Diabetic cataract in a dog

40 Diabetic cataract in a dog







CLINICAL EXAMINATION


General clinical examination will reveal the typical signs of diabetes in non-diagnosed patients, while those currently on treatment might have symptoms attributable to other disease processes which have affected their insulin metabolism. Thus they should be carefully examined for evidence of urinary tract infection, dental disease and signs of hyperadrenocorticism or hypothyroidism for example.


Ophthalmic examination will reveal reduced or absent menace responses and poor vision. Pupillary light reflexes are often normal, but occasionally are slightly sluggish. Some conjunctival hyperaemia or episcleral congestion can be present. The iris might be uniformly dark. However, the most striking abnormality is the presence of bilaterally symmetrical total mature cataracts. Frequently the lenses appear slightly ‘swollen’ (intumescent) and water clefts along the suture lines are apparent (Figure 40.1). Fundus examination is rarely possible. If intraocular pressure can be measured it is frequently slightly below normal (e.g. 8–12 mmHg). Lens-induced uveitis is very common in sudden onset cataracts, particularly those induced by diabetes mellitus. Schirmer tear test readings should be recorded and the cornea stained with fluorescein to check for ulceration.






CASE WORK-UP


Obviously the patient needs to be worked up for the diabetes and this should be stabilized as much as possible. Once the diagnosis is made via urine and blood glucose measurements, and the patient started on insulin therapy, discussions about referral for cataract surgery can be considered. Most ophthalmologists will only consider surgery when the patient is stable, with blood glucose curves and fructosamine assays used in addition to clinical parameters to assess this. Clearly full laboratory evaluation should be undertaken to ensure that they are free from other metabolic disease (such as hyperadrenocorticism) and severe dental disease is a contraindication for elective cataract surgery – this should be treated prior to elective phacoemulsification. However, some patients are difficult to stabilize, and since the surgical success is higher before complications such as severe lens-induced uveitis (with lens capsule rupture) have occurred, early surgical intervention is occasionally advocated. It is sensible to discuss the patient with your ophthalmologist as soon as the cataracts are diagnosed so that liaison can take place for the best outcome for the patient.



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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Diabetic cataract in a dog

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