Epidemiology
The National Institute of Health reports that SCA1 has a prevalence of approximately 1 or 2 per 100,000 however a review of literature has shown that these estimates vary significantly from study to study and can be less than 1 per 100,000 or as high as 6 per 100,000. Among all types of SCA, SCA1 is among the most common and the portion accounted for by SCA1 varies between geographic regions, with percentages as high as 40% of all SCA diagnoses in populations in Russia and South Africa being SCA1. In the United States SCA1 accounts for 6% of SCA diagnoses. Overall, SCA1 accounts for 6-27% of all cases dominant ataxias. : 6  Because of its late onset, often appearing after reproductive age, SCA1 exerts low selection intensity, ranking about 0.19 on the Crows index, but intensity may vary with time within a population or family, as anticipation increases the number of CAG repeats. One implication of this is that SCA1 is unlikely to disappear from a population by natural selection alone.Prevalence of each type of SCA varies with geographic region and ethnicity, possibly because of founder effects and historic migration patterns. High prevalence regions include central Poland, where 68% of autosomal dominant cerebellar disorders are SCA1; communities in Tamil Nadu, where up to 7.2% of the population has SCA1 in some small villages; the Tohoku region on the northern portion of Honshu Island, with 24.8% of cases being SCA1; and among Yakut populations in eastern Siberia, with a prevalence 46 per 100,000 in rural populations.
and has classified disease into four groups as follows:

Epithelial and subepithelial dystrophies
Epithelial basement membrane dystrophy
Epithelial recurrent erosion dystrophies (Franceschetti corneal dystrophy, Dystrophia Smolandiensis, and Dystrophia Helsinglandica)
Subepithelial mucinous corneal dystrophy
Meesmann corneal dystrophy
Lisch epithelial corneal dystrophy
Gelatinous drop-like corneal dystrophy

Bowman Layer dystrophies
Reis–Bücklers corneal dystrophy
Thiel–Behnke corneal dystrophy
Stromal dystrophies-
TGFB1 corneal dystrophies
Lattice corneal dystrophy, type 1 variants (III, IIIA, I/IIIA, IV) of lattice corneal dystrophy
Granular corneal dystrophy, type 1
Granular corneal dystrophy, type 2

Stromal dystrophies
Macular corneal dystrophy
Schnyder crystalline corneal dystrophy
Congenital stromal corneal dystrophy
Fleck corneal dystrophy
Posterior amorphous corneal dystrophy
Central cloudy dystrophy of François
Pre-Descemet corneal dystrophy

Endothelial dystrophies
Fuchs dystrophy
Posterior polymorphous corneal dystrophy
Congenital hereditary endothelial dystrophy
X-linked endothelial corneal dystrophyThe following (now historic) classification was by Klintworth:Superficial dystrophies:

Epithelial basement membrane dystrophy
Meesmann juvenile epithelial corneal dystrophy
Gelatinous drop-like corneal dystrophy
Lisch epithelial corneal dystrophy
Subepithelial mucinous corneal dystrophy
Reis-Bucklers corneal dystrophy
Thiel–Behnke dystrophyStromal dystrophies:

Lattice corneal dystrophy
Granular corneal dystrophy
Macular corneal dystrophy
Schnyder crystalline corneal dystrophy
Congenital stromal corneal dystrophy
Fleck corneal dystrophyPosterior dystrophies:

Fuchs dystrophy
Posterior polymorphous corneal dystrophy
Congenital hereditary endothelial dystrophy

Treatment
Early stages may be asymptomatic and may not require any intervention. Initial treatment may include hypertonic eyedrops and ointment to reduce the corneal edema and may offer symptomatic improvement prior to surgical intervention.Suboptimal vision caused by corneal dystrophy may be helped with scleral contact lenses but eventually usually requires surgical intervention in the form of corneal transplantation. Penetrating keratoplasty, a common type of corneal transplantation, is commonly performed for extensive corneal dystrophy.With penetrating keratoplasty (corneal transplant), the long-term results are good to excellent. Recent surgical improvements have been made which have increased the success rate for this procedure. However, recurrence of the disease in the donor graft may happen.