What is the intraocular pressure (IOP) value considered ocular hypertension in children under 18?

Ocular Hypertension in Children Under 18

Intraocular pressure (IOP) ≥21 mmHg is considered ocular hypertension in children under 18 years of age, in the absence of optic nerve damage or visual field defects. 1

Age-Related Considerations

IOP in children follows a developmental pattern:

• Infants and young children: Lower IOP values are normal

  • Under 3 months: Mean IOP under 8 mmHg 2
  • 6-9 months: Mean IOP under 12 mmHg 2
  • Formula for children up to 10 years: IOP = 0.71 × age (years) + 10 2

• Older children and adolescents: IOP gradually approaches adult values

  • By age 12: IOP approaches adult levels of 10-21 mmHg 2
  • Late adolescence: Normal range is 10-21 mmHg 3

Diagnostic Criteria for Ocular Hypertension

To diagnose ocular hypertension in children, all of the following must be present:

1. IOP ≥21 mmHg consistently
2. Normal optic disc appearance
3. Normal retinal nerve fiber layer (RNFL)
4. Normal visual field testing
5. Open anterior chamber angle
6. Absence of secondary causes of elevated IOP 1

Measurement Considerations

Accurate IOP measurement in children presents unique challenges:

• Preferred instruments: Tono-Pen, Perkins tonometer, or iCare rebound tonometer 3
• Challenges: Non-compliance, blinking, and resistance to examination 2
• Central corneal thickness: Must be considered when interpreting IOP values 2
• Multiple measurements: Serial measurements are recommended to establish baseline and track trends 3

Risk Factors for Progression to Glaucoma

Children with ocular hypertension should be monitored for risk factors that increase likelihood of progression to glaucoma:

• Higher IOP values 1
• Family history of glaucoma 1
• Thinner central cornea 1
• Larger cup-to-disc ratio 1
• Disc hemorrhage 1
• African or Latino/Hispanic ethnicity 1
• Myopia 1

Clinical Approach

When evaluating a child with elevated IOP:

1. Confirm measurement: Repeat IOP measurement using appropriate technique and equipment
2. Assess optic nerve: Careful examination of optic disc for signs of damage
3. Visual field testing: Age-appropriate assessment when possible
4. Monitor regularly: Follow-up intervals based on risk factors and IOP level

Common Pitfalls

• Overdiagnosis: Non-contact tonometers often overestimate IOP in blinking children 2
• Measurement errors: Improper technique or inappropriate equipment can lead to inaccurate readings
• Misinterpretation: Failure to consider age-specific normal values
• Overlooking secondary causes: Conditions like uveitis, trauma, or post-surgical states can cause elevated IOP 3

Remember that ocular hypertension in children requires careful monitoring as it may represent a risk factor for developing glaucoma, but many cases of adolescent ocular hypertension normalize after the adolescent stage 4.