Section

Management FIVE

27.1 Lens collection

Insertion of lenses

Lenses are inserted after verification and after having been given time to settle before assessing acuities and fitting. An existing wearer needs only a few minutes, whereas a new patient requires 10–20 minutes depending upon lens type.

Assessment of vision

The visual assessment should confirm that acuities are the same as or better than those achieved during initial fitting.

Assessment of fitting

This should confirm:

•That the fitting appears as originally intended.

•The lenses have been accurately made. Apart from the main parameters, the practitioner should consider other factors such as blending, lenticulation, thickness and edge shape.

•The fitting appears satisfactory, even if the previous two criteria are met.

•Whether any discomfort is normal or excessive.

27.2 Insertion and removal

Patients often need to realize that handling is a hurdle to overcome but has little to do with comfort, vision or eventual wearing time. Insertion should always be

©2010 Elsevier Ltd, Inc, BV

DOI: 10.1016/B978-0-7506-7590-1.00011-X

Section FIVE Management

done over a flat surface or closed sink, while removal can be into the cupped hand for rigid lenses. Patients should be taught initially with a mirror but it is ultimately better for them to manage without. Soft and rigid lens insertion follow the same pattern but removal is different.

27.2.1 Rigid lenses

Insertion

The lens is cleaned, rinsed and wetted. The lids are held firmly apart while the patient looks at the reflection of the eye in a mirror. The head may be either vertical or horizontal and the lens is placed onto the cornea with the first or second finger of the dominant hand.

Removal

The eye must be held open wide enough for the taut lids to eject the lens from behind by means of blinking and:

•One finger pulling slightly upwards from the outer canthus.

•Two fingers from the same hand pulling from the lid margins.

•Two fingers, one from each hand, pulling with a sideways scissors motion.

•Two fingers, one from each hand, positioned vertically and pushing the lid margins against the globe of the eye and towards each other. This method, although more difficult to learn, is more consistently reliable.

•Holding the lids firmly and turning the eye nasally.

If all of these methods fail, a moistened suction holder can be applied perpendicular to the centre of the lens.

PRACTICAL ADVICE

•The alternate eye must be kept open to prevent Bell’s phenomenon.

•The lids should be held from underneath the base of the lashes to prevent reflex blinking.

•Reassure the patient that the lens does no harm on the sclera and cannot get lost ‘behind the eye’.

•Show the patient how to recentre the lens with indirect finger pressure on the lid margins or by massaging through the closed lids.

27.2.2 Soft lenses

Insertion

The general principles are the same as for rigid lenses. The key difference is that as lenses are self-centring patients need not be concerned if they are inserted out

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of position. Where near fixation is uncontrollable, especially with hypermetropes, lenses can be inserted onto the inferior sclera while looking upwards at a distant fixation target.

Air bubbles are trapped more frequently with silicone hydrogels and should be removed by sliding the lens off the cornea and recentring.

Removal

Rigid lens pulling methods do not generally work with soft lenses. They are removed by:

•Sliding the lens onto the temporal or inferior scleral and pinching out.

•Pinching directly off the cornea. This is less satisfactory as there is a risk of scratching the cornea.

•Squeezing at the edge of the lens with the upper and lower lid margins to create an air bubble and eject the lens.

PRACTICAL ADVICE

•To stop lens ejection at the moment of insertion because of an air bubble, advise the patient to take both hands away and look down slowly without blinking. The eyes should be gently closed and the lids squeezed together to remove any air bubble.

•A dry finger helps stop the lens reversing.

•Allow ultrathin lenses to dry on the finger for about 20 seconds to help insertion.

•With ultrathins, it may be necessary to pull the upper lid over the lens to prevent the lens rolling out of the eye on lid closure.

•If the lens is uncomfortable on insertion, it should be slid onto the temporal sclera and allowed to recentre. This usually dislodges a foreign body, make-up or very small air bubble; if discomfort persists the lens should be removed, rinsed and reinserted.

•Air bubbles with silicone hydrogels frequently need removal by sliding the lens off the cornea and recentring.

•Where there is difficulty seeing a lens on the eye (e.g. hyperopes and presbyopes), initial practice can be carried out with a daily disposable stained with fluorescein.

GENERAL ADVICE

•The patient should not be allowed to leave before being competent at lens removal (insertion can be safely practised at home).

•Where patients experience difficulty with handling, especially with thin lenses, they can initially be given thicker, higher powered disposables just for practice. This makes insertion much easier, gives some degree of confidence and avoids the possible breakage of complex or conventional lenses. When some proficiency has been achieved, the correct Rx can then be used and the wearing schedule commenced.

