Chief Complaint: Blurred vision right eye only presents for cataract evaluation
56 year-old male with longstanding Fuchs endothelial corneal dystrophy (FECD) OU and previously diagnosed cataracts OU, complaining of progressive blurry vision OD for the past few months (OS stable)
He had minimal additional symptoms related to corneal edema (no reported morning blur, minimal visual fluctuations)
Exam Findings
VAcc: 20/50+ 2 OD 20/20-1 OS
Refraction: -6.75 OD, -4.00 OS
IOP: 18mmHg OD 14mmHg OS
SLE Notable for:
K guttata OU, no obvious edema in either eye
Lens NSC 2+ OD ½ + OS
Additional Investigations
IOL Calculations
Corneal Placido disc-based Topography
Figure 1: Corneal Placido Disc-based Topography displaying unusual asymmetry between OD (on the left) and OS (on the right), with OS axial curvature revealing focal area of maximal steepening inferiorly displaced (classic appearance for keratoconus).
Patient Course
Patient received CE/IOL OD – uneventful
Postoperative week 1: UDVA= 20/20 OD
Patient content with results and requested cataract removal of left eye
No previous diagnosis of KC (rare to not have known he has keratoconus)
Topographic findings not c/w stable acuity for years
No visual symptoms beyond refractive error
Highly asymmetric presentation between OD and OS (rare)
Implications for Diagnosis
Keratoconus
Possible corneal cross-linking
Earlier cataract surgery should be okay
IOL calculations are probably accurate
Fuchs Endothelial Corneal Dystrophy
No cross-linking indicated
Avoid premature cataract surgery as could cause corneal decompensation
IOL calculations may be inaccurate due to induced keratometric steepening from edema
Additional Investigations
Scheimpflug corneal tomography
Anterior segment optical coherence tomography
Figure 2: Scheimpflug Corneal Tomography OS with axial/sagittal curvature map displaying inferior steepening and corneal thickness map displaying correlating corneal thickening. Anterior surface elevation map displays a focal elevation with the curvature (as expected in KC); however, there was no correlating posterior elevation shown on the posterior surface elevation map (as would be expected in KC presentation with this level of steepening).Figure 3: Scheimpflug Corneal Tomography OD with axial/sagittal curvature map displaying new post-operative inferior steepening (as compared to unremarkable pre-operative curvature map) with corneal thickness.Figure 4: OCT OS displaying focal thickening with the presence of edema.
Diagnosis
Atypical Fuchs Endothelial Corneal Dystrophy
Pathophysiology
KC is a bilateral non-inflammatory corneal ectasia which typically presents with stromal thinning and inferior steepening on axial / sagittal topography
Fuchs is a progressive disease characterized by the development of corneal edema with increased corneal thickness
The anterior curvature map OS showed inferior steepening classic for KC
The corneal thickness map, however, did not show correlated inferior focal thinning as we would predict in KC; rather it showed correlated thickening (expected in Fuchs)
Treatment
Avoid premature cataract surgery of the left eye (to avoid corneal decompensation)
Prognosis and Future Directions
The differentiation between concurrent KC and FECD vs. FECD alone can be difficult, as not all focal steepening indicates keratoconus
The differentiation is critical in determining appropriate intervention
Prior cases in the literature have reported concurrent KC and FECD; however, it is possible that many were actually atypical presentations of FECD, but diagnosed as KC
Therefore, Placido topography must be supplemented with regional corneal thickness measurements to achieve the correct diagnosis and guide appropriate intervention
References
Rabinowitz YS. Keratoconus. Survey of Ophthalmology. 1998 Jan 1;42(4):297-319.
Gain P, Jullienne R, He Z, et al. Global survey of corneal transplantation and Eye banking. JAMA Ophthalmol. 2016;134(2):167-73. doi:10.1001/jamaophthalmol.2015.4776
Cursiefen C, Jun AS, editors. Current Treatment Options for Fuchs Endothelial Dystrophy. Springer International Publishing; 2017.
Cremona FA, Ghosheh FR, Rapuano CJ, Eagle RC, Hammersmith KM, Laibson PR, Ayres BD, Cohen EJ. Keratoconus associated with other corneal dystrophies. Cornea. 2009;28(2):127-35.
Lechner J, Dash DP, Muszynska D, Hosseini M, Segev F, Geroge S, Frazer DG, Moore JE, Kaye SB, Young T, Simpson DA, Churchill AJ, Héon E, Willoughby CE. Mutational spectrum of the ZEB1 gene in corneal dystrophies supports a genotype-phenotype correlation. IOVS. 2013;54(5):3215-23.
Ham L, Dapena I, Van Luijk C, Van der Wees J, Melles GR. Descemet membrane endothelial keratoplasty (DMEK) for Fuchs endothelial dystrophy: review of the first 50 consecutive cases. Eye. 2009 Oct;23(10):1990.
