Differential corneal involvement in xeroderma pigmentosum
The following case has been reported in the Indian Journal of Ophthalmology.

A 7-year-old girl was brought with an inability to open the eyes in bright light for the past several years. Examination revealed multiple hyperpigmented skin nevi involving the face, neck, arms, and feet suggestive of clinical diagnosis of xeroderma pigmentosum. The child was extremely photophobic.

Lid margin was irregular with severe loss of lashes in the lower eyelid of both eyes. Conjunctiva was dry, atrophic, and pigmented. Cornea showed haze, edema, and vascularization. The left eye showed an area of corneal melt and perforation. As seen in both eyes, the upper one-third of the peripheral cornea was relatively unaffected corresponding to the area that is covered by eyelids.

The selective sparing of the superior part of the cornea is explained by the protective effect of the upper eyelid. This clinical observation emphasizes the fact that the corneal changes in xeroderma are secondary to the cumulative effect of exposure of ultraviolet radiation on the affected area. The disabling corneal changes can be prevented if adequate solar protection is emphasized at an early stage of life.

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