A Randomised Control Study to Investigate if the Continuation of Prostaglandin Analogue Treatments in the Post-operative Phase of Glaucoma Patients Undergoing Cataract Surgery Increases the Incidence of Cystoid Macular Oedema.
A Randomised Control Study to Investigate if the Continuation of Prostaglandin Analogue Treatments in the Post-operative Phase of Glaucoma Patients Undergoing Cataract Surgery Increases the Incidence of Cystoid Macular Oedema.
Post-operative cystoid macular oedema (CMO) is a common complication causing visual loss following routine cataract surgery. This complication is more prevalent in eyes with excessive inflammation as they heal from surgery.
Prostaglandin analogues (PGA) are the commonest first line drugs used in the long-term treatment of primary open angle glaucoma (POAG)- where they reduce the pathologically high pressure in the eye. Prostaglandins are inflammatory mediators.
In the post-operative care of glaucoma patients undergoing cataract surgery, there is a clinical dilemma whether to stop or continue the use of prostaglandin eye drops. Clinical practice is completely dichotomized between continuing and stopping PGA treatment in the postoperative period. There is conflicting scientific literature on the effect of PGA on the incidence of CMO; and only a single randomized control trial (Miyake K, Arch Ophthalmol 1999, 117:34-40), where the post operative regime is not applicable to present practice, compared the incidence of CMO following routine cataract surgery in POAG on PGA.
This study aims to answer the common clinical question of whether or not to stop PGA after routine cataract surgery. Cataract surgery is the commonest operation performed on the NHS and the prevalence of glaucoma is 5% in the population over 80 years old. Thus the clinical dilemma is a common one.
A current literature search reveals that a divided opinion over whether PGAs do increase the incidence of CMO. No study has yet established a causal relationship between the use of PGAs and the development of CMO. Anecdotal reports and small case series have associated peri-operative PGA use with the occurrence of CMO (Henderson BA et al, 2007 J Cataract Refract Surg 33:1550-1558; Moroi SE et al, 1999, Ophthalmology 106:1024-1029). Whilst, in direct contrast, other authors argue CMO as a rare phenomenon and the causative relationship is debated (Schumer RA et al 2000, Curr Opin Ophthalmol 11:94-100; Miyake K et al 2003 J Cataract Refract Surg 29:1800-1810)
The most similar previous study to the one proposed, was by Miyake K et al. (Arch Ophthalmol 1999, 117:34-40). The key difference, though, is in the postoperative drop regime of fluorometholone and diclofenac in that paper and current UK clinical practice of using dexamethasone. In terms of study design, this paper used an invasive method of investigating CMO by fundus fluorescein angiography compared to OCT proposed here.
A recent case report by Agange N & Mosaed S (Journal of Ophthalmology, 2010) concludes with 'conclusions about causal relationships cannot be made without well-designed, prospective clinical trials addressing this issue'.
This study will therefore use drops that are routinely used in current UK clinical practice and add to the body of evidence that helps answer the question should PGAs be continued after cataract surgery so as to prevent the progression of glaucoma in patients.
Aim
Design
Inclusion Criteria:
Exclusion Criteria:
Subjects with additional risk factors for macula oedema (eg. diabetic retinopathy, previous macula oedema, uveitis)
Subjects with advanced glaucoma
Subjects with non-controlled intraocular pressure (IOP) (pre-operative IOP >22 mmHg)
Any contra-indication to the use of topical prostaglandin drops
Any contra-indication to the use of routine post-operative dexamethasone 0.1% eye drops
Pregnancy
Patients unable to give informed consent
Intra-operative complication during cataract phacoemulsification and intraocular lens implantation