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October 1, 2005

Effect of Latrunculin B on Intraocular Pressure in the Monkey Eye—Reply

Arch Ophthalmol. 2005;123(10):1457. doi:10.1001/archopht.123.10.1457-a

In reply

We thank Dr Fan and colleagues for their comments about our article. We agree that specular microscopy, vital staining, and scanning electron microscopy are sensitive methods to directly reveal morphological changes in corneal endothelial cells. However, ultrasonic pachymetry is also a sensitive method to evaluate corneal endothelial function, and the process of the cytoskeletal drug-induced increase in corneal thickness (ultrasonic pachymetry) is highly consistent with drug-induced transient changes in the shape of corneal endothelial cells (specular microscopy). In previous studies,1,2 specular microscopy following a high dose of H-7 or latrunculin A (cytoskeletal drugs with effects similar to latrunculin B) only revealed transient indistinctness of cell borders and cell swelling, rather than disappearance of the cells, because the endothelial appearance and cell counts had completely returned to normal after hours or days following drug administration. Therefore, the statement that “a significant number of corneal endothelial cells needs to be lost before the cornea begins to swell” does not apply to the cytoskeletal drugs, where swelling can occur without loss of any endothelial cells. Latrunculin B or its derivatives may increase the permeability of corneal endothelium by altering the cell shape and weakening the cell-cell–adherent junctions and the cell–extracellular-matrix–adherent junctions. Recent electron microscopical examination of the cornea of the live monkey eye treated with a low dose of latrunculin B supports our conclusions.3

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