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27.3 Suggested wearing schedules

The aim is to achieve a wearing time with rigid gas-permeable lenses of 8–10 hours by the time of the first aftercare check-up at about 2 weeks. This interval may be longer with soft lenses, although all-day wear is often achieved more rapidly. The recommended schedule can be recorded as the starting time, increment and maximum before the first aftercare examination.

All-day wear is then achieved with hourly build-up if there are no contraindications at the first aftercare visit.

PRACTICAL ADVICE

•Wearing schedules must be easy to understand and follow.

•Advise the patient that, to avoid the risk of over-wear, the wearing schedule is a maximum and not a target.

•The total wearing time can be divided into two periods at different times of day, usually separated by a 4-hour gap.

•Lenses should be removed and advice sought in the event of persistent discomfort, redness or other unusual symptoms.

27.4 General patient advice

New patients should not be allowed to wear lenses home because of the risk of early loss or damage. Before leaving, they should be given further clear instructions both verbally and in writing to cover the following points.

Initial advice

•Lens identification for right and left.

•How to tell if a soft lens is inside out (a flatter shape that reverses on gentle squeezing).

•Wearing schedule.

•That lens comfort should be no worse than that already experienced at the initial visit and that the eyes should not become unduly red or sore.

•To bring to the first aftercare examination both lens case and spectacles.

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•That unless there is a serious problem with comfort or vision they should come to the aftercare visit having worn lenses for as long as possible that particular day.

•The lens case, containing solution, should be carried at all times.

•To handle lenses in a well-lit area with spectacles nearby.

•To follow a routine, always dealing with the same lens first and to handle only one lens at a time to avoid mixing them up.

Lens care

•Method of lens storage (rigid) or disinfection (soft).

•Not to change the brand or type of solution without first consulting the practitioner.

•Names of solutions equivalent to the original recommendations.

•Some solutions are sold overseas with the same brand name but have a different formulation.

•The distinction between cleaning, rinsing and disinfection solutions.

•Lenses should be cleaned daily, immediately after removal from the eye.

•Never to use rigid lens solutions with soft lenses and vice versa.

•That soft lenses are very fragile if they dry out but are not necessarily spoiled since they recover after rehydration.

•To avoid placing two soft lenses in the same compartment of the case since they may stick together and prove impossible to separate.

•The lens case should be changed at regular intervals.

Unusual symptoms

•Sudden acute discomfort is probably caused by foreign bodies.

•Spectacle blur should not be experienced (except with PMMA and some back surface gas-permeable multifocals).

•Difficulty with near vision may be noticed during the first few days.

•Some degree of adaptive photophobia is normal.

•Extreme environments in terms of temperature or humidity may affect both comfort and vision.

•Anything that makes the eyes feel dry may make the lenses temporarily uncomfortable. Factors include: air conditioning, central heating; using VDU screens; and some drugs (e.g. antihistamines, HRT and alcohol).

•Falling asleep with the lenses in or entering extreme environments may give temporary lens adhesion, which may be released by the application of normal saline and gentle lid pressure.

Precautions

•What to do and where to go in case of an emergency.

•Soft lenses should not be worn while eye drops or ointment are used for any reason (wait 1 hour for drops and 4 hours for ointment).

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•Rigid lenses could be worn with drops but not with ointment.

•Environments containing fumes, chemicals or sprays should be avoided.

•Traces of noxious chemicals must be very carefully removed from the hands before touching the lenses.

•If soft lenses have been left in their case without being worn for more than a few days, they should be disinfected again before use.

•Not to lick lenses prior to insertion.

•Not to use detergents like washing-up liquid with rigid gas-permeable lenses because they may damage the surface.

•To use goggles or photochromatic glasses for activities such as cycling or skiing to protect the eyes from wind, dust and dehydration.

•To take care with driving because of altered spatial judgement, and flare at night.

•When travelling or sunbathing, to be careful not to fall asleep with lenses in unless they are for extended wear.

•To avoid wearing lenses where possible on long flights because of the dry atmosphere on aircraft and the possibility of eye infection.

•Swimming is unwise with rigid lenses because of the risk of loss. Soft lenses are often better but may still be lost; they might also cause stinging and red eyes if chlorine is absorbed into the material. There is also the risk of infection if lenses are not subsequently cleaned and disinfected. Overall, it is better to use a well-fitted pair of prescription swimming goggles.

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