OP4.1-10 | Cornea, Keratitis and Eye Donation — Practice Quiz

Correct. Bowman's layer is acellular; once damaged it is replaced by scar tissue, not regenerated. The epithelium, by contrast, regenerates rapidly from limbal stem cells.

Bowman's layer is acellular and does not regenerate once destroyed. This is clinically important in keratoconus and other anterior stromal diseases.

Incorrect. The corneal epithelium regenerates from limbal stem cells; the stroma can partially repair, and Descemet's membrane can be secreted by endothelium. Bowman's layer is the one acellular layer that cannot regenerate.

Correct. A corneal diameter of 8 mm with normal IOP and no Haab's striae indicates microcornea. Buphthalmos (congenital glaucoma) would have elevated IOP and Haab's striae.

Microcornea is defined as horizontal corneal diameter less than 10 mm with normal IOP. Buphthalmos has elevated IOP and Haab's striae; megalocornea has a diameter greater than 13 mm.

Incorrect. The key differentiator between microcornea, megalocornea, and buphthalmos is IOP and corneal diameter. Normal IOP with a diameter less than 10 mm points to microcornea.

Correct. Feathery borders, satellite lesions, and immune ring after agricultural vegetative trauma = fungal keratitis. Natamycin 5% is first-line for filamentous fungal keratitis.

Vegetative trauma (paddy husk, thorn) in a rural agricultural setting with feathery borders, satellite lesions, and an immune ring is the classic presentation of fungal keratitis. Natamycin 5% is the first-line topical antifungal for filamentous fungi (Aspergillus, Fusarium).

Incorrect. Ciprofloxacin is for bacterial keratitis; acyclovir is for HSV; chlorhexidine is for Acanthamoeba. The agricultural history and morphological features (feathery borders, satellite lesions) indicate fungal keratitis requiring natamycin.

Correct. Topical corticosteroids in HSV dendritic (epithelial) keratitis drive uncontrolled viral replication and can convert a dendritic ulcer into a large geographic ulcer threatening vision. This is the single most dangerous clinical error in keratitis management.

Topical corticosteroids in active HSV epithelial (dendritic) keratitis cause massive viral replication and geographic ulceration. This is the classic dangerous error. Steroids are used only in immune stromal keratitis under antiviral cover.

Incorrect. The single most dangerous error is adding corticosteroids to active HSV epithelial keratitis. Acyclovir is appropriate treatment; contact lens discontinuation is mandatory but not dangerous if omitted short-term.

Correct. Acanthamoeba keratitis presents with a ring infiltrate, radial perineuritis, disproportionate pain, and contact lens + freshwater exposure. Treatment requires specific anti-amoebic agents (PHMB + propamidine isethionate).

Acanthamoeba keratitis: contact lens use with freshwater exposure, ring infiltrate, radial perineuritis, and severe disproportionate pain are the pathognomonic features. Treatment: polyhexamethylene biguanide (PHMB) + propamidine isethionate.

Incorrect. Pseudomonas causes rapid bacterial ulcer in contact lens wearers; HSV causes dendritic ulcer; Fusarium causes fungal keratitis in agricultural settings. The ring infiltrate, radial perineuritis, and freshwater exposure point to Acanthamoeba.

Correct. Dense leukoma (iris not visible) with full-thickness involvement and intact posterior segment function (positive projection of light test) is a classic indication for penetrating keratoplasty.

A dense full-thickness leukoma through which the iris is not visible, with a positive projection of light test (intact retinal function), is an indication for penetrating keratoplasty when the endothelium is involved.

Incorrect. Tattooing and contact lenses are cosmetic measures for non-visual-axis opacities or cosmetic rehabilitation. Optical iridectomy is for peripheral opacities with clear paracentral cornea. A central full-thickness leukoma with good retinal function needs penetrating keratoplasty.

