Top tips for testing

The eye examination by an experienced optometrist, with many years under their belt, usually differs from that of a newly qualified practitioner, even though both are essentially performing the same tasks.
Major differences would be the time taken and which tests are performed, or 'missed out', but there are often small, subtle 'tricks' which an experienced optometrist may employ that they have developed over the years.
These may have been devised by the individual or picked up from colleagues, pre-reg students or from their supervisor during their own pre-reg year. These might not be essential to the test but make results easier to arrive at and more accurate or save time.
This article sets out to share a few such 'top tips' gleaned from years of pre-reg supervision, examining and working alongside other optometrists, especially when conducting a peer review. I have tried to avoid 'clinical pearls' or 'best practice' advice and concentrate on small nuances, tips that I've seen someone do and thought, 'that's a good idea, I'll try that in my routine'. Some may seem trivial or obvious but, hopefully, there will be at least one tip even the most learned optometrist can employ.

VA measurement - hands-free methods of occlusion
When measuring monocular acuities with a person's existing spectacles, one eye is covered over, usually by the optometrist holding an occluder. This could be a time when it would be useful to be doing other things such as writing up notes or, with children, pointing to letters on the test chart. Wide micropore tape is very useful in this regard (Figure 1). A short strip can be stuck easily and quickly onto a spectacle lens to occlude an eye and is removable without leaving a sticky residue, thus leaving both of the practitioner's hands free. This is better than getting the patient to hold an occluder themselves as it looks a little like 'here, test yourself' and with children there is a tendency to peek.
For assessment of unaided visions on children, micropore tape can be used on a clear dummy lens of an unglazed frame from stock, or a pirate patch can be used. Children tend to find both methods fun and have both hands free to hold and point to Sheridan Gardiner letters.

Cover test 1 - improving accuracy by a subjective cover test
When performing a cover test it is extremely useful to ask the patient if the target they are fixating moves position as you cover their eyes.
This does two things: first, the patient needs to really concentrate on the object, rather than just generally staring towards it, thus showing up more easily, small angle deviations that might otherwise be missed. Second the patient's response will give a clue as to what deviation you could be expecting to see. For example, if a patient says 'Yes, the letter is jumping up and down,' then you may expect to see a vertical movement of the eyes.
This subjective cover test is sometimes referred to as the Phi test1 and the movement reported by the patient can be measured using prisms.

Cover test 2 - improving accuracy by a modified observation technique
When performing an alternating cover test, by the time the observer has refocused from the newly covered eye to the uncovered one, any small re-fixation movement by the patient has already occurred. The action of the occluder can also be performing an involuntary cover test on the observer as well as the patient.2
One way to avoid this, and to have a better chance of seeing the smallest deviation, is to look from the side of the patient with the occluder at a shallow angle (Figure 2). This allows the observer to see the occluded eye but still blocks the patient's view of the target. Thus, the occluder can be moved across, while the attention of the optometrist is fixed on only the one eye making the tiniest of movements easier to see. A similar effect may be reached using a frosted or translucent occluder.

NPC - improving accuracy
Patients can often lose interest in fixating on a target as it moves closer towards them and break into diplopia sooner than the near point, or be left staring into mid distance. To avoid this, try moving the target side to side in a slowly oscillating motion as it moves towards the nose. The resulting version movements of the eyes maintains the patient's continuing attention on the target.

Ocular motility - making the test more fun and more reliable for children
A loss of patient attention can reduce the accuracy or increase the time required for the test. This is especially true for children. If the target used is a penlight, flashing it on and off helps maintain attention. Putting a 'monsters head' on the light will increase a child's interest and help keep better fixation.

Retinoscopy 1 - keeping a child's attention easily on a distance target
Children are often the patients where retinoscopy is the most useful or indeed necessary, but they may also be the most difficult to assess because of poor attention or co-operation. One of the greatest advantages of a projector chart is that the remote control can be given to children to play with. Almost without exception children love to play with remote controls and they can be kept happy for many minutes. Most of their viewing is into the distance at the projector screen with only the briefest glances down to look at the remote. Worries about fully accommodative targets are always addressed by a cycloplegia.

