Glaucoma can worsen faster in some people due to differences in optic nerve vulnerability, blood flow, and systemic risk factors, not just eye pressure. Even with “controlled” pressure, glaucoma may progress if underlying risks are not identified and monitored over time, Dr Shibal Bhartiya explains.
Two patients. Same diagnosis. Similar eye pressure. Same drops. One is stable at ten years. The other has lost significant field within three. Patients often ask: Why Glaucoma Gets Worse Faster in Some People Than Others.
This is not unusual in glaucoma. It is one of the most clinically important, and least explained, aspects of the disease. Your doctor told you, you have glaucoma, gave you drops. Called you back for monitoring.
But did you discuss if your optic nerve might be more vulnerable than average? Or, what factors beyond eye pressure are quietly accelerating the damage.
This article, written by Dr Bhartiya, explains those factors. Understanding them changes how glaucoma is monitored, what investigations are relevant, and what questions to ask at your next appointment.
Dr Shibal Bhartiya is a fellowship-trained glaucoma specialist and Mayo Clinic Research Collaborator with over 25 years of experience. Her approach focuses on identifying risk before damage is irreversible, simplifying treatment decisions, and protecting vision long-term. Emphasis on early detection, risk assessment, and continuity of care. She is rated 5 stars across 1,500+ patient reviews on Google.
Why Intraocular Pressure Is Only Part of the Story
The historical model of glaucoma was simple: raised intraocular pressure damages the optic nerve. Lower the pressure, stop the damage. This model is incomplete.
Intraocular pressure is the only modifiable risk factor with proven treatment benefit. It remains central to glaucoma management. But a substantial proportion of glaucoma patients, particularly those with normal tension glaucoma, progress despite pressure that is well controlled by any standard definition. And among patients with elevated pressure, some progress quickly while others with similar pressures remain stable for decades.
Pressure level explains some of the variation. The factors below explain the rest.
Central Corneal Thickness: The Hidden Pressure Modifier
Central corneal thickness (CCT) is one of the most important risk factors for glaucoma progression, and one of the most underappreciated by patients.
Intraocular pressure is measured by the resistance the cornea offers to an applanation probe or air puff. A thicker cornea gives artificially high readings. A thinner cornea gives artificially low ones. Standard Goldmann tonometry assumes a corneal thickness of approximately 545 microns. Patients with thinner corneas have their true pressure systematically underestimated at every clinic visit.
But CCT is not merely a measurement correction factor. Thin central cornea is an independent risk factor for glaucoma progression, separate from any pressure effect. The Ocular Hypertension Treatment Study (OHTS) identified CCT below 555 microns as one of the strongest predictors of conversion from ocular hypertension to glaucoma. Patients with thin corneas progress faster and reach endpoints earlier than those with normal or thick corneas, even after adjusting for measured IOP.
If you have glaucoma and have never had your corneal thickness measured, ask for it. It changes how your pressure readings should be interpreted, and it tells your specialist something important about your intrinsic risk.
Disc Haemorrhages: The Warning Signal That Gets Missed
A disc haemorrhage is a small, splinter-shaped bleed at the margin of the optic disc. It is visible on fundus examination and resolves within weeks to months. Most patients never know they have had one.
Disc haemorrhages are one of the strongest predictors of glaucoma progression. They indicate localised ischaemia, a transient interruption of blood flow, at the optic nerve head, and they mark the site of imminent or ongoing retinal nerve fibre layer loss. Studies consistently show that the sector of the optic nerve that bleeds is the sector that subsequently loses nerve fibres on OCT, and the sector where visual field loss subsequently develops.
In normal tension glaucoma, disc haemorrhages are particularly common and particularly significant. Their presence in an NTG patient is a direct signal that vascular insufficiency is active and that the nerve is under ischaemic stress beyond whatever pressure-related stress is present.
A patient whose disc haemorrhage is detected at a routine visit is not unlucky. The hemorrahe is a timely warning. The appropriate response is not to note it and move on. It is to ask why the bleed occurred, whether pressure targets need revision, and whether vascular risk factors need investigation.
Systemic Hypotension and Nocturnal Dipping
The optic nerve is supplied by blood from the posterior ciliary arteries. Like all tissues, it requires adequate perfusion pressure, the difference between arterial blood pressure and intraocular pressure, to receive oxygen and nutrients. When perfusion pressure falls, optic nerve gets less blood supply.
Systemic hypotension is a direct cause of reduced optic nerve perfusion pressure. It is most relevant at night. During sleep, blood pressure falls physiologically, this is normal nocturnal dipping. In some people, blood pressure dips excessively, by more than 20 percent from daytime levels. This is called nocturnal over-dipping.
