The purpose of this study is to assess whether endoscopic cyclophotocoagulation added to cataract surgery lowers intraocular pressure more than cataract surgery alone in patients with normal tension glaucoma.

Subjects with normal tension glaucoma that is stable with current medication needing cataract surgery are recruited in the study. All patients meeting the inclusion criteria and giving informed consent will be randomized to whether having endoscopic cyclophotocoagulation performed in the same session with cataract surgery, or cataract surgery alone.

Inclusion Criteria:

• Signed Informed Consent
• Normal Tension Glaucoma with typical nerve fiber layer defects in red-free photographs and/or optical coherence tomography (OCT) and possible equivalent visual field defects, IOP never more than 21 mmHg, and open anterior chamber angle
• Glaucoma stable with current medication assessed by a glaucoma specialist
• Clinically significant cataract

Exclusion Criteria:

• Secondary Glaucoma e.g. due to previous injury or uveitis
• Exfoliation syndrome
• Pigment dispersion syndrome
• Previous transscleral or endoscopic cyclophotocoagulation
• Previous other glaucoma surgery
• Cataract due to eye injury or congenital cataract
• Zonular weakness due to Marfan syndrome or other
• Previous retinal detachment
• Previous intraocular surgery like vitrectomy and other retinal surgery
• Wet age-related macular degeneration
• Diabetic retonopathy
• Previous corneal transplant or previous refractive surgery
• Fuchs' dystrophy and other abnormalities compromising corneal clarity like scars
• The patient does not want to participate in the study
• The glaucoma progresses on current IOP
• The patient does not speak Finnish, Swedish or English
• Dementia
• Only eye with vision worse than 20/200 or loss of central visual field