UKEGS Consensus on MIGS

 

Minimally invasive glaucoma surgery (MIGS) offers safer, less invasive alternatives to traditional surgical procedures. Advantages include faster recovery, shorter operations and reduced medication burden via trabecular-bypass or suprachoroidal routes. There is increasing evidence of efficacy justifying adoption and integration into modern glaucoma care, yet considerable inconsistency in practice remains, emphasising the need for guidelines.

Members of UK and Eire Glaucoma Society (UKEGS) have performed a nationwide survey to assess variations in practice and gaps in current policies on MIGS.

The survey found that there was a firm belief among the respondents that MIGS procedures have an important role in glaucoma management and that they can slow vision loss (95%, n = 76), reduce the need for further pressure-lowering incisional glaucoma surgery (94%, n = 75) and lower the burden of medical therapy (98%, n = 78). 

There were some differences in opinion about whether MIGS might divert resources from more critical areas, with 57% (n = 45) expressing this concern, whilst 44% (n = 35) disagreed: highlighting the need for robust cost-effectiveness data to guide resource allocation.

When asked who should be offered MIGS procedures, responses varied: 33% (n = 26) favoured offering MIGS to a minority of carefully selected patients, 55% (n = 44) supported use for all patients taking intraocular pressure-lowering medications, 16% (n = 13) advocated offering MIGS to all glaucoma patients and 5% (n = 4) selected none of these options. 

These findings emphasise the need to establish clear guidelines for standardising patient selection, ensuring that the treating surgeon possesses a comprehensive understanding of glaucoma progression, risk assessment, and alternative treatments options. Such expertise is typically limited to those trained in the subspecialty. 

When asked whether MIGS procedures should be confined to glaucoma specialists, 88% (n = 70) agreed, 85% (n = 67) believed MIGS should not be carried out by surgeons whose primary focus is cataract surgery. This is a valid concern: while carrying out MIGS may be technically feasible, selecting the correct procedure is more complex. The growing range of devices and techniques—often lacking RCT evidence—means balancing immediate risks against long-term benefits demands a detailed understanding of prognosis as well as surgical expertise.

Areas of concern:

The survey raised concerns about independent sector treatment centres (ISTCs) performing MIGS or cataract surgery in glaucoma patients. ISTCs may not be best placed to provide the specialised expertise for the complexities of selecting appropriate MIGS and still less so the careful provision of long-term follow-up patients require.

A major concern is the lack of counselling about MIGS during surgical consultations for glaucoma patients. Not discussing these procedures risks missed opportunities to optimise intraocular pressure control, reduce medication burden, and enhance quality of life. Standardising this discussion could help reduce disparities in access and ensure equitable, comprehensive care.

Future outlook:

Most respondents (61%, n = 48) deemed the process of introducing these new procedures achievable, with 30% (n = 23) describing it as straightforward. However, 10% (n = 8) identified the process as challenging, reflecting mixed institutional readiness. Looking ahead, 78% (n = 62) anticipated an increase in the use of MIGS at their respective hospitals, signalling growing confidence in its clinical benefits and integration into glaucoma management.

Based on these findings, the UKEGS recommends the following guidelines:

1. The decision to perform MIGS should be made by the clinician overseeing a patient’s long-term glaucoma care, with the procedure only being performed by surgeons with specialist training and experience in managing the condition over time
2. Ensure all glaucoma patients undergoing cataract surgery are offered MIGS and made aware of the potential benefits.
3. Develop standardised materials to educate patients on MIGS and the evidence to help decision-making.
4. Limit MIGS use in independent sector treatment centres (ISTCs) to surgeons with glaucoma fellowship training.

REFERENCE:

Abdus Samad Ansari et al. Building consensus on MIGS: insights from a UKEGS survey. Eye volume 39, pages2107–2109.

COMPARISON OF DRI-OCT WITH HRT3

Glaucomatous optic neuropathy involves characteristic optic disc as well as retinal nerve fiber layer (RNFL) structural damage and related functional defects.

Tests of structural integrity include the Heidelberg Retinal Tomograph 3 (HRT3, Heidelberg Engineering GmbH, Heidelberg, Germany) and the continuously evolving technology of optical coherence tomography (OCT).

The HRT3 is a confocal scanning laser tomography (CSLO) device that uses a diode laser (670 nm) to scan the retinal surface at multiple consecutive parallel focal planes and produces repeatable and reproducible three-dimensional (3D) topographical images of the ONH and peripapillary RNFL. After image acquisition, the margins of the optic nerve head (ONH) need to be outlined by a manually drawn contour line to calculate ONH stereometric parameters. HRT3 also provides two different algorithms for ONH anatomy classification: the Moorfields regression analysis (MRA) that requires a contour line to be placed, and the newer contour-line independent Glaucoma Probability Score (GPS). The quantitative and objective measures of these structures are consequently classified as within normal limits (WNL), borderline, or outside normal limits (ONL) by automatic comparison with an ethnic-selectable normative database of eyes.

