To assess the prevalence of tilted disks and its association with refractive error
and visual field defects.
Population-based cohort study.
The Blue Mountains Eye Study examined urban Australians aged 49 years or older between
1992-1994. Of 4,433 eligible participants, 3,654 (82.4%) participated. The eye examination
included logMAR visual acuity, standardized refraction, cover testing, stereoscopic
optic disk photography, and Humphrey automated perimetry. Inferior or nasal optic
disk tilting was graded from stereoscopic photographs.
Of 3,583 participants with gradable photographs, inferior or nasal optic disk tilting
was observed in 77 eyes of 56 participants (1.6%). The prevalence of tilted disks
increased from 0.4% in eyes with astigmatism < 1.0 diopters to 17.9% in eyes with
astigmatism >or= 5.0 diopters. The mean astigmatic error was 2.2 diopters in eyes
with tilted disks compared with 0.7 diopters in eyes with normal disk appearance,
P <.001. Myopia was present in 66.2% of eyes with tilted disks compared with 12.4%
of eyes with a normal disk appearance, P <.001. The most common associated features
were astigmatism (93.5%), pallor, and tessellation of the adjacent chorioretinal tissues
(74.0%), situs inversus of the retinal vessels (70.1%), beta-peripapillary atrophy
(64.9%), strabismus (30.4%), visual field defects (19.4%), posterior staphyloma (18.2%),
inferonasal pigmentary accumulation (9.1%), and chorioretinal atrophy (5.2%). Superotemporal
(33.3%) and superior (25.0%) visual field defects were most frequent.
A tilted disk appearance was not a rare finding in our study population and was strongly
associated with astigmatism and higher levels of spherical refractive error, particularly
myopia. The tilted disk and its associated visual field defect should be distinguished
from other sinister causes.