Convergence Insufficiency: Improvement of the near point of convergence after Institute Freespace Stereogram exercises?

Status

Active, not recruiting

Phases

Unknown

Study type

Interventional

Source

DRKS

Registry ID

DRKS00014187

Enrollment

Registered

2018-03-29

Start date

2018-04-02

Completion date

Unknown

Last updated

2025-04-07

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

H51.1

Interventions

Group 1: Arm 1 is the verum group who will be performing the I.F.S. exercises. This training consists of four cards with detailed corresponding instructions, allowing the patient to independently perf

Eligibility

Sex/Gender

All

Age

18 Years to No maximum

Inclusion criteria

Inclusion criteria: Enlarged near point of convergence (more than 10cm)

Exclusion criteria

Exclusion criteria: Strabism, nystagmus, neurological diseases

Design outcomes

Primary

Measure	Time frame
The primary goal of the study is the evaluation of the change of the near point of convergence in people with convergence insufficiency after I.F.S. visual therapy. The measurement of the near point of convergence will take place in the following way: An object (e.g. a pen) is approached to the patients nose bridge from a starting distance of approximately 40cm with a constant speed of 3 to 5 cm per second. The result is defined as the distance in cm of the nose bridge to the break point (point in which the object is seen double the first time). To achieve greater accuracy, the measurement will be recorded with video and then evaluated. The measuring of the near point of convergence will be undertaken before and after training.	—

Measure

Time frame

The primary goal of the study is the evaluation of the change of the near point of convergence in people with convergence insufficiency after I.F.S. visual therapy. The measurement of the near point of convergence will take place in the following way: An object (e.g. a pen) is approached to the patients nose bridge from a starting distance of approximately 40cm with a constant speed of 3 to 5 cm per second. The result is defined as the distance in cm of the nose bridge to the break point (point in which the object is seen double the first time). To achieve greater accuracy, the measurement will be recorded with video and then evaluated. The measuring of the near point of convergence will be undertaken before and after training.

—

Secondary

Measure	Time frame
Additional measurements which may also change and improve due to the visual therapy will also be measured. These measurements are the positive fusional vergence (PFV) in cm/m, the score of the CISS questionnaire to quantify symptomatology, the Mallett criteria and the Sheard criteria in cm/m (prism diopters). The fusional reserve in the near is measured in 40 cm with the phoropter with which Risley prisms can be continually increased. The dissociated phoria is measured in 40 cm with a Maddox lens and the Thorington card ; the associated phoria is measured with the Mallett near-test in 40 cm and prisms in a trial frame. The symptomatology is measured with the CISS questionnaire (convergence insufficiency Symptom Survey) and consists of 15 questions.	—

Measure

Time frame

Additional measurements which may also change and improve due to the visual therapy will also be measured. These measurements are the positive fusional vergence (PFV) in cm/m, the score of the CISS questionnaire to quantify symptomatology, the Mallett criteria and the Sheard criteria in cm/m (prism diopters). The fusional reserve in the near is measured in 40 cm with the phoropter with which Risley prisms can be continually increased. The dissociated phoria is measured in 40 cm with a Maddox lens and the Thorington card ; the associated phoria is measured with the Mallett near-test in 40 cm and prisms in a trial frame. The symptomatology is measured with the CISS questionnaire (convergence insufficiency Symptom Survey) and consists of 15 questions.

—

Countries

Switzerland

Contacts

Public ContactVolkhard Schroth

Institut für Optometrie, Fachhochschule Nordwestschweiz FHNW

volkhard.schroth@fhnw.ch+41629572605

Outcome results

None listed

Source: DRKS (via WHO ICTRP) · Data processed: Feb 4, 2026