A Prospective Observational Study of Adult Strabismus

Eligibility Criteria for Convergence Insufficiency (CI) Group:

The following inclusion criteria must be met for the subject to be enrolled into the
study:

- Adults ≥18 years of age (adult onset of CI not required)

- No strabismus surgery within the past 10 years

- CI Symptom Survey score ≥21 points

- Near exodeviation of ≥4∆ and at least 4∆ larger than at distance by PACT

- Distance exodeviation ≤15∆ by PACT

- Vertical deviation ≤2∆ at distance and near by PACT

- No constant exotropia at distance or near

- Reduced positive fusional vergence (PFV) at near (<20∆ or fails Sheard's criterion
that the PFV measures less than twice the magnitude of the near phoria)

- Near point of convergence (NPC) of ≥6 cm break

- Visual acuity 20/50 or better in both eyes by ETDRS or Snellen

- No paralytic strabismus (e.g., 3rd, 4th, or 6th cranial nerve palsies, skew
deviation, Duane syndrome)

- No restrictive strabismus (e.g., blowout fracture, thyroid eye disease, post scleral
buckle, Brown syndrome)

- No monocular diplopia

- No paretic strabismus, thyroid eye disease, myasthenia gravis, chronic progressive
external ophthalmoplegia, or eye movement abnormalities associated with known
neurological disease. Patients with Parkinson's disease can be enrolled if
non-paretic deviation.

- No inferior or superior oblique overaction defined as 2+ or greater

- Ability to fuse with prism in space (see section 2.4.1)

- Ability to understand and complete a survey

- Investigator is initiating treatment with prism, orthoptic exercises, botulinum
toxin injection or surgery

- If initiating treatment with botulinum toxin or surgery, planned injection or
surgery to be within 60 days of enrollment

- Single treatment modality is planned (e.g., no combined prism and orthoptic
exercises)

- Treatment to be initiated has not been used within the past one year

Eligibility Criteria for Divergence Insufficiency (DI) Group:

The following inclusion criteria must be met for the subject to be enrolled into the
study:

- Adults ≥18 years of age

- Adult-onset DI (at ≥18 years of age)

- No prior strabismus surgery

- Symptoms of diplopia at distance with a frequency of sometimes or worse in primary
position (in current glasses if wearing glasses)

- Distance esodeviation of 2∆ to 30∆ and at least 50% larger than at near by PACT

- No more than 5∆ difference between right and left gaze by PACT

- No more than 10∆ difference between the primary position at distance and either
upgaze or downgaze ≤10∆ by PACT

- Any coexisting vertical deviation must be less than distance esodeviation and ≤10∆
by PACT

- Visual acuity 20/50 or better in both eyes by ETDRS or Snellen

- No paralytic strabismus (e.g., 3rd, 4th, or 6th cranial nerve palsies, skew
deviation, Duane syndrome)

- No restrictive strabismus (e.g., blowout fracture, thyroid eye disease, post scleral
buckle, Brown syndrome)

- No monocular diplopia

- No paretic strabismus, thyroid eye disease, myasthenia gravis, chronic progressive
external ophthalmoplegia, or eye movement abnormalities associated with known
neurological disease. Patients with Parkinson's disease can be enrolled if
non-paretic deviation

- No inferior or superior oblique overaction defined as 2+ or greater

- Ability to fuse with prism in space (see section 2.4.2)

- Ability to understand and complete a survey

- Investigator is initiating treatment with prism, orthoptic exercises, botulinum
toxin injection or surgery

- If initiating treatment with botulinum toxin or surgery, planned injection or
surgery to be within 60 days of enrollment

- Single treatment modality planned (e.g., no combined prism and orthoptic exercises)

- Treatment to be initiated has not been used within the past one year

Eligibility Criteria for Small-angle Hypertropia (HT) Group:

The following inclusion criteria must be met for the subject to be enrolled into the
study:

- Adults ≥18 years of age

- Adult-onset HT (at ≥18 years of age)

- No prior strabismus surgery

- Symptoms of diplopia at distance or near with a frequency of sometimes or worse in
primary or reading position (in current glasses if wearing glasses)

- Vertical deviation ≥1∆ to ≤10∆ at distance and near by PACT

- No more than 4∆ difference from the primary in any gaze position by PACT

- Any coexisting esodeviation must be less than the vertical deviation

- Any coexisting exodeviation ≤10∆ by PACT

- No convergence insufficiency as defined in section 2.2.1

- Visual acuity 20/50 or better in both eyes by ETDRS or Snellen

- No paralytic strabismus (e.g., 3rd, 4th, or 6th cranial nerve palsies, skew
deviation, Duane syndrome)

- No restrictive strabismus (e.g., blowout fracture, thyroid eye disease, post scleral
buckle, Brown syndrome)

- No monocular diplopia

- No paretic strabismus, thyroid eye disease, myasthenia gravis, chronic progressive
external ophthalmoplegia, or eye movement abnormalities associated with known
neurological disease. Patients with Parkinson's disease can be enrolled if
non-paretic deviation.

