Gordon Ruskell

Gordon was an established scientist, as we all know, and became an internationally recognised and sought-after speaker. He was always going to be a non-practising optician. I remember him telling me at college: 'I cannot see myself spending my life asking people if they see letters better on the red or the green.'
It was clear he was going to do something different, which he did with such success and recognition worldwide. The man was a genius. His contributions to both the optical and medical professions were impressive and his modesty was quite unbelievable. Optometry has every reason to be proud of Gordon Ruskell.
I nominate him for a special posthumous prize for contribution to the profession at the forthcoming optician Awards. I also request this annual prize be called the 'Gordon Ruskell Prize for Achievement' and be presented by his wife Valerie.
Kusoom Vadgama
London NW11

Material concerns
n Mr A Wills (Letters, February 20) suggests that the preservative benzalkonium chloride contains benzene. This is not true to the best of my knowledge and the 'benz' part of the name should not be taken to be indicative that this is the case. Benzalkonium chloride is a synthetic chemical that does not include benzene in its manufacture. Should Mr Wills have evidence benzene is included I would appreciate a copy.
Mr Wills suggests preservative levels in eye drops could be reduced if the patient was advised to keep the eye drops refrigerated. Apart from the potential impact of such a recommendation on patient compliance with the prescribed therapeutic regime, there is a technical reason for this not being likely to be successful.
Preservative activity against micro-organisms is determined by thermodynamic principles. If the recommended storage temperature is lowered, the activity of the preservatives would be reduced. In order to meet regulatory requirements Ð namely, to show compliance with the European Pharmacopoeia preservative efficacy test Ð would probably require the levels of preservative in the product to be increased rather than decreased.
Manufacturers are aware of the difficulties of the (relatively small) number of patients who have problems with the use of preserved products. One of the means of addressing this is to produce non-preserved unit of use eye drops. At present these have instructions to discard any remainder after they have been used once.
Recently, manufacturers approached the Quality Working Party at the European Medicines Evaluation Agency to seek agreement in principle that such unpreserved unit use of eye drops be labelled to allow their use over a period of, say, 18 to 24 hours, provided they were refrigerated during the period between doses. The Working Party did not accept the proposal. There is also resistance to the use of such products under national reimbursement schemes in most of Europe because the cost of producing a full course of therapy in such containers is higher than that of a single 5ml container.
The pack size of eye drops intended for use on more than one occasion is influenced by the requirements of the European Pharmacopoeia for containers usually to be of 5ml capacity (unless otherwise justified and authorised) and by the recommended maximum of use over a 28-day period (again, unless otherwise justified and authorised). Also, there is an expectation among reimbursement authorities that therapies offer perceived value for money. In various European countries (and elsewhere) it is normally expected that long-term use eye drop containers should provide 28 days' therapy. If they fail to, the authorities will want to know why not.
Manufacturers would be happy to meet any requirement for eye drop containers to hold sufficient product for one week's use. It must, however, be said that the costs associated with the production of this size container would be at least as high as those intended for 28 days' treatment. Therefore, the overall cost of long-term treatment on the basis of containers to be used for one week would be increased.
Mr Wills' comments on the possible use of purite are interesting. It has been used in certain tear and contact lens rewetting products. However, for it to be accepted for use in pharmaceutical products such as eye drops in the EU, manufacturers would need to provide a very large amount of data to show that its use was justified. Factors that would have to be considered would include compatibility of the stabilised oxychloro complex (which appears to be related to bleach) with the other ingredients in the eye drops and the container, and to show non-clinical and clinical safety. The amount of information needed to obtain regulatory clearance for a new preservative would be of the same order as that required for a new drug. In addition, there could be intellectual property restrictions on its use other than by the company that developed its use in contact lens care products.
Mr Wills' comments on the degradation of purite are unfortunately not truly reflective of the properties of this material. It remains present in the products containing it during the period of use. The period over which it degrades when the material reaches the environment is not dissimilar to that found for other preservatives.
Brian R Matthews,
Senior director, EC registration
Alcon Laboratories

Field guides
n I note your news item on the AOP's successful defence of Mr Barfield at a GOC disciplinary hearing (March 19). You report that the GOC referred to AOP and College guidelines stating that visual field tests should always be performed on patients over 40. I would like to make it clear the AOP does not have any such guidance.
The College, of course, does have guidelines, with a revised version recently issued. Practitioners may be interested to note that the section on examining the patient at risk from open-angle glaucoma states: 'Égood practice for these patientsÉmay include central visual field assessmentÉ' Since the College clearly does not regard such testing as mandatory it is difficult to see why the GOC Investigating Committee chose to pursue this case, at significant expense to us all.
Trevor Warburton
AOP director, Stockport