Pigment Dispersion Syndrome: Natural History and Possible Protective Effect of a YAG Laser Iridotomy
- To determine the 10-year conversion rate from pigment dispersion syndrome (PDS) to pigmentary glaucoma (PG)
- To evaluate the possible protective effect of a Yag-laser iridotomy
|Study Design:||Allocation: Randomized
Endpoint Classification: Safety/Efficacy Study
Intervention Model: Parallel Assignment
Masking: Single Blind (Investigator)
Primary Purpose: Prevention
|Official Title:||10-year Follow up of Patients With Pigment Dispersion Syndrome: Risk Factors for Conversion to Pigmentary Glaucoma and Potential Protective Effect of a Yag-laser Iridotomy in High Risk Eye|
- > 5 mmHg IOP increase vs baseline (average 2 highest readings, 8 am - 6 pm phasing, 6 readings) [ Time Frame: 10 years ] [ Designated as safety issue: No ]
|Study Start Date:||January 1993|
|Study Completion Date:||December 2003|
|Primary Completion Date:||April 2003 (Final data collection date for primary outcome measure)|
|No Intervention: observation|
Experimental: Yag laser iridotomy
the enrolled eyes will undergo an iridotomy performed by using a Yag-laser
Procedure: Yag laser iridotomy
the procedure will be performed by using a Yag laser. Single spot, 1 mJ power, beam aimed to an existing iris crypt
Other Name: iridectomy
1154 workers in the Parma area will be screened for eligibility to long-term use of video-monitors. Those referred to the Glaucoma Clinic for suspected PDS will be enrolled in the study.
In a prospective study on the natural history of PDS and PG, Richter et al. (Arch Ophtal 104:211-5, 1986) found an association between "active pigment dispersion" and elevated IOP. Therefore, in order to evaluate the "stability" of the pigment, a phenylephrine test will be performed following the method reported by Epstein et al (1978) AJO 85:43-50. The test will be performed by one investigator (SAG)and was considered positive if > "grade 1+" (i.e. at least 10 particles in a single light beam). Eyes showing a positive test will be considered as "high-risk" for conversion to PG.
Yag laser iridotomy will be performed in patients showing both eyes at high risk. One eye only (randomly chosen) will be treated. the fellow eye will be left untreated and considered as internal control.
Low risk eyes will be followed without any intervention.