Neurotrophic keratitis (NK) is a degenerative corneal disease related to alterations in trigeminal corneal nerve sensation and function, with consequent breakdown of the corneal epithelium, impairment of healing, and development of corneal ulceration, melting, and perforation. The hallmark of NK is decreased or absent corneal sensation (Bonini et al, 2003). The clinical presentation of NK ranges from superficial punctate keratopathy to a persistent epithelial defect (PED), which may progress to stromal melting and corneal perforation. Decreased stimulation to the tear gland causes deficient tear film production due to damage in the trigeminal sensory nerve fibers. The diagnosis of NK is based on history, conditions associated with trigeminal damage, presence of corneal surface changes such as PEDs, and decreased corneal sensitivity. Because patients have impaired or absent corneal sensation, they rarely complain about symptoms other than blurry vision if a PED is present. Reduction or absence in corneal sensitivity is pathognomonic of NK (Bonini et al, 2003).
The most common causes of NK are viral infections (herpes simplex and herpes zoster keratoconjunctivitis), followed by surgical alterations to the trigeminal nerve. Toxicity from chronic use of topical ocular medications also may cause nerve damage and result in decreased corneal sensitivity. NK has also been associated with systemic diseases such as diabetes mellitus (Mantelli et al, 2015).
The causes of NK in children can be the same as those in adults, although these are much less frequent in the pediatric population. Rather, congenital diseases are a more common cause of decreased corneal sensitivity in children. Congenital corneal anesthesia can be associated with systemic diseases such as familial dysautonomia (Riley-Day syndrome), Goldenhar syndrome, Möbius syndrome, and congenital insensitivity to pain. Typically, the congenital corneal anesthesia occurs bilaterally (Mantelli et al, 2015).
Scleral contact lenses can be used to promote healing of PEDs and to help protect and heal the ocular surface in those affected by NK (Dimit et al, 2013; van der Worp et al, 2014). Severe ocular surface disease is a primary indication for scleral lenses because they protect the surface from external dehydration and help heal the surface by enclosing it within a fluid-filled reservoir (Romero-Rangel et al, 2000; Pullum and Buckley, 2007).
Take for example a two-year-old girl who had a history of a PED due to NK in her right eye. She acquired corneal hypoesthesia due to third nerve damage from a right temporal intracranial glioma resection. Prior treatment of her eye condition consisted of preservative-free artificial tears, autologous serum tears, and cenegermin 0.02% eye drops. Although the patient was managed with topical medications, her cornea had a difficult time healing properly due to a habit of digging her fingers into her eye, which caused recurrent epithelial defects. She was finally fitted into an 18.2mm scleral lens to promote healing of her cornea and to protect her eye from mechanical harm (Figure 1).
Pediatric NK is a rare corneal condition that can lead to epithelial defects that are difficult to heal. In cases in which other medical therapies are not successful, scleral lenses may help resolve PEDs and protect the ocular surface in children who have NK. CLS
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