Dynamic point shifting with null screens using three LCDs as targets for corneal topography

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optical Metrology

Background:

• Corneal topography is crucial for diagnosing and managing eye conditions.
• Traditional methods often rely on mechanical components for target manipulation.
• Limitations exist in achieving dynamic and precise target adjustments in current topographers.

Purpose of the Study:

• To investigate the feasibility of using liquid crystal displays (LCDs) as dynamic targets for an experimental corneal topographer.
• To evaluate the effectiveness of the dynamic point shifting (DyPoS) method with LCD targets.
• To quantify the improvements in measurement accuracy and precision.

Main Methods:

• Three LCDs were employed as targets for an experimental corneal topographer.
• The dynamic point shifting (DyPoS) method was implemented by modifying the geometrical pattern on the LCDs.
• Measurements were validated using a 6.37 mm radius of curvature calibration sphere.

Main Results:

• The DyPoS method significantly reduced the error in radius of curvature measurements to 3% of the actual value.
• Root Mean Square (RMS) errors in elevation differences were reduced to approximately 15 μm, representing a 30% improvement.
• RMS errors in sagitta differences were reduced to approximately 15 μm, a 66% improvement compared to non-DyPoS methods.

Conclusions:

• LCDs provide a viable, mechanically simple alternative for dynamic targets in corneal topography.
• The DyPoS method, when used with LCD targets, substantially enhances the accuracy and precision of corneal measurements.
• This approach holds promise for advancing corneal analysis and diagnostic capabilities.