Relationship between retinal distance and object field angles for finite schematic eyes

Area of Science:

• Ophthalmology
• Optical Engineering
• Computational Biology

Background:

• Schematic eye models are crucial for converting retinal distances to object field angles in anatomical studies.
• The Drasdo & Fowler three-refracting surface model is a commonly used tool for these conversions.

Purpose of the Study:

• To compare the performance of the Drasdo & Fowler schematic eye with more sophisticated four-refracting surface models.
• To evaluate the accuracy of these models in converting retinal distances and object field angles.

Main Methods:

• Raytracing simulations were performed on various schematic eye models, including Drasdo & Fowler, Lotmar, Navarro, Liou & Brennan, Kooijman, and Atchison.
• Model performance was assessed for converting retinal distances to object field angles.

Main Results:

• The Drasdo & Fowler eye exhibited a ~5% greater rate of change in object field angle at the retinal center compared to other models.
• This rate of change increased more rapidly in the peripheral retina for the Drasdo & Fowler eye, attributed to its shorter length.
• Retinal shape became significant for accurate conversions beyond approximately 14 mm (~50°).

Conclusions:

• Adjusting the length of the Drasdo & Fowler eye to match four-refracting surface models improved agreement up to 14 mm (~50°).
• Refractive error, influencing axial length and retinal shape, must be considered for precise conversions.
• For retinal distances and visual field angles beyond 14 mm (~50°), accounting for retinal asphericity is essential.