Corneal haze is a clouding or scarring that develops within the cornea, the clear, outermost layer of the eye. This cloudiness interferes with the cornea’s function as a transparent window that focuses light onto the retina. The central question is whether this resulting cloudiness is a temporary setback or a permanent change to vision. The permanence of corneal haze depends heavily on its severity, underlying cause, and subsequent treatment.
Understanding Corneal Haze
Corneal haze represents a breakdown in the cornea’s precise structure, leading to a loss of transparency. The stroma, the middle layer, is composed of highly organized collagen fibers whose uniform arrangement allows light to pass straight through. When the cornea is injured, specialized cells called keratocytes activate and transform into myofibroblasts. These myofibroblasts produce new collagen, which is deposited in a disorganized pattern, disrupting the stroma’s structure. This disorganization causes light rays to scatter rather than refract cleanly, resulting in a hazy appearance and reduced visual clarity.
Causes and Triggers
Corneal haze results from the body’s natural healing response to damage to the corneal stroma. A frequent trigger is the surgical procedure photorefractive keratectomy (PRK), which involves reshaping the stroma with a laser. The depth of the laser ablation is a risk factor for developing postoperative haze. Haze can also be initiated by infectious causes, such as bacterial, viral, or fungal keratitis, which cause inflammation and tissue destruction. Physical trauma, including chemical burns or deep abrasions, also triggers this aggressive healing cascade, resulting in opaque scar tissue formation.
Prognosis and Expected Recovery Timeline
Corneal haze is often not permanent, especially when it is mild and post-surgical. For instance, mild haze following PRK is common but often resolves spontaneously. This mild haze typically peaks between three and six months post-surgery before diminishing over the following 12 to 24 months as the cornea remodels. However, haze resulting from severe chemical burns or deep infections is far more likely to be permanent and visually significant. Scars that penetrate deep into the stroma or are dense and central usually require intervention because natural resolution is insufficient.
Management and Treatment Options
If haze persists or severely impairs vision, medical intervention is necessary.
Medical Management
The first line of treatment is often topical corticosteroids, anti-inflammatory drops used to suppress the wound healing response. Steroid use must be closely monitored due to potential side effects like increased intraocular pressure. In surgical settings, Mitomycin-C (MMC) is often applied immediately after a laser procedure to prevent haze by inhibiting keratocyte proliferation.
Surgical Interventions
For established, persistent haze, phototherapeutic keratectomy (PTK) may be performed. PTK uses an excimer laser to precisely remove the superficial scarred tissue. If the haze is deep, dense, and unresponsive, a corneal transplant (keratoplasty) may be required to restore clarity.