The operation

This involves -

• General anaesthesia – The anaesthesia involves induction with an intravenous drug but maintenance for the duration of the surgery is oxygen and an anaesthetic gas (Isofluorane).

This ensures – (a) A smooth and quick post operative recovery.

(b) Minimal risk for older patients (a lot of our cataract patients are dogs over 10 years of age).

(c) A respiratory monitor is used in the anaesthetic system to warn of any problems during the surgery.

• Opening the cornea 180 degrees or if phacoemulsification is utilised, then a 3mm incision at 12 o’clock is used. Phaco is used on dogs up to 6 years of age. After this the lens becomes hard and the eye will have to be opened more

in order to extract the large lens.

• Removal of the lens material inside the capsule of the lens i.e. making the analogy between the lens and an egg – we remove the end of the egg shell and remove the contents leaving the residual egg shell to hold the eye contents in place.
• During the surgery these lens contents are released into the eye will cause an intense inflammatory reaction. The frequent drug therapy before and after surgery is designed to suppress this reaction but treatment may be necessary for several months afterward.
• The cornea is stitched back in place and the eye is reinflated with air and saline.

Pre and post-operative medications-what they achieve

• 1% Atropine – this keeps the pupil dilated to allow vision and reduce the possibility of adhesions of iris to residual lens capsule, reduces the pain from iris spasm in the eye and reduces the release of debris into the eye which can cause adhesions.

• Cortisone (steroid) eye drops eg. Predforte, – suppresses the inflammation within the eye. These drops:

(a) Will be used for a minimum of 4-6 weeks after surgery and maybe longer(months or indefinitely at a v low dose).

(b) Shake the bottle before use (esp. Predforte).

(c) If while using these drops the eye becomes ‘sore’ ie the eye blinks more than normal and is kept tightly closed, there is excessive production of tears, cornea goes blue with discomfort and the blueness is over most of the cornea or the animal suddenly starts rubbing the eye, stop the drops contact me or your own vet. I do not mind phone calls to my clinic or after hours to home or my mobile if you are concerned.

• Prednisone tablets – have the same effect as 2. A side effect of these tablets on the initial high dosage (we reduce the dose over a 4 week period) is that they:

(a) Increase your pets’ appetite – do not feed any more than necessary as they will put on weight.

(b) Increase the thirst and frequency of urination. Ensure there is plenty of fresh water available and let outside frequently!!!

(c) Cause your pet to be less active and pant a little more than normal. If you feel any of these side effects are excessive, please contact me.

• Rimadyl/Norocarp (20mg or 50 mg tablets) – has a similar effect to Prednisone but will not be used together. This drug is best given with food and has very good anti-inflammatory and pain relieving properties. We will often use these for the first 14-21 days after surgery then change onto Prednisone tablets if needed.

• Antibiotics – used immediately after surgery but will only be used as a course of treatment in diabetic animals because of their greater risk of infection.

The stitches in the cornea will dissolve in 6-8 weeks and they may cause a mild reaction in the cornea so that a low dose of eye drops may be needed.

The assessment of whether vision has been returned is best left for at least 2 weeks to allow debris within the eye to clear, although some vision may be attained within hours to several days. Creating an obstacle course, letting cotton wool balls fall in front of the eye or general behaviour around the house can be some guide. An examination by myself would allow more accurate assessment. The fact that the pupil is dilated with Atropine will reduce good optical function but this will improve when the pupil starts moving again (takes 5-7 days after the drops stop for this to occur)

It should be stressed that not every cataract operation is successful in restoring vision. Rarely is the eye ever lost or ends up looking a lot different to an observer but there are a variety of problems which can occur either during surgery or at varying periods afterwards, over which we have little or no control. These have already been mentioned.

These problems can be minimised by meticulous surgical technique, attendance to medicating the eye post operatively but even when everything seems right technically, restoration of vision may not eventuate. The success rate in my hands is high as we have the equipment and the experience to do this type of surgery.

My policy is not to charge for the first post operative visit as I would like to check on the progress of the eye for several months even years post operatively. The only future costs would be for any medication prescribed and a fee to cover rental costs at the clinics I use outside of Palmerston North.

Regards

Craig Irving -Specialist Veterinary Ophthalmologist

Ps –you have in the handouts relating to this ophthalmic service, my after-hours phone numbers and email address craigeyet@clear.net.nz which is probably the best means of contact unless the situation is urgent. I am very happy for you to ring if you have any problems or are unsure of what may be happening and cannot contact me at the clinic -a lot of time, effort and expense has gone into this surgery so I want to ensure its success. For peace of mind there may be a requirement for an earlier post-operative check than previously planned.