Primary lens luxation (PLL)
Primary lens luxation (PLL) is a canine familial disorder encountered at high frequency in several terrier breeds and in some other breeds with probable terrier coancestry. PLL is caused by displacement of the lens because of the stretching or rupture of the zonular fibers that link ocular lenses in place behind the pupil. The disease can be caused by trauma or by a variety of conditions that distort normal ocular anatomy, such as glaucoma and intraocular tumours. (Guld et al. 2011) In most instances, PLL goes undetected until one of the lenses is grossly displaced. Concurrent iridodonesis usually signals subluxation in the opposite eye. Gross displacement of the lens in the second eye often follows weeks or months later. Ultrastructural abnormalities of the zonular fibers are already evident at 20 months of age, long before the initial luxation that typically occurs when the dogs are 3 to 8 years old. This suggest that PLL results from defective development or maintenance of the zonular fibers, or both.
Farias, F.H.G., Johnson, G.S., Taylor, J.F., Giuliano, E., Katz, M.L., Sanders, D.N., Schnabel, R.D., McKay, S.D., Khan, S., Gharahkhani, P., et al. (2010). An ADAMTS17 Splice Donor Site Mutation in Dogs with Primary Lens Luxation. IOVS 51, 4716–4721.
Gould, D., Pettitt, L., McLaughlin, B., Holmes, N., Forman, O., Thomas, A., Ahonen, S., Lohi, H., O’Leary, C., Sargan, D., et al. (2011). ADAMTS17 mutation associated with primary lens luxation is widespread among breeds. Veterinary Ophthalmology 14, 378–384.