MRI IN GLAUCOMA (PART 1)

 

Magnetic resonance imaging (MRI) is currently not a standard investigation in most glaucoma patients. However, a number of studies have shown striking central nervous system (CNS) changes in MRI studies in such patients.

The advanced MRI used in glaucoma brain detection mainly involves the following 7 types of methods: 

1. MRI quantitative morphometry; 

2. Blood oxygenation level dependent functional MRI (BOLD-fMRI); 

3. Diffusion-weighted imaging (DWI); 

4. Magnetic resonance spectroscopy (MRS); 

5. Diffusion tensor imaging (DTI); 

6. Diffusion kurtosis imaging (DKI); and 

7. Magnetization transfer imaging (MTI).

MRI quantitative morphometry:

It is now possible to image brain structure, volume, and microstructural damage.

The techniques for quantitative evaluation of brain morphology can be divided into 2 types: voxel-based morphometry (VBM), and surface-based morphometry (SBM).

The VBM technique uses a statistical method to allocate the probability that a voxel is occupied by gray matter, whereas SBM determines the vertices defining the interface surface of gray matter cerebrospinal fluid (CSF) and gray and white matter, and uses these vertices to estimate the thickness of the cerebral cortex with submillimeter accuracy.

Using MRI VBM, Hernowo et al. found that the volume of all structures of the visual pathway in glaucoma patients was significantly reduced, including the optic nerve, optic chiasm, optic tract, LGN, and optic radiation. The volumetric MRI techniques have observed a decrease in occipital surface area or visual cortex volume in both hemispheres of glaucoma patients.

In terms of the severity of glaucoma, Wang et al. used T1 weighted MRI images to conduct VBM and SBM analysis on the whole brain. They found that in patients with glaucoma, the left LGN volume was negatively correlated with the bilateral optic cup disk ratio, the right LGN volume was positively correlated with the average deviation of the right VF, and the right V1 cortical thickness was negatively correlated with the right optic cup disk ratio. In patients with primary open angle glaucoma (POAG), these changes in brain visual structure can reflect the clinical severity of glaucoma.

Blood oxygenation level-dependent functional MRI (BOLD-fMRI):

The BOLD effect is the most commonly used method to obtain information related to brain function. It is an indirect measurement of cortical activity. The BOLD-fMRI is a non-invasive imaging method that uses deoxyhemoglobin as the natural contrast agent in vivo to monitor blood oxygen levels of the brain in real-time.

Different Rs-fMRI studies of glaucoma have shown decreased connectivity in regions associated with vision. 

POAG results in decreased cortical activity in the visual cortex, including the central region. Primary angle closure glaucoma (PACG) showed decreased activity in the bilateral secondary visual cortex (BA18). 

Reduction of BOLD activity may also involve many areas of non-visual pathways.

PACG is mainly related to frontal lobe dysfunction. Chen et al. used the ReHo method and found that PACG was involved in abnormal spontaneous brain activities in multiple brain regions, such as the left fusiform gyrus, left anterior cerebellar lobe, right frontotemporal space and right insula, bilateral middle occipital gyrus, and the right paracentral lobule. 

Patients with PACG show abnormal spontaneous neural activity in the visual cortex, sensorimotor cortex, frontal lobe, frontal parietal lobe network, and the DMN. This indicates that the visual, cognitive, and emotional functions of individuals with PACG may be impaired.

Zhang et al. used Rs-fMRI to analyze the brains of patients with NVG and revealed dysfunction in the brain regions of the right romantic operculum, left antagonist cingulate and paracingulate gyri, left precuneus, and the right caudate. Peng et al. observed abnormal spontaneous activity in NVG patients in the right cuneus, right middle occipital gyrus, left cingulate gyrus, right precuneus, left medial frontal gyrus, right superior frontal gyrus, and left middle frontal gyrus. These abnormal changes in specific brain regions can be considered possible clinical indicators of NVG.

