Rare Case of Concurrent Keratoconus and Fuchs Endothelial Dystrophy Reported in IJO
Dual Dystrophies can mask progression, unless clinical and investigation parameters are carefully assessed.
Dr Nancy Wang from University of Auckland, New Zealand and her colleagues have reported an interesting case of Keratoconus with Fuchs Dystrophy where the dual dystrophy presented challenges in evaluation and management of the patient.
The case report has been published in the Indian Journal of Ophthalmology.
A 58-year-old woman who had been diagnosed as Keratoconus at the age of 43 presented with complaints of progressively declining vision associated with glare over the past 3 years. Visual difficulty was most pronounced in the mornings. Interestingly, she had no history of any allergic disorders like asthma, eczema and Vernal Keratoconjunctivitis or any family history of Keratoconus. However, she had a strong family history of Fuchs Endothelial Dystrophy.
On examination she had a Best Corrected Visual Acuity of 6/9 and 6/18 in the right eye and left eye respectively. Slit lamp examination demonstrated bilateral central guttata which associated paracentral thinning in the left eye.
Pentacam tomography demonstrated irregular astigmatism with inferior steepening, consistent with Keratoconus in the left and Forme Fruste Keratoconus in the right eye. Corneal thickness at the thinnest location was 535 μm on the right and 486 μm on the left.
Accurate assessment of central endothelial cell counts was not possible due to severe endothelial cell loss in both eyes. However, peripheral counts demonstrated cell densities of 2439 cell/mm2 for the right eye and 2658 cell/mm2 in the left eye. High-definition (HD) Cornea Optical coherence tomography (OCT) showed hyper-reflective endothelium bilaterally as expected in Fuchs Dystrophy and granularity of stroma suggestive of mild stromal oedema in the right eye.
A diagnosis of concurrent Keratoconus and Fuchs Endothelial Dystrophy was made. The patient, however declined any treatment and was asked to follow up to assess for progression of the disease.
During the 7 months following the presentation, VA deteriorated from 6/18 to 6/36 in the left eye and remained stable at 6/9 in the right eye. Comparison of the Pentacam Berlin/Ambrosio Display (BAD) of the left eye at presentation and after 7 months showed a decrease in the relative size of the red elevation islands (both front and back) along with an increase in corneal thickness. The ABCD progression analysis of KC showed improved D indices (sum of standard deviations away from the mean) and improvement in the BAD-D value from 7.95 to 7.41. Thus, despite the deterioration of visual acuity, the Pentacam findings suggested a decrease in the severity of Keratoconus.
The authors suggest that the improvement noted in the Pentacam indices was due to increase in corneal thickness as a result of progression in Fuchs Dystrophy and not due to improvement in Keratoconus.
According to the authors, "This case highlights the need to carefully evaluate the progression of KC in the context of other factors that may influence corneal parameters typically used to quantify Keratoconus severity and progression. In this case, the Keratoconus appears to be mildly improving, masked by corneal thickening associated with worsening Fuchs Endothelial Dystrophy. Meanwhile, the vision deteriorates from the combination of progressive Keratoconus and Fuchs Endothelial Dystrophy."
After understanding the different modalities of management, the patient requested Left Descemet Membrane Endothelial Keratoplasty. She was explained the possible need for Corneal Collagen Cross Linking at a later date.
"Dual Dystrophies can mask progression, unless clinical and investigation parameters are carefully assessed" is the take home message from the case, according to the authors.
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https://www.ijo.in/article.asp?issn=0301-4738;year=2020;volume=68;issue=12;spage=3074;epage=3076;aulast=Wang
