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Clinical Decision Making--contact lens complications in routine practice.

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Contact lens complications can affect the contact lens corrected visual acuity (VA), the lens comfort and wearing time and the lens condition. The problems arising can cause disturbances to the eyelids and ocular surfaces that can result in long-term changes and reduction in contact lens tolerance. The clinician should try to help the patient overcome the lens-related problems, not only to promote satisfactory lens wear and to prevent the patient giving up contact lenses, but to prevent future ocular infections, inflammation and eyestrain.

There are five aspects one should consider when faced with a clinical problem presented by the patient attending for contact lens aftercare. These are: Symptoms, Signs, Tests, Initial Diagnosis, and Management.

One should also take into account the history, general health and medication, as these can be major influences. The clinician should carefully question the patient and study the previous records to build-up a collection of information to help 'solve the case'.

Here are ten examples of contact lens related problems and recommendations on how to tackle them:

1) Stinging sensation

Symptoms: Stinging sensation in both eyes especially at the initial insertion of soft lenses. The eyes become sensitive and suffer increased discomfort in reaction to dust, allergens, lens deposits and/or lens care solutions. The patient may therefore report an ocular redness response to the lenses and may complain of reduced wearing time and lens intolerance.

Signs: Using the slit lamp biomicroscope the clinician will notice slight bulbar conjunctival hyperaemia, especially if the lenses have been inserted a short time earlier, indicating the presence of an active ocular reaction. Prolonged irritation may result in tarsal conjunctival swelling, hyperaemia and papillae. The lids may become tensed, narrowing the palpebral apertures.

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Tests: Examination of the eyes after instillation of fluorescein into the tear film is likely to reveal toxic epithelial reaction staining. The staining appears as a general diffuse pattern of many scattered punctate epithelial erosions over the cornea. Often there may also be some epithelial staining on the tarsal surface. If the soft lenses are reinserted into the eyes, the red eye reaction (Fig. 1) and discomfort are likely to recur, especially if originally caused by the lens care solution.

Initial diagnosis: Toxic or allergic reaction to the soft lens solution.

Management

* Refit the patient with new soft lenses. As the original lenses are likely to retain the toxic solution chemicals, these should be discarded together with remaining lens solution.

* A more suitable lens solution and fresh storage case should be offered or the patient should be refitted with daily disposable soft lenses.

* The patient should be advised that recovery from the ocular reaction may take some time and that they should resist from wearing their lenses, or at least keep their wearing time to a minimum, for several days.

2) Sticky lens and hazy vision

Symptoms: The patient complains that the lenses feel sticky and less comfortable. They are aware of lid sensations on blinking and feel that the lids are pushing the lens, increasing lens movement. The VA is liable to decrease and is reported to be hazy, smeary and variable.

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Signs: A toric soft lens may be pushed to an incorrect axis orientation by the lids, which tend to adhere to the lens rather than smoothly glide over the lens surface. Sometimes there is increased lid attachment such that a rigid gas permeable (RGP) lens is lifted to a high riding position and the back optic zone no longer fully covers the pupil. Sticky lens deposits, for example mucous spots (Fig.2) and protein films, reduce the wettabilty of the lens surface, which reduces the optical quality and retinal image contrast, causing a reduction in VA. This can be exacerbated by the adherence of debris, dust or make-up to the sticky lens deposits.

Tests: Over refraction may not be able to improve the VA. Full blinks to spread the tear film over the lens may temporarily help VA.

Observation of the tear film reveals poor tear quality and more frequent mucous strands. Thorough cleaning of the lens may partly improve the surface wetting and help VA.

Slit lamp observation with fluorescein shows patches of poorly wetting protein deposits on the lens surface. Sometimes these cause areas of corneal and tarsal epithelial staining.