In terms of the severity of glaucoma, some researchers have observed that in mild and moderate cases of glaucoma, the primary visual cortex seems to be more affected than other advanced visual areas. For example, abnormal spontaneous neural activity in the left wedge, bilateral middle temporal gyrus, and the right prefrontal cortex have been shown to be associated with the severity of POAG.

At present, fMRI is a very interesting clinical research tool for understanding how glaucoma functionally affects the central nervous system; however, it still has some limitations. First, fMRI technology is based on the premise that neural networks are associated with anatomic known visual regions, but other neural network components which may be affected by glaucoma cannot be clearly defined. Second, fMRI signal has low-temporal resolution due to down-sampling and indirectly measures underlying neuronal activity.

DRIVING DIFFICULTIES IN GLAUCOMA PATIENTS

Glaucoma patients with significant visual field (VF) defects show poorer driving performance, higher collision risks, and a greater likelihood of driving cessation. They face difficulties with lane maintenance, slower hazard responses, and self-regulation while driving.

A systematic review to study the impact of glaucomatous VF loss on the driving performance of glaucoma patients, the extent of driving limitation and cessation, as well as the risk of motor vehicle collisions (MVCs) has been conducted by Toh et al.

23 studies were included for the final review. 

The study reported that moderate to severe VF defects resulted in poorer driving performance, with slower response times to road hazards, decreased ability for lane maintenance, and increased difficulty driving at night. 

Patients with more severe VF defects and with bilateral glaucoma were more likely to limit or cease driving compared with those with milder and unilateral glaucoma. 

A greater severity of VF loss was associated with a higher risk of MVCs.

The study concluded that more severe glaucomatous VF and bilateral glaucoma is associated with worse driving performances and a higher risk of MVCs, in both simulator and real-world settings.

REFERENCE:

Toh, Zhi Hong MBBS (S’pore), MMed (Ophth), FRCOphth*; Koh, Serene Yi Ning†; Yang, Wei Yun Lily MBBS (S’pore), DAvMed (Lond.)‡; Munro, Yasmin Lynda MSc (IS)§; Ang, Bryan Chin Hou MBBS (S'pore),FAMS (S'pore), FRCOphth*,†,§,∥. The Effect of Glaucomatous Visual Field Defects on Driving: A Systematic Review. Journal of Glaucoma 34(11):p 837-852, November 2025. | DOI: 10.1097/IJG.0000000000002633 

SEGMENTAL AQUEOUS HUMOUR OUTFLOW

Does aqueous humor outflow (AHO) occur uniformly from the eye?

Studies have reported wide variation in the AHO in glaucomatous and non-glaucomatous eyes. 

A study using aqueous angiography (AA) was performed by Beri et al, to evaluate AHO pathways in nonglaucomatous subjects. The study found there is a segmental pattern of outflow, with the nasal quadrant having the maximum and the temporal quadrant having the least AHO pathways.

A cross-sectional, observational, single-center study recruited 30 subjects with visually significant age-related cataract planned for phacoemulsification. AA was performed using indocyanine green (ICG) dye 0.1% just before phacoemulsification. Images were analyzed at 60 seconds from the injection of ICG dye for angiographic signal intensity in 4 quadrants and 8 sectors, circumferentially (360 degrees) along the limbus. Signal intensities were evaluated and compared between quadrants and sectors as the primary outcome measure. Signal intensities between males and females, right and left eyes were assessed as secondary outcome measures, using appropriate statistical tests.

Segmental AHO was noted in all patients. The median signal intensity was highest in the nasal quadrant [45.95(35.59–54.34)] followed by the inferior [31.56 (24.82–41.71)], superior [30.16 (28.2–37.43)], and temporal [26.66 (22.92–34.33)] quadrants, and their difference was statistically significant (P<0.0001). Median signal intensity among 8 sectors was highest in the nasosuperior sector [23.05 (17.14–29.20)] and least in the temporoinferior sector [12.98 (10.82–17.51)] (P<0.0001). 

No significant difference was observed in median signal intensities between males [132.83 (115.82–174.18)] and females [143.74 (122.43–166.00)] (P=0.771) and right eyes [143.74 (118.53–170.6)] and left eyes [133.51 (122.43–153.86)] (P=0.967). 

