Hypothesis: poly-(R)-3-hydroxybutyrate is a major factor in intraocular pressure.

Short chain poly-(R)-3-hydroxybutyrate (cPHB) is a ubiquitous molecule that readily adheres to others, that is covalently added to proteins and that forms, with polyphosphate, ion channels. High levels of cPHB have been implicated in atherosclerosis and in diabetes. Here, we propose a hypothesis in which cPHB adheres to filaments in the extracellular matrix and this raises intraocular pressure. In a corollary, we propose that a positive feedback relationship between cPHB adherence to filaments, raised IOP and filament stretching constitutes a switch.

Macular edema after corneal graft: a prospective study by optical coherence tomography.

PURPOSE: Vision recovery after corneal graft is sometimes limited by the occurrence of macular edema. The aim of this prospective study of 62 keratoplasty patients was to assess the incidence of macular edema by using optical coherence tomography (OCT 3; Stratus, Carl Zeiss Meditec, Dublin, CA) and to identify factors associated with edema. METHODS: Sixty-two patients who were all operated on by the same surgeon were examined by OCT 3, 1 and 3 months after corneal graft. RESULTS: The incidence of macular edema after keratoplasty was 9.6%. The surgical technique (penetrating vs lamellar keratoplasty) had no influence on the occurrence of edema (P > 0.05), but combined surgery significantly increased the risk of developing an edema (P < 0.05). CONCLUSION: Macular edema after keratoplasty seemed to be less frequent than expected (9.6%) and associated mainly with combined surgery.