Optometry’s evolving role in AMD

Optometry is at the frontline of detection and management of age-related macular degeneration (AMD).

The current optometry role includes screening for early AMD; disease monitoring; lifestyle education, including modifiable risk factors; symptom awareness and vision self-monitoring; nutritional supplement treatment; and quality referral of wet AMD.

We can expect this role to expand with a rapidly ageing population, an increasing burden of wet AMD treatment and the likelihood that there will be more validated treatments for intermediate AMD and late AMD with geographic atrophy.

Screening

Optometry currently screens for early AMD through non-targeted comprehensive eye examinations. The case for a government-funded AMD screening programme is being well made and is close. Screening for early AMD fulfils the World Health Organisation’s guidelines in the most part: it is an important health problem, has an accepted treatment and an early and asymptomatic stage. There remain two areas where modifications are required to make the screening case: improvements in detection and making the cost of detection economically balanced in relation to total medical expenditure.

The problem with detection lies with the reliability of dilated fundus examination. A recent study in the States found 25% of AMD cases were missed by primary eye specialists (both optometrists and ophthalmologists). One third of these had intermediate AMD that would have been treatable with nutritional supplements had it been diagnosed. Potential means for improving this poor detection rate includes the increasingly widespread use of OCT imaging and some progress towards automated analysis of colour photo and OCT using big data algorithms.

The economics of screening a very large, older population is problematic. There are currently around 1.2 million over 55-years-old in New Zealand. To reduce the enormity of the task, we can choose to screen only those at greater risk; the most obvious way to do this is by age. Increasing the threshold to 65 years old reduces the current screening population to 700,000, but a rapidly ageing population means this age-group is projected to rise to a mind-boggling 1.4 million by 2046. Thus, other risk factors may be chosen to further reduce the screening population. A recent study from Italy, for example, validated a very simple 12-item STARS (Simplified Théa AMD Risk-assessment Scale) questionnaire for general practitioners, that results in an AMD-risk score for over 55-year-olds. This focuses on risk factors such as cardiovascular disease, socio-demographic characteristics, family history and systemic and ocular risk factors, resulting in three risk categories: low, moderate and high. The study found good discrimination of patients with and without AMD. However, such a tool would first need to be validated for our population.

Patient education

Optometry has the lead role in patient education. Once early AMD is detected, patients need to be aware of modifiable risk factors such as smoking and diet. To monitor for progression of early AMD, an annual optometric review is likely to be sufficient. Once intermediate AMD has developed, commencing AREDS-2 nutritional supplements is the standard of care. It is crucial the patient is knowledgeable about the early symptoms of wet AMD and performing regular Amsler grid testing.

Quality referral of suspected wet AMD has a direct impact on the likelihood of timely treatment and visual outcome. Fortunately, optometry’s rapid adoption of OCT imaging should be improving detection and quality referral.