PURPOSE: To report the changes in the iris-lens contact length pre and
post Nd-Yag laser iridotomy, employing UBM.
METHODS: Thirty-one primary closure angle glaucoma patients (16 after
the crisis and 15 with intermittent closure of the angle) were
studied by UBM. In 16 eyes, the
medical treatment was sufficient to overcome the crisis. All patients were
submitted to UBM, being at least
48 hours without medication,: the measurements of the iris-lens contact length were
conducted twice at the temporal quadrant by the same observer on the different
days.
DISCUSSION: Mapstone (1968) described geometrically the forces involved
in the relative pupillary block at the angle closure crisis: the sphincter, the
dilator and the iris stretch. His theory is discussed and analyzed with respect
to the UBM data before and after Nd-Yag laser iridotomy. The iris lens contact
length after the iridotomy was twice the value measured previously to the
intervention. Some papers show that more important at the angle closure
glaucoma crisis are the anatomical configuration of the eye (position and
morphology of the iris, ciliary body and scleral spur combined with a relative
larger crystalline lens).
CONCLUSION: UBM showed that the iris-lens contact length doubled its
value after the Nd-Yag Laser iridotomy. This result suggest that the iris's muscle forces (sphincter,
dilator and stretch) have a minor role in the genesis of the primary closure
angle glaucoma.