The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [552]
Oil-based solutions: these are used for lubricating the eyeball. Usually one drop is instilled and repeated as required.
Anaesthetic drops: used to anaesthetize the eye; one drop should be instilled at a time. This is repeated until the drop cannot be felt on the eye.
The dropper should be held as close to the eye as possible without touching the lids or the cornea. This will avoid corneal damage and reduce the risk of cross-infection. If the drop falls from too great a height, it is difficult to control and will be uncomfortable for the patient. The eye should be closed for as long as possible after application, preferably for 1–2 minutes.
Useful properties of eye ointment include:
longer duration of action than eye drops
a soothing emollient action
easy to apply
long shelf-life (Downie et al. 2003).
Ointments are applied to the upper rim of the inferior fornix using a similar technique to eye drops (Figures 13.14, 13.15). A 2 cm line of ointment should be applied from the nasal canthus outwards. Similarly to the instillation of eye drops, the nozzle should be held approximately 2.5 cm above the eye to avoid contract with the cornea and eyelids (Aldridge 2010, Alexander et al. 2007).
Figure 13.14 How to instil eye drops.
Figure 13.15 How to instil eye ointment.
Preprocedural considerations
Equipment
A variety of droppers and bottles are available for the instillation of eye preparations. These include pipettes, bottles incorporating pipettes, plastic bottles with a dropper attachment and single-dose packs. Pipettes are easy to use but need to be dried and sterilized between doses. Plastic bottles can be squeezed and so avoid the need for a pipette and they are also cheaper than glass bottles with a dropper. Each patient should have their own indivdual eye drop container for each eye and single-dose containers should be used for all patients in eye clinics or in accident and emergency departments (BNF 2011).
It is important that eye preparations are sterile before use and attempts are made to reduce microbial contamination. Eye preparations being used at home should be discarded after 4 weeks whereas eye preparations being used in hospital should be discarded after 1 week. If concerns exist around cross-contamination from one eye to another, separate bottles should be issued.
A number of patients experience problems instilling eye medication. This may be due to difficulty aiming eye drops or squeezing the bottle. Aids are available to assist patients with both these problems. Patients will need guidance in how to use any aids (Downie et al. 2003).
If patients are going to use more than one eye drop preparation, they may experience overflow and dilution so they should be advised to leave an interval of 5 minutes between the two (BNF 2011). If both drops and ointments are prescribed, the drops should be applied before the ointment as ointment will leave a film on the eye and hamper the the absorption of the medication in drop form (Aldridge 2010).
Pharmacological support
Drugs may be given either systemically or topically to exert an effect on the eye (BNF 2011). However, if given systemically, the prescribing doctor needs to take account of the blood–aqueous barrier which exists within the eye. This barrier is selective in allowing drugs to pass into the intraocular fluids. The permeability of this barrier may increase during inflammatory conditions or following paracentesis – the removal of excess fluid with a needle or cannula (Andrew 2006).
Medications applied topically meet some resistance at the barrier presented by the lacrimal system (tear film barrier). A further barrier