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Home , Eye examination, Retinoscopy

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Routine examination Part 6 – Objective Andy Franklin and Bill Harvey look at objective refraction, the various ways of undertaking it and what may influence the outcome. Module C8872, two general point for optometrists and dispensing

bjective refraction Adjusting the trial frame includes and The optical centres of the trial frame the use of autorefractors, should be set to the distance PD. If which are appearing in there is marked facial asymmetry you optometric practice in may need to measure half-PDs and increasing numbers. In adjust the trial frame accordingly. Later, O general, objective methods are not when you move on to near vision tests required to give us a final prescription. the optical centres can be adjusted to They merely need to get us to a point equal the near PD, and dropped slightly from which subjective methods can by adjusting the nosepiece of the trial take us to the end point accurately and frame. However, this should only be quickly. With an alert and compliant done if the spectacles that you intend subject it is possible to get an accurate to prescribe are to be set for near vision result using subjective methods alone, only. On a pre-presbyopic patient the but it takes time. In general, excessively optical centres should stay set for prolonged refraction of normal patients distance throughout the refraction, as is usually indicative of poor technique the near ocular motor balance will be rather than ‘professionalism’. With affected by the centration of the lenses practice, and if a previous prescription (Table 1). is known, objective refraction should Figure 1 If and the position of the nasal limbus is ● Look at the trial frame and check take seconds rather than minutes. the frame is measured, ensuring that you have not that it is level, allowing for any facial There are patients who are unable not level, moved the rule meanwhile. asymmetries that may be present. If the to participate in a subjective refrac- the cylinder The pupillary distance for near may frame is not level, the cylinder axis that tion, because of limitations of under- axis you be measured by instructing the patient you find may be wrong, and vertical standing or communication. The very find may be to look at the bridge of your nose. The prismatic effects may cause artefacts on young, those with Alzheimer’s disease wrong zero is lined up using the left eye and the binocular tests (Figure 1). or a learning disability may require that PD read using the right eye as before. ● Check that the pantoscopic angle of a prescription is arrived at purely from Quite why you would wish to do this the frame is sensible (Figure 2). If the the objective findings. is another matter. The actual amount of frame is wrongly tilted, high powered We should have realistic expectations inset required will vary with both the prescriptions may throw up significant of retinoscopy. It has been found that PD and working distance of the patient, errors in both sphere and cylinder. there is only a 50 per cent probability so unless you know these and place your ● Make sure that the back vertex that two consecutive measurements of nose in precisely the right position the distance is sensible. If the power of the sphere power would be within 0.40D. measurement is of dubious value. The sphere you find is over +/-4.00DS you They found that cylinder axis was the actual inset required is shown in Table should measure the BVD and note it on most repeatable, followed by cylinder 1 below. the final Rx. power, then sphere power. And, unless you are fully ambidextrous, you are likely to be better with one eye than Table 1 the other. Of course, the skill of the Trial frame inset for near vision for a range of PDs examiner will influence both accuracy and repeatability. Binocular inset for near vision at; PD 33cm 40cm Measuring pupillary distance It is important that we set up the trial 74mm 5.5mm 4.5mm frame accurately, because failure to do 70mm 5.0mm 4.5mm so may introduce significant artefacts 66mm 5.0mm 4.0mm into the result obtained. Use a frame 62mm 4.5mm 4.0mm rule and instruct the patient to look 58mm 4.5mm 3.5mm first at your left eye. Line up the zero 56mm 4.0mm 3.5mm cursor with the temporal limbus. The patient now looks at your right eye,

20 | | 11.04.08 opticianonline.net CET Continuing education

(a) (b) Figure 2 If the frame is wrongly tilted (a), high powered prescriptions may throw up significant errors

