A variant in the RBP4 gene causes multiple eye abnormalities due to a fetal serum vitamin A (retinol) deficiency. Vitamin A is needed to synthesize retinoic acid (RA), a potent molecule needed for the proper development of the eye and other tissues. The eye is the most sensitive among organs to reduced RA levels during the formation of the embryo.

  • Signs and symptoms

    Affected dogs may have small or undeveloped eyes or other defects of the retina, iris, or optic nerve. Because their vision is impaired, this may cause dogs to often hesitate on stairs, bump into doorways or walls, have difficulty fetching toys, and be disoriented if the furniture is moved.

    Microphthalmia may be observed at birth or as soon as the puppies open their eyes, and other changes may be noted on an ophthalmic exam at a few weeks of age, though they are present from birth.

    Uncover health risks with Embark

    Embark Breed + Health Test

    Original price:


    Sale price:



    Embark for Breeders Dog DNA Test

    $129 - $159


  • Diagnosis

    Microphthalmia can be observed during a basic eye examination; however, a veterinary ophthalmologist may be needed for a comprehensive diagnosis of the more subtle changes.

  • Treatment

    There is no specific treatment for Microphthalmia.

  • What to do if your dog is at risk


    • Owners should help affected dogs navigate their environments by keeping furniture in the same location in the home, ensuring they are on a leash in an unfamiliar territory outside, and training them to understand verbal commands.

  • Genetic Information

    This variant was first identified in the Soft Coated Wheaten Terrier.

    Microphthalmia is transmitted as an autosomal recessive trait with penetrance determined by the maternal genotype.

    Gene names:

    RBP4 Exon 2 ‐ chr

    Inheritance type:


  • Breeds affected

    This health condition affects the following breeds

Learn about your dog’s unique genetic health

Dog owners

Breed identification, health and trait insights, personalized care recommendations, and the world’s first canine relative finder—all in one leading dog DNA test.

Learn about the report for dog owners
Shop the test
Breeding programs

Embark’s test for breeding programs is one comprehensive DNA test designed with your needs in mind.

Learn about the report for breeders
Shop the test