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R. Velasco, R. Chavez, O. Baca, L. Perdiz, A. Babayan, A. Galicia, O. Fernandez; Ultrabiomicroscopy (UBM) Study in Corneal Rings Implantation for Keratoconus. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3542.
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To determine the depth of intrastromal corneal rings in keratoconus with Ultrabiomicroscopy (UBM) and to measure the distance between the corneal epithelium/corneal ring and the endothelium/corneal ring.
This is a prospective, transversal and observational study. Patients with keratoconus who underwent intrastromal corneal ring implantation between January 2004 to September 2006 were included.Size of corneal rings implanted was 0.45mm. All rings were implanted at 80% of depth according to the Orbscan. Ultrabiomicroscopy (UBM) at 50 - 80 MHz resolution with a Paradigm P45 ultrabiomicroscope (Paradigm, Rochester UK) was done. We measured the depth between the epithelium and the corneal ring and the corneal ring with the endothelium in different meridians (XII, III, VI and IX). Twelve images were taken per eye. Preoperative corneal thickness measured by Orbscan II was compared with the postoperative corneal thickness measured by UBM. Intended depth against obtained depth was compared.
We included 12 eyes of 24 patients. Mean preoperative ring depth vs postoperative was as follows: MXII 482/334, MIII 464/322, MVI 425/264, MIX 449/294 (p<0.05). The mean distance between epithelium and corneal ring was: MXII 288, MIII 277, MVI 322, MIX 297. The mean distance between endothelium and corneal ring was: MXII 268, MIII 246, MVI 267, MIX 267. Topographical measurements before surgery differs with UBM results.
UBM is helpful in measuring the depth of corneal rings. Total thickness after surgery, is bigger in meridians M6-M9 by UBM. Corneal ring implantation is always more superficial than intended.
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