contact lens case reports

A New View of Keratoconus

BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ

This month's case history is more like a pictorial illustrating two patients who have asymmetrical keratoconus as viewed through the new Anterior Segment OCT Visante instrument (Carl Zeiss Meditec, Inc.). The Visante uses a time delay of reflected backscattered light to rapidly visualize and ultimately measure many of the anatomical features located in the anterior segment of the eye (Figure 1). The system doesn't require pupil dilation and has good resolution through corneal opacities and scars. Through this technique it's possible to visualize:

• Anterior corneal curvature.
• Posterior corneal curvature.
• Corneal sagittal height.
• Central and midperipheral corneal thickness.
• Anterior chamber angle.
• Anterior chamber depth.

Patient 1 has asymmetrical keratoconus with an apical radius OD of 48.87D (6.90mm) and OS 86.87D (3.90mm) (Figure 2). Figure 3 shows the high resolution OCT scans of the right and left eyes. Figure 4 shows the two corneas superimposed on one another; the black image is the more normal right eye and the red image is the left eye.

Figure 1

Figure 2

Figure 3

Figure 4

Patient 2 also has asymmetrical keratoconus with an apical radius OD of 43.00D (7.85mm) and OS 103.25D (3.27mm) (Figure 5). Figure 6 shows the high resolution OCT scans of the right and left eyes, and again Figure 7 shows the two corneas superimposed on one another; the black image is the more normal right eye and the red is the left.

Figure 5

Figure 6

Figure 7

In both cases, note the significant paracentral ectasia of the left eyes as well as the rather profound posterior corneal changes. CLS

Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Paragon Vision Sciences and SynergEyes, Inc. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision and SynergEyes, Inc.