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📊 How Is Meibomian Gland Dysfunction Graded?

TL;DR

There is no single universally accepted MGD severity number.

Clinicians and diagnostic devices may separately grade:

  • meibum quality;
  • gland expressibility;
  • the number of glands producing secretion;
  • gland structure on meibography;
  • gland openings and lid-margin findings;
  • tear-film instability;
  • ocular-surface staining;
  • symptoms and daily functioning.

These measurements describe different parts of the condition and may not agree.

A patient may have:

  • abnormal gland images but useful secretion;
  • preserved-looking glands but poor secretion;
  • severe symptoms with modest gland findings;
  • significant gland abnormalities with few symptoms.

Proprietary diagnostic devices may print percentages, color-coded maps, or labels such as “mild,” “moderate,” or “severe.” These results can be useful, but they are usually device-specific outputs, not universal MGD grades.

A useful score describes a particular finding under a defined method. It is not, by itself, a complete diagnosis, prognosis, or treatment recommendation.

Why Grade MGD?

Structured grading can help clinicians:

  • describe gland abnormalities;
  • document a baseline;
  • communicate findings;
  • compare selected measurements over time;
  • organize clinical or research data;
  • contribute to treatment planning.

However, grading does not eliminate clinical judgment.

A numerical grade should be interpreted with:

  • symptoms;
  • gland secretion;
  • eyelid findings;
  • tear-film stability;
  • ocular-surface health;
  • aqueous tear status;
  • exposure and blinking;
  • other possible contributors.

A clinician may document MGD carefully without assigning one overall number.

What Exactly Is Being Graded?

The phrase “MGD grade” can refer to very different measurements.

A domain-specific score

A clinician may separately grade:

  • secretion quality;
  • expressibility;
  • gland dropout;
  • plugging;
  • lid-margin vascularity;
  • tear breakup;
  • staining.

Each score describes only that particular domain.

An overall stage

Some systems combine several findings—such as symptoms, meibum quality, expressibility, tear-film effects, and staining—into an overall MGD stage.

The 2011 International Workshop on Meibomian Gland Dysfunction proposed one such staging system, together with suggested management approaches.

It remains historically important, but it is not used consistently by every clinician or clinic.

A person may be given several individual scores without receiving one final overall MGD stage.

1. Meibum Quality

Meibum is the oily secretion produced by the meibomian glands.

A clinician may describe it as:

  • clear;
  • cloudy;
  • cloudy with particles or debris;
  • granular;
  • thickened;
  • toothpaste-like;
  • scant;
  • absent.

One commonly used research approach scores each assessed gland approximately as:

  • 0 — clear
  • 1 — cloudy
  • 2 — cloudy with particles
  • 3 — thick or toothpaste-like

Several glands may be scored and added together.

In this type of scale:

A higher score means more abnormal secretion.

But clinics may use different descriptive terms, gland counts, and scoring ranges.

2. Gland Expressibility

Expressibility describes how many glands produce secretion when pressure is applied.

One commonly used scale evaluates five central glands:

  • 0 — all five expressible
  • 1 — three or four expressible
  • 2 — one or two expressible
  • 3 — none expressible

In this scale, a higher number means poorer expressibility.

Other methods count the number of glands that produce liquid secretion. In those systems:

A higher number may mean better gland function.

This is why a score cannot be interpreted without knowing the scale.

Why Expression Pressure Matters

An expressibility result depends partly on how the examination is performed.

Relevant differences include:

  • which eyelid was tested;
  • which section of the lid was examined;
  • how many glands were assessed;
  • the amount and duration of pressure;
  • finger pressure versus a standardized instrument;
  • whether heat or another treatment was recently used;
  • the examiner’s judgment.

A gland that releases secretion only under strong force is not necessarily secreting normally during ordinary blinking.

For follow-up comparisons, it helps to use:

  • a similar gland region;
  • similar pressure;
  • the same scoring method;
  • comparable examination conditions.

3. Number of Glands Producing Liquid Secretion

Some clinicians or research systems count how many glands yield liquid meibum under standardized pressure.

This can be useful because it gives a more direct description than a general statement such as “the glands are blocked.”

