Reference: Griffin, Ch. 3, pg. 64-73, 87-92

Scheiman, pg. 34-56; 58-60; 263-276 Richman and Cron, pp. 18-19

I. Introduction: The convergence excesses are a group of fusional dysfunctions that are characterized by:

- increased esophoria at near with distant normal heterophorias

- decreased BI vergence (negative) at near

- increased NPC (with an eso break)

- intermittent suppression/diplopia at near

A. These dysfunctions fall along a "split" continuum

1. At one end, a "true" convergence excess (a convergence dysfunction at near). In it's pure form, a true CE will respond to plus lenses at near

2. At the other two ends, are "pseudo"-convergence excesses (a group of accommodative dysfunctions which have, as their most prominent feature, over convergence at near). This dysfunctional group is quite baffling (on the surface). Both accommodative excesses AND accommodative insufficiencies may exhibit symptoms consistent with these "pseudo"-convergence excess cases.

3. Along the line is a range of "mixed bag" dysfunctions, either led by a fusional convergence excess at near or accommodative dysfunction. Most all PATIENTS FALL IN THIS NEBULOUS AREA!!

B. Boring Demographics: Convergence dysfunctions strike at any age, but in general, it doesn't rear its ugly head until the age of 11-13. "True" C.E. cases are a bit easier to remediate than the "pseudo" type, but it is best to catch these dysfunctions early (less mal-adaptations)

II. "True" Convergence Excess: #: indicates it shares this characteristic with a pseudo CE secondary to an accommodative excess

*: indicates it shares this characteristic with a

pseudo CE secondary to an accommodative insuff.

A. Signs found during a normal P.C. exam

#*1. increased esophoria at near with distant normal heterophorias.

#*2. decreased BI vergence (negative) at near.

#*3. increased NPC .

#*4. intermittent suppression/ diplopia at near.

*5. minus is difficult on binocular accom. facility.  

*6. PRA may be reduced.

B. Additional tests reveal:

7. AC/A (calculated or gradient) is above expected values.

8. High and variable lag of accommodation results.

*9. (+) Significant plus acceptance (MEM, Binoc. X-Cyl.)

#*10. Reduced jump vergence at near (8 BI/BO flippers).

*11. Increased performance in divergence at near through + 1.00 add.

#*12. Eso fixation disparity.

(*)13. Large positive kinetic cover test (due to a secondary suppression of the accommodative response)

B. Rationale for test results:

1. high AC/A ratio and excessive fusional/proximal convergence abilities are at the root of this dysfunction

2. They may tend to under accommodate at near to compensate (ie. eliminate accommodative convergence)

3. A "true" convergence dysfunction WILL be to eager to let go of accommodation, as relaxation of accommodative convergence can increase fusional ranges. Therefore, a near point add is indicated immediately, followed by vergence therapy, if necessary.

III. "Pseudo" Convergence Excess: a group of accommodative dysfunctions, which have led to a secondary convergence problem. Although it's most salient feature is high esophoria at near, at it's root is an ACCOMMODATIVE DYSFUNCTION.

A. The Pseudo- Convergence Excess secondary to and Accommodative Excess

@: indicates it shares this characteristic with a True CE

*: indicates it shares this characteristic with a pseudo CE

secondary to an accommodative insufficiency

1. Signs found during (normal P.C. exam)

@*a. Increased esophoria at near with distant normal heterophorias

@*b. Decreased BI vergence (negative) at near

@*c. Increased NPC

@*d. Intermittent suppression/ diplopia at near

e. plus is difficult on accom. facility (monocular or binocular)

@*f. minus may be difficult on binocular testing if:

i. esophoria at near is high

ii. BI reserves at near are low

g. NRA is reduced

@*h. PRA is usually reduced as well

2. Additional tests reveal:

*a. AC/A (calculated) is high; AC/A (gradient) is normal- high normal

b. (-) plus acceptance (MEM, Binoc. X-Cyl.)

c. below normal lag of accommodation.

@*d. Reduced jump vergence at near (8 BI/BO flippers): BI more difficult

@*e. Eso fixation disparity curve

f. Negative KCT.

B. The Pseudo- Convergence Excess secondary to an Accommodative Insufficiency:

@: indicates it shares this characteristic with a True CE

#: indicates it shares this characteristic with a pseudo CE

secondary to an accommodative excess

1. Signs found during (normal P.C. exam)

@#a. Increased esophoria at near with distant normal heterophorias

@#b. Decreased BI vergence (negative) at near

@#c. Increased NPC

@#d. Intermittent suppression/ diplopia at near

@e. minus is difficult on accom. facility (monocular or binocular).

@f. PRA is reduced.

2. Additional tests reveal:

#a. AC/A (calculated) is high; AC/A (gradient) is normal- high normal

@b. (+) plus acceptance.

c. normal- high normal lag results.

@#d. Reduced jump vergence at near (8 BI/BO flippers): BI more difficult

@#e. Eso fixation disparity curve

@f. Positive KCT.

