Extra row of eyelashes behind the grey line is called as?

Correct Answer: C. Distichiasis

Distichiasis is the presence of an extra row of eyelashes (cilia) arising from the meibomian gland orifices along the lid margin, posterior to the normal lash line (grey line of Fuchs). This is the defining anatomical feature that distinguishes it from other lash abnormalities. The condition can be congenital (often inherited as autosomal dominant) or acquired secondary to chronic inflammation, trauma, or blepharitis. The extra lashes are typically thinner and shorter than normal lashes and may be asymptomatic or cause foreign body sensation, tearing, and photophobia depending on their stiffness and direction. In Indian clinical practice, distichiasis is commonly encountered in outpatient clinics and may require epilation, electrolysis, or surgical ablation of the affected lash follicles if symptomatic. The key discriminator is the location "behind the grey line"—this anatomical landmark is crucial for diagnosis and differentiates distichiasis from trichiasis, where aberrant lashes arise from normal lash follicles but grow inward.

Why the other options are wrong

A. Madarosis — Madarosis refers to loss or absence of eyelashes, the opposite of the clinical presentation described. This is a trap for students who confuse lash pathology categories. Madarosis occurs in conditions like alopecia areata, leprosy (common in India), and chronic blepharitis—but the question describes an extra row, not loss. B. Trichiasis — Trichiasis is misdirected growth of normal eyelashes (arising from normal lash follicles) that grow inward toward the cornea. The critical difference is that trichiasis involves aberrant lashes from the normal lash line, whereas distichiasis has an extra row posterior to the grey line. This is the most common NBE trap—both involve abnormal lashes, but anatomical location differs. D. Tylosis — Tylosis refers to thickening of the palms and soles (keratoderma), unrelated to eyelash pathology. This is a distractor testing whether students confuse dermatological terms with ocular conditions. Tylosis may be associated with esophageal cancer (Howel-Evans syndrome) but has no connection to eyelash abnormalities.

High-Yield Facts

Mnemonics

LASH PATHOLOGY: D-T-M Distichiasis = extra row (Distal/Double), Trichiasis = misdirected (Turned inward), Madarosis = Missing. Use when sorting eyelash abnormalities. GREY LINE RULE If lashes are behind the grey line → Distichiasis. If lashes are from the grey line but turned inward → Trichiasis. Anatomical location is the key discriminator.

NBE Trap

NBE pairs trichiasis and distichiasis to trap students who know both involve abnormal lashes but confuse the anatomical origin—trichiasis arises from the normal lash line (misdirected), while distichiasis is a separate row posterior to it. The phrase "extra row" is the discriminating clue NBE expects students to anchor on.

Clinical Pearl

In Indian outpatient clinics, congenital distichiasis often presents in children with recurrent foreign body sensation and mild tearing; acquired distichiasis following severe blepharitis or chemical burns (common post-acid attack injuries) may require surgical intervention. The condition is benign but can impact quality of life if lashes are stiff or directed toward the cornea.

_Reference: Bailey & Love Ch. 32 (Eyelid pathology); Parson's Diseases of the Eye Ch. 4_