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An investigation of CO2 laser scleral buckling using moiré interferometry
Saher M Maswadi1, Peter E Dyer, Dinesh Verma
1Department of Physics, University of Hull, United Kingdom.
Background And Objective:
To demonstrate suitability of moiré interferometry to assess and quantify laser-induced shrinkage of scleral collagen for buckling procedures.
Materials And Methods:
Scleral buckling of human cadaver eyes was investigated using a Coherent Ultrapulse CO2 laser. Projection moiré interferometry was employed to determine the out-of plane displacement produced by laser exposure, and in-situ optical microscopy of reference markers on the eye was used to measure in-plane shrinkage.
Results:
Measurements based on moiré interferometry allow a three dimensional view of shape changes in the eye surface as laser treatment proceeds. Out-of-plane displacement reaches up to 1.5 mm with a single laser spot exposure. In-plane shrinkage reached a maximum of around 30%, which is similar to that reported by Sasoh et al (Ophthalmic Surg Lasers. 1998;29:410) for a Tm:YAG laser.
Conclusion:
The moiré technique is found to be suitable for quantifying the effects of CO2 laser scleral shrinkage and buckling. This can be further developed to provide a standardized method for experimental investigations of other laser sources for scleral shrinkage.