On questioning the patient regarding their general health, a history of cold, flu or other viral infections is likely to be reported, since increased mucous is produced with these conditions. Also, for those with allergies such as hay fever, the lids and likely to become irritated and this can also increase the production of mucous and protein. The protein deposits lead to increased friction between the lids and the lens. Therefore, what was initially a good fitting lens may apparently become a loose fitting lens, as it can be more easily decentred and rotated by the lids.

Initial diagnosis: Deposition on lens surface.

Management

* Leave the lens out until the infection or allergy recovers.

* Reduce lens wearing time.

* Try regular lens treatment with protein removal tablets, ensuring the patient correctly follows the instructions for their use.

* Try lens re-wetting drops.

* Refit the patient with a better lens material less liable to attract protein deposits.

* Refit with daily disposable lenses.

* Give a refresher lesson on hand washing, lens care and the avoidance of getting make-up and contaminants on the lens.

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3) Variable hazy vision with contact lens

Symptoms: VA decreases during the day. The reduction in image quality can vary from day to day and can make perception of low contrast images difficult. Eyestrain and problems with discerning detail, both for distant and near objects, may lead to symptoms of tired eyes and accommodation spasm. Fatigue and headaches may result. The patient may demand a stronger lens power than is really needed as they strain to see more clearly.

The lens comfort decreases as the lens surface retains a film of grease (Fig.3), which has poor wettability and a greater coefficient of friction. The lids feel as if they drag over the lens during blinks.

Signs: Poor condition of the lens surface, greasy film and patchy dried grease deposits are seen on the lens using the slit lamp. Sometimes scratches on the lens due to lens ageing, normal wear and tear, or rough lens handling, act as a site for dried grease deposits to adhere to the lens. Persistent deposits may inhibit correct disinfection of the lens surface by some soaking solutions.

Examination of the eye using the slit lamp shows increased grease disturbing the normal lipid patterns of the tears. Whilst watching the specular reflection of the tear film over the lens surface, the clinician observes the rapid drying of the tears on the greasy lens, indicating poor surface wettability.

Tests: Tear film assessments of invasive and non-invasive tear break-up time, lipid layer quality using the Tearscope, and Schirmer tear volume test can be carried out.

Examination of the lens and lid margin movement during blinking, with high magnification, can provide clues on any interaction, e.g. RGP lenses with excessive edge clearance may stimulate excessive production of lipid (grease).

Ask the patient to demonstrate their usual method of lens handling, cleaning and soaking in the lens case. Observations may discover that they do not wash their hands properly before touching the lens. They may still have greasy skin cream on their hands and lids which is transferred to the lens. Bad habits can include forgetting to use surfactant cleaner, not rubbing the lens properly to loosen deposits, inadequate lens rinsing, placing the clean lens into a dirty lens case, and topping-up old solution in a lens case as opposed to replacing this with flesh solution.

Discussion with the patient may indicate that they are unwilling to buy flesh lens solutions and/or cases, or are perhaps unwilling to replace their lenses regularly. For example, some may try to make a lens last longer than its actual replacement date, and then wonder why the comfort and VA decreases.

Although the increased lens awareness can be a symptom of dry eyes, where the aqueous portion of the tears evaporates in air conditioning and dry atmospheres, some patients mistakenly try inappropriate artificial tears. Some preparations, e.g. Viscogel, are not compatible with contact lenses as they are too viscous (thick) and make the lens surface sticky. Some have preservatives, which are retained by the soft lenses and build up in concentration in the lens to trigger an allergic reaction.

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On discussion, some patients admit that they borrow a relative's artificial tears, e.g. thick hypromellose drops, to soothe the eye but this also makes the lens sticky. They may even use lacrilube at night to reduce dryness symptoms, but if this remains on the lids it will be transferred to the lens the next day and will seriously impair the lens surface wettability.

Initial diagnosis: Greasy tear film causing lens surface greasing.

Management

* Give a tactful refresher lesson on correct methods of lens cleaning and care.

* Explain the importance of hygiene and regular replacement of lenses.