Adding lenses to the trial frame visible, though complete darkness can ● Place spheres in the back cells of the stimulate . It might also trial frame. Where you are using more be difficult to find the trial lenses. than one sphere in the trial frame the most powerful should be at the back Position to minimise the vertex distance effects. You must try to work within 5° of the However, if you are using an Oculus visual axis, both horizontally and verti- or similar trial frame, which incorpo- cally. Adjust the chair height for verti- rates a built in vertex distance scale, cal alignment, allowing for the fact that the most powerful sphere should be the test chart may be above the patient, placed in the first of the rear cells (the so the patient may be looking slightly back cell one nearest the front). This is upwards. Errors of the order of -0.50DC the cell to which the scale is referenced x 90 occur if 10 degrees off horizontally. (Figure 3). Unless you have reduced vision in one ● When you change spheres, try to eye, use your RE to test the patients RE, ensure that the patient is never grossly Figure 3 The sphere in the first of the rear cells and LE for the patients LE. If this is under-plussed when you change lenses. impossible, the Barrett method should It is best to add the next plus lens before there is some evidence that the rings be employed. For horizontal alignment, you remove the current one. It can be on the green block of the duochrome get the patient to look at the green of the tricky with modern trial frames but it might be the one that produces least duochrome, get your head in the way becomes easier with practice. accommodation. In the absence of any and ask the patient to tell you when ● It is essential to make sure that all contradictory evidence the rings on they can just see the green panel. Ask lenses are thoroughly clean throughout the green would be the recommended the patient to tell you if your head gets refraction. Experience suggests this is fixation target for retinoscopy. in the way. often not the case. conditions Working distance A note on phoropters A darkened room will cause You should work at a distance that allows Increasingly, heads are dilation and make the reflex more you to change the lenses in the trial used instead of trial frames. Modern automated lens carriages allow fast lens insertion, greater accuracy in axis location, more rapid comparison and presentation of lenses, use of variable prism, and a variety of further options depending on the model, such as immediate comparison of new refrac- tive findings with previous results. They are not advisable for a few situa- tions, notably low vision assessment and over-refraction of multifocal contact lenses, where the reduced light levels may affect visual performance or pupil size respectively (Figure 4).

Retinoscopy

Target Ideally, we want a target that will promote accurate and steady fixation but Figure 4 no stimulus to accommodation. Various A modern targets are used and they probably make phoropter little difference to the end result, but head opticianonline.net 11.04.08 | Optician | 21 Continuing education CET