Deep range imaging OCT (DRI-OCT, Triton, Topcon, Tokyo, Japan) is a recently introduced swept-source OCT (SS-OCT) that uses a center wavelength of 1,050 nm and a bandwidth of approximately 100 nm compared to the fixed 850 nm wavelength of spectral-domain OCT (SD-OCT). The instrument achieves a high scan speed (100,000 A-scans/second) that allows for the acquisition of high-quality wide-field images containing both the ONH and the macula in a 12 mm × 9 mm single scan. SS-OCT, similar to SD-OCT, also provides separate standard macula and optic disc scan modes. Both thickness measurement values and normative comparisons are provided for all SS-OCT measurements.

DRI-OCT Triton: 3D wide(H) glaucoma report. A 75-year-old female with primary open-angle glaucoma in her left eye.
(A) Conventional color photography of the ONH. (B, C) macular GC analysis*. (D) Color-coded RNFL thickness map that corresponds to numeric RNFL thickness measurements. (E) SuperPixel-200 map. The uncolored pixels indicate the normal range, whereas the yellow- and red-colored pixels indicate abnormality at P = 1-5% and P < 1% of the normal level, respectively. (F) cpRNFL analysis*. (G) Numeric measurements of five ONH parameters

Kourkoutas and colleagues from Greece, have performed a study to determine the diagnostic performance of the ONH, macular, and circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements of wide-field maps (12 × 9 mm) using SS-OCT compared to measurements of the ONH and RNFL parameters measured by HRT3. 

They also evaluated the diagnostic ability of wide-field DRI-OCT thickness measurements (optic disc, RNFL, and macular) to differentiate glaucomatous from healthy eyes and compared them with the six main ONH stereometric parameters as well as with the GPS and MRA classification algorithms of the HRT3.

The authors found the highest sensitivities were achieved by the DRI-OCT categorical parameters of Superpixel-200 map and cpRNFL (12 sectors) thickness analysis. The best performing HRT3 continuous parameter was rim volume (AUC = 0.829, 95% confidence interval (CI) = 0.735-0.922), and the best continuous parameter for DRI-OCT wide-field was vertical CDR (AUC = 0.883, 95% CI = 0.805-0.951), followed by total cpRNFL thickness (AUC = 0.862, 95% CI = 0.774-0.951). Area under the curve (AUC) for disc area, rim area, linear CDR, and RNFL thickness were not significantly different between the two technologies. Using either the most or the least specific criteria, SuperPixel-200 map always showed the highest sensitivity among the categorical parameters of both technologies (82.1% and 89.7%, respectively). The highest sensitivity among HRT3 classification parameters was shown by MRA and GPS classification algorithms.

The study concluded that both wide-field DRI-OCT maps and HRT3 have good diagnostic performance in discriminating glaucoma from healthy eyes. However, DRI-OCT thickness values and normative diagnostic classification report the best performance.

REFERENCE:

Kourkoutas D, Triantafyllopoulos G, Georgiou I, Karamaounas A, Karamaounas N, Sotiropulos K, Kapralos D. Comparison of Diagnostic Ability Between Wide-Field Swept-Source Optical Coherence Tomography Imaging Maps and Heidelberg Retina Tomograph 3 Optic Nerve Head Assessment to Discriminate Glaucomatous and Non-glaucomatous Eyes. Cureus. 2022 Aug 19;14(8):e28188. doi: 10.7759/cureus.28188. PMID: 36158420; PMCID: PMC9482818.

24-HOUR FLUCTUATIONS IN IOP FOLLOWING TREATMENT

 

Glaucoma patients are assessed in the clinic during the office hours and their IOP checked in the sitting position. 

However, supine positioning during sleeping hours is associated with decreased blood pressure and increased IOP, which results in decreased perfusion to the eye, including the optic nerve. It has been theorized that this reduced ocular perfusion pressure (OPP) may increase optic nerve damage and associated vision loss.

Fluctuation in IOP over a 24-hour period is attributed to autonomic or humoral control, changes in vascular tone, and bodily postural changes. 

A pilot study to evaluate and compare the 24-hour habitual fluctuations in IOP and OPP in glaucoma patients treated with medical therapy, selective laser trabeculoplasty (SLT) or trabeculectomy was performed by Ruparelia and colleagues from the Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS, Canada.

Recruited patients were admitted to the sleep lab for 24-hour serial habitual IOP and blood pressure measurements. IOP and OPP fluctuation among the 3 treatment groups were compared.

