An in-depth characterization of development-related electroretinographical and morphological changes in Landrace pigs.

Purpose: Landrace pigs are increasingly used as a large-animal model in ophthalmic research due to their cone-enriched visual streak and anatomical similarity to the human eye. However, they are commonly studied at 16-20 weeks of age, a timeframe in which the animals double their weight and development-related physiological changes may occur. This study aims to characterize retinal function and morphology and establish reference values for future translational studies.

Methods: Landrace pigs (16-20 weeks old) underwent standardized examinations of the left eye at baseline (16 weeks), 18 and 20 weeks. The left eye was examined by optical coherence tomography (OCT), fundus photography, histology, and full-field electroretinography (ffERG) under light- and dark-adapted conditions, using the ISCEV-compliant 6-step Dog, Cat, Nonhuman Primate protocol.

Results: A total of 30 animals were included. Retinal morphology remained stable throughout the study period, with no significant changes in retinal thickness observed by OCT (baseline: 252 ± 24 µm; week 20: 249 ± 11 µm; p = 0.17) or by histology. ffERG revealed increased amplitudes under light- and dark-adapted conditions at 20 weeks compared to baseline at 16 weeks of age (e.g. light-adapted b-wave: + 65 µV, + 18.4%, p < 0.01), while latencies remained stable without clinically relevant changes.

Conclusions: During this phase of rapid development, Landrace pigs undergo significant functional retinal maturation without corresponding morphological changes emphasizing importance of functional testing in retinal assessments. This study provides reference data in a large number of animals.