Corneal transplantation (keratoplasty) replaces diseased corneal tissue with healthy donor tissue. While highly successful, the transplanted cornea remains susceptible to the recipient’s immune system, which identifies the new tissue as foreign. Recognizing the signs of this immune response, known as graft rejection, is important for preserving the transplant’s clarity and function. Prompt identification allows for immediate medical intervention, maximizing the chances of saving the graft.
Understanding Corneal Graft Rejection
Corneal graft rejection occurs when the recipient’s immune system launches an attack against antigens on the donor tissue, triggering an inflammatory response. This immune process can affect different layers of the transplant: the epithelium, stroma, or endothelium.
Rejection involving the epithelial and stromal layers is relatively uncommon, representing a small percentage of total cases. The most frequent form of rejection is the attack on the endothelial layer, accounting for up to 50% of rejection episodes. The endothelium is a single layer of cells responsible for pumping fluid out of the cornea, maintaining its clarity.
When the endothelium is attacked, its ability to regulate the cornea’s fluid balance is compromised. Damage to these cells causes the corneal tissue to swell, leading to a loss of transparency and vision. Because the survival of the transplant is tied to the health of this layer, endothelial rejection requires urgent attention.
Key Visual and Sensory Indicators of Rejection
A sudden decrease in visual acuity is often the first sensory indicator of rejection. Patients frequently describe their vision as cloudy, foggy, or hazy, which is due to edema (swelling) in the corneal tissue caused by the damaged endothelium.
An abrupt increase in light sensitivity (photophobia) often accompanies the vision changes. The eye may appear visibly red, especially around the edges of the transplant, and the patient may experience new or worsening pain and irritation. These sensory changes represent the inflammation occurring as the immune system activates.
Visually, the transplant may lose its normal, glass-like transparency and take on a ground-glass or milky appearance. A specific sign of endothelial rejection is the Khodadoust line, a visible line of white blood cells (keratic precipitates) migrating across the back surface of the graft.
The Khodadoust line moves across the cornea, leaving a path of damaged endothelial cells and resulting in a cloudy, swollen section behind it. Other signs include small, fine white spots, or keratic precipitates, adhering to the back surface of the graft. When these visual cues combine with pain, redness, and severe blurriness, rejection should be strongly suspected.
Immediate Steps When Rejection is Suspected
If the sudden onset of redness, pain, light sensitivity, or decreased vision occurs, the patient must act urgently. The window for successful reversal of a rejection episode is narrow, often measured in hours rather than days. Immediate action increases the likelihood of saving the graft from permanent failure.
Contact the transplant ophthalmologist or the clinic’s emergency line without delay, explaining the specific combination of symptoms. Patients should not wait for a regular appointment or assume the symptoms will resolve. The medical team needs to be aware of potential immune rejection so immediate evaluation and treatment can be initiated.
Patients must continue using all currently prescribed eye drops and oral medications exactly as directed unless instructed otherwise. Stopping medications prematurely can worsen the inflammatory process and accelerate the rejection. The goal is to facilitate an emergency appointment, often the same day, to confirm the diagnosis and begin aggressive anti-rejection therapy.
Differentiating Rejection from Other Post-Operative Issues
Several common issues following a corneal transplant cause redness and irritation but lack the specific visual signs of rejection. For example, a loose or broken suture causes foreign body sensation and localized redness. A suture issue does not cause the severe, central graft clouding characteristic of endothelial rejection.
Dry eye syndrome is a frequent post-operative complaint resulting in mild redness, a gritty feeling, and fluctuating vision. Unlike rejection, dry eye symptoms are usually relieved with lubricating drops and are not accompanied by a rapid drop in vision or inflammatory cells within the graft. The distinction lies in the severity of the vision change and the presence of internal inflammation.
Infection (keratitis) is a serious emergency that shares the symptoms of pain and redness with rejection. Infections often present with a purulent discharge and a dense, focal white or yellow infiltrate in the corneal tissue, which differs from the more diffuse clouding of rejection. Primary graft failure causes the cornea to swell due to non-functioning donor cells, occurring without signs of active immune inflammation like keratic precipitates or a Khodadoust line.