How to look for ptosisi in resting position

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Examining Ptosis in the Resting (Primary) Position

Ptosis is an abnormally low position of the upper eyelid. Assessing it in the resting (primary gaze) position is the first and most important step of the clinical examination.

Step 1 - Know What Normal Looks Like

In primary gaze (eyes looking straight ahead at rest), the normal eyelid positions are:

Upper lid: covers the upper 1-2 mm of the iris (sits just below the upper limbus)
Lower lid: just touches the lower border of the iris (lower limbus)
Palpebral fissure height: normally 12-15 mm (7-10 mm in males; 8-12 mm in females)

Normal eyelid position - upper lid covers upper 1-2 mm of iris, lower lid touches lower iris border

Normal Eyelid Position - Bradley & Daroff's Neurology

Step 2 - Observe in the Resting Position (Observe for at Least 1 Minute)

With the patient looking straight ahead in primary gaze, check for:

Palpebral fissure asymmetry - compare the two sides
Where the upper lid margin falls relative to the iris edge - if it covers more than 2 mm of the iris, suspect ptosis
Margin-Reflex Distance (MRD1) - distance from the upper lid margin to the corneal light reflex when you shine a pen torch at the patient. Normal = 4-5 mm. A reduced MRD1 confirms ptosis
Scleral show - if sclera is visible above the iris (upper scleral show), the lid is retracted, not ptotic; if visible below the iris, lower lid is retracted
Brow elevation/frontalis contraction - patients with bilateral ptosis often raise their eyebrows reflexively to lift the lids. This can mask the degree of ptosis

Step 3 - Grade the Ptosis

Using palpebral fissure height compared to the normal side (for unilateral cases):

Grade	Droop
Mild	up to 2 mm
Moderate	3 mm
Severe	4 mm or more

Step 4 - Rule Out Pseudoptosis

A false appearance of ptosis can come from:

Contralateral lid retraction - the other eye looks abnormally wide, making the normal eye look ptotic
Ipsilateral hypotropia - the upper lid follows the depressed globe downward; disappears when that eye fixes
Brow ptosis / dermatochalasis - excess forehead skin droops; elevate the brow manually to distinguish
Small/absent globe - e.g., phthisis bulbi, artificial eye, enophthalmos

Causes of pseudoptosis: (A) artificial eye, (B) contralateral lid retraction, (C) ipsilateral hypotropia, (D) bilateral brow ptosis with dermatochalasis

Causes of pseudoptosis - Kanski's Clinical Ophthalmology

Step 5 - Additional Observations in Resting Position

Upper lid crease height: measured in downgaze. Normal ~10 mm (females), ~8 mm (males). A high crease suggests aponeurotic (involutional) ptosis; absent crease suggests poor levator function (often congenital)
Pretarsal show: distance between lid margin and skin fold in primary position
Fatiguability: if ptosis worsens after sustained upgaze or during the day - think myasthenia gravis

Quick Summary Table

What to Look For	Normal Value	Abnormal Finding
Upper lid position	1-2 mm below upper limbus	More than 2 mm below = ptosis
MRD1 (margin-reflex distance)	4-5 mm	Reduced = ptosis
Palpebral fissure height	12-15 mm	Asymmetry or reduced = ptosis
Lid crease	8-10 mm	Absent or high crease
Brow position	Relaxed	Elevated = compensatory sign

Sources: Bradley and Daroff's Neurology in Clinical Practice, Box 17.1 & pp. 279-280 | Kanski's Clinical Ophthalmology, 10th ed., pp. 89-90

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