Accommodative and vergence difficulties interfering with image clarity through a binocular indirect ophthalmoscope

Area of Science:

• Ophthalmology
• Optometry
• Vision Science

Background:

• Binocular indirect ophthalmoscopes (BIOs) are essential tools for eye examinations.
• Standard BIOs incorporate +2.00 D lenses, which can present visual challenges for some individuals.
• Understanding the underlying visual deficiencies is crucial for optimizing diagnostic tool usage.

Purpose of the Study:

• To identify specific accommodative and vergence deficiencies in optometry students experiencing difficulty with standard +2.00 D BIO lenses.
• To differentiate visual function between students able and unable to achieve clear focus with BIO lenses.

Main Methods:

• A survey identified 3rd and 4th-year optometry students experiencing difficulty with +2.00 D BIO lenses (BIO plano group) versus those who could use them (BIO plus group).
• Forty-seven participants underwent comprehensive testing of accommodative amplitudes, facilities, NRA/PRA, and vergence ranges.
• Binocular vision assessments included phorias, Worth 4-dot, and near point of convergence.

Main Results:

• The BIO plano group demonstrated significantly poorer accommodative facility, particularly in the right eye.
• Statistically significant differences were observed in accommodative facility with both eyes and left eye, as well as distance base-out blur and near base-out recovery.
• A higher prevalence of accommodative or binocular vision syndromes was noted in the BIO plano group.

Conclusions:

• No single test definitively predicted difficulty with +2.00 D BIO lenses.
• Impaired plus lens acceptance (part of accommodative facility) and reduced convergence ability are likely contributors to visual challenges with BIOs.
• Targeted interventions for these visual skills may enhance student performance with diagnostic ophthalmoscopy.