Corneal Opacity and Keratoplasty
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Direct answer
A white line of endothelial rejection creeping across a donor cornea is the Khodadoust line, and recognising it can save a graft in days. Corneal opacity — scarring, oedema or dystrophic change in a once-transparent tissue — follows infectious keratitis (the dominant cause in India), trachoma, trauma, chemical burns, dystrophies and endothelial failure. Keratoplasty replaces the opaque tissue and is classified by indication (optical, therapeutic, tectonic, cosmetic) and by depth: penetrating keratoplasty for full-thickness scars, deep anterior lamellar keratoplasty for stromal disease with healthy endothelium, and endothelial keratoplasty (DSEK/DSAEK) for Fuchs endothelial dystrophy and pseudophakic bullous keratopathy. Graft rejection can occur any time — even decades later — presenting with redness, pain, photophobia and decreasing vision, and is treated with intensive topical corticosteroids.
What you must remember
- Commonest causes in the Indian context: post-infectious scarring (bacterial, fungal, viral keratitis), trachomatous scarring and trauma; corneal opacity remains a leading cause of corneal blindness tracked by the National Programme for Control of Blindness and Visual Impairment.
- Indications for keratoplasty, in one quartet: optical (to improve vision — commonest), therapeutic (to remove refractory infection), tectonic (to restore structural integrity), cosmetic (rarely, for appearance).
- Matching operation to pathology: full-thickness central scar — penetrating keratoplasty; stromal dystrophy or keratoconus with good endothelium — DALK, which abolishes endothelial rejection risk; endothelial disease (Fuchs, pseudophakic bullous keratopathy) — DSEK/DSAEK with rapid visual recovery and a small incision.
- Graft rejection triad: ciliary congestion, keratic precipitates and the Khodadoust endothelial rejection line with graft oedema; epithelial and subepithelial rejection variants also occur.
- Rejection timing: classically after the second week, with highest risk in the first year, but the eye stays at risk lifelong — any red, painful, photophobic graft is rejection until proved otherwise.
- Risk factors for rejection: corneal vascularisation (the "high-risk" graft), regrafting, large grafts, previous rejection episodes, and young recipient age.
- High-risk graft prophylaxis: topical corticosteroids long-term, and systemic immunosuppression (for example mycophenolate or cyclosporine) in specialist centres for vascularised beds.
- Donor dependence: every keratoplasty begins at an eye bank, which is why procurement, consent and storage rules matter clinically in India.
Choosing the right graft for the right scar
Three patients illustrate the reasoning. A 30-year-old has a dense central leucoma after a healed bacterial ulcer; the peripheral cornea and endothelium are healthy. A full-thickness penetrating keratoplasty replaces the scar, but DALK is the better offer: host endothelium is retained, endothelial rejection — the graft killer — is eliminated, and the peeling of a big bubble or manual dissection to Descemet membrane spares the immunogenic stromal-endothelial boundary. A 65-year-old with Fuchs endothelial corneal dystrophy has stromal oedema and guttata but an otherwise clear stroma; replacing only the posterior lamella (DSEK/DSAEK) through a small incision gives faster rehabilitation and a stronger globe, and graft rejection, when it happens, is treated by intensive steroids. A farmer with a desmetocele after fungal keratitis unresponsive to medication needs a therapeutic penetrating graft today to save the eye — vision is secondary to integrity. The surgical choice therefore follows the layer at fault: stroma alone, spare the endothelium; endothelium alone, spare the stroma; everything, replace everything. After any of these, the follow-up discipline is identical — unexplained redness with decreased vision is an emergency, and a rejection episode treated within hours usually reverses, while one treated after a week often ends the graft.
Where candidates slip
The classic MCQ presents a quiet eye two years after keratoplasty that turns red and hazy, and offers "suture removal" or "raise antibiotic drops" as decoys; the answer is rejection and corticosteroids, because candidates wrongly assume grafts have a safe expiry date. The second slip is matching the operation to the disease — offering penetrating keratoplasty to a Fuchs patient ignores that the stroma is healthy, and offering DSEK to a full-thickness scar ignores that the host stroma must stay. Third, the Indian programme dimension: corneal blindness is second only to cataract among causes of avoidable blindness in national surveys, and the gap between corneas donated and corneas needed frames many a short-answer question on eye banking, including the National Eye Donation Fortnight each 25 August to 8 September.
Frequently asked questions
What is the Khodadoust line?
A line of endothelial rejection — inflammatory cells destroying donor endothelium as they march across the graft — accompanied by keratic precipitates, ciliary congestion and graft oedema.
Which keratoplasty is preferred for keratoconus with a healthy endothelium?
Deep anterior lamellar keratoplasty, which replaces stroma while retaining host endothelium, removing the risk of endothelial rejection.
What are the four indications for keratoplasty?
Optical (visual restoration), therapeutic (eradication of unresponsive infection), tectonic (structural support) and cosmetic.
How is acute graft rejection treated?
Intensive topical corticosteroids (frequently hourly, with a short oral steroid course in severe cases) started immediately; the outcome depends on how early treatment begins.
What makes a corneal graft "high risk" for rejection?
Deep stromal vascularisation extending into the graft bed, previous graft failure, regrafting and active ocular inflammation.