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Ophthalmology – Pediculosis Ciliaris (Phthiriasis Palpebrarum)
Basics
Description
Pediculosis ciliaris, also called phthiriasis palpebrarum, is infestation of the:
- Eyelashes
- Eyelid margins
- Occasionally eyebrows
by the pubic or crab louse:
Phthirus pubis
It typically causes:
- Intense eyelid pruritus
- Burning
- Chronic blepharitis
- Conjunctival irritation
Because the lice and nits may be subtle, the condition can be mistaken for ordinary blepharitis.
Synonyms
Terms include:
- Pediculosis ciliaris
- Phthiriasis palpebrarum
- Phthirus pubis infestation
- Pubic lice
- Crab lice
Transmission
P. pubis is most commonly transmitted through:
- Close physical or sexual contact
Eyelash infestation may occur through:
- Hand transfer from another body site
- Close face-to-face contact
- Contaminated bedding or clothing, less commonly
Fomite transmission is possible but generally less important than direct close contact.
Pediatric Considerations
Identification of pubic lice on a child’s eyelashes requires:
Careful safeguarding assessment
because sexual transmission or abuse must be considered.
However, ocular infestation does not by itself prove sexual abuse, since nonsexual transmission can occur.
Evaluation should include:
- Detailed history
- Examination for infestation elsewhere
- Assessment for other injuries or concerning findings
- Consideration of STI testing when appropriate
- Involvement of pediatric safeguarding/child-protection professionals according to local law and clinical circumstances
Epidemiology
Pubic lice occur worldwide.
They can affect:
- Adolescents
- Adults
- Children
There is no important sex predilection.
Ocular infestation is much less common than genital infestation.
Risk Factors
Risk factors include:
- Close contact with an infested individual
- Multiple sexual partners
- Shared bedding or clothing
- Household exposure
- Crowded living conditions
Poor hygiene is not required for infestation and should not be assumed.
Organism
Phthirus pubis is:
- Short
- Broad
- Crab-like
- Approximately 1–2 mm in size
It possesses prominent claws adapted for gripping coarse hair.
Life Cycle
The life cycle includes:
- Egg / nit
- Nymph
- Adult louse
Nits are firmly cemented to hair shafts.
Adult lice feed repeatedly on:
Human blood
and cannot survive for long away from the host.
Pathophysiology
The louse attaches to hair and feeds by piercing the skin.
Symptoms result from:
- Mechanical irritation
- Local inflammatory response
- Hypersensitivity to louse saliva
- Excoriation from scratching
Associated Ocular Disease
Ocular infestation may cause:
- Blepharitis
- Blepharoconjunctivitis
- Follicular conjunctivitis
- Eyelid edema
- Excoriation
- Secondary bacterial infection
History
Typical complaints include:
- Intense eyelid itching
- Burning
- Foreign-body sensation
- Red eye
- Chronic “blepharitis” not responding to routine therapy
Symptoms may be worse:
- At night
Ask about:
- Pruritus elsewhere on the body
- Genital itching
- Household contacts
- Sexual contacts when age-appropriate
- Previous unsuccessful blepharitis treatment
Physical Examination
Slit-lamp examination may directly demonstrate:
- Adult lice
- Nymphs
- Nits
Look carefully at:
- Lash bases
- Lash shafts
- Eyelid skin
- Eyebrows
Appearance of Lice
Adult lice may appear as:
- Brown-gray
- Translucent
- Small mobile bodies
They may be difficult to see because they remain close to the lid margin.
Movement under magnification can confirm the diagnosis.
Appearance of Nits
Nits appear as:
- Small
- Oval
- White-gray or translucent structures
firmly attached to:
Eyelash shafts
Unlike ordinary debris, they cannot be easily brushed away.
Eyelid Findings
Other findings may include:
- Crusting
- Excoriation
- Blood-tinged debris
- Eyelid erythema
- Eyelid edema
Severe infestations may produce significant inflammatory swelling.
Conjunctival Findings
Possible findings include:
- Conjunctival injection
- Follicular conjunctivitis
- Irritation
- Tearing
Maculae Ceruleae
Occasionally, painless:
Blue-gray macules
may occur around affected skin.
