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THE LIGHT MICROSCOPIC APPEARANCE OF DYSPLASIC ZONULAR LIGAMENT PROTEIN IN BREED RELATED LENS LUXATION. Dick Dubielzig Rebecca Morris Class of 2006. Lens displacement is a common cause of secondary glaucoma in the dog. Lens displacements particularly common in terrier breeds
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THE LIGHT MICROSCOPIC APPEARANCE OF DYSPLASIC ZONULAR LIGAMENT PROTEIN IN BREED RELATED LENS LUXATION Dick Dubielzig Rebecca Morris Class of 2006
Lens displacement is a common cause of secondary glaucoma in the dog • Lens displacements particularly common in terrier breeds • Abnormal zonular ligament morphology SEM, PAS in Tibetan Terriers, Curtis et.al. J.Comp.Path., 1983 • Lack of description of nature of abnormality using standard histopathlogy
Study Design • Hypothesis: determine whether LM can detect abnormal patterns in zonular ligament protein, any breed correlation • Search of COPLOW database for glaucoma caused by lens displacement • Selection criteria • Exclusions • Evaluation • From records: signalment and laterality • Histopathology: zonular ligament morphology, other morphological features
The normal make-up of the zonule • Fibrillin 1 & Fibrillin2 • Glycoprotein sub-units • Strung together as a “string of beads” • Surrounded by microfibril associated glycoprotein • Fibrillin also found as a component of elastin
Zonular protein classification • Normal • Abnormal • Zonular ligament dysplasia • Thick lamellar protein sheet tightly adherent to nonpigmented ciliary body epithelium • Collagenization • Filamentous, not tightly adherent
StainingCharacteristics Normal zonular protein Zonular ligament dysplasia Collagenization PAS Trichrome Elastin Stain
Results *includes 4 Shar-Peis
Average Age • Normal Zonule Profile: 10.7 years • Collagenization: 8.9 years • Zonular Ligament Dysplasia: 5.2 years
Laterality • OS: 39 • OD: 28 • Unknown: 5 • 9 dogs had both globes involved and 8 of these had zonular ligament dysplasia
Conclusions • LM is useful in detecting abnormal patterns in zonular ligament protein • “Normal” zonular ligament with glaucoma • Secondary to trauma or other disease process? • Zonular ligament dysplasia • Terriers and Shar-Peis, young, bilateral, distinct morphology • Collagenization • No breed predilection, older, possibly secondary to disease process