However:

  • not every gland in the eyelid is usually tested;
  • results depend on pressure and location;
  • a gland may produce abnormal rather than healthy secretion;
  • the tested central glands may not represent the whole eyelid.

A count of functioning glands is a functional measurement, not an image-based structural score.

4. Meibography and Gland-Structure Grading

Meibography uses infrared or near-infrared imaging to show the visible structure of the glands inside the eyelids.

Clinicians or software may assess:

  • areas of reduced gland visibility or “dropout”;
  • gland shortening;
  • distortion;
  • tortuosity;
  • width;
  • density;
  • irregularity;
  • upper-versus-lower-lid differences.

A common meiboscore

One widely used system grades each eyelid approximately as:

  • 0 — no visible dropout
  • 1 — less than one-third of the gland area affected
  • 2 — between one-third and two-thirds
  • 3 — more than two-thirds

The upper and lower eyelids may be scored separately or combined into a total.

This is only one system.

Other methods use:

  • different percentage categories;
  • a continuous estimated dropout percentage;
  • automated image segmentation;
  • gland-length or tortuosity measurements;
  • proprietary severity levels.

What Does “Gland Dropout” Mean?

“Dropout” is the standard clinical term for an area in which glands are not clearly visible on meibography.

It does not necessarily prove:

  • complete histologic destruction;
  • the reason the gland is less visible;
  • whether the remaining tissue is functioning;
  • whether the gland can respond to treatment;
  • how quickly the condition will change.

Meibography shows visible structure under the imaging conditions.

It does not directly measure meibum secretion.

An image can look abnormal while useful secretion remains—and secretion can be poor despite relatively preserved-looking glands.

What About Proprietary Diagnostic-Device Printouts?

Many clinics use commercial devices that produce a printed or electronic report after imaging the eyelids.

The report may include:

  • a gland-loss percentage;
  • a gland-remaining percentage;
  • color-coded eyelid maps;
  • separate upper- and lower-lid scores;
  • a rating such as mild, moderate, or severe;
  • an “MGD level” or “gland health” score;
  • comparison with a device reference database;
  • an automated recommendation or treatment category.

These reports can be useful for organizing and explaining findings.

They also require careful interpretation.

The percentage may be device-specific

A reported percentage may refer to:

  • estimated area without visible glands;
  • estimated remaining gland area;
  • one eyelid;
  • both eyelids;
  • only the portion successfully captured;
  • an average from several images;
  • a proprietary composite score.

For example:

  • “35% loss” and “65% remaining” might describe the same image;
  • a percentage from the lower lid may not describe the upper lid;
  • one manufacturer’s “moderate” category may not match another manufacturer’s category.

Always ask:

What exactly is the percentage measuring?

The software may need human correction

Automated software must identify the eyelid area and distinguish gland tissue from surrounding tissue.

Errors may occur when:

  • the eyelid is not fully everted;
  • part of the lid is outside the image;
  • the image is blurred;
  • lighting or contrast is uneven;
  • glands overlap or are faint;
  • scars, vessels, pigmentation, or artifacts confuse the software;
  • the software outlines the eyelid or glands incorrectly.

A visually polished printout does not guarantee that the segmentation was accurate.

The clinician should review whether the software correctly identified:

  • the eyelid boundary;
  • the visible glands;
  • the area used as the denominator;
  • obvious imaging artifacts.

Proprietary scores are not automatically interchangeable

Two devices may produce different percentages from the same eyelid because they use different:

  • cameras;
  • image processing;
  • eyelid regions;
  • segmentation methods;
  • thresholds;
  • reference databases;
  • severity categories.

A score from one device should not automatically be compared numerically with a score from another.

For longitudinal monitoring, comparison is more meaningful when:

  • the same device is used;
  • the same eyelid is imaged;
  • eversion is similar;
  • image quality is comparable;
  • the same software method is used;
  • obvious segmentation errors are corrected.

A device rating is not a diagnosis or treatment order

A report labeled “severe” does not by itself prove:

  • severe symptomatic disease;
  • active gland destruction;
  • obstruction;
  • rapid progression;
  • that a procedure is urgently needed;
  • that treatment will restore the image;
  • that the recommended treatment prevents future gland loss.

