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.

• Prism (Device): Ground-in or Fresnel prism
• Orthoptic Exercises (Other): Orthoptic exercises- fusion, convergence, divergence, and others, including computer-based therapy
• Eye Muscle Surgery (Procedure): * Bilateral medial rectus muscle resection surgery * Single medial rectus muscle resection surgery * Recess lateral rectus muscle resection medial rectus muscle surgery * Bilateral lateral rectus muscle recession surgery * Single lateral rectus muscle recession surgery * Bilateral lateral rectus muscle resection surgery * Single lateral rectus muscle resection surgery * Recess medial rectus muscle resection lateral rectus muscle surgery * Bilateral medial rectus muscle recession surgery * Single medial rectus muscle recession surgery * Vertical rectus muscle recession surgery * Vertical rectus muscle mini-tenotomy (snip) surgery
• Botox Injection (Procedure), also known as Botulinum toxin injection: Botulinum toxin injection

Primary outcomes

• Number of Participants With Symptom Success at 10 Weeks [10 weeks after enrollment]: In the convergence insufficiency group, the primary outcome will be symptom success at the 10-week and 12-month visit, defined as improvement of CI Symptom Survey (CISS) score of at least 9 points and an outcome score of <21 points. In the divergence insufficiency group, the primary outcome will be symptom success at the 10-week and 12-month visit, defined as diplopia "rarely" or "never" in primary position at distance on the diplopia questionnaire. In the small-angle hypertropia group, the primary outcome will be symptom success at the 10-week and 12-month visit, defined as diplopia "rarely" or "never" both in primary position at distance and in reading position on the diplopia questionnaire.
• Number of Participants With Symptom Success at 12 Months [12 months after enrollment]: In the convergence insufficiency group, the primary outcome will be symptom success at the 10-week and 12-month visit, defined as improvement of CI Symptom Survey (CISS) score of at least 9 points and an outcome score of <21 points. In the divergence insufficiency group, the primary outcome will be symptom success at the 10-week and 12-month visit, defined as diplopia "rarely" or "never" in primary position at distance on the diplopia questionnaire. In the small-angle hypertropia group, the primary outcome will be symptom success at the 10-week and 12-month visit, defined as diplopia "rarely" or "never" both in primary position at distance and in reading position on the diplopia questionnaire.

Secondary outcomes

• Mean of Near Point of Convergence in Convergence Insufficiency Group [12 months after enrollment]: Near point of convergence (convergence insufficiency group only).
• Mean Positive Fusional Vergence in Convergence Insufficiency Group [12 months after enrollment]: Positive fusional vergence (convergence insufficiency group only).
• Adult Strabismus 20 Questionnaire Score (DI) [12 months after enrollment]: Adult Strabismus Quality of Life Questionnaire (AS-20) For AS-20, scores are reported for the following subscales. A total score will not be reported. 1. Self-perception score 2. Interaction score 3. Reading function score 4. General function score Values for each subscale range from 0 to 100. 0 indicates poor quality of life (the patient reported "always" for all questions) and 100 represents good quality or life (patient reported "never" for all questions)
• Mean Convergence Insufficiency Symptom Survey Score [12 months after enrollment]: Mean Convergence Insufficiency Symptom Survey Score (convergence insufficiency group only) For CISS, the range is from 0 (having no symptoms of CI) to 60 (always showing all symptoms of CI).
• Adult Strabismus 20 Questionnaire Score (CI) [12 months after enrollment]: Adult Strabismus Quality of Life Questionnaire (AS-20) For AS-20, scores are reported for the following subscales. A total score will not be reported. Self-perception score Interaction score Reading function score General function score Values for each subscale range from 0 to 100. 0 indicates poor quality of life (the patient reported "always" for all questions) and 100 represents good quality or life (patient reported "never" for all questions)

Sex: All, ages: 18 Years to any

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

Participant flow

Outcome results

• Number of Participants With Symptom Success at 10 Weeks (Primary), Count of participants, Participants: Convergence Insufficiency 25; Divergence Insufficiency 91; Small-angle Hypertropia 12
• Number of Participants With Symptom Success at 12 Months (Primary), Count of participants, Participants: Convergence Insufficiency 25; Divergence Insufficiency 73; Small-angle Hypertropia 6
• Mean of Near Point of Convergence in Convergence Insufficiency Group (Secondary), Mean, centimeters: Convergence Insufficiency 14.1 +/- 6.2
• Mean Positive Fusional Vergence in Convergence Insufficiency Group (Secondary), Mean, prism diopters: Convergence Insufficiency 11.6 +/- 7.1
• Adult Strabismus 20 Questionnaire Score (DI) (Secondary), Mean, score on a scale: Divergence Insufficiency 62 +/- 22
• Mean Convergence Insufficiency Symptom Survey Score (Secondary), Mean, points: Convergence Insufficiency 37.5 +/- 9.1
• Adult Strabismus 20 Questionnaire Score (CI) (Secondary), Mean, points: Convergence Insufficiency 55.7 +/- 24.6

Adverse events

Time frame: Adverse event data was not collected since treatment was prescribed per usual standard of care.

• Results publication: Crouch ER, Dean TW, Kraker RT, Miller AM, Kraus CL, Gunton KB, Repka MX, Marsh JD, Del Monte MA, Luke PA, Peragallo JH, Lee KA, Wheeler MB, Daley TJ, Wallace DK, Cotter SA, Holmes JM; Pediatric Eye Disease Investigator Group. A prospective study of treatments for adult-onset divergence insufficiency-type esotropia. J AAPOS. 2021 Aug;25(4):203.e1-203.e11. doi: 10.1016/j.jaapos.2021.02.014. Epub 2021 Jul 13. PMID 34271207
• Results publication: Lorenzana IJ, Leske DA, Hatt SR, Dean TW, Jenewein EC, Dagi LR, Beal CJ, Pang Y, Retnasothie DV, Esposito CA, Erzurum SA, Aldrich AE, Crouch ER, Li Z, Kraker RT, Holmes JM, Cotter SA; Pediatric Eye Disease Investigator Group; Pediatric Eye Disease Investigator Group. Relationships among Clinical Factors and Patient-reported Outcome Measures in Adults with Convergence Insufficiency. Optom Vis Sci. 2022 Sep 1;99(9):692-701. doi: 10.1097/OPX.0000000000001929. Epub 2022 Aug 2. PMID 35914096

• Study Protocol (PDF, 2016-04-11)
• Statistical Analysis Plan (PDF, 2020-06-04)
• Informed Consent Form (PDF, 2015-08-10)

• Earl R Crouch, III, MD, Study chair, Virginia Pediatric Eye Center

NIH grants: U10EY011751