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Updated: Sep 28, 2025
Measuring Retinal Vessel Diameter from Mouse Fluorescent Angiography Images
Published on: May 19, 2023
Mouse microphthalmia-associated transcription factor (Mitf) mutations affect the structure of the retinal vasculature
Stefán Broddi Daníelsson1, Andrea García-Llorca1, Hallur Reynisson1
1Department of Physiology, Biomedical Center, Faculty of Medicine, University of Iceland, Reykjavík, Iceland.
Purpose:
Mice carrying pathogenic variants in the microphthalmia transcription factor (Mitf) gene show structural and functional changes in the retina and retinal pigment epithelium. The purpose of this study was to assess the vascular changes in Mitf mice carrying pathogenic variants by determining their retinal vessel diameter.
Methods:
Mice examined in this study were: B6-Mitfmi-vga9/+ (n = 6), B6-Mitfmi-enu22(398) /Mitfmi-enu22(398) (n = 6) and C57BL/6J wild type mice (n = 6), all 3 months old. Fundus images were taken with a Micron IV camera after intraperitoneal injection of fluorescein salt. Images were adjusted to enhance contrast and a custom written MATLAB program used to extract the mean vascular diameter at a pre-defined distance from the optic disc. The number of vessels, mean diameter and mean total diameter were examined.
Results:
The mean diameter of retinal veins in Mitfmi-enu22(398) /Mitfmi-enu22(398) mice was 18.8% larger than in wild type (p = 0.026). No differences in the mean diameter of the retinal arteries were found between the genotypes. Mitfmi-enu22(398) /Mitfmi-enu22(398) mice have 17.2% more retinal arteries (p = 0.026), and 15.6% more retinal veins (p = 0.041) than wild type. A 24.8% increase was observed in the mean combined arterial diameter in mice with the Mitfmi-enu22(398)/ Mitfmi-enu22(398) compared to wild type mice (p = 0.024). A 38.6% increase was found in the mean combined venular diameter in mice with the Mitfmi-enu22(398) /Mitfmi-enu22(398) pathogenic variation as compared to wild type (p = 0.004). The mean combined retinal venular diameter in the Mitfmi-vga9/+ mice was 17.8% larger than in wild type (p = 0.03).
Conclusion:
An increase in vascularization of the retina in Mitfmi-enu22(398) /Mitfmi-enu22(398) mice was found, indicating an increased demand for blood flow to the retina.
Insights
Mice with pathogenic variants in the microphthalmia transcription factor (Mitf) gene exhibit increased retinal vascularization. This study quantifies these vascular changes, revealing significant increases in retinal artery and vein diameters and numbers.
Area of Science:
- Ophthalmology
- Genetics
- Vascular Biology
Background:
- Pathogenic variants in the microphthalmia transcription factor (Mitf) gene are known to cause retinal and retinal pigment epithelium abnormalities.
- Understanding the vascular implications of Mitf gene variants is crucial for comprehending retinal development and disease.
Purpose of the Study:
- To investigate and quantify the vascular changes in the retina of mice carrying pathogenic Mitf gene variants.
- Specifically, to determine the retinal vessel diameter in Mitf mutant mice compared to wild-type controls.
Main Methods:
- Three groups of 3-month-old mice were studied: B6-Mitfmi-vga9/+ (n=6), B6-Mitfmi-enu22(398) /Mitfmi-enu22(398) (n=6), and C57BL/6J wild type (n=6).
- Fundus imaging was performed after fluorescein injection, and a custom MATLAB program was used to measure mean vascular diameters.
- Analysis included the number of vessels, mean diameter, and mean total diameter of retinal arteries and veins.
Main Results:
- Mitfmi-enu22(398) /Mitfmi-enu22(398) mice showed an 18.8% larger mean retinal vein diameter (p=0.026) and a 24.8% larger mean combined arterial diameter (p=0.024) compared to wild type.
- These mice also had 17.2% more retinal arteries (p=0.026) and 15.6% more retinal veins (p=0.041).
- A significant 38.6% increase in mean combined venular diameter (p=0.004) and a 17.8% increase in mean combined venular diameter in Mitfmi-vga9/+ mice (p=0.03) were observed.
Conclusions:
- The study found a significant increase in retinal vascularization in Mitfmi-enu22(398) /Mitfmi-enu22(398) mice.
- This heightened vascularization suggests an increased demand for blood flow to the retina in these Mitf mutant models.
- These findings highlight the role of Mitf in regulating retinal vascular development.