These are called:
Maculae ceruleae
and are thought to result from altered blood pigments at louse feeding sites.
Papular Reaction
Small erythematous papules may occur at feeding sites because of:
- Local hypersensitivity
- Inflammation
Lymphadenopathy
Reactive:
- Preauricular
- Submandibular
lymphadenopathy may occasionally occur.
Diagnosis
Diagnosis is usually clinical and made by:
Direct visualization of lice or nits on the eyelashes
under slit-lamp magnification.
Microscopy
Microscopic examination can confirm the organism when diagnosis is uncertain.
Characteristic findings include:
- Broad crab-like body
- Large claws on posterior legs
Differential Diagnosis
Important differentials include:
- Seborrheic blepharitis
- Staphylococcal blepharitis
- Demodex blepharitis
- Allergic blepharitis
- Atopic dermatitis
- Eyelid eczema
- Rosacea
- Viral blepharoconjunctivitis
- Herpes simplex blepharitis
- Eyelid malignancy in persistent unilateral disease
Pediculosis vs Demodex
Phthirus pubis
- Visible lice
- Firmly attached nits
- Intense pruritus
- Blood/debris at lash bases
Demodex
Classically produces:
- Cylindrical dandruff / collarettes at lash bases
- Chronic blepharitis
- No visible crab-like lice or nits
Treatment Principles
Treatment has several goals:
- Eradicate adult lice.
- Remove nits.
- Treat infestation elsewhere on the body.
- Treat close or sexual contacts when appropriate.
- Prevent reinfestation.
Mechanical Removal
For eyelash infestation:
Mechanical removal of lice and nits is a key treatment.
Under magnification, lice and nits may be removed with:
- Fine forceps
This can substantially reduce parasite burden immediately.
Ophthalmic Ointment / Petrolatum
A bland occlusive ophthalmic ointment or petrolatum may be applied to:
- Eyelid margins
- Eyelashes
several times daily for approximately:
7–10 days
The purpose is to:
- Immobilize
- Suffocate
lice.
Examples may include:
- Plain petrolatum
- Bland ophthalmic ointment
Antibiotic ointment such as erythromycin may be used if there is significant secondary blepharitis, although the antibiotic itself is not the primary pediculicidal mechanism.
Important Medication Safety
Standard pediculicide shampoos or lotions should not be applied directly to the eye or eyelid margin unless specifically formulated and supervised for ophthalmic use.
Avoid ocular exposure to:
- Permethrin creams/rinses
- Pyrethrin products
- Malathion
- Other insecticidal lotions
because they can cause significant ocular irritation or toxicity.
Treatment of Pubic or Body Infestation
If lice are present at genital or other body sites, treatment may include:
- Permethrin 1%
- Pyrethrins with piperonyl butoxide
according to current pediculosis protocols.
These are applied to:
Nonocular affected hair-bearing areas
and should be kept away from the eyes.
Oral Ivermectin
Oral ivermectin may be considered for:
- Extensive infestation
- Refractory disease
- Treatment failure
A common regimen is approximately:
200–250 µg/kg orally, repeated after 7–14 days
depending on local protocol.
Ivermectin does not reliably kill eggs, which is why repeat dosing is often used.
Pregnancy and Breastfeeding
Medication selection requires additional caution.
In general:
- Mechanical removal
- Local bland ophthalmic ointment
are attractive options for eyelash disease.
Systemic ivermectin is generally avoided during pregnancy unless specifically justified.
Lindane
Lindane is no longer favored and is generally avoided because of:
- Neurotoxicity
- Resistance
- Safer alternatives
It should not be considered routine therapy.
Malathion
Malathion may be effective for pubic lice but:
- Is irritating
- Is flammable
- Must not contact the eyes
It is not a standard eyelash treatment.
Treatment of Contacts
Recent sexual partners should be:
- Informed
- Examined when appropriate
- Treated if infested or according to applicable public-health recommendations
Close household contacts should also be considered if exposure is suspected.
