Clinical

Binocular Vision

Four reasons why binocular vision matters in myopia management

Binocular vision is a much neglected (and even maligned?) domain of eye care where I’ve had numerous colleagues say their professional excitement and learning opportunities have been reinvigorated through seeing the clinical imperative and application in practice. Not only does binocular vision assessment add so much more to your clinical picture, and make optometric life more interesting, it could be the secret sauce that helps us bridge the gap towards 100% efficacy.

Measuring near lag of accommodation

Assessing accommodative function, such as measuring near lag of accommodation, is a vital component of understanding the myopia profile of your patient. In this post Dr Kate Gifford describes how to measure accommodation lag in practice.

Kids, contact lenses, dry eye and binocular vision

Only a minimal percentage of children are likely to suffer dry eye symptoms (4%) compared to 56% in adult contact lens wearers.(1) Teens may be more likely to report contact lens related dry eye than younger children,(2) and consideration should be given to any systemic medications which could exacerbate dry eye symptoms, such as acne medications and those taken for anxiety and depression.

What about the exophores?

While esophoria and myopia have a long-associated link,(1-3) exophoria must also be on our myopia management agenda. The punchline, up front – research has shown that of kids with intermittent exotropia, 50% are myopic by age 10 and 90% are myopic by age 20,(4) and we need to be extra wary if considering fitting a myopic child like this into contact lenses.

The esophoric myope and contact lenses

When it comes to contact lens corrections for young myopes, the impact of orthokeratology (OK) and multifocal soft contact lenses (MFSCL) on binocular vision is pertinent to visual comfort and understanding mechanisms of myopia progression and control.

Specs to contacts – what happens to BV?

Changing a myope from spectacle to contact lens wear can alter their binocular vision (BV) function. The myope reading through their spectacles experiences base-in prism at near, as demonstrated in the image above, which moves the image further away and decreases vergence demand.

Prescribing adds for near esophoria

From a myopia control point of view, esophoria and accommodative lag are the key clinical red flags in assessing your patient’s visual efficiency, and thankfully both will usually respond positively to a near addition.

Assessing near phoria

Kate describes near heterophoria to her patients as where their eyes aim in space – the posture of their vergence system – and esophoria is our key enemy in the myopia control battle.