A Comparison of Cataract Surgery Alone and Cataract Surgery With iStent

Glaucoma is the commonest cause of irreversible blindness in the world. Treatment centres around lowering intraocular pressure (IOP) and typically includes medication (least invasive), laser, to surgery (most invasive). The gold-standard glaucoma operation is the trabeculectomy. Whilst it is effective at lowering IOP, it is associated with potentially devastating complications including bleb leak, hypotonous maculopathy, blebitis and endophthalmitis. In recent years, minimally- invasive glaucoma surgery (MIGS) has become an increasingly popular option of treating mild to moderate glaucoma. It is usually performed in conjunction with cataract surgery. The iStent (Glaukos Corporation, California, USA) is one of the most commonly utilised MIGS devices in the world and one of two Therapeutic Goods Administration (TGA)- approved MIGS devices in Australia. The iStent Inject® is the second generation iStent device and Australia is one of the first countries in the world to have access to this. So far there are no published randomised controlled trials comparing the effect of cataract surgery alone to combined cataract surgery with insertion of iStent Inject®.

This study aims to recruit patients of the Glaucoma Investigative and Research Unit (GIRU) of Royal Victorian Eye and Ear Hospital (RVEEH) with mild to moderate glaucoma who are due to undergo cataract surgery and randomise each to either cataract surgery or combined cataract surgery with iStent Inject® insertion. Only patients who meet the inclusion criteria and none of the exclusion criteria will be recruited. The outcomes measures of the study will be a comparison of: 1) extent of IOP reduction; 2) reduction in number of topical glaucoma medications; 3) patient treatment satisfaction - between the two treatment groups.

Inclusion criteria

• >18 years of age
• Diagnosis of mild-to-moderate open angle glaucoma
• Presence of cataract requiring surgery
• Good understanding of both verbal and written English
• Able to provide informed consent

Exclusion criteria

• Recent intraocular surgery within last 3 months
• Other ocular pathology affecting vision
• Inability to complete the elements of the study, eg: coma, hemodynamic instability, ventilator dependence, that could be of concern in the investigator's judgment.
• Non-elective hospitalisation within the past 60 days that could be of concern in the investigator's judgment.
• Medical illness that in the judgment of the investigator would jeopardise the safe completion of the study. Examples include cancer, chronic inflammatory disease, chronic liver insufficiency, epilepsy, thrombocytosis.