frame without changing body position, Table 2 and for most people this means that the Working distance lenses for retinoscopy working distance will be less than the 2/3m which seems to be the expected Working distance (cms) Working lens allowance (D) norm. Only the tall can reach if they 50 2.00 work at 2/3m and for many 1/2m is more realistic. It doesn’t matter what the 57 1.75 distance is provided that you know how 66 1.50 much to allow for your working lens 80 1.25 and the distance is maintained through- 100 1.00 out the test. Measure your customary working distance so that you know how much spherical power to allow for it. Make sure that you can return to it by Table 3 measuring with your arm. Usually the Acuity associated with mean sphere values base of the fingers or the wrist is used as a reference point, as this allows you Vision Equivalent sphere (/manifest to change lenses without moving your hyperopia) body position. Check your working 6/5 PLANO distance when you have moved from 6/6 0.25 - 0.50 DS it (eg to change a lens). If your working distance allowance is wrong, errors in 6/9 0.50 - 0.75 DS the power of the sphere (and usually the 6/12 0.75 - 1.00 DS cylinder too) will result. For example, 6/18 1.00 - 1.25 DS if you are 100mm out at 2/3m the 6/24 1.25 - 1.75 DS sphere will be approximately 0.25D in 6/36 1.75 - 2.25 DS error. Note, however, that the shorter the working distance, the greater the error that will be introduced by 100mm variation (Table 2). Table 4 Acuity with uncorrected cylinder Fogging During retinoscopy, it is the fixating eye Vision Equivalent cylinder (with best vision that controls accommodation, so it must sphere in place) be fogged to ensure that accommoda- 6/9 1.00 - 1.25 DC tion is relaxed. However, if you overdo 6/12 1.25 - 1.75 DC it, you can induce accommodation, so the fogging should be less than 2.00D. 6/18 1.75 - 2.25 DC Initially both should be corrected 6/24 2.50 - 3.00 DC with what you think is likely to be 6/36 3.00 - 4.00 DC the full plus correction, based on the patient’s existing correction (if availa- ble), VA and symptoms and history, plus the working distance allowance. Check Table 5 with the retinoscope that you have an Far point for a range of ‘against’ movement in either eye. From time to time during retinoscopy, pass the Spherical refractive error () Far point (centimetres) retinoscope beam across the fixating eye 2.00 50 to make sure that it is still fogged. This is 4.00 25 particularly important with hyperopic 6.00 16.7 patients. 8.00 12.5 Initial lens 10.00 10 If you have the patient’s last specta- 12.00 8.3 cle prescription, this is a good start- ing point. If the patient has lost their spectacles or no previous prescription is available, consider the unaided vision In purely astigmatic refractive errors inversely with refractive error (Table and far point. A little thought at this (or with the best vision sphere in place) 5). stage can save a lot of time and effort. (Table 4). The working lens should be incorpo- There is nothing to stop you checking It is important to remember that these rated into the correcting sphere. The use the VA when you have neutralised the are only average values. Patients with of a separate working lens introduces an more positive meridian, to get an idea small (usually presbyopes) will extra set of reflections and it uses up one of the cylinder power required. experience less blur per , and of the trial frame spaces you may need Distance unaided vision is related to those with large pupils more. for the patient’s prescription. For the refractive error in myopes and manifest For myopes, the far point at which ideal starting point, we would want the hyperopes (Table 3). small print can be seen clearly varies patient slightly fogged (over-plussed)