Sexual Activity
Patients should avoid:
- Sexual contact
- Close intimate contact
until:
- They have been treated
- Their relevant partners have been treated
Condoms do not reliably prevent pubic lice transmission because lice infest hair-bearing skin outside the area covered by a condom.
Clothing and Bedding
Clothing, towels, and bedding recently used by the affected person should be:
- Machine washed in hot water
- Dried on a hot cycle
Items that cannot be washed may be:
- Dry-cleaned
- Sealed away from body contact for an appropriate interval
Environmental fumigation is unnecessary.
STI Evaluation
Because pubic lice can be sexually transmitted, adolescents and adults with genital infestation should be assessed for risk of other sexually transmitted infections.
Testing may include, according to individual risk:
- HIV
- Syphilis
- Gonorrhea
- Chlamydia
This should be based on sexual history and local recommendations rather than performed identically in every patient.
Pediatric Safeguarding
In a child with phthiriasis palpebrarum:
- Examine for lice elsewhere
- Assess other household members
- Determine whether plausible nonsexual transmission exists
- Consider sexual abuse and other safeguarding concerns
When concern exists, involve:
- Pediatrician
- Child-protection team
- Appropriate safeguarding authorities
according to local legal requirements.
Follow-Up
Re-examination is generally appropriate after approximately:
1 week
Assess for:
- Persistent live lice
- Newly hatched nymphs
- Remaining nits
- Secondary infection
Repeat treatment may be required.
Treatment Failure
Persistent infestation may result from:
- Inadequate mechanical removal
- Failure to repeat treatment
- Untreated contacts
- Re-exposure
- Incorrect diagnosis
- Resistance to topical pediculicides
Prognosis
Prognosis is:
Excellent
when lice are eradicated and reinfestation is prevented.
Symptoms usually resolve promptly after successful treatment.
Complications
Possible complications include:
- Chronic blepharoconjunctivitis
- Excoriation
- Secondary bacterial infection
- Eyelid edema
- Recurrent infestation
Permanent visual loss is extremely unusual.
Ophthalmology Pearls
- Pediculosis ciliaris = infestation of the eyelashes by Phthirus pubis.
- Think of it in persistent, intensely pruritic blepharitis that does not respond to routine treatment.
- Slit-lamp examination may reveal mobile crab-like lice and firmly attached nits on the lashes.
- Nits are attached to the lash shaft and do not brush away like ordinary debris.
- Mechanical removal with fine forceps plus bland occlusive ophthalmic ointment/petrolatum is a mainstay of eyelash treatment.
- Do not apply standard pediculicide shampoos or lotions directly to the ocular surface.
- Treat any simultaneous pubic or body infestation and address exposed contacts to prevent reinfestation.
- Lindane is no longer routine therapy because safer alternatives exist.
- Consider screening for other STIs when sexual transmission is plausible.
- In children, phthiriasis palpebrarum should prompt careful safeguarding assessment for possible sexual abuse, while recognizing that nonsexual transmission can occur.
Synonyms Terms include: Pediculosis ciliaris Phthiriasis palpebrarum Phthirus pubis infestation Pubic lice Crab lice
Transmission P. pubis is most commonly transmitted through: Close physical or sexual contact Eyelash infestation may occur through: Hand transfer from another body site Close face-to-face contact Contaminated bedding or clothing, less commonly Fomite transmission is possible but generally less important than direct close contact.
Pediatric Considerations Identification of pubic lice on a child’s eyelashes requires: Careful safeguarding assessment because sexual transmission or abuse must be considered. However, ocular infestation does not by itself prove sexual abuse, since nonsexual transmission can occur. Evaluation should include: Detailed history Examination for infestation elsewhere Assessment for other injuries or concerning findings Consideration of STI testing when appropriate Involvement of pediatric safeguarding/child-protection professionals according to local law and clinical circumstances
Epidemiology Pubic lice occur worldwide. They can affect: Adolescents Adults Children There is no important sex predilection. Ocular infestation is much less common than genital infestation.
Risk Factors Risk factors include: Close contact with an infested individual Multiple sexual partners Shared bedding or clothing Household exposure Crowded living conditions Poor hygiene is not required for infestation and should not be assumed.
