Understanding Heterophoria Concepts

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Questions and Answers

What does the Maddox Wing test primarily assess?

Cyclo/torsional elements (correct)

Accommodative status

Vertical fusion range

Convergence ability

What does the term 'prism fusion range' refer to?

The amount of convergence/divergence before fusion is compromised (correct)

The maximum amount of accommodation

The amount of visual field available

The ability to maintain binocularity at varying distances

When assessing prism fusional ranges, which condition may indicate poor control of heterophoria?

Normal fusion range

Increased accommodative response

Sub-normal fusion range (correct)

Low diplopia threshold

What is typically fixed during the prism fusion range assessment?

Accommodative status Signup and view all the answers

What is a practical method for measuring prism fusion range?

Employing a rotary prism Signup and view all the answers

What is the definition of heterophoria?

A latent deviation that remains unnoticed during normal viewing Signup and view all the answers

What does 'NMD' stand for in the context of orthophoria?

No movement detected Signup and view all the answers

Which test would NOT be used to measure heterophoria?

Visual acuity test Signup and view all the answers

What is a key characteristic of heterophoria during a dissociation test?

Eyes deviate from the fixation point Signup and view all the answers

Which factor does NOT contribute to normal binocular single vision (BSV)?

Fixed gaze at one point only Signup and view all the answers

What term describes a rapid and smooth recovery movement when correcting for heterophoria?

Quality of movement Signup and view all the answers

In describing heterophoria, what does 'size of movement' refer to?

Amount of deviation measured in prism dioptres Signup and view all the answers

What is NOT a characteristic used to describe heterophoria?

Visual accommodation Signup and view all the answers

What characterizes concomitant heterophoria?

The angle of deviation is constant in all directions of gaze. Signup and view all the answers

Which condition describes a failure to converge at near distance?

Convergence insufficiency Signup and view all the answers

What defines diverging insufficiency?

Insufficient divergence at distance. Signup and view all the answers

In which of the following scenarios is esophoria present?

Divergence weakness greater at near than at distance. Signup and view all the answers

What is the primary factor in determining if a deviation is eso or exo?

The measurement of deviation angle. Signup and view all the answers

Which of the following terms refers to an anomaly occurring at distance?

Divergence insufficiency Signup and view all the answers

What distinguishes incomitant heterophoria from concomitant heterophoria?

Incomitant heterophoria varies in deviation based on gaze direction. Signup and view all the answers

What is true about the fixation distance in relation to concomitant horizontal heterophoria?

It applies only for concomitant horizontal heterophoria. Signup and view all the answers

What is the purpose of using prism flippers in the context of convergence exercises?

To create alternating convergence stimuli Signup and view all the answers

In the Stereogram exercise, what must the patient focus on while holding the card?

A distant target behind the card Signup and view all the answers

What type of diplopia occurs with positive relative convergence during the XOP?

Homonymous physiological diplopia Signup and view all the answers

What is the recommended frequency for performing convergence exercises?

Short periods frequently, 5-7 times daily Signup and view all the answers

Which type of correction is suggested for symptomatic diplopia in horizontal heterophoria?

Minimum horizontal and full vertical correction Signup and view all the answers

What should be avoided during convergence exercises to prevent complications?

Inducing accommodative/convergence spasm Signup and view all the answers

What should the base orientation of prisms be to effectively correct for XOP?

Base IN for relief Signup and view all the answers

What is the primary goal when prescribing prisms for a patient?

To alleviate symptoms and prevent decompensation Signup and view all the answers

What is the first step in formulating a management plan for convergence or accommodative issues?

Determine patient motivation Signup and view all the answers

Which of the following is included as a conservative treatment method?

Use of prisms Signup and view all the answers

What does a decrease in fusional reserves indicate?

Possible need for intervention Signup and view all the answers

When considering refractive management, which of the following is true regarding lens prescription?

Negative lenses reduce esophoric deviations. Signup and view all the answers

What symptom might indicate a need for intervention in decompensated patients?

Decreased binocular visual acuity Signup and view all the answers

How should you adjust treatment for patients with a known aetiology?

Maintain regular reviews and patient motivation Signup and view all the answers

In orthoptic therapy for horizontal heterophoria, which action should be emphasized?