* Advise on appropriate lens rewetting drops and the need for full blinks.

* Possibly refit the patient with a more appropriately contoured RGP lens or with a lens material that does not attract lipid deposit build-up.

* Encourage the patient to change to a soft lens of more frequent replacement pattern, e.g. from monthly to daily disposable lens.

* The patient may benefit from medical advice regarding a general health problem or greasy skin condition, if this was the cause of greasy tears.

4) Reduced. vision with the lenses, feeling off-balance

Symptoms: Recent reduction in contact lens acceptance. The VA with the lenses is reduced and is not improved by cleaning or re-wetting. A feeling of being off-balance may be reported. Comfort may not be affected if the lens contours are similar for right and left eyes. However, if they are dissimilar then one eye has a loose fitting lens and the fellow eye has a tight fitting lens. Depending on the lens movement and edge contours, the patient may complain of excess awareness of the loose fitting lens, or may describe corneal hypoxia-type symptoms in the eye with the tight fitting lens. This is a particular problem with RGP lenses where the lens edge can irritate the lids or press into the corneal epithelium.

Signs: The loose fitting RGP lens will have poor centration, increased movement and will show central touch and excess edge clearance on fluorescein assessment (Fig.4). The tight fitting lens can ride low or centrally and will display sluggish movement. The fluorescein pattern will reveal central pooling and inadequate edge clearance.

Tests: VA and over refraction should indicate that a similar power change in preferred is each eye but of opposite sign, e.g. right eye -0.50D = 6/6, left eye +0.50 = 6/6. In some cases with RGP lenses this does not hold true, depending on the power of the tear lens produced behind each lens.

The focimeter can be used to discover the powers of the cleaned RGP lenses and the results compared to those noted in the records.

The cleaned lenses can also be inserted into the correct eyes and the fit, VA and over refraction rechecked.

Initial Diagnosis: Lenses mixed up.

Management

* Once the lenses are inserted in the correct eyes, the patient can be reassured that the VA and lens fit are satisfactorily restored. They can be tactfully advised about ways to avoid this problem from recurring. For example, the patient can develop a pattern of always inserting and removing the right lens from the right eye, followed by the left eye, which decreases the likelihood of error if they are tired or distracted.

* Contact lens cases with distinctively coloured lens caps for right and left sides are helpful. Daily disposable lens packets can be marked with an easily seen 'R' and 'L'.

* For patients with poor vision, ordering the RGP lenses in differing colours is useful, e.g. grey tint for right lens and blue tint for left lens.

* If the patient has persisted with incorrect RGP lens wear for a few days, conjunctival hyperaemia and epithelial erosions may have resulted. The loose fitting lens edge may have caused abrasions on the lids or limbal conjunctiva. The tight fitting lens edge may have caused arcuate corneal epithelial erosions, localised corneal oedema or epithelial dimpling due to trapped bubbles beneath the lens (Fig.5). If ocular damage has occurred, the patient is advised to cease lens wear for a few days to recover, and then gradually rebuild the lens wearing time.

5) Blurring of vision with the contact lens, especially for near ranges

Symptoms: There are complaints of eyestrain, especially after prolonged periods of detailed near work, causing blurring of near vision. This can persist even if the patient changes to a larger print size, reduces the amount of detailed work carried out at near, or stops reading. The strain on accommodation may cause headaches and increased difficulty in changing focus from distance vision to near vision, and vice versa. They may also report intermittent blurring of distance vision. The slowness of this readjustment may also apply to convergence, leading to symptoms of decompensated esophoria with distance fixation. In some cases intermittent binocular diplopia results as the binocular control of the phoria decreases with fatigue.

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Signs: No signs of problems are found on slit lamp examination of the contact lens and the eye. However, the practitioner may notice that the patient tends to frown or narrow their palpebral aperture in an attempt to accommodate or to improve VA by the 'pinhole effect'. The typical patient is in the age group of 45 to 55.