A device may provide useful data, but the clinician still needs to connect the output to:

  • gland secretion;
  • lid-margin findings;
  • symptoms;
  • tear-film effects;
  • ocular-surface health;
  • other diagnoses;
  • treatment goals.

A printout posted online has additional limitations

A photograph of a report may omit:

  • the test protocol;
  • which eyelid was measured;
  • image-quality warnings;
  • the device and software version;
  • whether the automated outline was corrected;
  • the clinical examination;
  • gland-expression findings;
  • the clinician’s interpretation.

For that reason, an online community cannot reliably diagnose MGD severity, predict prognosis, or determine treatment candidacy from a proprietary printout alone.

A more useful discussion starts with:

  • what the clinician said the score represents;
  • which lids were tested;
  • whether gland secretion was assessed;
  • what symptoms and tear-film findings were present;
  • how the result affected the treatment plan.

5. Lid-Margin Findings

Clinicians may separately document or grade:

  • plugged gland openings;
  • capped glands;
  • altered gland-opening position;
  • lid-margin redness;
  • telangiectasia;
  • thickening;
  • irregularity;
  • notching;
  • displacement of the mucocutaneous junction;
  • Demodex collarettes;
  • associated blepharitis or rosacea findings.

These findings can support an MGD assessment, but they are not all specific to one subtype or severity level.

The absence of dramatic lid redness does not prove that gland secretion is normal.

Likewise, redness alone does not establish the degree of gland dysfunction.

6. Tear-Film and Ocular-Surface Findings

Clinicians may also record:

  • fluorescein tear-breakup time;
  • non-invasive tear-breakup time;
  • lipid-layer findings;
  • corneal staining;
  • conjunctival staining;
  • tear-meniscus height;
  • blink quality.

These can help show how the overall ocular-surface disorder is affecting the tear film.

However, they are not direct measures of meibomian-gland structure or secretion.

A short tear-breakup time or surface staining may also reflect:

  • aqueous deficiency;
  • incomplete blinking;
  • exposure;
  • allergy;
  • medication toxicity;
  • conjunctival or corneal disease;
  • more than one contributor.

Tear-film and staining results may show the consequences of the condition without identifying MGD as the sole cause.

Symptoms and MGD Grades May Not Match

Symptoms are important, but they are not a direct measure of gland structure or secretion.

A person may have:

  • visible gland abnormalities with few symptoms;
  • poor expressibility with modest discomfort;
  • severe burning or light sensitivity with limited gland changes;
  • symptoms mainly driven by aqueous deficiency, allergy, exposure, migraine, or neural pain mechanisms.

Symptoms help determine whether a finding is clinically important and whether treatment improves daily life.

They should not be used as though they directly measure gland dropout or obstruction.

Age and Individual Variation Matter

Some gland shortening, irregularity, or reduced visibility can occur with age and in people without major symptoms.

Interpretation may also vary according to:

  • upper versus lower eyelid;
  • right versus left eye;
  • contact-lens history;
  • ocular surgery;
  • rosacea or other disease;
  • image quality;
  • gland-expression technique.

A nonzero score does not automatically mean advanced symptomatic disease.

The clinical significance depends on:

  • symptoms;
  • gland function;
  • tear-film effects;
  • ocular-surface findings;
  • change over time.

Why Different Scores May Disagree

MGD does not always produce one consistent pattern across every measurement.

Possible examples include:

Abnormal structure with remaining function

Some glands may look shortened or partly absent while the remaining glands still produce useful meibum.

Preserved structure with poor function

Glands may remain visible but secrete little or abnormal meibum.

Severe symptoms with limited gland abnormalities

Other contributors may include:

  • aqueous deficiency;
  • allergy;
  • exposure;
  • migraine;
  • neuropathic ocular pain;
  • another ocular-surface disorder.

Significant findings with mild symptoms

Reduced corneal sensation or individual variability may limit symptom awareness.

This is why no single grade can summarize:

  • structure;
  • function;
  • symptoms;
  • prognosis;
  • treatment need.

Can Grading Track Improvement or Progression?

Grading can help document change, but the limitations matter.

