Lancaster

Technical Specifications

Test Components

1. Equipment

- Red-green glasses (complementary colors)

- Tangent screen or wall chart

- Red and green torches/projectors

- Standard testing distance (1 meter)

2. Screen Features

- Grid pattern

- Central fixation point

- Numbered coordinates

- Horizontal and vertical meridians

Clinical Protocol

Test Setup

1. Patient Preparation

- Red filter over right eye

- Green filter over left eye

- Proper head positioning

- Standard room illumination

2. Testing Distance

- Primary position: 1 meter

- Alternative distances for specific cases

- Head straight and level

Testing Procedure

1. Basic Assessment

- Examiner projects lights in nine diagnostic positions

- Patient reports relative positions of lights

- Sequential testing of all gaze positions

- Documentation of separation and direction

2. Detailed Examination

- Pattern of misalignment

- Comitancy assessment

- Torsional component evaluation

- Measurement of deviation magnitude

Clinical Applications

1. Primary Uses

- Isolating paretic muscles

- Measuring incomitant deviations

- Documenting cyclodeviation

- Tracking changes over time

2. Specific Conditions

- Cranial nerve palsies

- Mechanical restrictions

- Post-surgical evaluation

- Thyroid eye disease

- Recent diabetics

Interpretation

Pattern Analysis

1. Horizontal Deviations

- Esotropia patterns

- Exotropia patterns

- Incomitant shifts

2. Vertical Deviations

- Hypertropia patterns

- Hypotropia patterns

- Superior oblique palsy

3. Torsional Components

- Excyclotorsion

- Incyclotorsion

- Combined deviations

Clinical Significance

Advantages

1. Diagnostic Benefits

- Subjective diplopia assessment

- Precise measurement capabilities

- Documentation of changes

- Treatment planning aid

2. Clinical Utility

- Non-invasive

- Quantifiable results

- Easy serial monitoring

- Patient demonstration tool

Limitations

1. Technical Constraints

- Requires patient cooperation

- Cognitive understanding needed

- Color vision dependency

- Room lighting requirements

Documentation

Recording Methods

1. Standard Protocol

- Numerical coordinates

- Directional arrows

- Pattern diagrams

- Digital recording

2. Follow-up Documentation

- Progress tracking

- Treatment response

- Comparative analysis

- Outcome measurement

Special Considerations

1. Patient Factors

- Age requirements

- Cognitive ability

- Color vision status

- Cooperation level

2. Technical Aspects

- Room illumination

- Testing distance variations

- Equipment maintenance

- Calibration needs

Quality Assurance

Test Reliability

1. Factors Affecting Accuracy

- Patient understanding

- Testing environment

- Equipment condition

- Examiner expertise

2. Quality Control

- Regular calibration

- Standardized procedures

- Result verification

- Documentation accuracy

Best Practice Guidelines

Testing Protocol

1. Standard Procedure

- Systematic approach

- Complete documentation

- Regular monitoring

- Result interpretation

2. Advanced Applications

- Complex cases

- Research protocols

- Teaching applications

- Clinical trials

Future Developments

Technology Integration

- Digital recording systems

- Automated analysis

- Remote testing capabilities

- Enhanced documentation

Conclusion

The Lancaster Red-Green test remains a cornerstone in orthoptic assessment, providing valuable information for diagnosis, treatment planning, and monitoring of complex ocular motility disorders. Its systematic application and proper interpretation are essential skills for orthoptic practitioners.

Note : This document serves educational purposes exclusively and does not constitute medical advice or treatment guidelines