]PURPOSE. Albinism involves the mutation of one or more of the genes associ
ated with melanin synthesis and has many ramifications for vision. This stu
dy focuses on the refractive implications of albinism in the context of emm
etropization.
METHODS. Refractive, biometric, and visual acuity data were collected for a
group of 25 albino individuals that included the following: 18 oculocutane
ous (13 tyrosine positive, 5 tyrosine negative); 7 ocular (2 autosomal rece
ssive, 5 sex-linked recessive). Their age range was 3 to 51 years. All exhi
bited horizontal pendular nystagmus.
RESULTS. There were no statistically significant differences relating to al
bino subtype for any of the measured parameters. All the subjects had reduc
ed visual acuity (mean: 0.90, logMAR) and overall, there was a bias toward
hyperopia in their refractive errors (mean: +1.07 D). However the refractiv
e errors of the group covered a broad range (SD: 4.67 D) and included both
high myopia and high hyperopia. An axial origin to the refractive errors is
implied by the high correlation between refractive errors and axial length
s. Refractive astigmatism averaged 2.37 D and was consistently with-the-rul
e and highly correlated with corneal astigmatism, which was also with the-r
ule. Meridional analysis of the refractive data indicated that the vertical
meridian for hyperopic subjects was consistently nearer emmetropia compare
d to their horizontal meridian. Myopic subjects showed the opposite trend.
CONCLUSIONS. The overall refractive profile of the subjects is consistent w
ith emmetropization being impaired in albinism. However, the refractive err
ors of hyperopic subjects also can be explained in terms of "meridional emm
etropization." The contrasting refractive profiles of myopic subjects may r
eflect operational constraints of the emmetropization process.