Reliability of the Effect of Artificial Anterior Chamber Pressure and Corneal Drying on Corneal Graft Thickness.
OBJECTIVE
To investigate the effect of artificial anterior chamber (AAC) pressure and corneal drying on the graft thickness in preparation for Descemet stripping automated endothelial keratoplasty.


METHODS
Twenty-seven corneoscleral discs were placed in an AAC. The AAC pressure (15, 45, 92, 109, and 198 mm Hg) was controlled using the height of an infusion bottle and a roller clamp. The endothelium was removed in 1 subgroup. Corneas were exposed to room air or repeatedly dried using cellulose spears. Central corneal thickness was measured every 90 seconds for the first 15 minutes and again at 20 minutes using an ultrasound pachymeter (SP-100, Tomey).


RESULTS
There was a significant linear relationship between the corneal thickness and both AAC pressure and corneal drying. Very high coefficients of determination and narrow 95% confidence intervals were present, in particular for high pressures and drying. The rate of thinning increased with increasing pressure and drying to 1.6% per minute. At the maximum rate of thinning, a 10% reduction in corneal thickness occurred in 6 minutes or 100 μm in 8.8 minutes. Removal of the corneal endothelium reduced the rate of thinning to 0.3% per minute (R = 0.72).


CONCLUSIONS
Increasing AAC pressure and corneal drying reduced the graft thickness at a very predictable rate. Adequate corneal thinning can be achieved by increasing the pressure in the AAC by closing the clamp followed by removal of the residual corneal epithelium and repeated drying with a cellulose spear for 5 to 10 minutes, depending on the initial corneal thickness. This method is simple and is both suitable for use in the eye bank and by the surgeon.
*Department of Corneal and External Eye Diseases, St Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom; †Department of Eye and Vision Science, University of Liverpool, Liverpool, United Kingdom; and ‡School of Engineering, University of Liverpool, Brownlow Hill, Liverpool, United Kingdom.
Vito
V
Romano
Bernhard
B
Steger
Jern Y
JY
Chen
Sherif
S
Hassaan
Mark
M
Batterbury
Colin E
CE
Willoughby
Sajjad
S
Ahmad
Ahmed
A
Elsheikh
Stephen B
SB
Kaye
D000867:Anterior Chamber / Q000502:physiology*; D002452:Cell Count; D003315:Cornea / Q000473:pathology*; D063171:Corneal Pachymetry; D003890:Desiccation; D004728:Endothelium, Corneal / Q000473:pathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D009924:Organ Culture Techniques; D015203:Reproducibility of Results; D014019:Tissue Donors; D041623:Tomography, Optical Coherence