Nocturnal over-dipping is strongly associated with glaucoma progression, particularly in normal tension glaucoma. The optic nerve, already under whatever pressure stress is present, faces additional ischaemic stress during the hours of maximum blood pressure reduction, precisely when patients are asleep and not being monitored.
The clinical implications are significant. Antihypertensive medications taken in the evening can exacerbate nocturnal dipping. A glaucoma patient who begins a new blood pressure medication and subsequently shows accelerated progression deserves a medication timing review. Taking antihypertensives in the morning rather than the evening, where clinically possible, may reduce nocturnal dipping and its consequences for the optic nerve.
A 24-hour ambulatory blood pressure monitor is a simple, non-invasive investigation that identifies nocturnal dipping. In standard glaucoma management, doctors forget about night time BP. In any patient with normal tension glaucoma or unexplained progression, however, it is essential.
Sleep Position: The Factor Nobody Mentions
The side on which a patient sleeps affects their intraocular pressure. This is documented, reproducible, and almost never discussed.
IOP is higher in the dependent eye, the eye facing down, when lying on one side. The mechanism involves increased episcleral venous pressure from the gravitational position. For a patient who sleeps consistently on one side, the dependent eye is exposed to elevated pressure for six to eight hours every night. Entirely outside the window of clinic measurement.
Studies using continuous IOP monitoring have shown that the dependent eye IOP during sleep can be 3 to 6 mmHg higher than the fellow eye. This is a clinically significant asymmetry in a disease. Especially where even 1 mmHg differences in pressure can result in measurable differences in progression rates.
This is relevant for any patient with asymmetric glaucoma, where one eye is worse than the other despite similar measured IOPs. If the worse eye is consistently the dependent eye, sleep position may be contributing.
Head-of-bed elevation, raising the head of the bed by 20 to 30 degrees, may reduce nocturnal IOP in both eyes. It is a simple, free, non-pharmacological intervention with evidence behind it.
Myopia: The Optic Nerve That Was Already Vulnerable
High myopia, short-sightedness above minus 3 to 5 dioptres, is an independent risk factor for glaucoma and for faster progression. The mechanism involves the structural anatomy of the myopic eye.
In a myopic eye, the scleral canal through which the optic nerve exits, the lamina cribrosa, is tilted, stretched, and biomechanically weaker than in an emmetropic eye. This altered geometry means the optic nerve is more susceptible to the same level of intraocular pressure that a normal eye would tolerate well. The lamina cribrosa in a myopic eye bends and deforms at lower pressure thresholds.
Myopic eyes also have thinner retinal nerve fibre layers at baseline: not from glaucoma, but from the axial elongation that stretches the retina. This makes OCT interpretation more complex: the baseline is lower, so the threshold for detecting abnormality shifts, and early glaucomatous loss can be masked within the range of normal myopic variation.
A highly myopic patient with glaucoma requires more conservative pressure targets, more careful OCT interpretation, and more frequent monitoring than a non-myopic patient with equivalent measured pressures.
Vascular Risk Factors: The Systemic Contributors
Glaucoma, particularly normal tension glaucoma, has a significant vascular component. The optic nerve depends on adequate, well-regulated blood flow. Conditions that impair vascular autoregulation or reduce perfusion contribute to nerve damage independently of intraocular pressure.
Migraine with aura is associated with glaucoma progression. The same cortical spreading depression and vasospasm that produces the migraine aura can affect the posterior ciliary circulation and cause episodic optic nerve ischaemia.
Raynaud’s phenomenon, episodic vasospasm of the extremities, is similarly associated with NTG. The vasospastic tendency that causes cold hands and feet also affects the microvasculature of the optic nerve.
Anaemia reduces oxygen delivery to the optic nerve and can accelerate progression in borderline cases. Obstructive sleep apnoea, covered in detail in a separate article, causes nocturnal hypoxia and IOP spikes that operate entirely outside clinical monitoring.
A complete glaucoma risk assessment includes a systemic vascular history. It is not sufficient to measure eye pressure, examine the disc, and send the patient home. The systemic picture matters.
What This Means for Your Monitoring
Understanding your personal risk profile changes what investigations are appropriate and what targets are realistic.
A patient with thin corneas, a history of disc haemorrhages, nocturnal dipping on antihypertensives, and high myopia has a fundamentally different risk profile from a patient with normal corneas, stable discs, well-controlled blood pressure, and no myopia: even if their measured IOPs are identical.
The first patient needs more aggressive pressure targets, more frequent OCT and field testing, 24-hour IOP monitoring consideration, an ambulatory blood pressure study, and a sleep apnoea screen. The second patient may be safely monitored annually with standard measurements.
