BLOG: Guttae or guttata? Some thoughts on Fuchs’

I took Latin with Mrs. Wheeler many years ago, but I still remember that a noun ending in an “a” is often a feminine noun, and its plural typically ends in an “ae”.

So I was confused when I first learned about corneal guttata: Where did this “ata” suffix come from? When we see a patient with characteristic bumps on the endothelium (neutered, singular form), which term should we put on the chart: corneal gutta, guttata or guttae?

Gutta is a Latin noun meaning “drop, as in a teardrop or a small, rounded amount of liquid. It’s a feminine, singular noun (Latin gives its nouns masculine, feminine or neutered identities, and then inflects them accordingly) and its plural form is guttae. So that means when we are referring to multiple drop-like extrusions on the corneal endothelium, we should use the word guttae.

The “ata” ending is used for adjectives formed from a feminine noun and typically describes something as possessing the quality of the noun or being “full of” the noun. So to use the word guttata would mean a cornea full of drops, which would not be an incorrect term to use in Fuchs’ dystrophy.

The phrase “cornea guttata” would translate to “speckled cornea” or “cornea full of drops,” and the phrase “cornea guttae” would translate to “drops on the cornea.” Essentially, both are correct, and over the years the literature has come to use guttae to refer to the drops themselves, and guttata to refer to the condition of having the drops – the noun and the adjective. Use either one; just don’t use gutta unless you see only one drop.

And what of these corneal guttae? How should we be managing them? First, remember that patients with Fuchs’ dystrophy but clear corneas need no treatment. Sometimes we can get ahead of ourselves when we find several guttae in our 20/20, 75-year old female patient and prescribe sodium chloride solution based on our clever discovery. But if the patient has good vision and no corneal edema, treatment is unnecessary. And this would likely not be welcome by the asymptomatic patient given the stinging/burning side effects.

Second, remember that sodium chloride solution is mostly beneficial for epithelial edema and not much so for stromal edema, given its relatively low penetrance. A patient could very well have some stromal edema but still have good vision. Vision doesn’t usually become significantly obscured until the edema migrates to the epithelium. Make your decision on whether to prescribe sodium chloride based on the symptoms of vision change (especially in the morning, typically between 7 a.m. and 10 a.m. and resolving after that) and the presence of epithelial or significant anterior-stromal edema findings on your slit lamp exam.

The difference between mild and moderate stromal edema in the absence of epithelial edema can be difficult to determine clinically. Corneal pachymetry is a great test for Fuchs’ patients, but know that it can be highly variable between patients. Pachymetry is best used in these cases as a serial test, allowing the clinician to consider treatment if the thickness changes significantly over time compared to the baseline. The development of Descemet’s membrane folds is the best clinical determinate for significant stromal edema, rather than declaring any pachymetry finding over a certain thickness as “edema.” Regarding patients with guttae and cataract surgery, though, the American Academy of Ophthalmology guidelines suggest that a corneal thickness more than 640 µm increases the risk of corneal decompensation after cataract surgery.

And what of endothelial cell count? If your clinic has access to a specular microscope, you could determine the endothelial cell density, measured in cells/mm². The average cell density decreases with age, but a normal patient 60 to 80 years old could expect to have somewhere between 1,800 cells/mm² and 2,800 cells/mm². It’s thought that below 500 cells/mm² the endothelial cells become so spread out that the normal compensatory mechanisms fail and edema results. If this number gets too low, simple treatment with sodium chloride will not be enough.

Next month we’ll get into the surgical options for your patients with Fuchs’ and how 2016 is bringing new options to the mainstream.

References:

American Academy of Ophthalmology. Basic and Clinical Science Course, Section 8, External Disease and Cornea. p. 325.

Edelhauser HF. Cornea. 2000; 19: 263-273.

Lietman T, et al. Br J Ophthalmol. 2003;87(4):515–516.

Rapuano CJ, Luchs JI, Kim T. Anterior Segment: The Requisites. St. Louis, MO: Mosby; 2000.

Seitzman GD, et al. Ophthalmology. 2005;112:441-446.