Ophthalmology

at a Glance

Second EditionJane Olver, Laura Crawley, Gurjeet Jutley, Lorraine Cassidy

Case Studies

Case 4: Poor vision in a child

A mother brings her 7-year-old child to clinic complaining that he has difficulty watching the TV. Furthermore, his teacher complained that he is struggling to read the blackboard since he joined the school, after arriving from Ghana. In clinic, he has a VA of logMAR 0.0 in the left eye and 0.7 in the right. You give a putative diagnosis of right amblyopia.

  • 1. Give a definition of amblyopia.

    Correct answer: Whilst being extremely difficult to define, one can think of amblyopia as a neurodevelopmental disorder. Visual stimulation fails to transmit or is poorly transmitted through the optic nerve to the brain (for a period of time). Hence, this area of the brain is not stimulated, and the visual pathway does not develop to its full potential.

  • 2. Name three causes of amblyopia.

    Correct answer: The causes of visual stimulation not being transmitted include:

    • Strabismus
      • The image of the deviating eye is suppressed by the neuroplastic brain.
    • Stimulus deprivation
      • Anything occluding the visual axis, such as ptosis or cataract.
    • Anisometropia or high refractive error
      • Anisometropia means there is a difference between the refractive errors of the two eyes. The eye providing the brain with a clearer image becomes the dominant eye.

  • 3. At the age of 7, is it worth treating him? At which age does treatment give the biggest impact with respect to improving long-term visual outcomes?

    Correct answer: Yes! Even though treatment should be started as early as possible, it has been shown that some improvement can be seen from treatment even up to the age of 12. If treatment is started between ages 28 and 33 months, there is a 90% improvement of visual potential, so the job of the ophthalmic team is to both identify and treat amblyopia as early as possible.

  • His mother is very reluctant to patch, as she does not see the value of it. You discuss the merits of pharmacological penalisation.

  • 4. What is the evidence that atropine would work?

    Correct answer: The Paediatric Eye Disease Investigator Group (PEDIG) showed that 2 years after patients were randomised to either atropine or patching, both groups had similar improvements in VA (3.7 versus 3.6 lines from baseline, respectively), suggesting equal efficacy. Clinically, most paediatric ophthalmologists would prescribe patching before considering atropine penalisation.

  • 5. Should it be given every day? Can it be given less frequently in order for it to work?

    Correct answer: The PEDIG studies have shown that giving atropine at weekends alone is equally efficacious as administering it daily: hence, this is the treatment regime prescribed if it is decided that this is the regime required.

  • His mother tells you that his eyes sometimes point inwards, especially when he is trying to play ‘Where’s Wally?’ A doctor in Ghana told him to wear glasses, but he hadn’t bothered. Mum is keen for surgical management to get it over and done with. Her concern is that the kids will tease him at school.

  • 6. What type of strabismus is this most likely to be? Is surgical management indicated for him?

    Correct answer: It sounds like this is an intermittent accommodative esotropia, one of the most common types. The underlying cause is due to a high accommodative drive, and as such if the refractive error is corrected, surgery is seldom required. Usually, executive bifocals are prescribed.

Read more about reduced visual potential in the paediatric ophthalmology chapters (Chapters 22, 23, 24 and 25).

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