Macular Holes: Interfacial Forces (Surface Tension) as a Mechanism of
Closure Macular Holes
Vincent Reppucci (New York)
Purpose: Describe
interfacial forces generated at a bubble surface (liquid-gas/oil interfaces)
to explain macular hole closure, and failure.
Methods: All interfaces generate a force. Molecules at a fluid interface
experience an unbalanced
force, resulting in a net inward pull and contraction of the interface
(“surface of tension”) which resists deformation, much like
a trampoline. This interfacial tension explains why particles at an interface
will aggregate. This force can be transmitted to the retinal surface and,
by exceeding the tensile strength (“stiffness”) of the retina,
allow the edges of a macular hole to aggregate. Review of the surface
physics and presentation of this "surface of tension" model
in macular hole closure will be discussed.
Results: Clinical observations of macular hole surgery; i.e role of posterior
hyaloid, ILM peeling, larger or longer-acting bubbles can all be explained
by this “surface of tension” model. Larger bubbles create
a greater “surface of tension” (force). Mechanical barriers,
such as posterior hyaloid or vitreous, reduce the transmittal of these
forces to the retinal surface; peeling ILM or epiretinal membrane reduces
the “stiffness” of the retina.
Conclusion: Successful macular hole closure occurs when the fluid–air
interface generates a “surface of tension” (force) at the
edges of the hole, which exceeds the “stiffness” of the retina,
allowing for reapproximation of the hole edges.