Such findings have been reported from glaucomatous eyes also. These reports can be used to find the optimum place for MIGS insertion and possibly for performing Trabeculectomy.

REFERENCE: 

Beri, Nitika MS*; Patil, Anuja MD†; Midha, Neha MD‡; Angmo, Dewang MD†; Bari, Aafreen MD†; Sharma, Namrata MD†; Dada, Tanuj MD†. Quantitative Assessment of Functional Aqueous Humor Outflow by Aqueous Angiography. Journal of Glaucoma 34(11):p 888-894, November 2025. | DOI: 10.1097/IJG.0000000000002617 

AI out performs humans in glaucoma screening

Artificial Intelligence (AI) utilizes the latest cutting technology to identify human diseases.

Screening for glaucoma remains challenging due to the myriad presentations of the condition. Presently, screening is regarded as economically and practically unfeasible.

However, studies are being performed to investigate the possibility of using AI to screen for glaucoma.

A study presented at the 129th annual meeting of the American Academy of Ophthalmology by Anthony Khwaja and his colleagues from the University of London, Institute of Ophthalmology and Moorefields Eye Hospital, has shown that AI can out-perform humans in screening for glaucoma.

The study used 6,304 fundus images gathered for a large, population-based cohort study (EPIC-Norfolk Eye Study) to compare the accuracy of their algorithm and a trained human grader to estimate a key measure of glaucoma, vertical cup-disc ratio. A glaucoma specialist examined the patients to confirm the diagnosis.

Results showed the algorithm correctly identified patients with glaucoma 88 to 90 percent of the time; human graders were correct 79 to 81 percent of the time. The algorithm did not differentiate between those who had glaucoma or might have glaucoma.

It remains to be seen how a single feature of glaucoma (the vertical C:D R) can be used to diagnose glaucoma patients. This feature is dependent on the ISNT rule and is often seen in only 50% of the population.

URIC ACID AND GLAUCOMA

Uric acid (UA) is a purine metabolite present intracellularly and in all body fluids. Usually high UA levels have been associated with gout and kidney stones.

However, UA has both pro-oxidant and antioxidant features in-vitro by production and scavenging of reactive oxygen species. 

The beneficial impacts of UA have been shown in certain neurodegenerative conditions, such as Parkinson's disease, Huntington's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. However, the role of UA in the underlying mechanism of glaucoma is still unclear.

A meta-analysis was performed by Mohammadi et al, to identify case-control studies comparing the serum UA concentrations of the patients with glaucoma and controls. The mean ± standard division difference was used to assess the difference in serum UA concentrations between the glaucoma patients and controls.

The meta-analysis involved 6 studies involving 1,221 glaucoma patients and 1,342 in the control group.

The pooled analysis included all six studies, showing that serum UA level was higher in glaucoma patients than in other patients without glaucoma. In detail, the meta-analysis using a random effect model indicates that the mean UA level in glaucoma patients was 0.13 (I2 = 91.92%, 95% CI = −0.42 to 0.68) higher than the controls; however, it was not statistically significant.

Three out of six case-control studies within this meta-analysis found a significant inverse association. In comparison, three other studies have reported a positive association between high UA levels and glaucoma.

These findings provide evidence that glaucoma patients have a higher serum UA level compared to the controls, but this difference is not statistically significant. Prospective studies are needed to determine the possible association between increased UA and glaucoma pathogenesis.

REFERENCE:

Mohammadi M, Yarmohammadi A, Salehi-Abargouei A, Ghasemirad H, Shirvani M, Ghoshouni H. Uric acid and glaucoma: a systematic review and meta-analysis. Front Med (Lausanne). 2023 Jul 28;10:1159316. doi: 10.3389/fmed.2023.1159316. PMID: 37575992; PMCID: PMC10422028.