Tests: Over refraction with the lenses on the eyes may indicate that excessive minus power had initially been prescribed/supplied. As such, when new lenses of the correct power are inserted, the patient may cope better with the reduced accommodative demand, therefore comfortably resuming contact lens wear.

Near vision can be helped by the prescription of a positive reading addition power, reducing the demand on natural accommodation and improving the range of clear vision.

Tests assessing the quality of binocular vision, such as fixation disparity, should be carried out for distance and near vision. Initial Diagnosis: Presbyopia.

Management

* Take time to explain presbyopia to the patient, discussing the substantial help that can be gained from simple measures such as using better lighting for near tasks, using bigger print font sizes, holding objects further away from the eyes and taking regular breaks to rest accommodation between prolonged periods of near work.

* The various contact lens options for correcting presbyopia, including near-focused spectacles worn over single vision distance contact lenses, monovision and simultaneous vision multifocal (varifocal) contact lens options, ought to be discussed, along with the advantages and disadvantages of each.

* Further trial fitting sessions with several lens types are usually required.

6) The VA with the lens is blurred for distance and near detail

Symptoms: The patient reports 'smudging' of lettering or 'image ghosting', particularly when studying detailed objects. This occurs even with new or cleaned contact lenses. This problem may be more noticeable in dim light conditions e.g. driving at night or reading numbers on a TV or video in a dimly lit room. Eyestrain and headaches can result. The up-to--date distance spectacle correction is likely to give a superior VA to that achievable with contact lenses.

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Signs: On examination using the slit lamp, the lenses and eyes appear undisturbed. The patient may adopt a habit of narrowing the palpebral apertures to give improved vision by the 'pinhole effect'.

Tests: Full refraction over the lenses reveals residual astigmatism which, when corrected, restores good distance and near VA. The ocular astigmatism may have increased naturally and therefore the patient may simply be comparing their vision with new, clear spectacles to the reduced VA provided by the now 'old' contact lens correction. They may also have changed to a thinner soft contact lens material. Thin lens materials mould more closely to the natural corneal contour compared to thicker lenses and may therefore reveal previously existing corneal astigmatism that was otherwise masked by the thicker lens.

The patient may have changed from a monthly toric contact lens design that provided a full astigmatic correction to a daily disposable toric contact lens that has a limited range of correctable powers and axes, or even a spherical lens design, due to issues relating to lens cost.

Initial Diagnosis: Residual astigmatism disturbing VA.

Management

The problem should be carefully explained to the patient and various options offered to help them to cope or adapt to the situation. Examples include:

* Revert to the monthly disposable soft toric contact lens that provides the full astigmatic correction, and only use daily disposable lenses where the best VA is not vital, e.g. sports, holidays or social occasions.

* Allow time for adaptation to the residual astigmatic blur (easier with binocular vision), but wear contact lenses or spectacles that provide the best VA for critical tasks such as driving.

* Wear 'top-up' spectacles, which correct the residual astigmatism, over the contact lenses for occasions when the best VA is critical e.g. driving at night.

* Refit the patient from spherical to toric contact lens designs or to RGP lenses.

* Refit the patient to a more appropriate toric contact lens design that can better correct the astigmatic refractive error.

* Consider specially made or piggyback lenses in some cases.

7) Lateral conjunctival redness at the end of lens wearinng time

Symptoms: Careful questioning regarding the location and timing of the conjunctival hyperaemia is important. The patient reports that during the 12 to 14 hours of normal soft lens wear, comfort is fair and VA is good. No significant hyperaemia is noticed until the end of the day, when they report that the lenses stick to the eye and are more difficult to remove even with fingernails.

Signs: Long or rough fingernails. The practitioner observes that the patient has only slight lateral conjunctival redness when the lens is on the cornea. However, immediately after the patient has pinched out the lens (especially if several attempts were made) conjunctival redness and limbal vessel engorgement appears at the four and eight o'clock locations.

