Open Angle Glaucoma and Cataract Clinical Trial
Official title:
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
- This study investigates if the occurrence of CMO after cataract surgery is affected
by the use of PGA drops by patients with glaucoma
- The null hypothesis states there is no increase in the incidence of CMO on OCT
scanning in the 4 weeks following cataract surgery whether PGA eye drops continue
or are stopped.
- Design
- Randomised control study with parallel group design
- Single masking of outcome assessors
;