If you have glaucoma and have never had a conversation about any of the factors above, you are not receiving complete care. A second opinion that includes a structured risk assessment, not just a pressure check, may change your management in ways that protect your vision for decades.
Clinical Reality (What’s not always obvious)
- Progression in glaucoma is not equal across patients—two people with the same eye pressure can behave very differently over time.
- “Controlled pressure” does not guarantee safety—factors like thin cornea, fragile optic nerve, or vascular instability can drive faster damage.
- Systemic conditions (e.g., obstructive sleep apnea, low blood pressure at night, diabetes) can accelerate progression silently.
- Missed doses, drop intolerance, or poor absorption reduce real-world protection even when prescriptions look adequate.
- Progression is often only obvious in retrospect—which is why early, consistent follow-up matters more than occasional “good” visits.
What You Must Remember
| Factor | What It Means for You |
|---|---|
| Eye pressure level | Higher pressure → higher risk, but not the only driver |
| Optic nerve susceptibility | Some nerves are more vulnerable even at lower pressures |
| Corneal thickness | Thin cornea can underestimate risk and true pressure |
| Type of glaucoma | Normal tension vs high-pressure behave differently |
| Blood flow factors | Poor perfusion or fluctuations affect optic nerve health |
| Systemic conditions | Sleep apnoea, diabetes, vascular disease increase risk |
| Medication adherence | Irregular use reduces protection significantly |
| Response to treatment | Some patients are non-responders to certain drops |
| Stage at diagnosis | Late detection = faster apparent progression |
| Follow-up consistency | Long gaps → missed early warning signs |
| Big picture | Glaucoma progression is multi-factorial—pressure is just one piece of the puzzle |
Frequently Asked Questions
Why is my glaucoma getting worse even though my eye pressure is controlled?
Intraocular pressure is one of several factors driving glaucoma progression. Thin corneas, disc haemorrhages, nocturnal blood pressure dipping, sleep position, myopia, and vascular conditions can all accelerate damage independently of measured IOP. A structured risk assessment should investigate these factors in any patient with unexplained progression.
What is a disc haemorrhage and should I be worried?
A disc haemorrhage is a small bleed at the optic disc margin. It is one of the strongest predictors of glaucoma progression and indicates localised ischaemia at the nerve head. If one is detected, it should prompt a review of pressure targets, vascular risk factors, and monitoring frequency, not simply be noted and observed.
Does blood pressure affect glaucoma?
Yes, significantly. Low blood pressure, particularly nocturnal over-dipping, reduces optic nerve perfusion pressure and accelerates glaucomatous damage. Evening antihypertensive medications can exacerbate nocturnal dipping. A 24-hour ambulatory blood pressure monitor identifies this pattern and can guide medication timing.
Does sleep position affect eye pressure?
Yes. The dependent eye in a side-sleeping patient has measurably higher IOP than the fellow eye, due to increased episcleral venous pressure. In patients with asymmetric glaucoma, sleep position may be a contributing factor. Head-of-bed elevation reduces nocturnal IOP in both eyes.
Does myopia make glaucoma worse?
High myopia makes the optic nerve more vulnerable to glaucomatous damage at any given pressure. The lamina cribrosa in a myopic eye is structurally weaker and deforms at lower pressure thresholds. Myopic patients with glaucoma require more conservative targets and more careful monitoring.
What is central corneal thickness and why does it matter?
Central corneal thickness affects the accuracy of IOP measurement and is an independent risk factor for glaucoma progression. Thin corneas lead to underestimation of true IOP and carry intrinsically higher progression risk. Every glaucoma patient should have their corneal thickness measured and their pressure readings interpreted in that context.
Read the research articles.
This article was written by Dr Shibal Bhartiya, fellowship-trained glaucoma specialist and Mayo Clinic Research Collaborator, Clinical Director at Marengo Asia Hospitals, Gurugram, known for ethical, patient-centred glaucoma care and independent glaucoma second opinions. She is also the Program Director for Community Outreach & Wellness; and for the Marengo Asia International Institute of Neuro and Spine,.
She has published peer-reviewed research on glaucoma management, examining how treatment decisions should balance medical evidence, patient preferences, and long-term vision outcomes.
As Editor-in-Chief of Clinical and Experimental Vision and Eye Research and Executive Editor of the Journal of Current Glaucoma Practice (Pubmed Indexed, official journal of the International Society of Glaucoma Surgery), Dr Shibal Bhartiya brings editorial and research depth to every clinical decision. Her 200+ publications, including 90+ PubMed-indexed publications and 28 edited textbooks span glaucoma biology, surgical outcomes, health equity, and emerging diagnostics.
Access her work on Pubmed, Google Scholar, ResearchGate and ORCID.
Dr Shibal Bhartiya
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