Detection system for ocular refractive error measurement

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optical Physics

Background:

• Accurate measurement of ocular refractive errors (myopia, hyperopia, astigmatism) is crucial for vision correction.
• Existing refractors often rely on subjective patient responses or complex optical alignments.
• Development of objective and automated systems is essential for efficient and precise diagnosis.

Purpose of the Study:

• To develop an automatic and objective system for measuring ocular refractive errors.
• To introduce an innovative ring-shaped target and matrix CCD detector for enhanced measurement capabilities.
• To validate the system's accuracy and precision against established methods.

Main Methods:

• A diode laser (850 nm) projects a ring target onto the patient's fundus.
• Scattered light from the retina is analyzed for vergence using a matrix CCD detector.
• Commercial frame grabber and heuristic search software replaced dedicated circuits for signal processing.

Main Results:

• The system demonstrated good agreement with retinoscopic measurements in both model and human eyes.
• Achieved measurement precision of 0.125D and 5 degrees, meeting clinical requirements.
• The innovative design simplified optical alignment and expanded the measurement range.

Conclusions:

• The developed system provides an accurate, objective, and precise method for measuring ocular refractive errors.
• The use of a ring target and matrix detector offers advantages over conventional refractor designs.
• This automated system has the potential to improve the efficiency and reliability of refractive error assessment.