The IOP measurements were obtained using Goldmann applanation tonometry and with the patient in upright position. Nocturnal (8 pm, 12 am, 4 am) IOP measurements were obtained via Perkins applanation tonometry and with the patient in the supine position for at least 30 minutes prior to measurement. Brachial blood pressure (BP) was measured using an automated sphygmomanometer. 

Thirty three (33) eyes from 33 patients were recruited in this study, including 11 patients in the medical therapy group, 11 patients in the SLT group, and 11 patients in the trabeculectomy group. 

The medical therapy group was found to have significantly higher 24-hour IOP fluctuation (8.3 ± 1.6 mmHg) than the SLT (3.5 ± 1.9 mmHg) and trabeculectomy (4.3 ± 1.3 mmHg) groups (P < 0.001). 

Mean 24-hour OPP fluctuation was also significantly higher in the medical therapy group (18.5 ± 4.0 mmHg) than the SLT (11.9 ± 7.3 mmHg) and trabeculectomy (14.1 ± 3.9 mmHg) groups (P < 0.05). 

No difference in IOP or OPP fluctuation was found between SLT and trabeculectomy groups (P > 0.05).

Therefore, both SLT and trabeculectomy may be more effective in reducing 24-hour IOP and OPP fluctuation than medical therapy alone. IOP and OPP fluctuation was comparable between SLT and trabeculectomy cohorts. 

REFERENCE:

Ruparelia S, Bonatti R, Murphy JA, Nicolela MT, Eadie BD, Chauhan BC, Dyachok OM, Shuba LM. Twenty four-hour intraocular pressure fluctuation in treated glaucoma patients: a pilot study. Can J Ophthalmol. 2025 Aug;60(4):216-221. doi: 10.1016/j.jcjo.2024.11.010. Epub 2025 Jan 14. PMID: 39719016.

HEAD ELEVATION AND GLAUCOMA

Several nighttime events including increased IOP, decreased ocular perfusion pressure (OPP), and possibly obstructive sleep apnea (OSA) contribute to the development and progression of glaucomatous optic neuropathy. These events may explain the occurrence and progression of glaucomatous disease in the setting of seemingly controlled office-measured IOP. [1]

A study by Buys et al., has shown the 30-degree head-up sleeping position lowers IOP compared with the flat position. Although this effect varies between individual patients, mean IOP was 20% lower in one third of patients in this series.[2]

Several studies have shown that raising the bed head by 30-degrees significantly lowers IOP compared to the supine position. However, the method applied to elevate the head plays a significant role in IOP reduction. For example, while bed head elevation (BHE) is useful, resting on multiple pillows (MP) does not appear to offer the same IOP reduction in glaucoma patients.[3]

Some researchers studied the effect of sleeping in a head-up position using a wedge pillow in glaucoma patients, and healthy subjects. They have demonstrated reduction of mean IOP by 1.5–3.2 mm Hg in the head-up position compared with the flat position.[3]

Lazzaro et al also studied the effect of sleeping in a 20° head-up position in 15 glaucoma patients and 15 non-glaucoma patients. They demonstrated lower nocturnal IOPs (−1.5 mm Hg) with head-up position as compared with the head-flat position in patients with and without glaucoma.[4]

However, Natasha G reported that lying down increases IOP but also improves ocular blood flow. This could affect progression of glaucomatous optic nerve degeneration.[5]

REFERENCES:

1. Aref AA. What happens to glaucoma patients during sleep? Curr Opin Ophthalmol. 2013 Mar;24(2):162-6.
2. Buys YM, Alasbali T, Jin YP, Smith M, Gouws P, Geffen N, Flanagan JG, Shapiro CM, Trope GE. Effect of sleeping in a head-up position on intraocular pressure in patients with glaucoma. Ophthalmology. 2010 Jul;117(7):1348-51.
3. Yeon DY, Yoo C, Lee TE, Park JH, Kim YY. Effects of head elevation on intraocular pressure in healthy subjects: raising bed head vs using multiple pillows. Eye (Lond). 2014 Nov;28(11):1328-33. 
4. Lazzaro EC, Mallick A, Singh M, Reich I, Elmann S, Stefanov DG, et al. The effect of positional changes on intraocular pressure during sleep in patients with and without glaucoma. J Glaucoma. 2014;23:282–287.
5. https://www.medscape.com/viewarticle/night-shift-should-patients-glaucoma-sleep-their-head-raised-2025a10005rn

Seeing the bigger picture in glaucoma care

 

In some cases, systemic causes can be associated with glaucoma. 

Occasionally, it becomes difficult to understand the mechanism of glaucoma in patients. In such cases systemic evaluation might prove to be a useful approach. 

touchOPHTALMOLOGY recently conducted this interview to have a view about this issue.

The complete interview is available at this link:

https://touchophthalmology.com/insight/seeing-the-bigger-picture-in-glaucoma-care/