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Figure 5 The deviation is apparent when the beam is static Figure 6 Rotating the streak will align the reflex for distance to discourage accommo- Rotating the streak will align the a reversed direction. Therefore a ‘with’ dation, but rather less than 2.00D. The reflex and the direction of sweep. When movement is seen, which is neutralised easiest type of reflex to interpret is a the two coincide, you are sweeping with negative lenses. This technique is quick ‘with’ movement which should along one of the principal meridians, also useful as a check test, and in high occur if the patient is slightly under- the other being at 90º if the ametropia where no initial reflex can plussed for your working distance. is regular (Figure 6). be seen. They will still be somewhat fogged for Neutralise the more positive or least the distance that the patient is fixating negative meridian first. To decide Francis method as your retinoscope and the patient are which this is: ● Neutralise the more positive separated by 1.50D. ● If you have a ‘with’ movement in meridian both meridians, the meridian showing ● Set the collar for maximum diver- Plus or minus cylinder? the slowest movement is the more gence (ie down). The immediate source Plus cylinders do tend to give a clearer, positive will lie behind the retinoscope at about more easily neutralised streak and are ● If you have ‘with’ in one meridian, 1m with a working distance of 2/3m favoured by some practitioners who and ‘against’ in the other, the meridian ● Add -0.50DS. The reflex will become rely on retinoscopy to provide a final showing the ‘with’ movement is the a narrow line prescription (eg working with special more positive ● Rotate the beam through 90°. If the needs patients). However, using minus ● If you have an ‘against’ movement in reflex stays narrow, no significant astig- cylinders does ensure that accommoda- both meridians, that showing the faster matism is present. Even a tiny amount tion is more easily controlled and most movement is the more positive or least causes the reflex to fill the pupil as the automated refractor heads do not have negative. beam completes its rotation. The orien- a plus cylinder option. Minus cylinders When you think you have reversal, tation of the beam that produces the are more commonly used in routine use a bracketing technique to check. narrowest reflex is 90° off the minus refraction. cylinder axis For power ● Add +0.50DS and neutralise the Streak or spot? ● Move slightly backwards and second meridian. Either type of retinoscope will do the forwards. The reflex should change job, in the hands of someone famil- from ‘against’ to ‘with’ Alternative methods iar with it. Streak retinoscopes are ● Use +/- 0.25D twirls. Again the reflex There are a number of methods which currently fashionable and they do should change from ‘against’ to ‘with’. may be worth trying if conventional make axis determination easier where methods are not possible or are not there are high cylinders, but spot retin- For axis (Lindner’s method) working on a particular patient. oscopes probably make it easier to do ● Neutralise the more positive lower levels of astigmatism. Some meridian Parker method retinoscopes now come with a choice ● Sweep the beam across meridians ● Identify the meridians in the usual of bulb, so practitioners can experiment at +45° and -45° to the axis of the trial way for themselves. cylinder. The reflexes should be identi- ● Set the streak along the axis, and cal. If one is ‘with’ and one ‘against’, adjust the streak to give a minimum Streak retinoscopy move the axis towards the meridian width reflex Initially the retinoscope should be set to showing ‘with’ movement. ● As the ametropia is corrected, the give maximum divergence (the collar width of the streak increases. When should be down). The beam is swept Small cylinders the reflex fills the pupil the ametropia along the 90º and 180º meridians and the If small cylinders are present, use either is neutralised. reflex observed. If the patient’s princi- of the following two methods: pal meridians lie along 90º and 180º the Barratt method reflex within the pupil will be seen to Move the collar up The patient fixates a bright luminous move parallel to the direction that you ● Neutralise the more positive fixation object binocularly. The target are sweeping. If not, the reflex moves meridian should ideally be non-accommodative obliquely to the direction of sweep. With ● Move the collar up so that the though the retinoscope target often medium to high degrees of astigmatism, immediate source is between the retin- used is not, completely. Alternatively this deviation is apparent even when the oscope and the eye. You should see a the practitioner’s forehead may act as beam is static (Figure 5). narrow reflex which moves rapidly in the target.

