Deborah Sweeney -

Deborah Sweeney is Professor and Chief Executive Officer of the Vision Cooperative Research Centre.  Her major research area has been corneal physiology, and her work has been instrumental in developing an understanding of the physiology of the human cornea and the effects of contact lens wear on corneal function characteristics.  Associate Professor Sweeney is also active in national and international optometric and ophthalmic organizations, including Executive roles in the International Society for Contact Lens Research, The Keratoprosthesis (KPro) Study Group and the International Association of Contact Lens Educators.

In Part I of this Editorial we covered the first stage in successful continuous wear - patient selection and fitting. We will now examine the second stage - patient management and education. It is important that adequate support is provided for the CW patient, and that CW is carefully monitored, particularly in the first 6 months and on an ongoing basis. Patient education is also vital to ensure compliance and vigilance over the long term.

The early period of CW should be accompanied by frequent contact with the patient. Patients that are newly fitted to high Dk lenses, regardless of whether they have worn EW previously, should be seen after the first night of wear, then at the first week, first month, 3 months and every three months thereafter. As much as possible, the appointments should be made in the early morning, to allow the practitioner to assess the eye when it is in a state which is regarded as most illustrative of the stress that CW places on the eye. If possible, the supply of lenses should coincide with the scheduled aftercare visits to further encourage patient compliance.

Overall the aftercare visits should entail a thorough patient history, including wear time and symptoms including comfort and vision rating, as well as an assessment of the patient's ocular appearance and visual acuity. For previous lens wearers it is also important to include a subjective refraction as regression of myopia has been reported to accompany the reduced hypoxia with the high Dk materials [1].

Each aftercare visit should include a thorough slit-lamp biomicroscopy examination that includes lid eversion, irrespective of whether the patient is symptomatic. This is particularly important for patients that have SEALs, possibly CLPC, CLPU or relatively minor infiltrative events that often can be asymptomatic. As high Dk silicone hydrogel lenses have a slightly higher modulus of rigidity than conventional low Dk lenses, there may be a greater potential for increased pressure on the cornea, and for mechanically-induced problems such as SEALs. Hypoxic effects, degree of vascularisation, and endothelial polymegethism should be measured. Corneal and conjunctival staining and bulbar redness should be assessed. There should be a less than 1 grade increase in papillae or redness of the eyelid and no significant increase in ocular redness or neovascularisation [2,3].

Unacceptable grade 1 change from slight to moderate bulbar redness

The successful extended wear patient [Brennan NA, Coles MLC - In: Sweeney 2000] [4]
Characteristic	Requirement
Wear time	Ability to wear contact lenses for 6 or more nights consecutively
Comfort	Grade 3 (comfortable) or better
Subjective vision rating	Grade 3 (good) or better
Visual acuity	Within 1 line of best spectacle acuity
Hypoxic effects	10 microcysts or vacuoles No striae 1 hour after eye opening No endothelial folds
Vascularisation	0.5 mm vessel penetration
Endothelial polymegethism	1 grade increase (Vision Cooperative Research Centre (VisionCRC) grading scale)
Changes in corneal curvature or refractive error	No irregular corneal distortion or warpage 0.5D in flat K and/or 0.75D in steep K 0.5D sphere and/or 0.75D cyl in spectacle refraction
Corneal staining	Grade 2 type of staining (macropunctate) Grade 1 depth of staining (superficial epithelial involvement) Grade 1 extent of staining (1-15% surface involvement)
Lens adherence	No signs 1 hour after opening
Eyelid changes	Grade increase in papillae or redness of superior palpebral conjunctiva
Bulbar redness	Grade increase
Patient appearance	No unacceptable change

Example of stria (above). No striae should be present 1 hour after eye opening

The patient's lenses should also be examined for any irregularities or deposition. Low levels of deposits are common, however the interaction of relatively stiffer lenses with the tear film and ocular surface may be responsible for higher levels of deposition in some patients. These deposits can usually be easily removed with the rub and rinse technique. Patients should be encouraged to rub and rinse their lenses regularly and possibly try a new lens if the deposition becomes problematic. Patients should also bring their cleaner, disinfectant, unit dose saline and lens case to each aftercare visit so that their care and maintenance procedures can be appraised.

