Comparison of optic disk features in preterm and term infants

Area of Science:

• Ophthalmology
• Neonatal Research
• Pediatric Imaging

Background:

• Optic disk morphology in neonates is crucial for identifying potential visual pathway abnormalities.
• Understanding variations in optic disk features between preterm and term infants can aid in early diagnosis and management.
• The double ring sign and optic disk shape are key morphological indicators.

Purpose of the Study:

• To compare optic disk features, including the double ring sign and shape, between preterm and term infants.
• To investigate the relationship between gestational age and optic disk morphology in neonates.

Main Methods:

• Digital fundus images of 649 infants (324 preterm, 325 term) obtained within one week of birth were analyzed.
• Key metrics assessed included the optic disk horizontal to vertical diameter ratio, disk-macula to disk-diameter ratio, and presence of the double ring sign.
• Infant ethnicity and gestational age were considered in the analysis.

Main Results:

• The double ring sign was present in 40% of preterm infants versus 4% of term infants.
• The double ring sign was more prevalent in infants of European descent and with younger gestational age.
• Preterm infants' optic disks were more vertically oval (mean H:V ratio 0.75) initially, becoming less oval (0.80) by final examination, compared to term infants (0.79).

Conclusions:

• Preterm infants commonly show a double ring sign without optic nerve hypoplasia, suggesting it's a normal variation.
• Optic disks in preterm infants tend to be more vertically oval, with this shape normalizing closer to term.
• The disk-to-macula to disk-diameter ratio in preterm infants was higher than previously reported in similar populations.