The American Academy of Ophthalmology (AAO) Preferred Practice Pattern defines high refractive errors as +3.00 D or more of hyperopia (with low-to-moderate hyperopia being less than +3.00 D).[1] However, many clinical studies use a higher threshold:
- ≥+5.00 D is the most widely used cutoff for “high hyperopia” in pediatric amblyopia and strabismus research.[2][3] - ≥+4.00 D is used in some epidemiologic studies as the threshold for “moderate to high hyperopia”.[4][5] - ≥+7.00 D is often used to define the extreme end of the spectrum, particularly in the context of structural conditions such as nanophthalmos and posterior microphthalmos.[6][7]
Amblyopia — The most strongly associated condition. Among preschoolers with hyperopia >+3.25 D, amblyopia prevalence was 34.5% compared to 2.8% in non-hyperopic children, rising to 51.5% in those with ≥+5.00 D. Both unilateral (anisometropic) and bilateral (isoametropic) amblyopia occur; isoametropic amblyopia was found in approximately 8.6% of children with ≥+4.5 D of hyperopia.[1][2]
Strabismus (especially accommodative esotropia) — Prevalence of strabismus was 17% in hyperopic children (>+3.25 D) versus 2.2% in non-hyperopic children, increasing to 32.9% in those with ≥+5.00 D. The risk of esotropia rises with increasing hyperopia.[1][3]
Angle-closure glaucoma — Hyperopic eyes have shorter axial lengths, shallower anterior chambers, and thicker, more anteriorly positioned lenses, all of which predispose to primary angle-closure disease (PACD). The risk of PACD rises rapidly with greater hyperopia (OR 1.41 per diopter). This is particularly prominent in nanophthalmos, where angle-closure glaucoma occurs in up to 67% of affected individuals.[4][5][6]
Reduced stereoacuity — Even in non-strabismic, non-amblyopic hyperopic children, stereoacuity is significantly worse (median 120 arcsec vs. 60 arcsec in non-hyperopic children), worsening with higher degrees of hyperopia.[1]
Anisometropia and astigmatism — Both are significantly more prevalent in children with high hyperopia (26.9% and 29.4%, respectively, vs. 5.1% and 10.3% in non-hyperopic children).[1]
Diabetic retinopathy — Hyperopia has been associated with progressive retinopathy in patients with type 1 diabetes.[7]
Several genetic conditions include high hyperopia as a characteristic feature:[9][10][11]
Mutations in MYRF (myelin regulatory factor) have been identified as a cause of autosomal dominant high hyperopia, with some affected individuals also developing angle-closure glaucoma.[13] Mutations in MFRP cause autosomal recessive nanophthalmos (NNO2).[8]