CLOSED EYE IOP AND EM MONITORING

Normally, intraocular pressure (IOP) exhibits a significant circadian rhythm, typically peaking in the early morning hours before the end of sleep (3–4 mmHg higher than daytime levels), with a trough occurring at the end of the day. This phenomenon is closely associated with changes in body position (supine posture increases episcleral venous pressure by 3–6 mmHg) and fluctuations in glucocorticoid levels.

Furthermore, frequent eye movements during sleep, such as those occurring during rapid eye movement (REM) sleep, can increase resistance to aqueous humor outflow. This is particularly concerning in patients with angle-closure glaucoma, where the risk of acute attacks is 3–5 times higher at night compared to during the day.

Smart contact lenses have emerged as a promising solution for continuous, noninvasive ocular signal monitoring instead of discrete measurements.

While Goldman Appalanation Tonography (GAT) is the ideal method, it requires topical anesthesia and fluorescein instillation before measurement, and the fluorescein concentration can influence accuracy. Furthermore, GAT-like instruments often require a slit lamp examination. Corneal thickness, stiffness, and tear film characteristics can also introduce measurement errors. 

Contact lenses are a practical solution to the problems of continuous monitoring. Gan and colleagues have proposed a stretchable self-decoupled BCL comprising electromagnetic capacitive IOP (CIOP) and neodymium-iron-boron (NdFeB)-MEM components. The design features an NdFeB/polydimethylsiloxane (PDMS) interlayer film that separates double-layered serpentine-geometry spiral copper (Cu) films.

This innovation involves a stretchable bimodal contact lens (BCL) amalgamating self-decoupled electromagnetic capacitive intraocular pressure (CIOP) and magnetic eye movement (MEM) monitoring components. This integrated system offers a non-invasive and comfortable solution for real-time eye health monitoring, providing accurate measurements and continuous tracking of eye status. 

In this way, both IOP and EM can be monitored continuously through closed lids.

REFERENCE:

Gan, X., Yao, G., Li, C. et al. Closed-eye intraocular pressure and eye movement monitoring via a stretchable bimodal contact lens. Microsyst Nanoeng 11, 83 (2025). https://doi.org/10.1038/s41378-025-00946-y

ALI IBN ISA AL-KAHHAL

Absar Alam, a first year student of BUMS at Ajmal Khan Tibbiya College in Aligarh, made a presentation on Ali Ibn Isa al-Kahhal.

His presentation in Urdu is available on YouTube.

Kindly follow the link below:

https://youtu.be/NcZBZi0ildQ?si=ZulHSJSykaJcdCmF

Some more information on Kahhal can be accessed here:

https://ourgsc.blogspot.com/search?q=Kahhal

OXFORD MICROSTENT

Zhang et al, working at Oxford University, have developed a novel deployable microstent for MIGS applications, leveraging deployable structure concepts and biocompatible nitinol to mechanically separate ocular tissues in the subconjunctival space (SCS).

The microstent can be delivered minimally invasively, ab internally via a needle and subsequently expands within the SCS. 

This design incorporates structural elements to sustain conjunctival-episcleral separation without relying on anti-fibrosis treatments. It is specifically optimized to form a posterior, consistently elevated bleb while preventing migration, improving durability, and ensuring long-term efficacy.

The device is constructed from nitinol, a biocompatible metal renowned for its proven long-term ocular safety and successful use in larger filtration devices like the EX-PRESS shunt.

The enhanced flexibility allows the stent to conform to surrounding tissues, potentially reducing fibrosis and minimizing patient discomfort. 

This microstent consists of a flexible tube that connects the AC to the SCS and a self-expanding element to support a subconjunctival bleb. The expandable element is designed to triple its original size upon deployment, a transformation enabled by the superelasticity of nitinol.

It features four slender struts asymmetrically arranged along the central axis of the flexible tube. After deployment, these struts self-expand to lift the conjunctiva and Tenon’s layer from the sclera, creating a bleb.

Results showed that a 1 mm expandable element can create a spindle-shaped bleb approximately 0.7 mm in radius and 6 mm in length without permanent deformation.

