Emmetropization and eye growth in young aphakic chickens

Area of Science:

• Ophthalmology
• Developmental Biology
• Animal Models

Background:

• Congenital cataracts often require early intervention, such as lensectomy.
• Understanding eye growth and emmetropization post-surgery is crucial for visual development.
• Chickens provide a valuable model for studying ocular development and refractive error progression.

Purpose of the Study:

• To establish a chick model for investigating eye growth and emmetropization after early lensectomy.
• To analyze refractive error and axial length changes following lens extraction in young eyes.
• To explore the role of the lens in providing essential growth factors for ocular development.

Main Methods:

• Monocular treatments included lens extraction (LX), sham surgery with lenses, and LX with different power lenses.
• Chickens underwent surgical procedures, and refractive errors were measured over 28 days.
• Axial and external ocular dimensions were recorded to assess eye growth patterns.

Main Results:

• Experimental eyes with induced hyperopia showed increased growth and myopic shifts.
• Lens extraction alone led to significant axial elongation compared to sham surgery.
• Lensectomized eyes exhibited equatorial enlargement, resulting in an oblate shape, regardless of optical correction.

Conclusions:

• Refractive changes in aphakic eyes suggest emmetropization in response to defocus.
• Differences between lensectomy and sham surgery indicate the lens may supply critical growth factors.
• Oblate eye shape in aphakic eyes may be explained by optical and mechanical factors.