Organism Phthirus pubis is: Short Broad Crab-like Approximately 1–2 mm in size It possesses prominent claws adapted for gripping coarse hair.
Life Cycle The life cycle includes: Egg / nit Nymph Adult louse Nits are firmly cemented to hair shafts. Adult lice feed repeatedly on: Human blood and cannot survive for long away from the host.
Pathophysiology The louse attaches to hair and feeds by piercing the skin. Symptoms result from: Mechanical irritation Local inflammatory response Hypersensitivity to louse saliva Excoriation from scratching
Associated Ocular Disease Ocular infestation may cause: Blepharitis Blepharoconjunctivitis Follicular conjunctivitis Eyelid edema Excoriation Secondary bacterial infection
History Typical complaints include: Intense eyelid itching Burning Foreign-body sensation Red eye Chronic “blepharitis” not responding to routine therapy Symptoms may be worse: At night Ask about: Pruritus elsewhere on the body Genital itching Household contacts Sexual contacts when age-appropriate Previous unsuccessful blepharitis treatment
Physical Examination Slit-lamp examination may directly demonstrate: Adult lice Nymphs Nits Look carefully at: Lash bases Lash shafts Eyelid skin Eyebrows
Appearance of Lice Adult lice may appear as: Brown-gray Translucent Small mobile bodies They may be difficult to see because they remain close to the lid margin. Movement under magnification can confirm the diagnosis.
Appearance of Nits Nits appear as: Small Oval White-gray or translucent structures firmly attached to: Eyelash shafts Unlike ordinary debris, they cannot be easily brushed away.
Eyelid Findings Other findings may include: Crusting Excoriation Blood-tinged debris Eyelid erythema Eyelid edema Severe infestations may produce significant inflammatory swelling.
Conjunctival Findings Possible findings include: Conjunctival injection Follicular conjunctivitis Irritation Tearing
Maculae Ceruleae Occasionally, painless: Blue-gray macules may occur around affected skin. These are called: Maculae ceruleae and are thought to result from altered blood pigments at louse feeding sites.
Papular Reaction Small erythematous papules may occur at feeding sites because of: Local hypersensitivity Inflammation
Lymphadenopathy Reactive: Preauricular Submandibular lymphadenopathy may occasionally occur.
Diagnosis Diagnosis is usually clinical and made by: Direct visualization of lice or nits on the eyelashes under slit-lamp magnification.
Microscopy Microscopic examination can confirm the organism when diagnosis is uncertain. Characteristic findings include: Broad crab-like body Large claws on posterior legs
Differential Diagnosis Important differentials include: Seborrheic blepharitis Staphylococcal blepharitis Demodex blepharitis Allergic blepharitis Atopic dermatitis Eyelid eczema Rosacea Viral blepharoconjunctivitis Herpes simplex blepharitis Eyelid malignancy in persistent unilateral disease
Pediculosis vs Demodex Phthirus pubis Visible lice Firmly attached nits Intense pruritus Blood/debris at lash bases Demodex Classically produces: Cylindrical dandruff / collarettes at lash bases Chronic blepharitis No visible crab-like lice or nits
Treatment Principles Treatment has several goals: Eradicate adult lice. Remove nits. Treat infestation elsewhere on the body. Treat close or sexual contacts when appropriate. Prevent reinfestation.
Mechanical Removal For eyelash infestation: Mechanical removal of lice and nits is a key treatment. Under magnification, lice and nits may be removed with: Fine forceps This can substantially reduce parasite burden immediately.
Ophthalmic Ointment / Petrolatum A bland occlusive ophthalmic ointment or petrolatum may be applied to: Eyelid margins Eyelashes several times daily for approximately: 7–10 days The purpose is to: Immobilize Suffocate lice. Examples may include: Plain petrolatum Bland ophthalmic ointment Antibiotic ointment such as erythromycin may be used if there is significant secondary blepharitis, although the antibiotic itself is not the primary pediculicidal mechanism.
Important Medication Safety Standard pediculicide shampoos or lotions should not be applied directly to the eye or eyelid margin unless specifically formulated and supervised for ophthalmic use. Avoid ocular exposure to: Permethrin creams/rinses Pyrethrin products Malathion Other insecticidal lotions because they can cause significant ocular irritation or toxicity.
