SLO/OCT Eye Tracking for Visual Acuity Testing

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Solution Overview

Problem

Standard visual field and perimetry examinations lack fundus tracking, leading to inaccurate results when patients with poor fixation move their eyes during testing, as they fail to differentiate between central and peripheral vision and do not provide structural information essential for precise diagnosis.

Innovation Solution

A combined Scanning Laser Ophthalmoscope and Optical Coherence Tomography (SLO/OCT) system is used to image the eye, with software tracking eye motion during examinations, allowing for accurate fundus imaging and overlaying functional and structural information for precise diagnosis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If standard visual field or perimetry examination is performed without fundus tracking, then the examination procedure is simple, but the measurement precision deteriorates when patients move their eyes during testing

Engineering Contradiction:
Improveaccuracy of visual acuity measurementVSAvoidcomplexity of examination system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines a scanning laser ophthalmoscope (SLO) with perimetry examination equipment to create an integrated system. The SLO component continuously captures fundus images while visual field stimuli are presented, allowing simultaneous tracking of eye position and measurement of visual acuity. This merging of functions enables accurate localization of visual responses on the fundus even when patients move their eyes, resolving the contradiction between measurement precision and device complexity.

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If fundus tracking is added to perimetry examination, then measurement precision improves, but device complexity increases

Engineering Contradiction:
Improveaccuracy of fixation locationVSAvoidcomplexity of tracking system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses the scanning laser ophthalmoscope as an intermediary device that serves dual purposes: it tracks eye position by capturing fundus images and simultaneously presents visual field stimuli. The SLO's scanning laser beam acts as a mediator that can be dynamically positioned based on detected eye movements, ensuring stimuli are always presented at the correct retinal location even when fixation drifts. This intermediary approach enables precise fundus tracking without requiring a completely separate complex tracking system.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If separate examination systems are used for visual field testing and fundus imaging, then each system can be optimized independently, but examination time increases

Engineering Contradiction:
Improveexamination efficiencyVSAvoidcorrelation between functional and structural data
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent merges the scanning laser ophthalmoscope and OCT capabilities into a single integrated examination system. This allows simultaneous acquisition of functional visual field data and structural fundus images during the same examination session. The integrated system eliminates the need for separate examinations, reducing total examination time while ensuring that functional and structural data are perfectly correlated through precise eye movement tracking and stimulus localization.

Inventive Principle:
Principle #5Merging (Combining)

4Loss of information

If multiple separate examinations are performed, then comprehensive diagnostic information can be obtained, but loss of time increases

Engineering Contradiction:
Improvecompleteness of diagnostic informationVSAvoidtotal examination time
Core Design Contradiction:
Loss of informationVSLoss of time

Solution Approach 1:

The patent implements continuous fundus imaging and eye tracking throughout the perimetry examination. The scanning laser ophthalmoscope continuously captures fundus images and monitors eye position during the entire visual field testing process, eliminating gaps between separate examinations. This continuous action ensures that both functional and structural diagnostic information are obtained in a single uninterrupted session, preventing information loss while minimizing examination time.

Inventive Principle:
Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach ensures accurate tracking of eye movement, providing detailed fundus images and correlating visual loss with structural eye features, reducing examination time and operator training while enhancing diagnostic accuracy.

Implementation Method 1

SLO imaging from a combined Scanning Laser Ophthalmoscope and Optical Coherence Tomography (SLO/OCT) system is used to image the eye

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

Optical Coherence Tomography (SLO/OCT) system is used to image the eye... the patient can be scanned using the OCT portion of the system so the doctor can see structural information

Methodology Applied
Scientific EffectOptical interference: Interference

Data Source

PatentEP2209414B1A method for performing visual acuity testing
Publication Date: 2015.04.15 OPTOS PLC
  • EP2209414B1 patent drawingFigure 1~2
  • EP2209414B1 patent drawingFigure 3~4

AI summary

A visual acuity examination is performed on a patient by bringing a confocal imaging apparatus up to a patient's eye. Stimuli at various points in the patient's field of view are generated while the patient fixates on a point. The patient's responses to the stimuli are recorded with the movement of the eye with is tracked with the aid of the confocal imaging apparatus. The position of said stimuli on the retina is corrected to take into account any movement of the eye between stimuli.