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Advantages claimed include: ● Working closer to the visual axis ● Smaller pupil due to near reflex. Fewer aberrations as a result (but also a less bright reflex) ● Only one of the practitioner’s eyes is used. This makes the method particu- larly useful for those optometrists with reduced acuity in one eye. The disadvantage is that the patient will accommodate especially younger ones. The sphere must be checked with distance fixation in one eye either before or after using the Barratt method and the final result adjusted accordingly.

Near retinoscopy Mohindra’s technique is a development of near-fixation retinoscopy which allows refraction of infants and young children without the use of cyclople- gics. The room are slowly extin- guished and the child encouraged to look at the retinoscope light. It is usual Figure 7 Portable autorefractors now exist and some are to ask the parent to occlude one eye, used in child screening programmes though opinions vary as to whether this makes a significant difference. Feeding you have a rapid ‘with’ movement in keep reminding the patient to look at tends to relax accommodation. The this meridian. This means that you are the circles on the green, and eventu- pupil will initially constrict but after 0.25D to 0.50D under-plussed for the ally you will see a ‘with’ movement, a few seconds dilation will occur. At distance you are working at, but the albeit a transient one. Neutralise it, this point the refractive error may be patient should still be fogged for their and repeat until you are sure that all of neutralised. Lens racks may be used for fixation distance. The cylinder power is the hyperopia is corrected. If you are speed, each meridian being neutralised increased until the reflex is circular and consistently under-plussing on retinos- separately. Accurate fixation may be its speed in the two principal meridians copy, check your working distance, and encouraged in older children by asking is the same, then you add the final bit slow down. the child when they can see ‘the black of sphere. spot in the light’ (ie the sight hole in the The stenopaic slit mirror, on a spot retinoscope). Difficult retinoscopy This is an elongated pinhole which is The working distance is usually Split reflex used to find an approximate correction 0.5m, so the expected allowance for , corneal scarring or lens of astigmatism in cases where retinos- the working distance would be 2.00D. changes. Check that the lenses are copy will not give an accurate result However, near retinoscopy does tend to clean, correctly centred and that you and high astigmatism is suspected. It is underestimate hyperopia, so a correc- are working on axis. Don’t try to obtain placed before the eye being tested with tion factor of 1.25D is used for adults, reversal, use bracketing. the BVS in place. The slit is rotated though it has been suggested that a slowly and the position which gives correction factor of 1.00D is appropri- Opacities the patient the best acuity is noted. ate for children older than two years old You may have to work around them by This approximates one of the principal and 0.75D for those younger. moving off axis. Allow for this when meridians of the eye. Opinions vary on the accuracy of this estimating the cylinder. It might also ● With the slit still in place, plus and technique, particularly in infants and be necessary to work closer to obtain a minus spheres are added to give a ‘best those with higher refractive errors. brighter reflex. vision sphere’ for this meridian ● The slit is then rotated through 90° Spot retinoscopy Ocular abnormalities and the best sphere for the second Spot retinoscopy is performed in the Localised bulges or asymmetries may meridian is found. same way as streak retinoscopy but the mean that the fovea is on a different The powers found are then converted reflex is circular in a patient without plane to the slightly off-axis point which to sphero-cylindrical form and the significant astigmatism. An astigmatic forms the reflex. Therefore the sphere result placed in the trial frame, where patient will give a reflex that is ellipti- power may be some way out. it can be refined by normal subjective cal, and this shape and the movement techniques if appropriate. It must be of the reflex relative to the direction Accommodative tonus remembered that the axis is at right of sweep (which is the same as with In young hyperopes the retinoscope angles to the power meridian. a streak) enables rapid identification result will often be considerably more of the degree and axis of astigmatism. positive than the eventual subjective Non-refractive uses of It is usually recommended that the refraction due to high accommodative retinoscopy more positive meridian is neutralised tonus. Patience is a virtue here if you Retinoscopy may be performed before before correcting the cylinder, but you suspect that there might be more plus , so it may be the first may find that it is easier to do when to add. Keep sweeping the beam across, chance to view the internal structure of

