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Comparison of the UniversalKeratome and the Automated Corneal Shaper
P S Binder1, R W Lambert, R G Koepnick
1Ophthalmology Research Laboratory, National Vision Research Institute, San Diego, California 92121, USA.
Purpose:
To compare the morphologic appearance and measurements of in situ keratomileusis performed with the UniversalKeratome (UK) with those done with the Automated Corneal Shaper (ACS).
Setting:
Surgical suite within private practice.
Methods:
Procedures were performed the same day on mate eye-bank eyes. In situ keratomileusis was done using existing nomograms for each instrument to resect a cap thickness of 160 microns and a myopic resection of 100 microns. Intraocular pressures were increased by inflating the globes with balanced salt solution and were measured with the suction fixation rings in place. The excised caps and stromal resections were measured twice independently after surgery, again after tissue fixation, and then evaluated with light and scanning electron microscopy.
Results:
No complications were encountered. Compared with the ACS, the UK was easy to set up, use, clean, and take down. Its excised tissue dimensions were greater and more predictable, it resected a concave shaped lenticule (edges imperceptibly blending with the host stroma), and it created a smoother power resection surface and primary resection base.
Conclusions:
Smoother, predictable tissue resection, and simple assembly/disassembly and use give the UK an apparent advantage over the ACS. The UK corrects astigmatism and hyperopia by changing the shape of the poly(methyl methacrylate) optical insert.