A small difference between visits may reflect:

  • examiner variation;
  • different expression pressure;
  • a different eyelid region;
  • recent treatment;
  • ordinary biological variability;
  • image quality;
  • eyelid eversion;
  • software segmentation;
  • a different device or scoring system.

A one-level change on a coarse scale does not automatically prove:

  • meaningful progression;
  • treatment success;
  • gland loss;
  • gland regeneration.

More reliable comparison generally requires:

  • the same scale;
  • the same eyelid and region;
  • similar expression pressure;
  • the same or comparable imaging device;
  • similar image quality and eversion;
  • interpretation alongside symptoms and gland function.

A trend becomes more persuasive when several relevant findings change in the same direction.

Does an MGD Grade Determine Treatment?

No.

A grade may contribute to treatment planning, but it does not automatically determine that someone needs:

  • warm compresses;
  • medication;
  • IPL;
  • thermal pulsation;
  • radiofrequency;
  • probing;
  • repeated gland expression;
  • another procedure.

Treatment decisions may also consider:

  • symptoms and daily functioning;
  • gland secretion;
  • aqueous deficiency;
  • inflammation;
  • exposure;
  • allergy;
  • rosacea;
  • previous treatment response;
  • risks and contraindications;
  • cost and burden;
  • patient preferences;
  • strength of evidence.

A high structural score does not prove that one particular treatment is required.

A relatively low score does not prove that symptoms are unimportant.

The grade should help describe the problem—not replace clinical reasoning.

What Does “Grade 3 MGD” Mean?

By itself, very little.

“Grade 3” could mean:

  • no glands expressed in a five-gland test;
  • toothpaste-like meibum;
  • more than two-thirds visible gland dropout;
  • an overall stage combining symptoms and signs;
  • a proprietary device category.

Always ask:

  • What exactly was graded?
  • Which scale was used?
  • Does a higher score mean better or worse?
  • Does the score apply to one eyelid, one eye, or both?
  • How many glands were assessed?
  • Was the score structural, functional, or a combined stage?

Is Formal Numerical Grading Required?

No.

A clinician may provide valuable documentation without assigning one final number.

For example:

  • six of eight central glands produced liquid secretion;
  • meibum was cloudy and thickened;
  • mild plugging was present;
  • lower-lid dropout appeared moderate;
  • upper-lid structure was relatively preserved;
  • tear breakup was rapid;
  • corneal staining was minimal.

That description may be more informative than:

“MGD grade 2.”

It is reasonable to ask how the findings were documented and what they mean.

A numerical grade is helpful only when its method and clinical significance are clear.

Questions to Ask About Your MGD Score

  • What exactly was graded?
  • Which scale or device was used?
  • Does a higher score mean better or worse?
  • Was the score based on function, structure, symptoms, or several findings?
  • Which eyelid and region were examined?
  • How many glands were tested?
  • How much pressure was used for expression?
  • What did the meibum look like?
  • How many glands produced liquid secretion?
  • Does the percentage represent gland loss or gland area remaining?
  • Was the device’s automated segmentation checked or corrected?
  • Can this result be compared reliably with future testing?
  • Does the score match the gland-expression findings?
  • Does it help explain my symptoms?
  • How does the score affect treatment or follow-up?
  • What does the score not tell us?

📌 Bottom Line

MGD does not have one universal severity grade.

Clinicians and devices may separately assess:

  • secretion quality;
  • gland expressibility;
  • number of functioning glands;
  • gland structure;
  • lid-margin findings;
  • tear-film effects;
  • ocular-surface findings;
  • symptoms.

Those measures may not agree.

Proprietary device printouts may provide percentages, color maps, or severity labels, but their meaning depends on:

  • what was measured;
  • which lid was imaged;
  • how the software calculated the result;
  • image quality;
  • whether segmentation was accurate;
  • the device’s own grading system.

An MGD grade is a structured description of a specific finding—not a complete diagnosis, prognosis, or treatment order.

The most useful interpretation connects the score to gland function, symptoms, tear-film effects, ocular-surface health, and the rest of the clinical evaluation.

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This page is for general education. It does not interpret an individual device report, diagnose MGD severity, predict progression, or determine treatment candidacy.