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It is impossible to remove every unnecessary referral and a percentage of 'false positive' referrals will always need to be factored into a screening programme. A specificity of over 90 per cent is often thought to be a good result for a diabetic retinopathy or open-angle glaucoma shared care programme, but of course this will result in 10 per cent false positives.
Shared care programmes deal with patients who are at a specific risk of eye disease, so these false positives are a fact of life. There are, however, a whole host of other eye conditions that result in referrals from the bigger 'not at risk' bank of patients we see on a day to day basis. Sometimes this can be due to the patient asking for a second opinion, although more often it can be due to practitioners not being able to offer the perceived correct degree of follow-up. This is especially the case for mobile optometrists that aren't always sure when they might re-visit the practice concerned, so it often feels better to deal with any unusual eye condition by referring the patient on the day of the sight test.
There is no attempt here to produce a comprehensive list of every ocular condition that does not warrant referral, but let us discuss some of the more common scenarios.
Pigmentary retinal lesions
The technology used to investigate the retina has improved markedly over the past 20 years. Binocular indirect ophthalmoscopy (BIO) allows a greater field of view than direct ophthalmoscopy and also allows a stereoscopic view, and digital retinal photography has also become more the norm than the exception. Retinal photography is especially good at detecting pigmentary lesions - particularly congenital hypertrophies of the retinal pigment epithelium (CHRPE) and choroidal naevi (Figures 1 and 2).
CHRPE are caused by a thickening of the retinal pigment layer and are common. They often appear dark and have distinct edges - often they are circular in shape, but they can also take on distinct shapes such as bear's paw. They are of little significance and no danger to sight at all, although they can be associated with Gardner's syndrome. If a patient suffers from a colon-related condition it would be wise to inform the patient's general practitioner.
Choroidal naevi are very common, occurring in 2 per cent of the population. They are similar to a freckle or mole that may be found on the skin and are caused by melanocytes grouping together in the choroid. They are grey in colour, often with slightly uneven edges; long-standing naevi often have drusen on their surface. There is no danger to the eye from these lesions, although if they are close to the macula they can sometimes affect vision.
The risk of a choroidal naevus transforming into a malignant melanoma is approximately 1:20,000, and this should always be in the practitioner's mind. It is fair to say, however, that malignant melanoma generally appear far bigger and paler than choroidal naevi, and are raised. There will often be an orange colour to these lesions - lipofuscin, which is an indication of cell death. It is also reported that if the posterior margin of the lesion is within 3mm of the optic disc that this should viewed more seriously. Both conditions can be symptomless, although patients with malignant melanoma can sometimes complain of a brown spot in their vision or photopsia.
Any suspicion of malignant melanoma should of course be referred for an ophthalmologist's opinion, although remember they are very rare. A dilated fundus examination with BIO and digital photography would be extremely advisable, with an early recall to review the size of the lesion, especially if it has not been recorded in the past. The lack of previous evidence of any pigmented lesion shouldn't automatically result in a referral, as it may simply be that it hasn't been spotted by any previous practitioner.
Macular lesions
Ophthalmologists often feel very frustrated when having to see patients with dry AMD, mainly because there is little that they can do beyond that which the optometrist can offer. Fast-track macular units would much prefer to use their time to investigate and treat patients with wet AMD. With this in mind, patients with a rapid recent loss of vision or distortion (metamorphopsia), or signs suggestive of a wet AMD - macular oedema, retinal haemorrhage or hard exudates near the fovea.
Drusen and hard exudates can sometimes be difficult to differentiate. Drusen occur deeper into the retina, in the RPE layer and generally have a round and regular appearance. Hard exudates are more superficial, occurring in the outer plexiform layer and generally appear brighter and less regular.
Diabetic retinopathy
The classification and management of diabetic retinopathy (DR) has been widely discussed in other articles, and most optometrists are comfortable with the criteria for referral and when to simply monitor. Signs of background DR require annual review, unless there is evidence of maculopathy ie hard exudates within 1 disc diameter of the fovea, circinate hard exudates within the extended macular region or a visual acuity of 6/12 or less with any sign of DR within 1DD of the fovea. Also any sign of pre-proliferative or proliferative DR will need prompt referral, the latter ideally needs to be seen by an ophthalmologist within a week. To avoid any unnecessary and potentially sight-threatening delay, it is essential that any referral is generated through the local PCT's diabetic retinopathy screening service, which is almost always via an online digital retinal photography system. It's very tempting to use the GOS 18 route if your practice isn't involved with the local system or the practice photographer is unavailable on the day. However, it is far more safe and efficient to direct the patient to a local colleague within the programme (maybe with a phone call) to get the patient referred through the correct process.
Unusual optic nerve appearance
The incentive to write this article was inspired by a colleague referring a patient with a slightly unusually shaped optic nerve head (Figure 3). Interestingly the local ophthalmology department queried the referral before agreeing to see the patient, and I will leave you all to consider your management of this patient.
The optic nerve is the most striking feature of the fundus and will be investigated with every patient we see, although I have to say it can often be very difficult to interpret. Indistinct disc margins can cause a great deal of consternation, and of course papilloedema requires an emergency referral. However, pseudo-papilloedema due to high hyperopia or disc drusen can sometimes confuse matters. Previous clinical records, or better still photography, will help greatly to make a decision - it's also worth noting that the spontaneous venous pulsation will be absent in papilloedema, but should be present in the other ocular conditions.
