Tiffany Johnson Gates

Atypical keratoconus suspect with against-the-rule corneal topography

A 14-year-old Hispanic male presents with a history of gas-permeable (GP) orthokeratology wear. Best-corrected visual acuity (VA) right eye (OD) has decreased and OD corneal topography reveals an against-the-rule cornea. Keratoconus is suspected.

I. Case History

 14-year-old Hispanic male

 Chief complaint of blurred vision OD  History of orthokeratology wear OU for the past two years, OD best-corrected VA reduced in the past eight months  Medical and ocular history unremarkable; family history unremarkable  No oral medications, using artificial tears as needed  Referred for a contact lens evaluation

II. Pertinent findings

 Unaided VA o OD: 20/150 o OS: 20/40  Manifest Refraction o OD: -4.75 -7.50 x 064 20/25-2 o OS: -1.00 -0.25 x 125 20/20  Corneal Topography o OD: Sim K 52.5 x 43.5 @ 082 ATR pattern o OS: Sim K 41.8 x 41.4 @ 157  Orbscan-posterior float revealed a ‘hot spot’ > 40 microns, OD>OS  Slit Lamp Examination: OU (-) Fleischer ring, (-) Vogt’s striae, (-) scarring. No obvious signs consistent with keratoconus, ocular health within normal limits.

III. Differential diagnosis

 Keratoconus  Pellucid marginal degeneration  Orthokeratology corneal warpage

IV. Diagnosis and discussion

 Diagnosis: atypical presentation of keratoconus OD>OS  No apparent clinical signs of keratoconus with slit lamp examination, likely indicating early disease development  Corneal topography against-the-rule pattern not consistent with keratoconus, but posterior float revealed obvious ectasia (Lim et al., 2007)  The discontinuation of orthokeratology wear requires consistent monitoring with refraction and corneal topography until baseline levels are reached. Refractive error returned 70% of the way to baseline levels 95 days after discontinuing orthokeratology wear in a study by Brand et al., 1983

V. Treatment, management

 The patient was prescribed a bitoric corneal GP lens OD and a spherical Biofinity soft lens OS  Monitor every 3-6 months for progression; if progression is noted, will consider referral for corneal cross-linking

VI. Conclusion

 Keratoconus may present in an atypical fashion; the eye care practitioner must consider the presentation as a whole and not rely solely on corneal topography  The posterior float on a topography elevation map may be helpful in diagnosis  Discussion of eye rubbing, flat fitting lenses, and association with keratoconus (Sugar and Macsai, 2012, Kenney and Brown, 2003)