Pachymetry changes during corneal crosslinking: effect of closed eyelids and hypotonic riboflavin solution

To evaluate pachymetry changes during standard corneal crosslinking (CXL) and the effect of closed eyelids and hypotonic riboflavin in thin corneas.

Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

Comparative case series.

Eyes with progressive keratoconus had standard epithelium-off CXL. In Group 1, a lid speculum was used during the procedure. In Group 2, the lids were closed during saturation with riboflavin. In Group 3, hypotonic riboflavin was used. In Groups 1 and 2, swelling was performed with hypotonic riboflavin if pachymetry was less than 400 μm. The thinnest corneal pachymetry (TCP) was measured preoperatively, after epithelium removal, and every 10 minutes thereafter.

Thirty-five eyes were evaluated. After epithelium removal, the mean TCP was 401 μm ± 15 (SD), 411 ± 35 μm, and 400 ± 24 in Groups 1, 2, and 3, respectively. In Group 1, the TCP decreased to 355 ± 23 μm after the first 30 minutes. In Group 2, the TCP remained stable throughout the saturation phase. In Group 3, the TCP increased. During the irradiation phase, a reduction in pachymetry occurred in all groups. Thinnest corneal pachymetry readings less than 400 μm were found in all eyes irrespective of the protocol.

Corneal desiccation with riboflavin with 20% dextran can be avoided when removing the lid speculum during saturation with riboflavin. The use of hypotonic riboflavin solution increased corneal pachymetry, although the final TCP remained unchanged. To increase endothelial safety, new isooncotic solutions are needed.