Glaucoma eye drops, or not: what five and six years of trials found

Almost every newly diagnosed patient starts on glaucoma eye drops. Two long UK trials tested what happens when they do not. In the Treatment of Advanced Glaucoma Study, at five years, the patients randomised to surgery and the patients randomised to drops rated their own vision almost identically: 83.3 out of 100 on the 25-item Visual Function Questionnaire against 81.3, a difference of 1.01 with a confidence interval running from –1.99 to 4.00. On the trial’s primary outcome, there was nothing in it.

Their visual fields were not identical. Mean deviation was –14.30 dB in the surgery arm and –16.74 dB in the medication arm, a difference of 1.87 dB that did not straddle zero (95% CI 0.87 to 2.87). Pressures were 12.07 mmHg against 14.76. Safety events, the worry with a primary trabeculectomy, occurred in 52.2% of the surgery arm and 57.9% of the medication arm, a relative risk of 0.92, which is to say no signal of extra harm.

TAGS recruited 453 adults with newly diagnosed advanced open-angle glaucoma from 27 UK secondary care departments. It answers the question an optometrist actually faces when a field comes back badly damaged at first presentation: does it matter what this patient is started on?

The same shape at the other end of severity

LiGHT asked the same question for newly diagnosed ocular hypertension and early glaucoma, with selective laser trabeculoplasty as the alternative to drops. At six years, 633 of the 692 patients who finished the first three years entered the extension and 524 completed. Quality of life came out level again: no significant difference on the EQ-5D-5L, the Glaucoma Utility Index or the GQL-15.

The clinical numbers did not come out level. Just under seven in ten eyes started on laser, 69.8%, were still at or below target pressure at six years with no drops and no surgery. And more eyes progressed in the drops arm than the laser arm: 26.8% against 19.6%, p = 0.006.

What a year of drops does to a surface that has never seen them

The ocular surface case against chronic drops is usually argued from patients who have been on them for years, which makes it hard to separate the drug from the disease from the decade. A 2026 prospective study took 88 eyes of 44 treatment-naive patients and measured them before and after a year of first-line therapy.

Total corneal thickness barely moved, from 537.6 to 533.8 µm, and that change was not significant. The epithelium did: total epithelial thickness fell from 45.6 to 43.9 µm, and that one was. Tear break-up time dropped from 8.3 to 6.9 seconds, the lipid layer from 3.8 to 3.0 nm, and OSDI nearly doubled, 7.3 to 13.4.

None of that is catastrophic in a year. All of it is the first year of what may be thirty.

Where glaucoma eye drops actually sit

The ocular surface argument is real, and measurable inside twelve months in eyes that had nothing wrong with them. It is not, on its own, the argument for laser or surgery first. That argument is progression: 19.6% against 26.8% in LiGHT, 1.87 dB in TAGS. The surface is why a patient stops taking the drops, which is a different problem and just as important.

Patients on drops and patients who avoided them rate their vision the same. The person in front of you has no way of feeling 1.87 dB. That makes the case for offering laser first an entirely clinical one, and it puts the job of making it on whoever is holding the fields, which, increasingly, is the high street. The Danish pathway in what putting OCT into 79 optician stores did to referrals is the same argument from the other end.

The limitations worth carrying into clinic

TAGS randomised people whose glaucoma was already advanced when it was found, so its result does not transfer to every new diagnosis. LiGHT randomised the opposite end: treatment-naive ocular hypertension and early glaucoma. Neither asked what happens to someone already established on drops, which is most of the patients an optometrist sees. The ocular surface figures are one cohort of 44 patients followed for a year; they show what the first year does, not the tenth.

Why it matters in practice

• A newly diagnosed patient who asks whether they have to be on drops for life now has a real answer: in LiGHT, seven in ten eyes started on laser were still controlled at six years without them.
• A patient already on drops who reports grittiness, fluctuating vision or a short break-up time is describing something the trials measured at one year in eyes with no prior disease. It is worth recording, and worth saying in the referral.
• A field that is already advanced at first presentation is the TAGS population. The referral letter that says so is the one that gets the conversation about primary surgery started.
• Neither trial says drops are wrong. Both say the choice is worth making deliberately rather than by default.

Sources

1. 1.Evaluating primary treatment for people with advanced glaucoma: five-year results of the Treatment of Advanced Glaucoma Study (TAGS) · Ophthalmology, 22 April 2024
2. 2.Laser in Glaucoma and Ocular Hypertension (LiGHT) Trial: six-year results of primary selective laser trabeculoplasty versus eye drops for the treatment of glaucoma and ocular hypertension · Ophthalmology, 1 February 2023
3. 3.Effect of first-line topical medications for the treatment of glaucoma on the ocular surface · International Ophthalmology, 1 January 2026
4. 4.Is primary trabeculectomy cost-effective for patients with advanced primary open-angle glaucoma? Five-year results of the Treatment of Advanced Glaucoma Study · British Journal of Ophthalmology, 26 August 2024