The objective of this study is to compare the long-term (6 months) effects of Direct Selective Laser Trabeculoplasty (DSLT) treatment and SLT (Selective Laser Trabeculoplasty) treatment on corneal endothelial cell counts and corneal thickness.

Rational:

SLT has known transient effect on corneal endothelial cell (CEC) counts yet no data is yet available with DSLT.

This study is relevant as the DSLT treatment area is at the limbus: CEC progenitor site

Inclusion Criteria:

1. Age 40 years or older, with visual acuity > 6/60 in both eyes
2. Open angle glaucoma including exfoliative or pigmentary glaucoma or ocular hypertension.
3. IOP ≥ 22mmHg or ≤35mmHg (after washout of any IOP-lowering medications) for participants with open angle glaucoma or IOP ≥ 24mmHg to ≤35mmHg (after washout of any IOP-lowering medications) for participants with ocular hypertension
4. Gonioscopically visible scleral spur for 360 degrees without indentation
5. Ability to visualize the peri-limbal sclera for 360 degrees (using a speculum)
6. Willing and able to participate in the 12-month study, to comply with the study procedures and to adhere to the follow-up schedule.
7. Participant capable of giving informed consent

Exclusion Criteria:

1. Contraindications to conventional laser trabeculoplasty (e.g. corneal abnormalities etc.)

2. Angle Closure Glaucoma

3. Congenital or developmental glaucoma

4. Secondary glaucoma except exfoliative or pigmentary glaucoma

5. Inability to conduct a reliable visual field (defined as fixation losses, false positives or false negatives greater than 33%)

6. Presence of any Peripheral Anterior Synechiae (PAS) in the study eye

7. Any of the following visual field findings using the Humphrey visual field analyzer the SITA-standard 24-2 program:

   1. A visual field MD of worse than -12dB
   2. Greater than or equal to 75% of points depressed below the 5% level and greater than or equal to 50% of points depressed below the 1% level on the PD plot
   3. At least 50% of points (i.e., 2 or more) within the central 5 degrees with a sensitivity ≤0dB on the decibel plot
   4. Points within the central 5 degrees of fixation with a sensitivity <15 dB in both hemifields on the decibel plot

8. A visual field MD of worse than -12dB in the fellow eye

9. Cup:Disc Ratio more than 0.8

10. More than three hypotensive medications required (combination drops are considered 2 medications)

11. Prior incisional or laser glaucoma surgery (including previous SLT) in the study eye

12. Prior corneal refractive surgery

13. Complicated cataract surgery ≤ 6 months prior to enrollment

14. Presence of visually significant cataract in the opinion of the investigator

15. Clinically significant disease in either eye as determined by the Investigator

16. Clinically significant amblyopia in either eye

17. Dense pigmentation or haemorrhage in the peri-limbal conjunctiva or anterior sclera

18. Women who are pregnant or may become pregnant during the course of the study

19. In the opinion of the investigator the participant might require other ocular surgery within the 12-month follow-up period, unless for further reduction of their IOP.

20. Concurrent treatment with topical, nasal, inhaled or systemic steroids.

21. Uncontrolled systemic disease that could impact the ability of the participant to attend follow up visits as per the discretion of the investigator

22. Participation in another clinical study, not including a GLAUrious sub-study

We plan to share the protocol, statistical plan and results