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Tests: Epithelial abrasions may be seen on fluorescein staining. By watching the patient's technique for removing their lenses, the practitioner can discover whether the cause of the redness is related to a faulty lens handling technique or not. Examination of the lens may show nail damage at the lens edge.

Initial Diagnosis: Conjunctival trauma due to faulty method of lens removal.

Management

* Give the patient a refresher lesson on the correct pinch-out lens removal method.

* Advise the patient tactfully on cutting/smoothing their fingernails.

* If the nails are long, an alternative lens removal method can be taught e.g. fingers on the outer edges of top lid and lower lid, using a lid squeeze method.

* Advise on the use of lens re-wetting drops if the lenses become dry and static by 12 hours of wear. Several blinks may also allow the lens to become lubricated and this can make the lens easier and safer to remove.

8) Reduced contact lens lerance and itchy, sticKy eyes Symptoms: Complaints of discomfort, lens awareness, and increased mucous

production. Symptoms of itching may increase on lens removal.

The mucous will disturb the VA and also make the lens sticky so that the lid will adhere to the lens and attempt to decentre it on version movements. Signs: Many papillae are noted on the upper tarsal conjunctival area with hyperaemia and oedema of the surface. Mucous strands in the tear film, increased lens movement and poor wetting of the lens surface are also observed. The foreign body sensation may trigger reflex lacrimation and bulbar conjunctival hyperaemia (Fig. 7).

Tests: Slit lamp examination using fluorescein shows the irregular surface of the tarsal regions and likely staining of the tops of the papillae.

Tear assessments indicate reduced quality of the tears. The lens condition is poor, often with protein deposits noted.

Initial Diagnosis: Contact lens associated papillary conjunctivitis.

Management

* Advise the patient to cease lens wear for several days if symptoms are significant. Possibly revise the cleaning and disinfection routines. Try changing to another lens care solution in case there may be an allergic reaction to certain chemicals. Try using protein removal tablets on the lenses to remove any sticky protein deposits.

* Try refitting with a different lens design e.g. a more wettable material, smoother lens surface with a lower modulus of friction, to assist the lids to glide smoothly over the lens during blinks. Try refitting with a more frequent lens replacement schedule, e.g. changing from monthly to daily disposable lens types.

* The more severely affected cases may require topical medication e.g. mast cell stabilisers, for long-term control of the inflammation. If the patient is taking antihistamines to control other allergies e.g. hayfever, these can also help to reduce the lid inflammation.

9) Dry eye feeling with contact lens wear at work

Symptoms: The patient reports that they are coping satisfactorily with soft lens wear at home or at weekends but experience ocular dryness and irritation during lens wear at work. The patient might claim that they have been supplied with faulty lenses since they were able to tolerate them well, but are now experiencing discomfort and a need to rub their eyes, which has reduced the amount that they can wear their lenses. It is only with further questioning that they will usually indicate that they are now working in a dry, possibly air-conditioned, environment or perhaps need to concentrate on a computer screen, or other visual display unit (VDU), for long periods of time. Alternatively, the dry feeling is worse when staring or driving a car with either air-conditioning or a fan heater blowing dry air onto their eyes.

Signs: Lens surface drying and poor wettability.

Often there are incomplete blinks, so the lower portion of the soft lens dehydrates and draws moisture from the corneal epithelium beneath. This shows as punctate fluorescein corneal staining. The lower region of the lens dries and attracts grease and protein films, further reducing surface wettability.

There may be signs of many small deposits on the lens e.g. spots from the fine mist of hairspray at a hairdressers job, or dust or particles if the workplace has a dusty atmosphere.

Tests: Tear volume and quality assessments can be performed. If the patient experiences dry and irritated eyes at work, even whilst spectacles are worn, this is likely to indicate a work environment cause, e.g. dust, dry air-conditioning or warm and dry offices where there are computers.'

Initial Diagnosis: Reduced contact lens tolerance due to the work environment.

