Suboptimal image focus broadens retinal vessel caliber measurement

Area of Science:

• Ophthalmology
• Medical Imaging
• Cardiovascular Health

Background:

• Central retinal arteriolar (CRAE) and central retinal venular (CRVE) calibers are used to assess systemic disease risk.
• Computerized image analysis is the standard for measuring these vascular calibers.

Purpose of the Study:

• To investigate if suboptimal image focus affects CRAE and CRVE measurements.
• To determine the impact of image blurring on vascular caliber calculations.

Main Methods:

• Thirty high-quality digital retinal images were selected.
• Nine progressively blurred versions of each image were created using image analysis software.
• Central retinal arteriolar (CRAE) and central retinal venular (CRVE) calibers were measured using IVAN software on original and blurred images.
• Defocusing was also simulated on volunteer retinal images to validate findings.

Main Results:

• Simulated blurring significantly increased CRAE measurements at all levels (P<0.01).
• Average CRAE increased by 3 μm (minimal blur), 12 μm (moderate blur), and 33 μm (severe blur).
• Blurring significantly increased CRVE measurements beyond the first level (P<0.01), with increases ranging from 0 to 11 μm.

Conclusions:

• Suboptimal image focus leads to erroneously enlarged retinal vascular caliber measurements.
• The degree of measurement error is directly related to the severity of image blurring.
• Accurate image focus is crucial for reliable CRAE and CRVE assessments in systemic disease risk detection.