New contact lenses or surgical techniques can bring unique challenges. Some are benign, while others may necessitate changes or therapeutic intervention, such as corneal haze with corneal cross-linking (CXL). CXL has provided many patients with an opportunity to slow their ectatic disease (specifically, keratoconus). CXL has been deemed a safe and efficacious treatment to slow or halt the disease, provide slight improvements in visual function, and reduce the need for corneal transplantation (Meiri et al, 2016; Raiskup et al, 2015). The procedure may also present contact lens practitioners with a more stable corneal structure on, or over, which to fit a corneal GP or scleral lens. However, the procedure is not without complications, some of which may depend on the precise details of the ultraviolet (UV) radiation parameters and whether the procedure was done with the epithelium intact or removed. Most studies have been performed in an epithelium-off manner.
A 2015 Cochrane review indicated total complication rates that ranged between 6% to 25% in the keratoconus population, some of which depended on the presenting keratoconus status and comorbidity (Sykakis et al, 2015). This analysis included only two studies of 12 months or longer and showed the reported events to be corneal edema, anterior chamber inflammation, recurrent corneal erosion, subepithelial infiltrates, and peripheral corneal neovascularization; many of these adverse events were reported as temporary and of minor significance.
This same report showed an 80% to 90% relative risk reduction in progression of the disease over the course of one year. Other reported complications include loss of effect, decrease in visual acuity, microbial keratitis, stromal opacities, endothelial cell disruption, and haze.
Corneal haze is a phenomenon that occurs post-surgically in most patients who have undergone CXL (Greenstein et al, 2010). The haze is unlike that seen with photorefractive keratectomy (PRK), which takes on a reticulated pattern and is observed in the subepithelial. CXL haze appears dust-like and can be found between the anterior and mid-stroma. Although different in the time frame for appearance, increase in severity and resolution are similar between the two.
The most posterior aspect of the haze has often been referred to as the “demarcation line,” which to some indicates the effectiveness of the procedure; this has more recently been challenged (Yam et al, 2012; Doors et al, 2009; Gatzioufas et al, 2016). The observed haze represents a histological effect from activated keratocytes and the extracellular remodeling after UV radiation-induced cross-linking.
The haze that is seen immediately after CXL does not respond well to steroids. However, a report from Vinciguerra et al (2012) indicated that the selective use of topical steroids would aid in preventing corneal haze in a group of patients younger than age 18.
Some corneal haze present after the third post-surgical month may require an intervention with your preferred low-dose topical steroid. In most cases, the haze will plateau around three months and disappear in three to 12 months. In rare cases, the haze may linger. At least one report showed that 8.3% of patients developed haze one year after CXL (Raiskup et al, 2009). Thus, the management will be based mostly on the honored virtue of the tincture of time. CLS
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