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. Treatment comparisons within the studied conditions will also be done to help develop future studies.

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