Increasing base out fusional vergence for exophorias Signup and view all the answers

What is the primary concern when managing a patient with large unresolved deviations?

Possibility of surgical intervention if all else fails Signup and view all the answers

Study Notes

Terminology

Orthophoria: no eye movement detected with both eyes uncovered, visual axes are aligned to the fixation target
Heterophoria: latent deviation, observed when fusion is disrupted.
Describing Heterophoria:
- Direction of movement (eso, exo, hyper, hypo, cyclo)
- Concomitancy (angle remains the same in all gaze directions, or varies)
- Fixation Distance (6m, 0.3m)
- Size of movement (small, moderate, large, measured in prism dioptres)
- Quality of recovery movement (rapid / slow, smooth / jerky)
- Compensation (if the phoria is resolved without intervention)
Concomitant Horizontal Heterophoria:
- Esophoria: (ESO)
  - Divergence Weakness (D>N) - ESO larger at distance
  - Convergence Excess (N>D) - ESO larger at near
  - Non-specific (N=D) - ESO equal at distance and near
- Exophoria: (EXO)
  - Divergence Excess (D>N) - EXO larger at distance
  - Convergence Weakness (N>D) - EXO larger at near
  - Non-specific (N=D) - EXO equal at distance and near
Prism Fusional Range (Fusional Reserve):
- Measures convergence or divergence before fusion breaks
- Used to assess relative convergence/divergence at different distances (6m, 0.3m)
- Can also be used to assess vertical reserves
- Sub-normal fusion range indicates poor control of heterophoria
- Can monitor progression of heterophoria and treatment efficacy
Types of Dissociation Tests:
- Maddox Rod
- Maddox Wing (can measure cyclo/torsional elements)

Investigation

Cover Test: Used to assess speed and quality of recovery, assess for decompensation
Maddox Rod: Distorts one image, used to assess horizontal and vertical deviations
Maddox Wing: Introduces two independent objects to assess cyclo/torsional elements
Near Point of Convergence (NPC): Measures accommodative convergence
Sheard’s Criterion: Helps determine if heterophoria is the cause of symptoms
Binocular Visual Acuity: Assesses the ability to see with both eyes working together
Stereopsis: Assesses the ability to perceive depth

Management

Conservative Treatment:
- Visual Hygiene Advice: Eliminate any potential causes of decompensation
- Refractive Correction: Optimise spectacle prescription
- Orthoptic Exercises: Active exercises designed to improve fusion and control eye movement
- Prism Relief: Passive prism correction
Non-conservative/Surgical Treatment: Consider only for large deviations, if all else fails
- Rarely used for heterophoria
- Requires knowledge of extraocular muscles
Criteria for Treatment:
- Symptomatic: Treat patients with symptoms
- Asymptomatic but at Risk: Treat patients without symptoms, but who are at risk of decompensation and binocular loss
- Patient Motivation: Patient must be willing to participate in treatment
- Enough Time: Adequate time for follow-ups and monitoring
- Colleagues’ Support: Ensure there are other practitioners to assist in treatment if needed

Specific Management Techniques

Refractive Management:
- Optimise prescription and refractive accuracy
- Consider adding +/- spheres to manipulate vergence
Orthoptic Exercises:
- Use prism bars, prism flippers, or computer-based exercises to improve fusional vergence
- Utilize stereograms (3 cats) to improve relative convergence
Prescribing Prisms:
- Use prism as a temporary solution or interim spectacles to correct for deviations
- Prescribe prism base opposite to deviation (base-in for exophoria, base-out for esophoria)

Clinical Findings for Decompensation:

Symptoms: Patient complaints like eye strain, headaches, or diplopia
Signs:
- Slow or jerky recovery on cover test
- Reduced fusional reserves
- Reduced binocular visual acuity
- Reduced NPC
- Reduced stereo acuity
- Use Sheard’s Criterion to identify a link between the heterophoria and patient symptoms

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Description

This quiz explores the terminology and concepts related to heterophoria, including its description, types, and characteristics. You'll learn about specific terms like esophoria and exophoria, as well as important factors such as movement direction and fixation distance.