A Prospective Observational Study of Adult Strabismus

The purpose of this study is to describe clinical characteristics, treatments, and one-year outcomes of adults with convergence insufficiency, divergence insufficiency, or small angle hypertropia.

The purpose of this study is to describe clinical characteristics, treatments, and one-year outcomes of adults with convergence insufficiency, divergence insufficiency, or small angle hypertropia. Treatment comparisons within the studied conditions will also be done to help develop future studies.

Eligibility Criteria:
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