aqueous release to treat iop spikes post-cataract surgery

Conditions: Post-Op Complication; Raised Ocular Pressure

Summary: intraocular pressure (iop) rise after cataract surgery is an important and common problem. over 300,000 cataract operations are done per year in the united kingdom alone. iop rise can adversely affect vision and can be particularly detrimental in glaucoma patients with pre-existing visual field defects. the aim of this study is to evaluate the efficacy and safety of aqueous humor release (also known as burping of the wound), a procedure that has been used for decades to quickly reduce acute iop spikes following cataract surgery. currently there is no published evidence on a standard technique to perform wound burping. similarly there is uncertainty around the amount and duration of the iop decrease, and the type and frequency of complications eventually associated. this will be the first research project formally evaluating this procedure. this study will also help allay issues over fluid release in high iops and consequences of such dramatic iop drop which concerns ophthalmologists who do not routinely use this technique.

at present there is no de facto standard to manage acute intraocular pressure (iop) rise following cataract surgery. several drugs, both topical and systemic, have been tested for their ability to blunt the acute iop spike, nevertheless none has proven to be superior and consistently effective. oral acetazolamide has demonstrated to help controlling iop spikes following cataract surgery in glaucomatous eyes. however there are still constraints in its widespread use, as it may be contraindicated in patients with poor renal function, sickle cell disease and sulpha drug allergy. as a result, many units including moorfields eye hospital have used a technique called known as 'burping of the corneal wound' to release fluid from inside the anterior chamber of the eye. this makes logical sense as it reduces the pressure immediately and may remove some of the causes for raised iop such as retained viscoelastic and inflammatory molecules from inside the eye. this technique has also been used to reduce iop in patients already receiving pharmaceutical treatment. the technique has been used for decades, however, there is no published evidence of a proposed technique, range of iop decrease or frequency of complications. thus, most surgeons in most units are cautious of 'burping the wound' as it may induce infection or other complications compromising the surgical outcome due to the sudden reduced iop reduction. nevertheless a similar approach, needle penetrating the eye to release aqueous and reduce iop, is becoming more popular as the first approach to treat an acute angle closure crisis, where the presenting iop is often very high, i.e. a much more difficult and dangerous situation than post cataract surgery.

Eligibility criteria:
inclusion criteria: * patient whose post-operative iop was regarded to be too high for visual safety, or higher than 30mmhg, on the same day or within 1 week of the surgery exclusion criteria: * patients with iop less than 30 mmhg or iop deemed by clinician not too high to treat * patients unable to cooperate * patients who have undergone complicated cataract surgery