REFERENCE:

A novel deployable microstent for the treatment of glaucoma. Zhang, Yunlan et al. The Innovation, Volume 6, Issue 8, 100935

PROSTAGLANDIN ASSOCIATED ORBITOPATHY (PAP)

Introduction:

Prostaglandin Associated Periorbitopathy (PAP) is the constellation of eyelid and orbital changes that accompany the administration of topical prostaglandin analogue (PG-A) eye drops.

PAP is a common occurrence following PG-A treatment. It has been claimed that once the clinician is looking for it, it can be noticed nearly 100 percent of the time.

PAP has been reported with the use of most PG-As, including bimatoprost, travoprost, tafluprost, and latanoprost.

Older patients (>60 years) are at a greater risk of developing this condition. 

This entity was first described by Peplinski and Smith in 2004. However, the specific term Prostaglandin Associated Periorbitopathy (PAP) was coined by glaucoma specialists Dr. Louis Pasquale and Dr. Stanley Berke. Other terms previously used in the literature included Deep Superior Sulcus Syndrome and DUES (Deepening of Upper Eyelid Sulcus).

The clinical features of PAP are upper lid ptosis, deepening of the upper lid sulcus, involution of dermatochalasis, periorbital fat atrophy, mild enophthalmos, inferior scleral show, increased prominence of lid vessels, and tight eyelids. 

Other known side effects of PG-As such as lengthening of lashes and increased pigmentation of the iris and periorbital skin, can possibly fit under the term PAP as well.

PAP can appear as early as a month after the use of bimatoprost and is caused by fat atrophy, inhibition of adipocyte production, and differentiation of orbital fat due to PGF receptor stimulation by PG analogs.

Severe orbital fat atrophy in a patient with prolonged bilateral PGA use. Very deep superior sulcus and "sunken" eye appearance.

Deep sulcus, loss of orbital crease and lengthening of eyelashes on the left side.

Histopathology:

In PAP, there is significantly reduced size of individual adipocytes, suggesting overall fat atrophy rather than adipocyte death. 

Some cases demonstrate a statistically significant increase in mean adipocyte density of treated eyes, suggesting that in a given area there was a higher total number of adipocytes and thus a smaller size of each individual adipocyte. Clumped nuclei suggesting adipocyte atrophy are also seen in some cases. 

Reports suggest that those treated with bimatoprost were most affected by PAP, followed by those treated with travoprost. Those treated with latanoprost showed an increased mean adipocyte density as well however this change was not found to be statistically significant.

Pathophysiology:

The proposed mechanisms for PAP include mitochondrial apoptosis pathway of adipocytes, inflammatory fibrotic changes to the eyelid or to Mueller's muscle, atrophy of existing adipocytes, and inhibition of adipogenesis. Currently, it is most widely thought that preaponeurotic and deep orbital fat atrophy are likely the main contributors responsible for the majority of PAP changes. 

Pharmacokinetic studies of a single topical administration of 0.1% bimatoprost in male cynomolgus monkeys indicate that eyelid specimens contain more than 2,000 times higher concentrations of bimatoprost compared with aqueous and more than 16 times higher concentrations compared with iris and ciliary body. Thus, there is significant periorbital absorption of PG-A  medication.

Diagnosis:

Some patients may complain of the onset of a droopy lid or their eyelid starting to get in the way of their vision when this was previously never an issue. Performing Goldman applanation becomes increasingly difficult on patients with PAP as their orbits seem increasingly sunken in. Rarely, patients may complain of diplopia. Most commonly, patients refer to such changes as "tired-appearing eyes".

On examination, MRD1 can be decreased as compared to measurements prior to the initiation of therapy. Hertel's exophthalmometry can reveal a mild degree of enophthalmos or at least a relative decrease in values as compared to baseline. MRD2 or a measurement of inferior scleral show may be increased as compared to baseline as well. Finally, prism alternate cover test or Maddox rod testing can reveal a relative muscle deficit, most commonly a slight limitation in abduction.

Imaging is not commonly done and is not usually indicated in patients suspected to have PAP.

