Day: January 4, 2021

How Good is Photoscreening For Young Children’s Vision Problems?

Patient Presentation
A 3-year-old male came to clinic for his health supervision visit. He was well and his mother had no concerns. The past medical history was non-contributory.
The family history was positive for stroke, heart attack, hypertension and glaucoma.

The pertinent physical exam had normal vital signs and his growth parameters were 50% for height and 85% for weight. His physical examination was normal including his eye examination. The diagnosis of a healthy male was made. Two days later his photoscreening results from the centralized screening service showed a possible amblyopia. The patient was referred to the ophthalmologist who found he had mild hyperopia and a prescription for spectacles was given. He was to be followed up in 2-3 months.

Discussion
Amblyopia is a decrease in visual acuity because of abnormal vision development in young children. It is sometimes called “lazy eye.” It is the leading cause of unilateral vision loss in children and occurs in 1-6% of children and causes permanent vision loss in 2.9% of adults. “Amblyopia is thought to develop during a critical time in infancy and early childhood when visual development depends on the eyes and the brain’s visual cortex working together. Inadequate stimulation of the visual pathways leads to disuse of the visual cortex and resultant amblyopia.” If the visual inputs are not the same, then the poorer visual signal (e.g. more blur, discordant visual image) will be suppressed by the visual cortex, and the reliance on the superior image will occur. Overtime this can results in visual loss in the poorer eye.

Major causes of amblyopia include:

  • Strabismic amblyopia- eyes are misaligned. The visual image from the deviating eye is suppressed. If not treated it can result in binocular vision and depth perception.
  • Anisometropic amblyopia – visual acuity in the eyes is not symmetric. The blurrier (higher refractive error) image is suppressed. Sometimes this is called refractive amblyopia.
    Farsightedness (hyperopia, image is focused behind the retina), near sightedness (myopia, image is focused in front of the retina) and astigmatism (image is focused unevenly on the retina) are often seen with anisometropic amblyopia.
  • Combined strabismic and anisometropic amblyopia – eyes are misaligned and visual acuity is not symmetric. The chronically blurred imaged is suppressed.
  • Ametropic amblyopia – visual acuity in both eyes has a high refractive error resulting in blurred vision in both eyes. There is inadequate development of the visual cortex in both eyes.
  • Deprivation amblyopia – visual acuity is caused by obstruction such as cataract or ptosis. The obstructed image is suppressed.

Patients with a family history of congenital eye abnormalities including amblyopia, cataracts and glaucoma, or if parents have strabismus, should be referred for ophthlamological care. Treatment for children under age 7 is much better than older children. Treatment includes spectacles, patching (usually of the better eye to improve use of the worse eye), atropine (blurs the vision in the better eye encouraging use of the worse eye) and possibly surgery. Careful monitoring is important as there is a high rate of recurrence.

Learning Point
Families should be asked if they have any concerns about their child’s vision and if so, usually referral should be made. Families may say they see strabismus or a wandering eye, squinting or torticollis. Turning of the head is done to try to improve the visual image. Vision examination can include inspection of the structures, movement of the eyes, alignment, pupils and red reflexes/retinal examination. Visual acuity testing is recommended starting at age 3-5 years. Children who have vision in either eye or both eyes of > 20/30 should be referred.

Photoscreening has the advantage of being relatively quick to perform, needs less cooperation from the patient, can be performed in non-verbal/younger children, and records the images for review. Photoscreening using a dedicated photoscreening device or more recently using a smartphone application, have had good results. The patient is asked to look at a light on the photoscreener and an image is taken. The image can be analyzed using computer software and/or human review and analysis.

A study of a smartphone photoscreening application in children 1-6 years old in pediatric ophthalmology practices found with manual grading and automatic computer grading (given in parentheses) that the sensitivity was 76% (65%), specificity was 85% (83%) with a positive predictive value of 0.76 (0.69) and negative predictive value of 0.85 (0.8). This study showed that not only was smartphone photoscreening feasible, but was quite good at screening for potential vision problems. Smartphone photoscreening has the advantages of being more ubiquitously available and thus children in almost any location can be screened.

A study of photoscreening using a handheld digital photoscreener in primary care offices validated the technology showing an overall referral rate of 10% to an ophthalmologist with suspected astigmatism, anisometropia and strabismus being the most common reasons. The overall positive predictive rate was 0.60. “…[O]ver 60% of children referred were found to have [amblyopia risk factors] and 13% had amblyopia detected on examination, both of which are significantly more than in the general population, which is thought to be 15-20% for [amblyopia risk factors] and 1-2% for amblyopia.”

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Questions for Further Discussion
1. What are causes of blindness in children? A review can be found here
2. What causes ptosis? A review can be found here
3. What causes congenital cataracts? A review can be found here

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Amblyopia and Vision Impairment and Blindness

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Bregman J, Donahue SP. Validation of photoscreening technology in the general pediatrics office: a prospective study. J AAPOS. 2016;20(2):153-158. doi:10.1016/j.jaapos.2016.01.004

Arnold RW, O’Neil JW, Cooper KL, Silbert DI, Donahue SP. Evaluation of a smartphone photoscreening app to detect refractive amblyopia risk factors in children aged 1-6 years. Clin Ophthalmol. 2018;12:1533-1537. doi:10.2147/OPTH.S171935

McConaghy JR, McGuirk R. Amblyopia: Detection and Treatment. Am Fam Physician. 2019;100(12):745-750.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa