A diagnosis of diabetes mellitus can be an overwhelming proposition for many families. Among the long list of possible complications is the almost inevitable prospect of blindness due to diabetic cataracts. Early client education and case management can help increase successful outcome for cataract surgery patients, and can also increase successful long-term management of cataracts in patients whose families elect to forgo surgery.
Diabetic cataracts are rapidly forming osmotic cataracts that form due to the shunting of excess glucose to the aldose reductase pathway in the dog lens. Aldose reductase metabolizes glucose to sorbitol, which is insoluble and accumulates within the lens, creating an osmotic gradient. When enough sorbitol accumulates in the lens, water from the surrounding aqueous humor spontaneously enters the lens, causing swelling of lens fibers and cataract formation.
Lens-induced (phacolytic) uveitis and its more severe counterpart phacoclastic uveitis are common complications of diabetic cataracts. In phacolytic uveitis, leakage of lens proteins causes an immune response and inflammation. This inflammation can range from mild to severe. Phacoclastic uveitis involves lens capsule rupture and exposure of a large amount of lens fibers, resulting in rapid fulminant inflammation. Some diabetic patients with high circulating triglycerides can develop lipemic flare, which is another extremely severe form of lens-induced uveitis. When lipid enters the anterior chamber, it exacerbates inflammation, increasing vascular leakage which increases lipid leakage, setting up a vicious cycle of escalating inflammation.
Both acutely severe and chronic mild inflammation can lead to secondary ocular complications. Common sequlae include posterior synechia, corneal endothelial damage and secondary glaucoma. The threat of complications has implications for all patients, whether or not cataract surgery is something the family wants to pursue. Therefore, I recommend early steps be taken to manage the threat of lens-induced uveitis regardless of a family’s inclination to pursue cataract surgery.
Because cataracts can develop rapidly at any time in a diabetic patient, I recommend topical non-steroidal anti-inflammatory drops be initiated BID OU at the time of diagnosis. A 0.5% Ketorolac, 0.03% Flurbiprofen or 0.1% Diclofenac ophthalmic solution are all good choices for this purpose.
If a family desires cataract surgery, early surgical intervention, when possible, maximizes successful outcome. I recommend beginning the above topical anti-inflammatory immediately, even before cataracts develop and an early referral to discuss and plan for cataract surgery. Watch for further installments in this newsletter regarding the degree diabetic control needed prior to surgery and for more information regarding the surgery itself.