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the eye. A number of conditions may Table 6 alter the appearance of the reflex. ● The light reflected from the Comparison of atropine, and topicamide retro-illuminates the lens, iris and . Opacities in the lens and iris Agent Onset of Duration of Duration of Tonus can be seen as dark areas against the adequate miosis allowance red background. The same effect may be cycloplegia needed? observed with an ophthalmoscope held Atropine 36 hours 7-10 days 10-14 days Yes (?) about 30-40cms from the patient’s eye. Cyclopentolate 30-60 minutes Up to 12 hours 24-48 hours No Early opacities may be easier to see by 30 minutes 2-6 hours 8-9 hours No retro-illumination than by direct obser- vation with the ophthalmoscope ● Where extensive transillumination Scheiner disc consisted of two holes in amounts of ametropia or anisometropia defects are present in uveitis or pigment a card placed before the eye. A myopic (Figure 7). dispersion syndrome it may be possible eye will see the two images from the Other new models incorporate some to see them as bright radial streaks on holes swapped over or crossed, while subjective assessment also, with the the iris. However, the is a better the hypermetrope sees them uncrossed. patient responding to prompts to clarify instrument to observe this This may be done in various meridian a presented image. ● Keratoconus distorts the reflex and to give information about the nature of produces a swirling motion astigmatism. Autorefractors simulate Cycloplegic refraction ● involving the this using LED light sources, the image When should cycloplegic refraction central area will distort the reflecting of which are detected by a light sensor be done? surface and a grey reflex may be seen. or photodetector and the position of the This is included in this section rather ● A tight soft will have LED needed to achieve a single image than that devoted to subjective refrac- apical clearance in the central area which over the photodetector is related to tion on the grounds that most ‘cyclos’ will cause distortion of the reflex. the patient refractive error. A further are performed on children whose ● It is possible to perform indirect method employed by a few machines subjective responses are not entirely ophthalmoscopy with a retinoscope is an adaptation of retinoscopy, where reliable. Some practitioners advocate and a high plus lens, provided that the the instrument analyses the speed of cycloplegic examination of all new instrument is bright enough. movement of a reflex of infra-red light child patients. This has the advantage to measure the refractive error. of providing more reliable baseline data Autorefractors Most studies suggest that autorefrac- on the refractive error at the expense of The use of a machine to measure refrac- tors are quick, simple, repeatable and time and some trauma for the patient. tive error has a long history. The original accurate (with some qualification). In general optometric practice, most optometers could use either subjective With cycloplegia or good accommoda- practitioners tend to use cycloplegics methods (the forerunners of modern tive control the results are very accurate. when: phoropters) or objective methods and it is Indeed the spherical aberration intro- ● There is undiagnosed manifest the automated objective refraction instru- duced by the dilation of a cycloplegic esotropia ments that are now described as autore- makes the method preferable to retin- ● An esotropia has been noticed by the fractors. Autorefractors use an infra-red oscopy in many cases. Its ease of use parent or guardian light source (around 800 to 900nm) makes it suitable to be carried out by ● There is unstable or uncompensated which allows good ocular transmission, ancillary staff, so reducing the burden esophoria but requires a -0.50D adjustment to the of the optometrist. The machines may ● There are significant risk factors final refraction due to error introduced directly link to an automated phoropter for esotropia and – Family by reflection from the choroid and . head, again making the routine refrac- history, significant refractive error, The source projects light via a beam split- tion more fluid. It is useful to remember birth history etc ter and a Badal lens system to form a slit that even the most accurate objective ● A satisfactory level of acuity is not image within the eye, the reflection of measurement may not be that preferred obtained in one or both eyes which passes out via the beam splitter by the patient, so a subjective approach ● Stereoscopic acuity is unsatisfactory/ to reach a light sensor. Throughout, the is always preferable to ensure a toler- absent patient is encouraged to relax accommo- able refractive error, even though this ● Latent hyperopia or pseudomyopia is dation (a major source of error for autore- is sometimes modified away from the suspected. fractor measurement) by use of a fixation actual refractive error present. target or, in some cases, an open view to The main error is due to poor fixation Should I use an anaesthetic first? allow fixation on a distant target. The (dependent very much on the target of Remember, cycloplegics sting, and very calculation of refractive error is based the instrument), accommodative fluctu- few children seem entirely grateful for upon analysis of how the patient’s eye ation (proximal accommodation in the the experience. This can be ameliorated influences the infra-red radiation. young invariably leads to overminussed somewhat by the use of proxymeta- The way this analysis is performed measurements) and media difficulties caine 0.5 per cent, a local anaesthetic. varies. Most of the original instruments (which are likely to reduce the effec- This stings rather less than the other used some form of image quality analy- tiveness of retinoscopy also). The lack local anaesthetics used on the eye, and sis, relying on positioning of the Badal of portability of the instruments is less will remove the sting of the subsequent lens system to achieve a maximum of an issue nowadays as several portable cycloplegic entirely. A further advantage signal to the light sensor. The major- models exist, and some have found use is the absorption of the cycloplegic will ity of modern autorefractors, of which in child screening programmes where be enhanced. Proxymetacaine is avail- there are many, rely on an adapted the main outcome is not precise error able in minims, but it needs to be stored Scheiner disc principle. The original measurement but detection of large in the fridge, which is not possible at opticianonline.net 11.04.08 | Optician | 27 Continuing education CET