B. Rationale for test results:

1. Accommodative dysfunction is the root of pseudo C.E. types

2. Excessive convergence at near is SECONDARY to the root of the problem.

a. accommodative excess: leads to excessive accommodative convergence at near (via the AC/A linkage * INCREASED ESO AT NEAR

b. accommodative insufficiency: leads to extensive volitional accommodation attempts at near * AC/A ratio (high-normal) drives accommodative convergence * INCREASED ESO AT NEAR

3. The pseudo convergence excesses require accommodation therapy and near point adds (when accepted) to remediate.

IV. Discrimination Between a True Convergence Excess and a "Pseudo-Convergence Excess" Secondary To an Accommodative Insufficiency

A. These two dysfunctions are two sides of the same BVA coin:

1. In a true CE, a high AC/A leads to a secondary adaptation: reduced accommodative response in order to decrease accommodative convergence (AC/A)

2. In a pseudo-convergence excess secondary to an accommodative insufficiency, low accommodative amplitudes leads to a secondary adaptation: increased volitional accommodative attempts gives rise to high ESO at near

B. They can be differentiated with clinical testing; in general:

*1. Gradient AC/A is consistently high (8-10/1) in a true C.E. while a gradient AC/A on a pseudo-convergence excess secondary to an accommodative insufficiency will be closer to normal levels.

2. A true C.E. will have a very positive KCT

V. Basic Esophoria: IS NOT CONSIDERED TO BE A CONVERGENCE EXCESS TYPE, but most of its characteristics do fit in the conversation today.

A. This dysfunction involves a high esophoria at distance and near

B. Esophoria at distance is due to high tonic convergence levels

C. Esophoria at near is due to low fusional divergence

D. AC/A is usually considered normal.

VI. System Control Analysis (Stereophonic Model) Approach to Convergence Excesses:

A. Theoretical/experimental considerations:

1. It has been suggested (and experimentally validated) that when the response AC/A ratio is high, the corresponding CA/C ratio tends to be low.

2. It has been suggested (and experimentally validated) that in most non- strabismic binocular vision anomalies, vergence and accommodative adaptation is weak.

3. Above all else, remember; I'D RATHER BE BLURRED THAN BE DOUBLE

B. Keeping these tidbits in mind, let us now examine our three diagnoses.

1. It is assumed:

a. our patient orthophoric at distance

b. numbers represent relative vergence demand (orthophoria @ near is 0)

2. True convergence excess: Near Phoria = 10EP'; AC/A = 9/1; CA/C = 0.13 D/6D; NRC = 9D BI; poor vergence adaptation.

a. initial vergence response is able to fuse target with _______ of (con/di) vergence.

b. this gives rise to (+/-) ________ of convergence accommodation.

c. to keep the target clear, _____ of blur driven accommodation is necessary.

d. unfortunately, with the (high/low) AC/A ratio, there is ______ D of accommodative convergence fed to the convergence side!

e. fusional divergence is highly stressed as is, and is stretched to it's limits here!

f. decay of this fast (di)vergence system begins and vergence adaptation doesn't help a lick!

g. to avoid diplopia, we must crank the accommodation way downward to relax accommodative convergence.

h. the results:

i. a tendency to under-accommodate (under binocular conditions)

ii. a fused, but blurry optical image

iii. an inability to succeed in long term near point tasks

iv. a cranky patient

2. Pseudo-convergence excess secondary to an accommodative insufficiency: Near Phoria = 10 EP'; AC/A = 6/1; CA/C = 0.4D/6D; NRC = 14D BI; poor vergence adaptation.

a. initial vergence response is able to fuse target with _______ of (con/di) vergence.

b. this gives rise to (+/-) ________ of convergence accommodation.

c. to keep the target clear, _____ of blur driven accommodation is necessary.

d. unfortunately, with accommodative abilities, it is a struggle to meet the accommodative demand; it delivers 1.50 D of accommodation. This results in _____ D of accommodative vergence

e. decay of the accommodative system begins and accommodative adaptation doesn't help a lick!

f. volitional accommodative effort is made, driving accommodative vergence upward (by leaps and bounds). Unfortunately, it results in little additional accommodative response!

-This is because the AC/A linkage is NOT dependent on accommodative output, but rather, accommodative effort!

g. It does, however, present a significant challenge to the fusional divergence system to avoid losing fusion!

h. the results:

i. a tendency to under-accommodate (under binocular conditions)

ii. a tendency to react to this by increasing attempts at volitional accommodation and gain significant accommodative convergence

iii. an inability to succeed in long term near point tasks

iv. a cranky patient

3. Pseudo-convergence excess secondary to an accommodative excess: NEAR PHORIA = 4 EP'; AC/A = 7/1; CA/C = 0.3D/6D; NRC = 14D BI; poor vergence adapt.

a. initial vergence response is able to fuse target with _______ of (con/di) vergence.

b. this gives rise to (+/-) ________ of convergence accommodation.

c. to keep the target clear, _____ of blur driven accommodation is necessary.

d. unfortunately, with accommodative stimuli everywhere (proximal and blur cues), it is a struggle to hold back the accommodative response from exceeding the demand; it delivers 2.75 D of accommodation. This results in _____ D of accommodative vergence

e. the additional accommodative vergence increases the demand of the fusional divergence system

f. the results:

i. a tendency to over-accommodate (under binocular conditions)

ii. a tendency to over-converge and slip into low to moderate esophoria

iii. an inability to succeed in long term near point tasks