- ICH GCP
- US Clinical Trials Registry
- Clinical Trial NCT00000121
The Prism Adaptation Study (PAS)
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.
Study Overview
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.
Study Type
Phase
- Phase 3
Participation Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Genders Eligible for Study
Description
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Treatment
- Allocation: Randomized
Collaborators and Investigators
Sponsor
Publications and helpful links
General Publications
- 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.
- 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.
Study record dates
Study Major Dates
Study Start
Study Completion (Actual)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Estimate)
Study Record Updates
Last Update Posted (Estimate)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- NEI-20
This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.
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