High level of lens deposits, seen in small percentage of silicone hydrogel lens wearers

Even with the new generation lenses we have yet to develop a perfectly biocompatible surface. Contact lens wearers therefore are prone to the sensation of ocular dryness. The two main symptoms of discomfort that are associated with soft contact lens wear are dryness and redness [5]. Although the lower water content of silicone hydrogels compared with hydrogels leads us to believe that dryness is less problematic in these lenses, in our experience dryness is still the most common symptom of high Dk contact lens wear that leads to patient discomfort [6]. Vision Cooperative Research Centre (VisionCRC) studies show that 38% of CW wearers still find dryness the factor that they liked least about their lenses [7].

We recommend that our patients rinse with unit dose saline or lubricating drop, or other appropriate lubrication, in the morning and before going to bed. This helps particularly to ease the sensation of dryness that may be reported on waking and also assist with the removal of debris. Fifty percent of CCLRU patients find this beneficial.

While the practitioner can make a major contribution to successful CW with the correct patient selection and lens fitting, the patient themselves must play their part in monitoring and supporting their ocular health.

Patients should check every morning and night to ensure that their eyes 'Look Good, Feel Good, and See Well'. If there are any problems, such as redness, watering, discomfort or pain, patients should immediately remove their lenses and contact their practitioner as soon as possible. If vision is blurry or the patient feels any irritation, they should remove their lens and rub and rinse it with unit dose saline. If there is no improvement then the patient should contact their practitioner. Many patients feel that if the lens does not feel quite right, sleeping in it will fix it. This must be avoided. Also importantly, patients should not sleep in lenses if they feel unwell, as they may be at higher risk of adverse events such as Contact Lens-induced Acute Red Eye [8].

Contact Lens-Induced Acute Red Eye [CLARE]

If a patient removes their lenses for any time they should be disinfected before they are reinserted or be replaced with a new lens.

The importance of patient compliance should be reiterated at every visit. Patients should be reminded of the potential risks of CW and the steps to take to avoid problems. Patients should also be reminded that their wear schedule can be flexible, and that they should remove their lenses whenever needed. It should be emphasised that lens care solutions are still needed and that an up-to-date pair of spectacles should always be available in case required.

It is important to foster patient loyalty so that patients will return for follow up care and will contact YOU promptly if there is a problem. Practitioners and patients must be aware that, although hypoxia-related problems have been eliminated with high Dk lenses, adverse events still occur. Inflammatory events occur at similar rates to other soft lenses, and there are higher rates of SEALs and localised CLPC, due to the stiffer materials of the high Dk lenses [9,10,11]. Patients that have previously experienced an event of CLARE, or contact lens induced peripheral ulcers during extended wear appear to be at a slightly greater risk of experiencing a recurrent event of the same contact lens complication in high Dk lenses [4,12,13]. Patients with a previous history of CLPC are unlikely to be successful with high Dk soft lenses. While to date the incidence of MK seems much reduced with high Dk lenses, patients should still be taught to be vigilant.

It is a good idea if patients are given documentation to take home with them, including an information brochure on contact lens and CW care, and a reminder card or similar which includes the reminder for them to check their eyes every day, and the contact details for your practice. The aim of this documentation is to provide clear instructions to follow to avoid complications, information on the support network available, and a description of the possible repercussions of non-compliance. It is important that instructions are given to patients in layman's terms, and that discussion confirms that they have understood the risks and procedures.

In order to minimise the effects of complications, it is vital that the patient have access to care 24 hours a day. This can allow early intervention in adverse events, and provide an added level of service for your patients. Contact procedures should be established to ensure a rapid response from your practice, or it may be advisable to organise a local practitioner network (i.e. a pager service, not an answering machine).

We hope that this information on CW in practice has been helpful, and we welcome any queries you might have about your own experiences (visit our FAQ page).