Purpose:
The purpose of this study was to evaluate corneal epithelium wound healing in an experimental model of dry eye in the guinea pig that exhibits an augmented responsiveness of corneal sensory receptors (Kovacs et al. 2010; ARVO E-Abstract 3403).
Methods:
The exorbital lacrimal gland of the right side was removed in guinea pigs causing dry eye signs. One and four weeks after the surgery, chemical wounds were performed in the corneal epithelium of both eyes, applying to the center of the cornea a 2mm-diameter piece of paper soaked in n-heptanol for 30s. Wounds were also performed in a group of non-operated, control guinea pigs. The epithelial wound was stained with fluorescein and photographed immediately and regularly until complete closure. Wound area was measured using image processing software. The epithelial migration rate (EMR, in µm/h) and the estimated time of healing (ETH, in h) were calculated. Tear secretion rate (phenol red threads) and blinking frequency were also measured before and 1 and 4 weeks after lacrimal gland removal surgery.
Results:
Tear secretion was significantly decreased after lacrimal gland removal; blinking rate increased 1 week after surgery and decreased afterwards (see table). The EMR, that reflects the velocity of wound closure, was significantly reduced in dry eyes (see table). Also, a 12 h-delay in the onset of wound healing was seen in dry eyes but not in control eyes. ETH was significantly increased in dry eyes 1 and 4 weeks after the surgery (see table). In contralateral eyes, EMR was also reduced (70±4 µm/h) and ETH was increased (35±1 h), 4 weeks after surgery.
Conclusions:
Corneal epithelial wound healing was delayed in lacrimo-deficient guinea pigs shortly after the onset of dry eye, due to a decreased rate of epithelial cell migration and a prolonged latency in the initiation of healing. Wound healing in eyes contralateral to lacrimal gland removal also exhibited a disturbed corneal wound healing.
Keywords: cornea: tears/tear film/dry eye • wound healing • lacrimal gland