all practices. The only other drawback would be if the patient did not like the Multiple-choice questions first drop, and decided to resist the instil- lation of the second. Which of the following measurements For uncorrected myopia of -1.50DS, which 1shows the best repeatability with 7of the following is the expected vision? Which cycloplegic? retinoscopy? A 6/24 At one time, it was common practice A Sphere power B 6/36 to hand out atropine sulphate to the B Cylinder power D 6/60 patient’s parents to administer at home C Cylinder axis D 6/12 for the three days necessary. In these D Near addition less innocent times, this potentially fatal For an uncorrected cylinder of -2.75DC hallucinogen has become rather less For a near vision distance of 40cm, what 8which of the following is the expected popular in the high street and patients 2inset should the trial frame be adjusted vision? requiring it would normally be referred to for a patient with a PD of 58mm? A 6/24 to a specialist clinic. It is no longer avail- A 4.0mm B 6/36 able to entry level optometrists. B 3.5mm D 6/60 Cyclopentolate is the most popular C 4.5mm D 6/12 cycloplegic agent. The 1 per cent solution D 5.0mm is suitable for most patients. One drop What is the far point for an uncorrected is usually enough, but for patients with What sphere value is generally 9myope of -8.00DS? dark irides a second drop may be needed 3considered the point beyond which A 10cm if nothing seems to be happening after measurment and noting of the back vertex B 12.5cm 15 minutes. It does not produce absolute distance is important? C 15cm cycloplegia, but the residual accommo- A +/- 1 DS D 20cm dative tonus is less than 1.50 dioptres. B +/- 2 DS No ‘tonus allowance’ needs to be made, C +/- 3 DS What is the recommended correction so you can prescribe the ‘full cyclo’ if D +/- 4 DS 10factor for near retinoscopy on an you need to (and only if). The 0.5 per adult patient? cent solution is needed for children For which of the following techniques is a A None required under three months, though few would 4phoropter head unsuitable? B 0.50DS be encountered in the general ophthal- A Overrefraction of mutifocal contact lenses C 0.75DS mic services. B Cycloplegic refraction D 1.25DS Tropicamide 1 per cent has been found C Assessment of complex prescriptions to be a useful, if short-acting, cycloplegic D Fusional reserve assessment What is the duration of cycloplegia of for patients in their late teens and older. 111 per cent cyclopentolate? In adult patients, the short duration is a What error is induced if undertaking A 7 to 10 days virtue and this is the ideal agent to inves- 5retinoscopy at 10 degrees off axis? B Up to 12 hours tigate the adult patient you think might A 0.50DS sphere error C 2 to 6 hours be a latent hyperope or a pseudomyope. B 0.50DC cylinder error D 30 minutes Two drops, about five minutes apart C 1.00DC cylinder error following proxymetacaine should do D 10.00DC cylinder error What is the duration of cycloplegia of the trick. 121 per cent tropicamide? What working distance lens allowance A 7 to 10 days How do I get the drops in? 6should be used for a retinoscopy working B Up to 12 hours Children are rarely very keen on having distance of 80cm? C 2 to 6 hours drops put in. A 1.00DS D 30 minutes ● Explain what you are going to do B 1.25DS in a calm way. Avoid words like ‘sting’ C 1.50DS and ‘pain’. Tell the patient that the drops D 2.00DS ‘might feel a bit funny’. Try to avoid lying to the child ● Watch the body language, as children To take part in this module go to opticianonline.net and click on the Continuing Education are rather good at reading it. You need to section. Successful participation in each module of this series counts as one credit towards be sending out the signals that reinforce the GOC CET scheme administered by Vantage and one towards the Association of your spoken advice Optometrists Ireland’s scheme. The deadline for responses is May 8 ● Sitting on mother’s lap is a safe place to be for most small children ● The child might move fairly suddenly, a variation of an old contact lens trick upper lashes at the lid margin. ● and you don’t want to stick a minim can be useful. While trying to raise in their eye. If they are co-operating, the upper lid with your thumb, out of Acknowledgements get the patient to look down, raise the the blue say ‘now, open your mouth as This series is based on Routine Eye upper lid gently with your thumb and wide as you can!’ It’s almost impossible Examination, W Harvey and A Franklin, Eye keep the neck of the minim against the to open your mouth wide and close your Essentials, Elsevier Science. thumb while you instil the drop. If the eyes tight at the same time as patient moves, so does your thumb and ● If the child closes their and ● Andrew Franklin works in private so will the minim steadfastly refuses to open them, the trick practice in Gloucestershire. Bill Harvey is ● If the child will not open their eyes is to put about three drops of cyclo on the Optician clinical editor

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