Abstract
Purpose: :
Congenital insensitivity to pain with anhidrosis (CIPA) is a rare autosomal recessive disorder characterized by reduced sensitivity to pain and heat, an inability to sweat, and mental retardation of variable severity. In patients with CIPA, sympathetic ganglion neurons and nociceptive sensory neurons are lost due to mutations in the TRKA gene encoding the receptor tyrosine kinase for nerve growth factor. The purpose of this study is to describe ocular manifestations in Japanese patients with CIPA, focusing particularly on the status of the ocular surface.
Methods: :
The subjects were 25 patients with CIPA. Seventeen men and eight women were included. The mean and standard deviation of age were 10.5 ± 5.8 years (range, 1–30 years). The study adhered to the tenets of the Declaration of Helsinki and informed consent was obtained from all subjects before examinations. The patients underwent applicable ophthalmologic examinations, including visual acuity, refraction, slit–lamp examination, tear breakup time, Schirmer 1 test, corneal sensitivity with Cochet–Bonnet aesthesiometer, corneal topography, blink rate, and expression of meibomian gland secretion with forceps.
Results: :
Corneal opacities were observed in 3 eyes of 2 cases and keratoconus was recognized in 2 eyes of 1 case. Visual acuity was within normal range in most of the eyes without these corneal complications. Superficial punctate keratopathy (SPK) was observed at the interpalpebral area in 22 of 50 eyes (44%). Tear breakup time was below the lower limit of the normal range and the value of Schirmer 1 test was above the lower limit of the normal range in all eyes examined. The Cochet–Bonnet aesthesiometer measurements were far below the lower limit (55 mm) of the normal range in all eyes examined (range; 0 to 30 mm). Corneal topography showed normal pattern in all eyes examined except one case, in which a keratoconus pattern was detected in both eyes. Blink rate was within normal range. The average number of expression of meibomian gland secretion with forceps in lower lids was 4.7 ± 3.1 glands (range, 1–12 glands), which was far below that in age–matched controls.
Conclusions: :
Dry eye of increased evaporation loss due to meibomian gland dysfunction might cause SPK in patients with CIPA. Investigation of dry eye in patients with CIPA will provide unique opportunities to explore the critical roles of the autonomic sympathetic nervous system as well as the sensory nervous system in the physiology of tear production.
Keywords: cornea: tears/tear film/dry eye • cornea: clinical science