Heritable susceptibility to environmentally induced glaucoma in several mutants of Japanese quail.

We compared albino (aI), dilute (aID), and wild-type (AI+) quail in their ocular responses to continuous light, the rearing condition that brings on light-induced avian glaucoma (LIAG) in domestic chickens. At age 3 months, all quail kept under 24L/OD showed the retarded corneal growth and corneal flattening characteristic of LIAG. Unlike chickens, quail did not suffer pathological eye enlargement during the early growing period. However, by 6 months of age, 24L/OD albinos showed an almost 20% increase in eye weight compared with 12L/12D albinos. The increase in eye weight for 24L/OD dilutes at 6 months of age was 18%; for 24L/OD wild types, it was 16%. Intraocular pressure, the key criterion for glaucoma, was almost twice as high at 6 months of age in 24L/OD wild types as it was in 12L/12D wild types and showed similar but even greater increases in dilutes and albinos reared under continuous light. Across-genotype comparisons revealed additional effects of the mutant genes themselves: the eyes of albinos were 22.6% larger. The eyes of dilutes showed a similar but smaller response--5% and 6.6%, respectively, and correlated increases in globe dimensional parameters. The flat cornea characteristic of LIAG appeared in all three mutants, but only when environmental light had been kept at 24L/OD. This further separates the LIAG effect from the phenomenon we call albino quail macrophthalmos.