Retinoscopy 2 - obtaining a useful ret reflex for a patient with cataracts
Retinoscopy can be difficult for patients with media opacities, due to the dim reflex obtained. The reflex can be made brighter by moving closer towards the patient and increasing the power of the working lens. For example, move to a working distance of 40cm and use a +2.50DS working lens. Remember, the closer you are, the more critical the distance.

Subjective refraction 1 - latent hyperopia/controlling active accommodation by refraction to 6/18
When refracting a patient with active accommodation it may be difficult to obtain a good level of acuity unless a sphere lens is used of much less value than is indicated by retinoscopy. A useful technique in such cases is to first correct astigmatism using whatever value of spherical lens is required to facilitate this, even if this seems very 'under-plussed'. Then correct the sphere correction so the patient can just see to 6/18. They should then be theoretically over-corrected by +1.00DS, or +1.25DS at the very most. When this has been repeated for the second eye the patient can then be asked to view the test chart binocularly and the sphere lens in front of both eyes reduced by 1.00DS. I have found this technique to be more effective than even a binocular refraction for patients with very active accommodation. It also gives a result which you know can be tolerated in spectacles, unlike a 'full' cycloplegic result. Obviously in cases of accommodative esotropia, no such adaptation is recommended.

Subjective refraction 2 - using contact lenses to relax accommodation
Another alternative to cycloplegia for relaxing accommodation is the use of contact lenses. Contact lenses cannot be 'peeked around' and therefore give constant, undistorted correction. If contact lenses of the full positive prescription are inserted into a patient's eyes, the eyes tend to relax accommodation. This technique is particularly useful on patients who are low hypermetropes on retinoscopy, have symptoms related to close work, but who subjectively appear close to plano.

Final sphere correction - avoiding over-plussing by use of +0.12 DS lenses
A patient can 'non-tol' to a spectacle refraction if it is as little as 0.25DS out.3 This is especially true with distance prescriptions where over-plussing will cause blurring when far distance viewing, especially when driving. Most test charts, however, are located just six metres away from the patient as an approximation of infinity. If a patient's refraction focuses them precisely on the chart then they are theoretically +0.167DS (one divided by six) over-corrected for infinity. To avoid this at the end of refraction for a patient, check whether the line of their best binocular corrected acuity is blurred by +0.12DS placed before both eyes. If +0.12DS binocularly does cause blurring then it is wise to reduce the final sphere by 0.25DS, which should only under-correct infinity by 0.083DS (0.25 - 0.167) rather than over-correcting by 0.167DS. Lenses of +0.12DS are used in the absence of +0.167DS ones as most trial cases come with these, even though most people tend to just stick them in a bottom drawer.

X-cyl 1 - alternative presentation methods for easier patient comprehension
Practitioners soon learn that, when starting X-cyl in a refraction, it is better to explain the test as you present the two options, rather than a lengthy explanation beforehand which tends to confuse the patient. Even then, the decision involved in choosing the clearest image between two options can still seem bewildering for some, especially young children and some elderly patients. I have found more success in such cases by using a slightly modified approach to presenting the X-cyl options. The cross cyl is placed in the 'first position' and the patient is simply asked 'Can you see the rings ok?' (or what ever the target used is). The X-cyl is then flipped over with the question 'What has that done? Made it clearer or more blurry?' No mention is made of first or second position. Patients seem to find this decision easier.

X-cyl 2 - using the X-cyl for prescription verification
Many practitioners forget that an 0.25 X-cyl, if focimetered, has the power +0.25/-0.50 x n, (where n is the angle of the -0.25 X-cyl axis), or alternatively, -0.25/+0.50 x n in plus cyl form. Having this combination in one lens is very convenient when checking changes in a patient's prescription in trial frames. For example, a patient's refraction result may be +1.25/-2.00 x 90 where existing spectacle prescription is +1.00/-1.50 x 90. Any subjective improvement from one prescription to the other can be quickly and easily checked by a 'better with or without' method using the X-cyl. This obviously works with the 0.50 X-cyl which focimeters at +0.50/-1.00 x n.
Another example of where this is useful is when deciding on a compromise cylindrical correction where a large increase in cyl has been found. Placing the cross cyl in front of the trial lens will reduce the astigmatic correction, while still keeping the circle of least confusion on the retina. Thus, any subjective deterioration from a possible compromise prescription can be quickly assessed.