Treatment of Pubic or Body Infestation If lice are present at genital or other body sites, treatment may include: Permethrin 1% Pyrethrins with piperonyl butoxide according to current pediculosis protocols. These are applied to: Nonocular affected hair-bearing areas and should be kept away from the eyes.
Oral Ivermectin Oral ivermectin may be considered for: Extensive infestation Refractory disease Treatment failure A common regimen is approximately: 200–250 µg/kg orally, repeated after 7–14 days depending on local protocol. Ivermectin does not reliably kill eggs, which is why repeat dosing is often used.
Pregnancy and Breastfeeding Medication selection requires additional caution. In general: Mechanical removal Local bland ophthalmic ointment are attractive options for eyelash disease. Systemic ivermectin is generally avoided during pregnancy unless specifically justified.
Lindane Lindane is no longer favored and is generally avoided because of: Neurotoxicity Resistance Safer alternatives It should not be considered routine therapy.
Malathion Malathion may be effective for pubic lice but: Is irritating Is flammable Must not contact the eyes It is not a standard eyelash treatment.
Treatment of Contacts Recent sexual partners should be: Informed Examined when appropriate Treated if infested or according to applicable public-health recommendations Close household contacts should also be considered if exposure is suspected.
Sexual Activity Patients should avoid: Sexual contact Close intimate contact until: They have been treated Their relevant partners have been treated Condoms do not reliably prevent pubic lice transmission because lice infest hair-bearing skin outside the area covered by a condom.
Clothing and Bedding Clothing, towels, and bedding recently used by the affected person should be: Machine washed in hot water Dried on a hot cycle Items that cannot be washed may be: Dry-cleaned Sealed away from body contact for an appropriate interval Environmental fumigation is unnecessary.
STI Evaluation Because pubic lice can be sexually transmitted, adolescents and adults with genital infestation should be assessed for risk of other sexually transmitted infections. Testing may include, according to individual risk: HIV Syphilis Gonorrhea Chlamydia This should be based on sexual history and local recommendations rather than performed identically in every patient.
Pediatric Safeguarding In a child with phthiriasis palpebrarum: Examine for lice elsewhere Assess other household members Determine whether plausible nonsexual transmission exists Consider sexual abuse and other safeguarding concerns When concern exists, involve: Pediatrician Child-protection team Appropriate safeguarding authorities according to local legal requirements.
Follow-Up Re-examination is generally appropriate after approximately: 1 week Assess for: Persistent live lice Newly hatched nymphs Remaining nits Secondary infection Repeat treatment may be required.
Treatment Failure Persistent infestation may result from: Inadequate mechanical removal Failure to repeat treatment Untreated contacts Re-exposure Incorrect diagnosis Resistance to topical pediculicides
Prognosis Prognosis is: Excellent when lice are eradicated and reinfestation is prevented. Symptoms usually resolve promptly after successful treatment.
Complications Possible complications include: Chronic blepharoconjunctivitis Excoriation Secondary bacterial infection Eyelid edema Recurrent infestation Permanent visual loss is extremely unusual.
Ophthalmology Pearls Pediculosis ciliaris = infestation of the eyelashes by Phthirus pubis. Think of it in persistent, intensely pruritic blepharitis that does not respond to routine treatment. Slit-lamp examination may reveal mobile crab-like lice and firmly attached nits on the lashes. Nits are attached to the lash shaft and do not brush away like ordinary debris. Mechanical removal with fine forceps plus bland occlusive ophthalmic ointment/petrolatum is a mainstay of eyelash treatment. Do not apply standard pediculicide shampoos or lotions directly to the ocular surface. Treat any simultaneous pubic or body infestation and address exposed contacts to prevent reinfestation. Lindane is no longer routine therapy because safer alternatives exist. Consider screening for other STIs when sexual transmission is plausible. In children, phthiriasis palpebrarum should prompt careful safeguarding assessment for possible sexual abuse, while recognizing that nonsexual transmission can occur.
