NBEO - National Board of Examiners in Optometry Binocular Vision and Pediatrics Questions and Answers — Questions and Answers
Question 1: A 4-year-old boy presents with a constant, large-angle esotropia that his parents report has been present since he was 4 months old. He cross-fixates, and visual acuity is equal in both eyes. Cycloplegic refraction reveals +1.50 D sphere in both eyes. Which of the following is the MOST likely diagnosis?
- Accommodative esotropia
- Infantile esotropia (Correct answer)
- Intermittent exotropia
- Sensory esotropia
Correct answer: Infantile esotropia
Infantile esotropia is characterized by a large-angle, constant esotropia with an onset before 6 months of age. Cross-fixation is a common feature, which often helps maintain equal visual acuity in both eyes. The refractive error is typically a low to moderate hyperopia, which is not the primary cause of the deviation, unlike accommodative esotropia. [4, 9, 11]
Question 2: A 9-year-old complains of headaches, intermittent blurred vision, and losing her place while reading. Clinical testing reveals a receded near point of convergence (NPC) to 15 cm break / 20 cm recovery, reduced positive fusional vergence (PFV) at near, and an exophoria of 10 prism diopters at near. What is the MOST appropriate initial management?
- Surgical consultation for lateral rectus recession
- Prescription of base-in prism for near work
- Office-based vision therapy (Correct answer)
- Full-time occlusion of the non-dominant eye
Correct answer: Office-based vision therapy
The patient's symptoms (asthenopia, blurred vision, difficulty with reading) and clinical signs (receded NPC, reduced PFV, near exophoria) are classic for convergence insufficiency (CI). [5, 6, 8, 10] Office-based vision therapy is the most effective and evidence-based treatment for improving convergence ability and alleviating symptoms in children with CI. [5, 8]
Question 3: According to the Amblyopia Treatment Studies (ATS), which of the following is an effective initial treatment for a 5-year-old child with moderate amblyopia (20/80) due to strabismus?
- Full-time occlusion of the sound eye
- Prescription of spectacles alone for 6 months
- Daily patching of the sound eye for 2 hours (Correct answer)
- Weekend-only patching of the amblyopic eye
Correct answer: Daily patching of the sound eye for 2 hours
The Pediatric Eye Disease Investigator Group (PEDIG) Amblyopia Treatment Studies (ATS) demonstrated that for moderate amblyopia (20/40 to 20/100) in children aged 3 to <7 years, patching the sound eye for 2 hours daily is as effective as patching for 6 hours daily. [16, 17, 18] This minimal effective dose is often preferred to enhance compliance.
Question 4: A 6-year-old child with intermittent exotropia (X(T)) is asymptomatic, but the deviation is manifest more than 50% of the time. Which of the following is a common non-surgical management option used to improve control of the deviation and potentially delay surgery?
- Base-in prism glasses
- High plus lenses to stimulate accommodation
- Over-minus lens therapy (Correct answer)
- Binasal occlusion
Correct answer: Over-minus lens therapy
Over-minus lens therapy (e.g., prescribing an additional -2.00 D to -3.00 D over the cycloplegic refraction) is a non-surgical option used in intermittent exotropia. The additional minus power stimulates accommodative convergence, which in turn helps to control the exodeviation. This is often used for younger children to improve fusion and delay the need for surgery. [2, 3, 21]
Question 5: A 4-year-old child is undergoing a binocular vision evaluation. Using the Randot Preschool Stereoacuity Test, what level of stereoacuity would be considered within the normal range for this age?
- 400 seconds of arc
- 200 seconds of arc
- 70 seconds of arc (Correct answer)
- 20 seconds of arc
Correct answer: 70 seconds of arc
Normative data for stereoacuity shows a developmental progression. For a 4-year-old child, the median stereoacuity on the Randot test is typically around 70 seconds of arc. Expecting adult-like levels (e.g., 20-40 seconds of arc) is not appropriate, while gross stereopsis like 400 seconds of arc would be expected in a younger child or could indicate a problem. [1, 15, 26]
Question 6: A 3-year-old presents with esotropia that is greater at near (30 PD) than at distance (15 PD), even after full hyperopic correction of +4.00 D OU is prescribed. This is a classic presentation of accommodative esotropia with a high AC/A ratio. Which of the following is the most appropriate next step in optical management?
- Prescribe base-out prism in a single vision lens
- Prescribe bifocal lenses with a near add (Correct answer)
- Increase the single vision plus prescription
- Recommend immediate surgical correction
Correct answer: Prescribe bifocal lenses with a near add
When a child has accommodative esotropia with a high accommodative convergence to accommodation (AC/A) ratio, the esotropia is greater at near fixation due to the increased accommodative convergence. After providing the full distance hyperopic correction, a residual near esotropia often remains. Prescribing a bifocal or progressive addition lens provides additional plus power for near work, which relaxes accommodation and consequently reduces the near esotropia, helping to restore binocularity. [22, 24, 29]