Management:

* Keep to spectacle wear at work, wear lenses at home or outdoors.

* If possible, adjust the work environment, e.g. ensure regular rest breaks from the visual display screen, use dust extractors, use air humidifiers, or move the desk away from hot air blowers, radiators or fans.

* Practise full blinks and try lens rewetting drops.

* Try refitting with another lens design, which resists dehydration or provides supplementary moisture to the eye.

* Consider lifestyle changes such as reduce caffeine intake, drink more water, increase omega-3 supplements in the diet and walk in the fresh air during work breaks.

10) The patient complains of a lost contact lens

Symptoms: Contact lens wear had been satisfactory but yesterday the a lens disappeared during removal. The patient reports intermittent discomfort, slight redness and stickiness in one eye, whilst the fellow is eye fairly comfortable.

Signs: Some conjunctival hyperaemia, often in the superior region.

Sometimes increased lacrimation or mucous strands in the tears. There may be lid oedema and hyperaemia, especially if the patient had repeatedly prodded the eye as they suspected the lens or a part of the lens remains on the eye.

Tests: Slit lamp examination using fluorescein will show erosion stains if the lens edge or the patient's finger has abraded the ocular surface. The fluorescein will be retained by the soft lens material, which makes the contact lens easier to find using blue light. The patient is asked to look in each direction of gaze as the practitioner lifts the lids to inspect the fornices for the remaining portion of the lens.

Initial Diagnosis: Contact lens lost under the lid.

Management

* If the folded lens or half of a torn lens is discovered in the upper fornix, the lid is gently massaged while the patient keeps looking downwards. The irritating lens is gradually nudged from beneath the lid until safely removed by the practitioner. Sometimes instilling saline drops lubricates the lens and assists the lens movement.

* The ocular surface and tarsal conjunctival surface on lid eversion are examined for erosions, using the slit lamp. Mucous strands and lens debris can be washed out if the eye is irrigated with several drops of sterile saline.

* The condition of the retrieved lens is inspected. If possible, the lens should be discarded. Howeyer, if this is an annual replacement RGP or soft lens soft lens, destruction is not feasible and the lens must be cleaned thoroughly, rinsed and soaked overnight in fresh solution.

* The patient is advised to allow the eye to recover for a few days before resuming lens wear.

* Some patients require further tuition in lens handling and care to prevent this problem from recurring in future.

Module questions Course code: c-9521

Please note, there is only one correct answer. Enter online or by the form provided

An answer return form is included in this issue. It should be completed and returned to CET initiatives (c-9521) OT, Ten Alps plc, 9 Savoy Street, London WC2E 7HR by October 17 2008

1) For a patient experiencing a lens care solution toxic reaction, which of the following is the most appropriate alternative?

a. Change the out of date bottle for a new one of the same solution.

b. Change to silicone hydrogel lenses using the same solution.

c. Change to daily disposable soft lenses.

d. Change to any other multipurpose solution.

2) For a patient wearing soft lenses with many protein deposits, which of the following is the most appropriate advice?

a. Change to a daily disposable lens of a material with delayed dehydration.

b. Use protein removal tablets each week.

c. Change to a peroxide disinfection method.

d. Re-teach how to rub the lens with surfactant cleaner before soaking.

3) For a patient experiencing dry eye symptoms at an office, computer-based job, which of the following is the most appropriate advice to obtain short-term relief?

a. Practise full blinking of the lids.

b. Use appropriate contact lens re-wetting drops.

c. Take breaks from staring at the VDU screen

d. All of the above plus resist rubbing the eyes.

4) For the patient in Question 3, which of the following is the most appropriate advice to obtain long-term relief?

a. Refit the eye with another lens of better material.

b. Move the desk further from the air conditioning vent or fan.

c. Add omega-3 supplements to the diet and drink less caffeine.

d. All of the above, including drink more water.