Management:

Typically, discontinuation of the medication results in partial to complete reversal of PAP characteristics. This change has been noted to occur as quickly as 4-6 weeks.

Switching from bimatoprost to latanoprost has been somewhat effective in reversing signs of PAP. In a prospective study of 13 patients who experienced PAP on bimatoprost, 11 of them had either a decrease or disappearance of their symptoms after switching to latanoprost in only 2 months. This change was reported to have maintained over a 6 month follow up.

CURCUMIN AND EYE DISEASE

Curcumin has been used in traditional medicine for many years. It's role in ophthalmic diseases has been reviewed in an article recently published by my colleagues and myself.

It is known that reactive oxygen species (ROS) play a role in the development and progression of glaucoma. Yue and colleagues have studied the effect of curcumin as an antioxidant in glaucoma patients. 

On the other hand, Lin and colleagues have shown that trabecular meshwork (TM) cells are damaged in glaucoma. Pre-treatment with curcumin protects the TM cells against oxidative stress-induced cell death. 

Cheng and colleagues developed a thermosensitive chitosan-gelatin-based hydrogel that contains 20 μm curcumin-loaded nanoparticles and latanoprost. This dual-drug delivery system acts as a sustained-release agent. Curcumin decreases the oxidative stress-mediated damage to the TM cells by reducing inflammation-related gene expression, mitochondrial ROS production, and apoptosis.

Please access the complete article at the following link:

https://www.florajournal.com/archives/

https://www.florajournal.com/archives/2025/vol13issue4/PartC/13-1-32-664.pdf

Also see: https://ourgsc.blogspot.com/search?q=CURCUMIN

COLLOIDAL DRUG AGGREGATES IN GLAUCOMA

Hollow nanoparticle and core-shell nanoparticle eye drops improve ocular retention and sustain release of drugs for up to 7 days. These strategies use either non-biodegradable materials, which can accumulate, or degradable materials with acidic degradation products that can trigger an inflammatory response.

Colloidal drug aggregates (CDAs) are self-assembled, amorphous, drug-rich nanoparticles.

CDAs can achieve high-loading (typically >70%) drug formulations by stabilizing them with small amounts of excipients, such as polymers, proteins, lipids,indocyanine dyes or other small-molecule aggregators. This contrasts with the typical <10% drug loading in nanoparticle formulations. Although CDAs have been studied for oral and intravenous administration, their use in local delivery had not been investigated until this study.

Incorporating timolol CDAs into a new hyaluronan (HA)-oxime hydrogel prior to ocular injection achieves adequate local delivery and mitigates the leakage and rapid drug release seen with nanoparticles.

Since topical application of timolol maleate reduces intraocular pressure (IOP) in healthy rodents, this model was used to test the IOP-lowering effects of the slow release timolol palmitate CDAs in rats over 56 days following a single subconjunctival injection versus those of free timolol.

Timolol palmitate CDAs have a critical aggregate concentration of 2.72µM and sustained in vitro release over 28 days. Timolol palmitate CDAs are dispersed throughout in situ gelling hyaluronan-oxime hydrogel and injected into the subconjunctival space of rat eyes. The IOP is significantly reduced for at least 49 days with a single subconjunctival injection of timolol-palmitate CDAs compared to 6 hours for conventional timolol maleate. 

The systemic blood concentrations of timolol are significantly lower, even after 6 hours, for timolol palmitate CDA-loaded hydrogel versus free timolol maleate, thereby potentially reducing the risk of systemic side effects. This innovative approach redefines the role of CDAs and provides a framework for long-acting ocular therapeutics, shifting their perception from a drug screening challenge to a powerful tool for sustained local drug delivery.

REFERENCE:

Dang M, Slaughter KV, Cui H, Jiang C, Zhou L, Matthew DJ, Sivak JM, Shoichet MS. Colloid-Forming Prodrug-Hydrogel Composite Prolongs Lower Intraocular Pressure in Rodent Eyes after Subconjunctival Injection. Adv Mater. 2025 Feb;37(8):e2419306. 

doi: 10.1002/adma.202419306. 

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