Purpose:
To graphically analyze a mathematical model for predicting Descemet’s stripping endothelial keratoplasty (DSEK).
Methods:
A mathematical model for estimating the refractive changes after DSEK has been described previously. This model is based on four variables: pre-surgical recipient corneal thickness (trecipient), recipient posterior radius of curvature (rpc), central to peripheral corneal graft ratio (CP ratio), and corneal thickness (ttransplant). Three-dimensional graphs comparing these four variables and their effects on the corneal and overall refractive power of the eye were generated in Matlab.
Results:
The four variables can be divided into two groups: donor corneal properties (CP ratio and ttransplant) and host corneal properties (rpc, trecipient). Analysis of the model suggests that donor corneal properties have the most effect on the refractive change after DSEK. CP ratios approximately less than one induce hyeropic shifts in the eye and ratios greater than one tend to induce myopic shifts. The CP ratio has a non-linear effect on the eye and graphical analysis suggests that the smaller the ratio, the larger the effect on the overall refraction. The transplant thickness appears to have a more linear affect on eye refraction where a thicker transplant induces a stronger hyperopic shift. The host corneal variables appear to have less of an effect on the overall refractive change. Trecipient has little to no effect on overall refractive change. While varying rpc does affect the refractive power of the eye prior to surgery, this variable does not appear to strongly affect the overall refractive change after DSEK surgery.
Conclusions:
The donor corneal properties, CP ratio and transplant thickness have the strongest affect on refractive changes after DSEK.
Keywords: cornea: endothelium • cornea: clinical science • optical properties