5) Which of the following are the primary symptoms of contact lens related papillary conjunctivitis?

a. Itchy lids and sticky eyes.

b. Lid oedema.

c. Tarsal papillae and hyperaemia.

d. Mucous deposits on the lens.

6) Which of the following is the most significant sign of a faulty technique for soft lens removal?

a. Lateral conjunctival hyperaemia if there is a long lens wear time.

b. Long fingernails.

c. Lateral conjunctival redness immediately following lens removal.

d. Split in the soft lens.

7) Which of the following symptoms is indicative of visual problems due to presbyopia?

a. Near detailed vision is a strain, distance VA is sometimes blurred, and the patient is aged 45 or over.

b. Near detailed vision is a strain and distance VA is sometimes blurred.

c. Near detail strain for RE, OK for LE, distance VA good each eye.

d. Distance and near VA are both blurred and are worse with longer contact lens wear.

8. Which of the following features indicates that a visual problem is due to residual astigmatism?

a. Astigmatic readings on keratometry.

b. Letters blur in one meridian with 'image ghosting' but soft lens clean.

c. Astigmatism shown on keratometry but spherical soft lens worn.

d. Blurred distance vision with lens, also with two year old spectacles.

9. Why may a presbyope be happy that his lenses are in the wrong eyes?

a. They are reassured that they have not lost a lens.

b. Relief that there is no eye pathology reason for the changed vision.

c. They are pleased that they won't have to buy a replacement for a scratched lens.

d. They like the inadvertent monovision effect achieved.

10) Which of the following is the most likely cause of grease build-up on lenses?

a. The patient eats too much fat in their diet.

b. They do not wash their hands correctly before inserting the lens.

c. They instill viscous 'artificial tears' drops on the lens if eyes feel dry.

d. They insert the lens after applying mascara.

11) When may a presbyope wear his distance spectacles over his lenses?

a. In a dusty environment, to protect the lenses from dust.

b. In sunshine, if the spectacles have a dark brown tint.

c. To help his binocular control.

d. To assist near vision, if the prescription is of low positive power.

12) Which method is best to find a daily disposable lens under the top lid?

a. Instill fluorescein so that the lens shows easier on blue light slit lamp examination.

b. Avoid fluorescein as the lens will need to be reinserted once found.

c. Hold the lids apart for a minute, forcing lacrimation to wash the lens out.

d. Drag the lens back onto the cornea using a dry cotton wool bud.

Further Reading:

1) Phillips AJ & Speedwell L, Eds. (2007) Contact Lenses, 5th edition. Butterworth Heinemann, Edinburgh, UK.

2) Kruse A, Lofstrom T, Meyler J, & Sulley A, Eds (2006) A handbook of contact lens management, 2nd Edition. Johnson & Johnson Vision Care & Synoptik.

3) Efron N, Ed. (2004) Contact lens complications, 2nd Edition. Butterworth Heinemann, Edinburgh, UK.

4) Stapleton F (2003) The anterior eye and therapeutics--diagnosis and management. Butterworth Heinemann, Sydney, Australia.

5) Bruce A & Loughnan M (2003) Anterior eye disease and therapeutics A-Z. Butterworth Heinemann, London, UK.

6) Efron N, Morgan P, & Jagpal R (2003) The combined influence of knowledge, training and experience when grading con tact lens complications. Ophthalmol. Physiol. Opt. 23(1);79-85.

7) Hem MM, Ed. (2000) Manual of contact lens prescribing and fitting with CD-ROM, 2nd Edition. Butterworth Heinemann, Boston, USA.

8) Ruben M & Guillon M, Eds (1994) Contact lens practice. Chapman and Hall, London, UK.

9) Tomlinson A (1992) Complications of contact lens wear. Mosby International, St. Louis, USA.

Dr Christine Astin
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Title Annotation:COURSE CODE: C-9521: 2: CET POINTS
Author:Astin, Christine
Publication:Optometry Today
Date:Sep 19, 2008
Words:5178
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