The Prism Adaptation Study (PAS)
Primary Purpose
Esotropia
Status
Completed
Phase
Phase 3
Locations
Study Type
Interventional
Intervention
Prisms in Eyeglasses
Sponsored by
About this trial
This is an interventional treatment trial for Esotropia focused on measuring strabismus
Eligibility Criteria
An eligible male or female must have been age 3 years or older (adults were included) and must have had esotropia that occurred at age 6 months or older, with no history of previous eye muscle surgery.
Sites / Locations
Outcomes
Primary Outcome Measures
Secondary Outcome Measures
Full Information
NCT ID
NCT00000121
First Posted
September 23, 1999
Last Updated
September 16, 2009
Sponsor
National Eye Institute (NEI)
1. Study Identification
Unique Protocol Identification Number
NCT00000121
Brief Title
The Prism Adaptation Study (PAS)
Study Type
Interventional
2. Study Status
Record Verification Date
September 2009
Overall Recruitment Status
Completed
Study Start Date
March 1984 (undefined)
Primary Completion Date
undefined (undefined)
Study Completion Date
May 1989 (Actual)
3. Sponsor/Collaborators
Name of the Sponsor
National Eye Institute (NEI)
4. Oversight
5. Study Description
Brief Summary
To determine whether the preoperative use of prisms in eyeglasses can improve the outcome of surgery for acquired esotropia, a type of strabismus.
To determine whether patients who respond to prism adaptation by developing a new stable angle of -deviation have a better surgical result than do patients who do not respond to prism adaptation.
To determine whether patients who respond to prism adaptation are more accurately corrected by operating for the prism-adapted angle or the original angle of deviation.
To determine the usefulness of certain input variables (e.g., age at the time of surgery, size of the deviation, visual acuity, binocular function, refractive error) in predicting which patients are more likely to benefit from prism adaptation.
Detailed Description
Acquired esotropia (crossed eyes that develop after a child reaches the age of 6 months) accounts for 25 percent of all patients with misaligned eyes. Surgery to correct esotropia is done primarily to attain functional use of the two eyes together. The cosmetic aspect of the surgery is secondary. In 40 to 50 percent of cases, more than one operation is needed to accomplish the primary goal, and in some cases even three and four operations are needed.
Preliminary studies from two eye care centers reported that the use of prisms on eyeglasses for about a month before surgery led to good results after a single operation in more than 90 percent of patients. These uncontrolled preliminary studies pointed to the need for a multicenter, randomized, controlled clinical trial designed to prove or disprove scientifically the beneficial effect of prisms.
The Prism Adaptation Study was a double randomization trial involving 286 patients. Three-fifths of the patients were randomly selected for prism adaptation before surgery. Of the patients who responded to the prisms, one-half were randomly selected to have surgery based on the amount of prism required to stabilize the deviation, and the other half had surgery based on the amount of esotropia originally measured. Patients who did not respond to the prisms also had surgery based on the amount of esotropia measured, as did the two-fifths of the patients who did not undergo prism adaptation.
Patients were examined postoperatively at 1 week, 1 month, 3 months, 6 months, and 1 year. An independent examiner, masked to the treatment assignment, evaluated the patient at the 6-month followup. The results were analyzed to determine whether the outcome was better in patients who underwent prism adaptation or in those who underwent conventional treatment. Because the examiner did not know what type of treatment a patient had received, he or she would have no bias in evaluating the results.
6. Conditions and Keywords
Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study
Esotropia
Keywords
strabismus
7. Study Design
Primary Purpose
Treatment
Study Phase
Phase 3
Allocation
Randomized
8. Arms, Groups, and Interventions
Intervention Type
Device
Intervention Name(s)
Prisms in Eyeglasses
10. Eligibility
Sex
All
Minimum Age & Unit of Time
3 Years
Eligibility Criteria
An eligible male or female must have been age 3 years or older (adults were included) and must have had esotropia that occurred at age 6 months or older, with no history of previous eye muscle surgery.
12. IPD Sharing Statement
Citations:
PubMed Identifier
2100986
Citation
Efficacy of prism adaptation in the surgical management of acquired esotropia. Prism Adaptation Study Research Group. Arch Ophthalmol. 1990 Sep;108(9):1248-56. doi: 10.1001/archopht.1990.01070110064026.
Results Reference
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PubMed Identifier
8643248
Citation
Repka MX, Connett JE, Scott WE. The one-year surgical outcome after prism adaptation for the management of acquired esotropia. Ophthalmology. 1996 Jun;103(6):922-8. doi: 10.1016/s0161-6420(96)30586-1.
Results Reference
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The Prism Adaptation Study (PAS)
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