Paradoxical hypotony after laser in situ keratomileusis

We present a case of paradoxically low (0 to 2 mm Hg) intraocular pressure (IOP) measured by Goldmann applanation and Tono-Pen tonometry in an eye with corticosteroid-induced high lOP after laser in situ keratomileusis. The patient complained of blurred vision and ocular pain in both eyes. The eyes were firm by palpation, and the IOP measured by Schiotz indentation tonometry was 38 mm Hg. An interface fluid pocket was identified by slitlamp examination, and the corneal surface became steeper. These findings resolved after flap relifting, interface irrigation, and addition of antiglaucoma medications. We postulate that the paradoxically low reading by applanation tonometry was due to fluid accumulation within the flap-bed interface. The applanation tonometry reflected the interface fluid pocket pressure rather than the real high IOP. An exceedingly low IOP should be verified by palpation or by Shiotz indentation tonometry, and interface fluid should be identified.