Should fogging be performed on every patient presenting for a refractive error examination?

Should Fogging Be Performed on Every Patient During Refractive Error Examination?

Fogging should be performed during distance refraction for all patients undergoing refractive error assessment to relax accommodation and obtain accurate measurements, though the specific technique (fogging versus cycloplegia) depends on patient age and clinical circumstances. 1

Standard Approach for Distance Refraction

The American Academy of Ophthalmology's 2023 Refractive Errors Preferred Practice Pattern explicitly states that distance refraction should be performed with accommodation relaxed, which may be accomplished by using manifest (noncycloplegic) refraction with fogging or other techniques to minimize accommodation. 1

Key Implementation Points:

• Fogging is a standard technique to control accommodation during manifest refraction in cooperative adult patients 1
• The goal is to prevent over-minusing the patient by ensuring accommodation is relaxed during measurement 1
• Fogging with +2.00 D lenses has been shown to achieve accommodation relaxation similar to cycloplegia in young adults 2

Age-Specific Considerations

Adults and Older Adolescents:

• Fogging is typically sufficient for accommodation control during routine manifest refraction 1
• Research demonstrates that +2.00 D fogging achieves comparable results to cycloplegia in young adults (ages 18-26) 2
• Up to 2 D of fogging can be used before accommodation begins to return to its resting state 3

Children and Young Adolescents:

• Cycloplegic refraction is especially indicated in children and many adolescents, as accommodation cannot be reliably relaxed with fogging alone 1
• A significant difference between manifest and cycloplegic refraction is observed frequently in children 1
• For detecting clinically significant hyperopia (≥+2 D) in school-aged children, fogging with +2 D has high sensitivity (100%) but lower positive predictive value (57%), meaning cycloplegia remains necessary for confirmation 4

When Cycloplegia Supersedes Simple Fogging

Cycloplegic refraction is specifically indicated when: 1

• Accommodation cannot be relaxed with fogging techniques
• Patient symptoms are inconsistent with manifest refractive error findings
• Accuracy of refraction is in question for any reason
• Patient is a child or young adolescent
• High hyperopia is suspected

Cycloplegic Agents in Adults:

• Tropicamide: Rapid onset, shorter duration 1
• Cyclopentolate: Greater cycloplegia for more accurate refraction but longer duration of effect 1

Common Pitfalls to Avoid

• Do not skip accommodation control entirely - this leads to over-minusing, particularly in younger patients with active accommodation 1, 5
• Do not assume fogging alone is adequate in children - cycloplegic refraction is the standard for pediatric patients 1
• Do not use excessive minus power when attempting to relax accommodation, as this defeats the purpose of fogging 1
• In patients with suspected hyperopia, fogging may not reveal the full extent of refractive error; cycloplegia is preferred 4

Practical Algorithm

For routine adult refractive examination:

1. Perform objective refraction (retinoscopy, autorefractor, or wavefront analyzer) 1
2. Use fogging technique during subjective refinement to relax accommodation 1
3. Refine with phoropter or trial lens set 1

For children, adolescents, or questionable cases:

1. Attempt manifest refraction with fogging 1
2. If symptoms don't match findings or accuracy is uncertain, proceed to cycloplegic refraction 1
3. Consider postcycloplegic refraction after full accommodation returns if substantial difference exists 1

The reproducibility of subjective refraction with proper accommodation control is within 0.50 D for spherical equivalent, spherical power, and cylindrical power 1, making proper fogging technique essential for accurate prescriptions.