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Cataract surgery and vascular changes in the eye

While modern cataract surgery is manifestly successful and safe for the majority of patients, there are nevertheless some non-surgical reasons for unexpectedly poor visual outcome, and vascular reasons predominate. Choroidal haemorrhage can be a sudden and catastrophic event during surgery producing capsular rupture, vitreous prolapse and even occasionally total loss of the eye gaffe 1981; Taylor 1974). Lesser degrees of choroidal haemorrhage are not uncommon (Carroll 1973). It has been suggested that these haemorrhages occur when the transmural stresses accompanying the rapid and marked intraocular pressure changes occuring when the eye is opened during cataract surgery, are sufficient to cause rupture of a choroidal blood vessel. Ischaemic optic atrophy is an occasional unexpected finding after cataract surgery. In some cases the cause may well precede the surgery, but in others vascular changes which occur during the post-operative period may be responsible. Glaucomatous disc and field changes are well documented to progress in association with both cataract and glaucoma surgery (Davidson 1986). Cystoid macular oedema is reported of variable prevalence after cataract surgery. Current extra-capsular techniques are associated with a clinically significant degree of occurence (0.5%). Hitchings (1975) reported that over 50% of patients who had cataract surgery by the intracapsular technique showed fluorographic evidence of cystoid macular oedema 3 weeks after surgery, although in none was there a clinically significant reduction in vision. These changes may be caused by, or at least prolonged by vascular factors which are related to transmural changes in pressure, either concerned with reduction or elevation of intraocular pressure during or after cataract surgery.