Blepharitis
Blepharitis is inflammation of the eyelid margins, the strip of tissue from which the lashes grow. It is one of the most common eye conditions seen in general ophthalmology, and it is frequently asymmetric. One eyelid can be significantly more inflamed than the other, with crusty debris around the lash roots, redness and thickening of the lid margin, and irregular or thinning lashes on the more affected side.
The inflammation in blepharitis disrupts the normal environment of the hair follicles from which the lashes grow. Chronic inflammation around the follicles can cause the lashes to grow abnormally, in the wrong direction, or to be lost and replaced more slowly than normal. In long-standing, inadequately treated blepharitis, the lash line can become permanently irregular or thin in the affected area.
The treatment for blepharitis is lid hygiene: regular, consistent cleaning of the eyelid margins with warm water and a dilute eyelid cleaning solution or dedicated lid wipes. Warm compresses applied to the eyelids for a few minutes before cleaning help to loosen the waxy debris and improve the function of the glands within the lids. This needs to be maintained as a routine rather than applied only during flare-ups.
Rubbing one eye habitually
This is a surprisingly common and often overlooked cause of one-sided lash loss. People who habitually rub one eye, whether due to itching from allergy, dryness, a tendency to rub during concentration, or simply habit, subject those lash follicles to repeated mechanical trauma. Over time, habitual rubbing can cause lash thinning on the more frequently rubbed side.
Allergic eye disease is a common underlying driver: a chronically itchy eye on one side, or one side more itchy than the other, leads to asymmetric rubbing. If you notice that you rub one eye far more than the other, this is worth paying attention to, both for the lash loss it may cause and because chronic vigorous eye rubbing has been associated with corneal thinning in susceptible individuals.
Prostaglandin eye drops for glaucoma
Prostaglandin analogue eye drops are one of the most commonly prescribed treatments for glaucoma, and they produce a well-documented set of changes to the lashes and periocular skin on the treated eye. The lashes typically become longer, thicker, and darker. They may also increase in number. Occasionally, the eyelid skin around the treated eye darkens slightly, a change called periocular pigmentation.
These changes are confined to the eye receiving the drops, which is why they can appear strikingly one-sided in someone being treated for glaucoma in only one eye. The changes are largely reversible if the drops are stopped, though this must always be weighed against the need to control intraocular pressure. Some patients also notice increased lash shedding alongside these other changes.
If you are using glaucoma drops in one eye and have noticed a difference in your lashes between the two sides, it is almost certainly the prostaglandin drops. This is worth mentioning to your ophthalmologist, who can discuss the options if the cosmetic asymmetry is troublesome.
Alopecia areata
Alopecia areata is an autoimmune condition in which the immune system mistakenly attacks hair follicles, causing patchy hair loss. It typically affects the scalp, but it can involve eyebrows and eyelashes. When alopecia affects the eyelashes, it can be asymmetric, particularly in earlier or milder forms of the condition.
The lash loss in alopecia areata tends to be focal rather than diffuse: affecting one patch of the lash line rather than thinning uniformly across the whole margin. There is no associated inflammation, thickening, or scaling of the eyelid margin itself, which helps to distinguish it from blepharitis. The skin of the eyelid appears normal despite the lash loss.
Thyroid disease and other systemic causes
Thyroid disorders, particularly hypothyroidism (underactive thyroid), can cause diffuse hair loss throughout the body, including the eyelashes and the outer third of the eyebrows. This tends to be bilateral rather than one-sided, though it can be asymmetric in milder cases. If you are experiencing lash loss alongside other symptoms suggesting thyroid dysfunction, such as fatigue, weight change, feeling cold, or hair loss elsewhere, a thyroid blood test is worthwhile.
Rosacea, a chronic inflammatory skin condition that frequently affects the central face, can involve the eyelids and cause blepharitis-like changes with associated lash abnormalities. As with blepharitis, this can be asymmetric.
Red flags for eyelash loss
Most causes of one-sided eyelash loss are benign and related to inflammation, mechanical trauma, or medication. However, there are specific patterns that should prompt a prompt eye examination.
- Eyelash loss that is focal, affecting one specific small area of the eyelid margin
- A thickened, nodular, or ulcerated area of the eyelid margin where the lashes are thinning
- A lash that grows in the wrong direction and cannot be removed easily
- Lash loss accompanied by a visible abnormality of the eyelid skin or margin
- Loss that has appeared rapidly and is worsening over weeks rather than months
An eyelid margin tumour, though uncommon, can present as focal lash loss with eyelid margin changes. It is important to examine the eyelid carefully rather than assuming all lash loss is inflammatory in origin, particularly if the pattern is focal rather than diffuse.
Common questions
Will my eyelashes grow back after blepharitis?
In most cases, yes. Eyelashes that have been thinned by blepharitis can recover once the inflammation is brought under control with consistent lid hygiene. However, follicles that have been damaged by severe or long-standing inflammation may not fully recover. Treating blepharitis promptly and maintaining the treatment long-term gives the best chance of preventing permanent lash changes.
Should I stop rubbing my eye if my lashes are thinning?
Yes. If habitual eye rubbing is contributing to lash loss, addressing the underlying reason for the rubbing, typically dry eye or allergic eye disease, and consciously avoiding rubbing, can allow the follicles to recover. Your optometrist or GP can assess and treat the underlying cause.
Can mascara or eyelash treatments cause one-sided lash loss?
Repeated use of certain mascaras, lash glues, or lash extensions can cause mechanical damage to the lash follicles, particularly if they are applied or removed carelessly. If you use lash products predominantly on one side, or have had extensions applied unevenly, this is worth considering as a contributing factor.
