Hyperopic Eyes Are Structurally More Dynamic Than Myopic Eyes During Accommodation: An In Vivo Investigation

Area of Science:

• Ophthalmology
• Optometry
• Biomedical Optics

Background:

• Refractive errors, including myopia and hyperopia, affect visual acuity.
• Understanding accommodative structural changes is crucial for visual function.
• Novel swept-source anterior segment optical coherence tomography (AS-OCT) allows in vivo study of the accommodating eye.

Purpose of the Study:

• To investigate ocular structural changes during accommodation in individuals with emmetropia, myopia, and hyperopia.
• To correlate structural changes with functional responses across different refractive errors.
• To assess the impact of refractive error magnitude on accommodative dynamics.

Main Methods:

• Recruited 46 adults with normal accommodation and diverse refractive errors (SER: -7.50 D to +7.88 D).
• Utilized CASIA2 AS-OCT to measure anterior segment structures during accommodation at various demands (0-6 D).
• Measured refractive state changes using PowerRefractor3 photorefraction and compared responses to internal and external accommodative stimuli.

Main Results:

• Significant accommodative changes observed in lens thickness (LT), anterior chamber depth (ACD), and other anterior segment parameters (P < 0.001).
• Accommodative changes in LT, ACD, and anterior segment length (ASL) correlated with spherical equivalent refraction (SER) (P < 0.05).
• Hyperopic eyes showed greater per-diopter changes in LT and ACD than myopic eyes during accommodation.

Conclusions:

• Significant differences exist in ocular structural changes during accommodation based on refractive error type and magnitude.
• Hyperopic eyes demonstrate more pronounced changes in lens thickness and anterior chamber depth compared to myopic eyes.
• These findings highlight the influence of refractive error on the accommodative mechanism and ocular structure.