Correct. Rheumatoid arthritis with a Schirmer I of 4 mm indicates aqueous-deficient dry eye. Secondary Sjogren's syndrome is the mechanism, with autoimmune destruction of lacrimal gland acini.

Rheumatoid arthritis can cause secondary Sjogren's syndrome with lacrimal gland lymphocytic infiltration, producing aqueous-deficient dry eye. A very low Schirmer I of 4 mm confirms aqueous deficiency.

Incorrect. Evaporative dry eye from meibomian gland dysfunction would have a normal Schirmer test. A Schirmer I of only 4 mm indicates severely reduced aqueous production — consistent with secondary Sjogren's in the context of rheumatoid arthritis.

Correct. Keratomalacia is an ophthalmic emergency. 200,000 IU oral vitamin A is given immediately (day 0, day 1, day 14 schedule per WHO). Delaying by even hours can lead to irreversible bilateral corneal perforation.

Keratomalacia from vitamin A deficiency is the most time-critical paediatric ophthalmic emergency. 200,000 IU oral vitamin A must be given immediately — hours matter. Delaying risks irreversible bilateral corneal melting.

Incorrect. The dose of 50,000 IU is insufficient for a child over 12 months with corneal signs. Waiting until next morning or for IV access is dangerous. Immediate oral 200,000 IU is the standard of care.

Correct. DALK is indicated for keratoconus when the endothelium is healthy. It replaces anterior stroma while preserving host Descemet's and endothelium, avoiding the risk of endothelial rejection which exists with penetrating keratoplasty.

Keratoconus with clear stroma and healthy endothelium is the primary indication for DALK. DALK replaces stroma and Bowman's while preserving the patient's healthy Descemet's membrane and endothelium, eliminating the risk of endothelial rejection.

Incorrect. DSAEK and DMEK replace the endothelium — inappropriate when the endothelium is healthy. Penetrating keratoplasty replaces all layers unnecessarily when the endothelium is normal. DALK is the tissue-sparing choice for keratoconus with healthy endothelium.

Correct. The eye bank standard is retrieval within 6 hours of death (8 hours if the body is refrigerated). This preserves endothelial cell viability. Moist pads over closed lids slow corneal desiccation while waiting for the team.

Corneal retrieval should occur within 6 hours of death (up to 8 hours if refrigerated at 4 degrees Celsius). Endothelial viability deteriorates rapidly after death. Moist chamber preservation at home helps delay this until retrieval.

Incorrect. 2 hours is unnecessarily restrictive. 12 or 24 hours allows unacceptable endothelial cell loss. The standard window is 6 hours (or up to 8 hours with body refrigeration).

Correct. The Seidel test uses fluorescein under cobalt blue illumination. A bright green rivulet streaming from the wound indicates aqueous leakage (perforation). Attempting FB removal in a perforated eye at the slit-lamp is contraindicated.

The Seidel test must be performed before any manipulation of a corneal foreign body. A positive Seidel test (aqueous streaming through fluorescein dye under cobalt blue light) indicates perforation — the patient requires immediate surgical management, not FB removal at the slit-lamp.

Incorrect. Topography and pachymetry assess corneal shape and thickness but cannot detect perforation. B-scan is for posterior segment. The Seidel test is the mandatory pre-removal test to exclude perforation.

Correct. Diabetes is not a contraindication to eye donation. There is no age upper limit. The eye bank evaluates endothelial cell count post-retrieval to determine suitability for keratoplasty. The family should be encouraged to consent.

Diabetes is NOT a contraindication to corneal donation. There is no upper age limit for corneal donation. The eye bank assesses endothelial cell count and tissue suitability after retrieval. The absolute contraindications are active infections (HIV, Hepatitis B/C, rabies, septicaemia, prion diseases) and intraocular malignancy.

Incorrect. Diabetes does not disqualify a donor. Age limits do not apply to corneal donation. The key contraindications are communicable blood-borne infections, prion diseases, and intraocular malignancy — not diabetes or advanced age.