CONCLUSIONS: Symptoms and signs are less prevalent when PF drops are used. Moreover, most of the adverse reactions induced by P glaucoma medication are reversible after removing preservatives.” [6]

We found no information to answer the second part of your question concerning reverting to preserved eye drops following administration of preservative-free products.

 

References
1. CKS. Blepharitis. April 2005. (http://cks.library.nhs.uk/blepharitis/view_whole_guidance)
2. CKS. Dry eye syndrome. February 2005. (http://cks.library.nhs.uk/corneal_superficial_injury/view_whole_guidance)
3. CKS. Corneal superficial injury. April 2005. (http://cks.library.nhs.uk/corneal_superficial_injury/view_whole_guidance)
4. CKS.  Conjunctivitis – allergic. February 2005. http://cks.library.nhs.uk/conjunctivitis_allergic/view_whole_guidance
5. Dworkin RH, Johnson RW, Breuer J et al. Recommendations for the management of herpes zoster. Clin Infect Dis 2007 Jan 1;44 Suppl 1:S1-26. (http://www.guideline.gov/summary/summary.aspx?doc_id=10222&nbr=5385&ss=6&xl=999)
6. Pisella PJ, Pouliquen P and Baudouin C. Prevalence of ocular symptoms and signs with preserved and preservative free glaucoma medication. Br J Ophthalmol. 2002 Apr;86(4):418-23. (http://www.hubmed.org/display.cgi?uids=11914211).

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