FP1015 : Improvement In Clinical Signs And Symptoms of Convergence Insufficiency (CI) With VTS 4 ( Vision Therapy System-4 ).

Dr.Kanak Tyagi, T10691


To study the improvement in NPC(Near Point of convergence) , Positive fusional vergence (PFV) reserve and CISS(Convergence insufficiency symptom survey) scores using VTS 4 as in office vision therapy for Convergence InsufficiencyVTS 4(Vision Therapy System-4).


  • To study the amount of changes/improvement in NPC by using VTS-4 in Indian eyes(Delhi NCR) in CI patients
  • Time taken for changes/improvement in NPC by using VTS-4 in Indian eyes in CI patients

Convergence insufficiency is the ability to obtain and or maintain adequate binocular convergence for any length of time without undue effort. It is the most common cause of ocular asthenopic symptoms.

Clinical Features:-

  1. Eye strain
  2. Headache and eye ache
  3. Difficulty in changing the focus from distant to near objects.
  4. Itching& burning of eyes.
  • Blurring of vision

Clinical evaluation of accommodative and vergence system is an essential part of the study of visual function. The diagnosis of general binocular disorders is performed by means of analysis of accommodative and binocular tests.2Recent studies surveying the ophthalmic community to determine the most widespread treatment modality for patients with symptomatic CI have found that pencil pushups is the most commonly prescribed treatment by both ophthalmologists and optometrists for young adults. In untreated cases it may lead to intermittent exotropia which may further lead to exotropia.

In VTS-4 vergence has three categories:-

  • SMP:- Simultaneous macular perception
  • Flat fusion 1and 2
  • Stereopsis

There are two mode of action auto and manual mode.

The goal is to work up to13 dioptre base in and 35 dioptre base out demand

Inclusion criteria:-

  • 18 to 30 yrs
  • Emmetropic- Visual acuity 6/6 each eye for distance & near (N6).

CI symptoms survey informed consent & willingness to participate in the study and be randomised

Exclusion criteria:-

  • Amblyopia
  • Constant strabismus
  • History of strabismus surgery
  • Any eye disease or pathologies
  • Any systemic disease which affects convergence & accommodation.
  • Any medication which affects convergence & accommodation.
  • Pregnancy & lactation.
  • Any ocular surgeries other than refractive surgeries.
  • Any eye care professional’s ophthalmic technician, medical student or optometry students.

 Study Population:-10 patients.


  • Patients falling in inclusion criteria, comprehensive eye examination were done.
  • Required orthoptic assessment Near point of convergence (NPC), Negative fusional vergence (NFV) and Positive fusional vergence (PFV) were done.
  • NPC measured by RAF Ruler (vertical line has taken as target. The endpoint for NPC was, break/doubling of the target. This reading was noted both objectively and subjectively, following recovery point has recorded.)
  • NFV & PFV measured by VTS 4 software
  • Patients fulfilling the inclusion criteria, CISS questionnaire (Validated and Reliable) was attended then undergone office therapy in VTS software system for 12 days
  • Weekly each patient’s was called for 4-5 sitting in VTS software system.
  • CISS questionnaire (Validated and Reliable) was repeated after last visit of VTS software system.

CISS questionnaire was compared in between first and last sitting in VTS software system

Statistical analysis:-

Statistical analysis was done by using SPSS software. (Version16.0). T-test was used. At study completion, the observed variability in the CISS-V15 was used to determine the statistical power available to detect meaningful differences among the treatment groups.

The group means used in the calculations were obtained from the mean CISS-V15 score of Day first and Day twelfth


A total 20 patients were enrolled in study, out of them 10(50%) were included and 10(50%) were excluded.(Table-1,Graph-1)


Included 50%
Excluded 50%

Out of 10 patients, 4 (40%) patients were male and 6 (60%) patients were female




Female 60%

Age ranges from 18-27yrs (mean age 23.1yrs with ±6.36)

No of patients Age
1 18
2 20
3 23
2 25
2 27

CISS Questionnaire were analysed by taking their mean of First and Last visit.(Table-4,


  First visit Last       visit
  3.3 1.7
  2.6 1.6
  2.3 1.53
C 3.4 1.66
I 4 1.6
S 2.9 1.33
S 3.2 1.33
  2.5 1.33
  2.6 1.26
  3.6 1.66

Comparison done in between first and last day of Base in (BI) value. (Table-5, Graph-5)


Flat Fusion B I 1st day Flat Fusion B I last day
4 13
5 13
4 13
2.5 13
2 13
4.5 13
5.5 13
6 13
7.5 13
4 13

Comparison done in between first and last day of Base out (BO) value. (Table-6,


Flat Fusion B O 1st day Flat Fusion B O Last day
15 32
17 35
20 35
16 35
14 34
15 35
16.5 33.5
18 35
24 34
16 35

Comparison done in between first and last day of stereopsis Base in (BI) value.(Table-7,Graph-7)


Stereopsis 1st day BI Stereopsis last day BI
3.5 11
4 11
2 12
3 12
2 10.5
3 11
5 12
5 11
6 12
2.5 11

Comparison done in between first and last day of stereopsis Base out (BO) value.(Table-8,Graph-8)


Stereopsis 1st day BO Stereopsis last day BO
13 30
15 30.5
18 32
13 30
11.5 32
14 30.5
15 32
24 31.5
21 32
16 30

Comparison done between first and last day of Near point of convergence (NPC).Table-9, Graph-9)


Mean Std. deviation
Day  1 15.3 cm ±3.53
Day 12 10.2 cm ±1.41


A randomized, placebo-controlled, Multi -center clinical trial studying the treatment of symptomatic CI in young adults, office-based vision therapy/orthoptic improved the signs associated with CI. Both the average near point of convergence and the average positive fusional vergence at near improved to roughly normal clinical values, although 58% of the patients in this group were still considered to be symptomatic after 12 weeks of treatment. There were statistically significant but not clinically relevant improvements.10 but in our single centre clinical trial study the treatment of symptomatic CI young adults, office based therapy improved (60%). The average near point of convergence, the average positive fusional vergence and negative fusional vergence improved. In our study both, the clinically relevant as well as statistically significant correlation was found.


This first single-center, clinical trial of the treatment of symptomatic CI in young adults demonstrated that the treatment modalities, only vision therapy/orthoptic was effective in achieving normal clinical values for the near point of convergence, negative fusional vergence and positive fusional vergence.

Based on the results of this preliminary study, it would appear that pencil pushups, the most popular treatment for CI, is not effective for achieving clinically significant improvements in    symptoms or signs associated with CI in young adults


1.Small sample size.

2.The CISS study was not designed to look at long-term results. This question needs to be answered in a prospective, large-scale with more sitting, randomized clinical.

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