Reading add - tips to ensure too strong a reading add is not given
When judging reading addition for a presbyopic patient it is easy to 'over-correct' by giving a higher reading add than is required. This will have the detrimental effect of reducing the depth of focus obtainable and may produce patient non-tolerance. When using trial frames this can be caused by the patient holding the reading chart at an artificially close position during the eye examination.
To avoid this, if it is possible, tilt the arm rests of the consulting room chair out of the way, thus stopping the patient putting their elbows on them. Also the near vision test type is best given to the patient before any extra reading addition is inserted into the trial frame. The patient will almost without fail report how blurry the type is, but after re-assurance they will more likely hold the chart at a normal, habitual working distance, rather than adapting to the add power given.

Ophthalmoscopy 1 - obtaining a more usable fundus image in direct ophthalmoscopy on high myopes
The magnification of a fundus image obtained with direct ophthalmoscopy is affected by the eye's spectacle prescription. For medium to highly myopic patients the resulting magnified image can make direct ophthalmoscopy quite difficult and virtually impossible to ensure all the retina is covered. An easy and quick method to obtain a more usable view is to perform ophthalmoscopy with a patient wearing their spectacles. Even though this restricts the proximity to the eye that can be achieved, the reduction in magnification more than compensates for this. This is also very useful for high astigmats where the fundus view without spectacles can be quite blurred or distorted. Again, a disposable contact lens might be useful.

Ophthalmoscopy 2 - a method to more accurately measure cup-to-disc ratio
I have often felt that it is quite difficult to accurately determine the ratio in size of two concentric ovals. This difficulty may explain some of the discrepancy often found when comparing the cup-to-disc ratio of an eye to that recorded by a previous practitioner. It is much easier to determine how many fifths a cup extends across half of the disc. For example, consider the disc representation in Figure 3a. The cup-to-disc ratio could be easily be estimated to be anywhere in the range of 0.3 to 0.5. If the ophthalmoscope light is shone half way across the disc to give a reference point as in Figure 3b, it can be quite easily be seen that the cupping extends midway across the bottom half of the disc. In the upper half the cupping extends approximately two-fifths of the way across. So we can more accurately see that the cup-to-disc ratio is 0.45 with the cup displaced slightly inferiorly.

Dispensing - insert daily contact lens to let high ametropes choose frames more easily
Patients with higher spectacle prescriptions can encounter difficulty when choosing new frames, as they cannot easily see themselves clearly in a mirror without their correction.
Various methods have been devised to get around this: 'magic mirror' computer imaging and magnifying mirrors are just two examples. Another great method is to insert a pair of daily disposable contact lenses into the patient's eyes - prescription, suitability and patient consent allowing, obviously.
Providing a slit-lamp examination was performed as part of the eye examination it should only take a few minutes to insert a pair of contact lenses at the end of an appointment.
The patient can be quickly seen later (after they have chosen their new frames) to remove the lenses and to check corneal integrity. Suitable patients find this extremely helpful and often return for a full contact lens trial and become contact lens wearers as well.

Peer review
I hope that at least some of the tips mentioned may prove of use. Most were gleaned during a peer review exercise performed with a group of optometrists around the Leicester area, where everyone sat in (with the patient's permission) on each other's eye examinations. Optometry is usually carried out behind closed doors and I imagine very few optometrists, post-registration, have had an optometric peer watch them perform an eye examination.
This is a shame as it proves most enlightening and educational for both the observer and the person observed, especially when open, constructive feedback is given. What was most apparent from the Leicester group were the differing methods used by individuals to achieve the same goal, such as listed in this article.
So if nothing so far has been of use then I hope at least this article may spur individuals to enquire of colleagues and optometric friends how they perform their eye examinations.

References
1 Evans BJW. Pickwell's Binocular Vision Anomalies, Investigation & treatment. Chapter 2 p22.
2 Evans BJW & Doshi S. Binocular Vision & Orthoptics. Chapter 1, p5.
3 optician, June 21, 2002 No 5856 vol223. pp18-21.

If you have a top tip email it to rob.moss@rbi.co.uk

Neil Constantine-Smith is an optometrist in practice in Lymington, and a College of Optometrists' PQE examiner and assessor