Managing the post-surgery cataract patient in practice

1 The correct answer is C. According to the Department of Health, cataract surgery is one of the most commonly performed operative procedures of any type in the UK with over 160,000 cases being done every year.

2 The correct answer is C. The operation itself is very safe and sight-threatening complications are very rare, most complications are transient and almost all patients have improved vision following surgery. Serious complications account for less than two in 1,000 cases. While this means that there will be several hundred serious complications each year due simply to the large number of cases being performed, the risk to each individual is very low.

3 The correct answer is A. Both studies reported similar levels of induced astigmatism. The mean difference from the pre-surgical refraction was 0.55DC for phaco surgery compared to 1.26DC for ECCE. The European study found a slightly higher rate of astigmatism but did not differentiate between phaco and ECCE surgery, stating simply that the majority of procedures were carried out by phaco.

4 The correct answer is D. Because the wound is so small and the scarring so slight with phaco surgery, the surgeon can perform the procedure along any axis. If the wound is made slightly bigger than required or is placed slightly closer to the visual axis than normal then this is thought to flatten the axis in which the incision is made. By delibetately operating in the steeper meridian, it is possible to reduce the level of pre-operative astigmatism.

5 The correct answer is B. The most serious complication is a supra choroidal haemorrhage (0.07 per cent in the UK study). When the incision is made in the eye, the IOP drops to zero. With the additional stress of the surgery, this can lead to bleeding of the choroidal vasculature. The choroid is so well vascularised that this haemorrhage quickly begins to fill the potential space between the choroid and the retina. The contents of the eye are forced forwards and out through the surgical incision in the cornea.

6 The correct answer is C. In the region of 23 per cent of patients are affected by transient early complications within the first 48 hours following surgery. In most cases these are not considered significant and many centres do not see patients for follow up until two weeks. Common complications include transient corneal oedema, raised IOP and mild anterior uveitis.

7 The correct answer is A. The most common cause of endophthalmitis is a coagulase-negative staphylococcus. These account for 70 per cent of cases. Other causes include streptococcus and other less virulent bacteria as well as fungi.

8 The correct answer is B. Complication rates are no higher for ECCE than for phaco. Phaco surgery is the newer technique and it is preferred by patients because of the faster recovery and improved visual outcome but it does appear to be a safer technique. However, even ECCE surgery is more safe now than it was 10 years ago. Complication rates for cataract surgery, regardless of the procedure used, have come down in the last 10 years and are likely to fall further as surgeons continue to improve their understanding of the causes of complications.

9 The correct answer is C. CMO can be treated with anti-inflammatory drugs including NSAIDs and steroids, but many cases resolve spontaneously after a few weeks. Alternatively, the vacuoles can coalesce and the CMO progresses to form a macular hole. CMO should be referred through a GP to see an ophthalmologist within a few weeks.

10 The correct answer is A. Retinal detachment following cataract surgery is likely to be of the rhegmatogenous type. RD is less common when a posterior IOL is used but is most likely to happen in patients who do not already have a posterior vitreous detachment (a common condition in older people). Cataract surgery can cause a PVD in patients who have not already had one but even in patients who have, the vitreous chamber is left more fluid after surgery because the space which used to be taken up by the cataractous lens is now filled with aqueous (the IOL is much smaller and thinner than the crystalline lens). Tears or breaks in the retina coupled with a more fluid posterior chamber are the requirements for a rhegmatogenous retinal detachment. Fluid seeps through the break and separates the retina from the underlying RPE.

11 The correct answer is C. In a senescent vitreous, white strands of coagulated vitreous which move around in the fluid vitreous are a normal finding. Look out though for small specs of brown pigment called tobacco dust. This pigmentation can be caused by pigment escaping from a retinal tear and in a healthy eye is strongly indicative of a retinal detachment.

12 The correct answer is A. Posterior capsule opacification is treated with YAG laser capsulotomy. The YAG laser is used to create a break in the posterior capsule on the visual axis. The surgery is very quick and painless, merely requiring the patient to sit at a slit lamp for a minute or two but YAG laser capsulotomy is not without risk.