Our patient is a 21-year-old male who was referred to our clinic for contact lens management of his recently diagnosed keratoconus. He presented wearing glasses with no previous history of contact lenses. His best-corrected visual acuities (VAs) with glasses were OD 20/40 and OS 20/30.
An Unusual Presentation
Routine composite corneal topographies showed that the patient appeared to have a peculiar form of symmetric corneal ectasia that we call superior/temporal keratoconus. Ectasia above the corneal midline is a rare presentation. The Ks OD were 52.00 @ 037/61.25 @ 127, with an apical radius 62.50D and corneal astigmatism of 9.25 D. The left eye K’s were 52.00 @ 096 / 56.00 @ 006 with an apical radius of 62.50D and corneal astigmatism of 9.25D. The Ks OS were 52.00 @ 096/56.00 @ 006 with an apical radius of 63.00D and corneal astigmatism of 4.12D (Figure 1). Associated with the peculiar topographical findings were a lack of positive slit lamp findings often associated with keratoconus.
Equally confounding were the elevation display maps, in which the elevation data OD did not correspond with the axial power display map, showing a relatively symmetric height throughout the cornea as noted by the height differential profile below the elevation map (275-micron height differential). In contrast was a much more typical elevation map OS, with the anticipated asymmetric height throughout the cornea and an 800-micron height differential.
Corneal pachymetry findings were also atypical. The OD map showed slight thinning at the geometric center of the cornea (471 microns) surrounded by concentric zones of normal corneal thickness out to a chord of 10.0mm superior nasal (521/521 microns, 603/604 microns, 674/675 microns). The OS map showed slight thinning at the geometric center of the cornea (468 microns) and minimal thinning of the superior-nasal cornea (511/488 microns, 594/566 microns, 669/658 microns) (Figure 2).
Because of elevated pingueculae on both eyes, we diagnostically fit corneal GP lenses; however, we were unable to achieve an adequate fit OS due to the significant height differentials. The patient was fitted with toric soft lenses, and surprisingly he was able to achieve endpoint VAs of 20/25 OD and 20/30 OS (Figure 3).
What’s Going on Here?
A number of questions remain unclear about this case. What is this condition? Why the disconnect between the axial and elevation display maps OD? Why the disconnect between the OD axial display and pachymetry maps? We hope to one day learn the answers. CLS