- No inferior or superior oblique overaction defined as 2+ or greater

- Ability to fuse with prism in space (see section 2.4.3)

- Ability to understand and complete a survey

- Investigator is initiating treatment with prism, orthoptic exercises, botulinum
toxin injection or surgery

- If initiating treatment with botulinum toxin or surgery, planned injection or
surgery to be within 60 days of enrollment

- Single treatment modality planned (e.g., no combined prism and orthoptic exercises)

- Treatment to be initiated has not been used within the past one year

Exclusion Criteria for Convergence Insufficiency (CI) Group:

The following criteria exclude a subject from enrollment into the study:

- Strabismus surgery within the past 10 years

- CI Symptom Survey score ≥21 points

- Near exodeviation of ≤4∆ and at least 4∆ larger than at distance by PACT

- Distance exodeviation ≥15∆ by PACT

- Vertical deviation ≥2∆ at distance and near by PACT

- Constant exotropia at distance or near

- Near point of convergence (NPC) of ≤6 cm break

- Visual acuity worse than 20/50 either eye by ETDRS or Snellen

- Paralytic strabismus (e.g., 3rd, 4th, or 6th cranial nerve palsies, skew deviation,
Duane syndrome)

- Restrictive strabismus (e.g., blowout fracture, thyroid eye disease, post scleral
buckle, Brown syndrome)

- Monocular diplopia

- Paretic strabismus, thyroid eye disease, myasthenia gravis, chronic progressive
external ophthalmoplegia, or eye movement abnormalities associated with known
neurological disease. Patients with Parkinson's disease can be enrolled if
non-paretic deviation.

- Inferior or superior oblique overaction defined as 2+ or greater

- Inability to fuse with prism in space (see section 2.4.1)

- Inability to understand and complete a survey

- Treatment to be initiated has already been used within the past one year

Exclusion Criteria for Divergence Insufficiency (DI) Group:

The following criteria exclude a subject from enrollment into the study:

- No adult-onset DI (at ≥18 years of age)

- Prior strabismus surgery

- Distance esodeviation outside the range of 2∆ to 30∆ and less than 50% larger than
at near by PACT

- More than 5∆ difference between right and left gaze by PACT

- More than 10∆ difference between the primary position at distance

- Any coexisting vertical deviation more than distance esodeviation and ≥10∆ by PACT

- Visual acuity worse than 20/50 in either eye by ETDRS or Snellen

- Paralytic strabismus (e.g., 3rd, 4th, or 6th cranial nerve palsies, skew deviation,
Duane syndrome)

- Restrictive strabismus (e.g., blowout fracture, thyroid eye disease, post scleral
buckle, Brown syndrome)

- Monocular diplopia

- Paretic strabismus, thyroid eye disease, myasthenia gravis, chronic progressive
external ophthalmoplegia, or eye movement abnormalities associated with known
neurological disease.

- Inferior or superior oblique overaction defined as 2+ or greater

- Inability to fuse with prism in space (see section 2.4.2)

- Inability to understand and complete a survey

- Treatment to be initiated has already been used within the past one year

Exclusion Criteria for Small-angle Hypertropia (HT) Group:

The following criteria exclude a subject from enrollment into the study:

- No adult-onset HT (at ≥18 years of age)

- Prior strabismus surgery

- Vertical deviation ≤1∆ or ≥10∆ at distance and near by PACT

- More than 4∆ difference from the primary in any gaze position by PACT

- Coexisting esodeviation must not be less than the vertical deviation

- Coexisting exodeviation ≥10∆ by PACT

- Convergence insufficiency as defined in section 2.2.1

- Visual acuity worse than 20/50 in either eye by ETDRS or Snellen

- Paralytic strabismus (e.g., 3rd, 4th, or 6th cranial nerve palsies, skew deviation,
Duane syndrome)

- Restrictive strabismus (e.g., blowout fracture, thyroid eye disease, post scleral
buckle, Brown syndrome)

- Monocular diplopia

- Paretic strabismus, thyroid eye disease, myasthenia gravis, chronic progressive
external ophthalmoplegia, or eye movement abnormalities associated with known
neurological disease.

- Inferior or superior oblique overaction defined as 2+ or greater

- Inability to fuse with prism in space (see section 2.4.3)

- Inability to understand and complete a survey

- Treatment to be initiated has already been used within the past one year