How is cataract diagnosed

In many instances an observant owner will notice a difference in the look of an eye(s). The pupil will appear more cloudy rather than dark and there will be subtle changes in the animals ability to see eg walking into objects, inability or clumsiness when fetching. Many cases get referred because a veterinarian may notice a change during routine health examination. Many breeds have a greater propensity to develop cataracts so there is a greater awareness by breeders and owners of these breeds.

What will happen if cataracts are not removed

The longer a cataract remains in a dogs’ eye the more likely cataract associated pathology which can cause severe pain or permanent blindness will be seen. In most cases these cataract-related disorders could be avoided by early surgical cataract removal. These disorders are:

• The leading one is Lens Induced Uveitis.(LIU)–this is an autoimmune disorder in which the immune system launches an inflammatory response within the eye, when lens protein materials leaks out of the lens through the lens capsule. We are suspicious this is happening when one is presented with an eye with a mature cataract and a ‘red eye’. LIU can result in glaucoma, adhesions within the eye, pigment deposition and dislocation (luxation) of the lens.
• Dislocation or Luxation of the Lens — the longer a cataract remains in an eye the thicker and more contracted the anterior and posterior capsules become. This contraction process tears the supporting zonular ligaments leading to subluxation and eventual luxation.
• Posterior Capsular Opacities — these are more likely to form in mature cataracts and will cloud vision when the lens is removed (the posterior capsule is always left intact in cataract surgery to prevent vitreous prolapse). The longer a cataract is left in place the greater the chance of these forming.
• Pigment Deposition — this may follow cataract surgery if there has been a prolonged bout of LIU prior to surgery and effectively cause the same problems as capsular opacities.
• Glaucoma — prolonged LIU can cause adhesions which disturbs the flow of aqueous through the pupil or out the angle of filtration, thus producing a secondary glaucoma.
• Retinal Detachment — in the Bichon Frise there appears to be a high correlation between mature cataract and retinal detachment which results in permanent blindness. Early removal will greatly reduce the risk and the chance of retinal detachment.

When is the best time to remove cataracts

In the situation where it is evident that there is progression of the cataract(s) and the animals vision is becoming compromised, early referral is advised so that a full ophthalmic examination can be done with particular reference to the state of the retina. Some cataracts can form secondary to retinal disease e.g. I would always be suspicious of retinal disease if a five to six-year-old English Cocker or Labrador retriever developed cataract. At this point it may be advisable, depending on the rate of progression and the maturity of the cataract, to either monitor the situation or go to surgery.

In the case of an acute onset cataract e.g. diabetes, bearing in mind what may happen if the cataract is not removed, then early surgical intervention is best advised. If surgery is not contemplated or has to be postponed, then the eyes must be monitored for LIU and a start made on prophylactic topical anti-inflammatories if needed e.g. Predforte one drop one to two times daily.

Why is cataract surgery so expensive

Currently the cost of cataract surgery in our clinic is in the region of $1700-1900 for one eye to $2700-2900 for both. The equipment used for this procedure expensive with phacoemulsification units currently costing $50-$80000 and the consumables such as sutures and instruments are costly. This cost structure will also include several post-operative checks in Palmerston North or in any of the other clinics I visit in New Zealand.