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The information - cataract

RCGP eye care clinical champion Dr Waqaar Shah uses PUNs and DENs to aid your diagnosis and management of this condition

 

The patient’s unmet needs (PUNs)

A fit and well 70-year-old man attends in a state of some anxiety, clutching a letter from his optician. I’ve been told I need I need to be referred for my cataracts,’ he says. The letter describes bilateral cataracts, though the visual acuities seem reasonable. ‘I don’t like hospitals,’ explains the patient. ‘Do I really need surgery? Is there nothing I can do to stop them getting worse? I’ll have them done if it’s going to stop me driving, but is the operation safe?’

The doctor’s unmet needs (DENs)

Some opticians seem to favour ‘early’ referral of cataracts? Is there any logic to this – or is the rationale that the cataracts are likely to have deteriorated by the time the patient ‘gets through the system’?

Cataracts generally progress slowly and - coupled with a reduction in waiting times for cataract surgery - there seems little justification in early referral. Many patients enjoy a good quality of life even with moderate cataracts, whereas others may be troubled with only minor or early cataractous change.

What factors should be taken into account when deciding whether or not referral is warranted?

The presence of a cataract should not automatically lead to a referral to ophthalmology – the patient’s desire for surgery and their acceptance of surgical risks is a significant consideration too.

There is no single test to assess the effect a cataract has on a patient, and it is important to look at the extent a person’s lifestyle or job is affected.  For example, does the  patient drive? A university professor who reads papers in the course of his profession might be referred for cataract surgery for minor lens opacification, whereas a patient in a nursing home who is happy watching television may not require referral for a relatively moderate cataract.

There is debate over the use of visual acuity thresholds to restrict referrals for cataract surgery, but it is important to consider the functional impact that cataract has on a patient.

What are the current regulations in terms of visual acuity and driving? Are there other factors to consider with cataracts and driving, such as the issue of glare from headlights at night?

Cataracts may cause the vision to fall below the legal threshold for Group 1 entitlement driving – roughly equal to 6/10 on the Snellen chart – or cataract-induced glare from oncoming headlights can reduce normal vision, which will prohibit the patient from driving. This may be another factor to discuss with patients when considering cataract surgery.

Are there any factors which affect the rate of progress of cataracts which might be under the patient’s or doctor’s control?

The majority of cataracts are age-related, of which there are various subtypes such as nuclear or cortical or posterior subcapsular or Christmas tree.

Cataracts are also associated with diabetes, smoking, exposure to ultraviolet B light, female gender, neurofibromatosis, direct trauma, drugs (such as steroids), and uveitis.

Patients should be advised to stop smoking and diabetes should be as well controlled as possible. Some patients wear sunglasses to protect their eyes in bright sunlight. Oral steroid doses – if needed – should be kept as low as possible. These measures will have some impact on cataract formation and progression, though increasing age is the single largest causative factor.

Cataracts can progress to a mature state where the entire lens becomes opaque, further reducing light entry into the eye.

What are the pros and cons of surgery, and what techniques are currently favoured, and why?

The main purpose of cataract surgery is to restore a patient’s vision to meet their needs, bringing about an improvement in their quality of life – it has been found that cataract surgery is associated with greater independence and reduced falls.1

Cataract surgery is also performed for medical indications, such as to allow a clear view of the retina for monitoring and treatment of retinopathy in diabetic patients, or where an intumescent lens causes angle closure glaucoma.

Surgery involves removing the cloudy natural lens of the eye and replacing it with an artificial clear implant (intra-ocular lens). Working through remarkably small, self-sealing incisions at the peripheral cornea (ranging from 1.8mm to 3.2mm), the surgeon makes a circular hole in the lens capsule, liquefies and sucks out the lens using a phacoemulsification probe, and fills the now empty capsule with a folded implant that spectacularly unfolds to take up its position.

The implant is usually made from silicone or acrylic polymer, and comes in a range of optical strengths (the correct strength is established at pre-assessment measurements of the eye called biometry).

The suitability for type of anaesthesia is determined at the pre-operative assessment, but in the majority of cases local anaesthesia (eye drops) is used. General anaesthetic is used for children, and for adults who are not able to lie still for about 20 minutes or who are nervous. Most patients cope well with surgery, will be discharged on the same day, and will need to apply regular steroids eye drops to the eye afterwards for a few weeks.

What are the possible complications of cataract surgery?

Complications after cataract surgery are relatively uncommon, and most patients can self-manage with steroid eye drops. Where complications occur, they include raised intraocular pressure, corneal decompensation causing it to become cloudy, haemorrhage, dislocation of the implant, retinal detachment, and macular swelling causing distortion of vision.

A rare but important post-operative complication is an infection or inflammation within the eye called endophthalmitis. This can lead to a loss of vision or even loss of both eyes. It is therefore important to urgently refer an operated eye that has become red, or painful, or developed reduced vision, in the post-operative period.

Posterior capsular opacification often occurs after cataract surgery, caused by proliferation of remaining lens epithelial cells, and causing the same symptoms of reduced visual acuity some months later as those caused by a cataract. This is treated with laser capsulotomy, where a hole is cleared out of the cloudy posterior capsule.

After surgery, the majority of patients achieve greater clarity in their vision and colour vision is noticeably better. If there is other pathology already present within the eye, such as macular degeneration, then the visual outcome may be limited.

Patients are likely to need their spectacle prescriptions adjusted after surgery, especially for reading vision.

High-energy (femtosecond) lasers are being used by some centres to assist cataract surgery by accurately cutting a hole in the lens capsule in order to dissect the cataract into pieces before aspiration. It is too soon to assess benefit.

Multifocal intraocular lenses are being trialled, and may lead to a reduction in the need for spectacles as this technology refines.

There is usually good functional outcome from first eye surgery which raises the debate of whether there is any value gained from subsequent eye surgery, given current limited healthcare resources.

Patients with second eye unoperated cataract may experience binocular vision inhibition, which can interfere with performing tasks such as driving.2,3

 

Dr Waqaar Shah is a GP partner at Chatfield Health Care, and the Royal College of General Practitioners clinical champion for eye health. More information about the RCGP clinical priority programme on eye health can be found here.

 

References

1 The College of Optometrists and the British Geriatric Society. (2011) The importance of vision in preventing falls

2 Azen SP, Varma R, Preston-Martin S et al. (2002) Binocular visual acuity summation and inhibition in an ocular epidemiological study: the Los Angeles Latino Eye Study. Investigative Ophthalmology and Visual Science, 43 (6); 1742-1748

3 Laidlaw DA, Harrad RA, Hopper CD et al. (1998) Randomised trial of effectiveness of second eye cataract surgery. Lancet, 352 (9132); 925-929

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