We are updating the design of this site. Learn more.
Show more
ClinicalTrials.gov
ClinicalTrials.gov Menu

The Prism Adaptation Study (PAS)

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00000121
First Posted: September 24, 1999
Last Update Posted: September 17, 2009
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by:
National Eye Institute (NEI)
  Purpose

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.


Condition Intervention Phase
Esotropia Device: Prisms in Eyeglasses Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Primary Purpose: Treatment

Resource links provided by NLM:


Further study details as provided by National Eye Institute (NEI):

Study Start Date: March 1984
Study Completion Date: May 1989
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.

  Eligibility

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.


Ages Eligible for Study:   3 Years and older   (Child, Adult, Senior)
Sexes Eligible for Study:   All
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.
  Contacts and Locations
No Contacts or Locations Provided
  More Information

Publications:
ClinicalTrials.gov Identifier: NCT00000121     History of Changes
Other Study ID Numbers: NEI-20
First Submitted: September 23, 1999
First Posted: September 24, 1999
Last Update Posted: September 17, 2009
Last Verified: September 2009

Keywords provided by National Eye Institute (NEI):
strabismus

Additional relevant MeSH terms:
Esotropia
Strabismus
Ocular Motility Disorders
Cranial Nerve Diseases
Nervous System Diseases
Eye Diseases