Assessment of the optic nerve is best done stereoscopically with BIO, and an estimation of the cup to disc ratio is vital. A large C:D ratio (over 0.7) might not always warrant referral, especially if the size of the disc is large. Also we need to look closely at the band of neural retinal tissue; if there is healthy tissue all around the cup and the ISNT rule is followed, then it is unlikely that a referral is necessary. Again clinical records will help with this decision, taking into consideration intraocular pressures, visual fields and assessment of the thickness of the nerve fibre layer (if you have access to an OCT).
Raised intraocular pressure
Since the NICE guidelines in 2009 changed the emphasis of intraocular pressure when referring for possible open-angle glaucoma, there has been a dramatic increase in the referral rates for patients with higher than 21mmHg. Many PCTs have tried to reduce the numbers entering the hospital eye service by supporting glaucoma refinement schemes run by optometrists that have passed their LOCS exam or undertaken the College of Optometrists' glaucoma A or B training.
Patients can be referred by their optometrist to a glaucoma refinement optometrist if their IOP is above those NICE guidelines in order to make a considered decision about referral or review. This is an excellent development opportunity for those optometrists wishing to get involved in a more clinical environment. However, it has to be said that is still involves the NHS in greater fees and still creates extra anxiety for patient (if not quite as much as that of referral to the eye department) as well as involving them in an extra appointment to a different practice.
It's hard to see why more optometrists don't just simply recheck the IOP with a contact applanation method of tonometry before referring even to the glaucoma refinement scheme. Goldmann or Perkins tonometry is a simple technique that can take less than five minutes to perform, and if the IOP is less than 21mmHg, so long as there are no other suspicious findings, the patient can leave happily reassured by their own optometrist.
Some people seem to take the view that we don't get paid for performing this technique and there is the additional cost of anaesthetic drops and tonometer heads etc. This seems to me a sad attitude, when at the end of the day the main winner is our patient. Possibly a more sensible fee structure in the first place would make this technique more economically viable.
Media anomalies
Common media anomalies can include cataract, corneal opacities and vitreous opacities, all conditions that can often be best managed within our practice.
The referral guidelines for patients with cataract can vary greatly between PCT areas, the philosophy of referring a patient solely on lifestyle issues is no longer commonplace. In north Staffordshire the best visual acuity needs to be 6/12 or worse before cataract surgery will be considered, unless a special case can be made due to severe glare problems or the patient's need to drive for their living. It is therefore essential to carefully counsel patients with cataract so they can make the best use of their vision. Keeping their refractive correction up to date, protection from UV and lifestyle choices (ie reduce smoking) can keep patients relatively happy until their visual acuity reaches the required standard.
Posterior vitreous detachment (PVD) can also lead to some local variations. Some local eye departments advise their optometrists to refer all patients complaining of flashing lights and floaters. However, as we know, PVD is common and generally not a sight-threatening condition. Routine dilation and careful fundus examination with BIO is always advisable, if no retinal tear or hole can be found it is vital to check the anterior vitreous for signs of tobacco dust (Schaffer's sign) in the retro-lental space.
If the retina appears sound and the patient is Schaffer's negative, I would reassure the patient that all was well, but advise them to take things easy for a couple of days (no heavy lifting) and report to their local eye casualty if there is an increase in the number of floaters, increased photopsia or a curtain in their vision. A patient information leaflet can be very helpful in these situations. It is often reassuring for the optometrist if a vitreous opacity, especially a Weiss ring can be observed.
There are a number of corneal conditions that can have an adverse effect on vision, but are unlikely to benefit from referral to an ophthalmologist. Most corneal dystrophies have no treatment options, unless the vision is so bad that a corneal transplant could be considered. Map-dot-fingerprint dystrophy is a slowly progressing condition and should be kept in practice. The same can be said for early Fuch's dystrophy so long as the IOP is normal, although should the patient have early cataract it may be worth considering surgery at an earlier stage to avoid post-surgical corneal problems.
Keratoconus is another common corneal dystrophy which we often feel should be referred for an ophthalmologist's opinion at an earlier stage than is really necessary. Most ophthalmologists would prefer to only see these patients when treatment options are becoming a possibility. As we know there are a lot of contact lens options for patients with keratoconus but if this is beyond your practice's experience or facilities, referral to a local contact lens specialist is always a good management.
Summary
There are of course many times when referral to an ophthalmologist is the best and maybe only option for our patient with an abnormal ocular condition; however, it is always wise to reflect for a moment or two on the benefits to the patient before filling in that GOS18. Ask yourself what the benefit of referral is for this patient. Also it is worth considering whether there are likely to be any treatment options. If the referral is more about passing on the responsibility for your patient, and really the only person benefiting is the referrer - it is maybe worth considering whether you have any other options.
There are many eye conditions that even in their worst possible outcome are still very benign, so would an early recall to monitor the patient be a better option? As we've discussed already our diagnostic tools have improved immeasurably over the past 10 years or so - an early retinal photograph or OCT may avoid an unnecessary referral.
An early recall is often the best management, although often there is the feeling among visiting practitioners that this won't be picked up at a later stage by a colleague, and litigation could be a possible outcome. I do feel we have to trust each other to manage all the practice's patients to the best of our ability. Clear and complete notes on the record card will certainly make this process easier for optometrists picking up these early recalls and avoid that litigation spectre. ?
? Andy Diddams is an optometrist practising in Staffordshire
