Abstract
Purpose: :
To present four cases of Fuch’s endothelial dystrophy (FECD) associated with a raised intraocular pressure (IOP), the therapies we decided to treat our patients with, and how these drugs modified the anatomy of the anterior segment and angle, analyzed with a Visante-Anterior Segment OCT.
Methods: :
Four patients with FECD presenting a raised IOP ( 26 mmHg±2.43), with no clinical sign of glaucoma and normal visual field; a scan with Anterior Segment Visante OCT was performed at baseline, after 1 hour and finally after 2 hours of NaCl 9% drops instillation, measuring the angle in the four quadrants. After each scan, applanation tonometry was performed.
Results: :
the three measurements, conducted at the same site thanks to an eye tracking device, showed an increase of 8.2°±2 nasally, 9°±0.2 inferiorly, of 1.3°±1 superiorly, and no increase in the temporal angle; consequentially, the IOP after two hours measured 17 mmHg±3.7.
Conclusions: :
The overall position of the iris depends on resistance to aqueous flow through the iris-lens channel, an appositional zone between the iris pigment epithelium and lens capsule. Thus said, since there is a net forward movement of aqueous, there must be a driving pressure differential for this flow; that is, the IOP is higher on the posterior than the anterior iris surface. The iris moves toward the cornea when there is a significant posterior-to-anterior pressure differential. Based on our findings, we postulate that in Fuch’s endothelial corneal dystrophy the endothelial pumping function is lost, leading to an accumulation of fluid in the corneal stroma and to a reduction of the fluid actively pumped in the anterior chamber: the posterior-to-anterior pressure differential in the anterior chamber increases and the iris moves forward, narrowing the angle. When NaCl 5% drops are administered, due to their hypertonic effect, water moves from the edematous stroma to the anterior chamber, thus increasing the total water content anterior to the iris; the pressure differential decreases, the iris moves backward, the angle gets wider and the IOP decreases.
Keywords: cornea: endothelium • intraocular pressure • anterior chamber