Abstract
Purpose::
To develop dry eye symptoms in one eye of 12 New Zealand white rabbits by 3 different gland removal methods, analyze the effects of the dry eye in terms of tear break-up time, volume, and osmolality, as well as the confocal appearance of the epithelial cells.
Methods::
The rabbits were divided into 3 equal groups each containing 4 animals. Each group had one of three types of glandular removal surgery performed on one eye: 1) main lacrimal gland removal (M), 2) main and accessory lacrimal gland removal (MA), and 3) Harderian, main, and accessory lacrimal gland removal (HMA). The contralateral eyes served as control. Dry eye development was determined by the tear break-up time (TBUT) of each eye using a TearscopeTM (Keeler Instruments). Once TBUT confirmed dry eye development in the experimental eyes, tear volume and osmolality tests and confocal microscopy were performed on all eyes.
Results::
All three rabbit groups developed significantly lower TBUTs in their surgical eye as compared to their contralateral control eye: 16 ± 4 secs as compared to 50 ± 6 secs, respectively, p=0.001. Tear volume was decreased in all three experimental eyes as compared to their contralateral control eyes. However, the differences were not statistically significant: mean 23.1 ± 3 mm versus 26.2 ± 3 mm for the experimental versus control eyes, respectively. Confocal microscopy showed no difference in cell appearance between the control and experimental eyes for any of the groups. Rose Bengal stain revealed no degeneration in the corneal epithelium.
Conclusions::
The HMA experimental eyes developed the most severe dry eye symptoms in terms of TBUT and tear volume. There was a general trend for all the experimental eyes to have a lower tear osmolality than the control eyes, reflecting the loss of tear protein and salt input from the lacrimal glands. Like the less severe and more common form of human dry eye, the HMA dry eye model has no detectable adverse corneal involvement (staining or appearance).
Keywords: cornea: tears/tear film/dry eye