Role of Orbscan II in screening keratoconus suspects before refractive corneal surgery1
Section snippets
Material and methods
Sixty consecutive eyes with suspicious videokeratography (TMS 1, version 1.61, Tomey, Waltham, MA) were evaluated as part of a routine preoperative LASIK examination. Suspicious videokeratography was determined for the purpose of this study as an area of central, inferior, or superior steepening; oblique cylinder > 1.5 diopters (D); and a steep keratometric curvature greater than 47 D. The preoperative workup of candidates for LASIK included a detailed medical history, manifest and cycloplegic
Results
Table 1 compares the Orbscan II data between the keratoconus suspects group and the control group. The mean anterior elevation of the keratoconus suspects group was 0.009 ± 0.007 mm. The mean posterior elevation of the keratoconus suspects group was 0.035 ± 0.015 mm. The mean thinnest pachymetry of the keratoconus suspects group was 515 ± 44 μm. The mean anterior elevation of the control group was 0.005 ± 0.002 mm. The mean posterior elevation of the control group was 0.021 ± 0.006 mm. The
Discussion
The role of Orbscan II in screening patients for refractive surgery has not been well defined. Previous authors have shown that Orbscan II topography can provide useful and accurate information in defining the morphology of keratoconus and in detecting subtle topographic changes present in early keratoconus.16 In addition, Wang et al17 have shown that the posterior elevation increases after LASIK, and the increase is correlated with residual corneal bed thickness.
We have shown that patients
References (17)
- et al.
Iatrogenic keratectasia after LASIK in a case of forme fruste keratoconus
J Cataract Refract Surg
(1998) - et al.
Delayed onset keratectasia following laser in situ keratomileusis
J Cataract Refract Surg
(1999) - et al.
Corneal ectasia detected after laser in situ keratomileusis for correction of less than −12 diopters of myopia
J Cataract Refract Surg
(2000) - et al.
Iatrogenic keratectasia after laser in situ keratomileusis for less than −4.0 to −7.0 diopters of myopia
J Cataract Refract Surg
(2000) - et al.
Corneal topography of early keratoconus
Am J Ophthalmol
(1989) - et al.
Factors affecting the forward shift of posterior corneal surface after laser in situ keratomileusis
Ophthalmology
(2001) - et al.
Videokeratography of the fellow eye in unilateral keratoconus
Ophthalmology
(1993) - et al.
Keratoconus evaluation using the Orbscan Topography System
J Cataract Refract Surg
(2000)
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None of the authors has a financial or proprietary interest in any material or method mentioned.