Children play computer games in the treatment of amblyopia

Paula Waddingham describes the results of recent trials using modified virtual reality technology and computer games in the treatment of amblyopia

Amblyopia is reduced corrected visual acuity which exists in the absence of any detectable organic disease. Typically, amblyopia is present in only one eye and is usually as a result of strabismus or anisometropia. This condition affects 2-3 per cent of the population.1

Current Management

Current management commences with a comprehensive orthoptic assessment, a cyclopentolate refraction and funduscopy.

If glasses are required, the full prescription should be prescribed and be worn full time. It is now recognised that a period of time is required to settle into the new glasses, during which the vision progressively improves without any other intervention. This is termed ‘refractive adaptation’ and may take up to 18 weeks2 or more.3 In various trials, about a quarter of the children referred with reduced vision, required refractive correction as the only treatment.3 When the vision no longer improves, the most commonly prescribed treatment for amblyopia is by wearing an occlusive patch on the non-amblyopic eye.

Understandably, being prescribed an occlusive patch to wear for several hours a day for many weeks and sometimes months is a difficult undertaking which requires commitment from both the child and the parent. Non-compliance with patch wearing is the main reason why treatment can be unsuccessful.4 There are variations of the occlusive patch, namely the use of an extension patch which fits over the glasses or ‘blenderm’ (the translucent patching tape used for dressings) which is attached to  the lens of the glasses in front of the non-amblyopic eye.  The former is popular as the patch is not sticky and blenderm is not as obvious as a patch on the face. Glasses must fit well, otherwise the motivation to ‘peep’ over the top of the glasses can be too tempting.

Avoiding a patch all together is the reason why pharmacological penalisation with atropine is seen as a more acceptable alternative for some parents and children.

Atropine is used as a primary treatment in those with vision of 6/30 or more,5 otherwise the non-amblyopic eye can still be used for fixation. Atropine is typically used when children are not compliant with occlusion.3 However, atropine has been found to be just as successful as patching5,6 and has better patient compliance which can be easily checked by observation of the pupil. It should be remembered that atropine is a potentially toxic drug and for that reason regular follow-up is required. In Nottingham, we have a protocol in place to ensure frequent appointments with the orthoptist and ophthalmologist are made and that a child has an initial 12 weeks of treatment, followed by a drug-free period.

The age at which children are offered visual screening varies throughout the country and some pre-school programmes have been stopped due to lack of evidence for its effectiveness.7 The age at which to screen for visual defects is much debated. It generally depends upon whether it is believed that the treatment of amblyopia should be carried out earlier within the critical period and will result in a more successful treatment.8 However, evidence shows that treatment effectiveness did not vary with age 9 and that improvements in vision are still achievable in older children10,11 and even adults.12,13 The gold standard which is advocated is examination of all children between the age of 4-5 years of age.14
Regardless of the timing of screening, if untreated, amblyopia is taken into adulthood and can result in exclusion from various professions15 but more significantly can lead to a dramatic lifestyle change if the non-amblyopic eye is lost through injury or pathology. A small but significant number on the partially sighted register have their amblyopic eye as their only remaining eye.16, 17 Adults with amblyopia do re-present to clinic hoping to have their amblyopia treated, typically because they wish to gain entry to the ambulance or police service.

Upon questioning it is often revealed that they remember not wearing their patch as they disliked it so much or they wore the patch but peeped. As mentioned in the preceding paragraph some evidence exists that treating amblyopia in adults may lead to visual gain. However, at present, adult amblyopia therapy is not typically offered by the majority of clinicians practising in this country.