fifteen healthy new zealand white rabbits of both sexes were used in this experimental study . the animals were approximately 4 months old with an initial body weight range of 1.8 to 2.2 kg . the study protocol was approved by the committee for animal care of baqiyatallah university of medical sciences . the animals were maintained in dust free bedding cages in a controlled environment with a specified range of temperature ( 65f-65f ) and relative humidity ( 30% or more ) . twenty five healthy new zealand white rabbits were divided into 4 groups of normal ( not exposed to sm or solution ) , solution ( exposed to solution ) , sm ( exposed to sm ) , and prophylactic bethametazone ( received eye solution of bethametazone then exposed to sm solution ; then treated for 2 weeks ) . on day 14 , the eyes were enucleated and were subsequently either fixed in a 4% neutral buffered paraformaldehyde solution or frozen for further analysis . five - micron - thick sections were stained with haematoxylin and eosin ( h&e ) for light microscopy evaluation . an experienced pathologist evaluated the thickness of the cornea , epithelium cornea , endothelium , limbos epithelium , and epithelium conjunctive in conjunction with the layer frequencies of the epithelium cornea , limbos epithelium , and epithelium conjunctive as well as the frequency of meibomian gland cells using a motic light microscope . statistical analyses were done using spss software ( statistical package for social sciences , version 13.0 , spss inc . , the sm exposure group was significantly different from normal and solution groups by means of number of keratocyte in 10000 m , thickness of cornea ( m ) , thickness of corneal epithelium ( m ) , and number of corneal epithelial layers ( table 1 ) . it was also significantly different from normal and solution groups by means of thickness of limbal epithelium ( m ) and thickness of descemet 's memberain and endothelium ( m ) ( table 1 ) . moreover , the sm exposure group was significantly different from normal and solution groups by means of number of meibomian gland 's cells in 2500 m , thickness of palpebral conjuctival epithelium ( m ) , number of palpebral conjuctival epithelial layers , thickness of epithelial of palpebral skin ( m ) , number of epithelial layers of palpebral skin , number of goblet cells in conjunctival sac in 1000 m ( table 1 ) . comparisons of mean  sem ocular morphometric characteristics between study groups bethamethazone group was significantly different from sm exposure group by means of number of keratocyte in 10000 m , thickness of cornea ( m ) , and thickness of corneal epithelium ( m ) ( table 1 ) . bethamethazone group was also significantly different from sm exposure group by means of number of meibomian gland 's cells in 2500 m , thickness of palpebral conjuctival epithelium ( m ) , thickness of epithelial of palpebral skin ( m ) , number of epithelial layers of palpebral skin , and number of goblet cells in conjunctival sac in 1000 m ( table 1 ) . the sm exposure group was significantly different from normal and solution groups by means of number of keratocyte in 10000 m , thickness of cornea ( m ) , thickness of corneal epithelium ( m ) , and number of corneal epithelial layers ( table 1 ) . it was also significantly different from normal and solution groups by means of thickness of limbal epithelium ( m ) and thickness of descemet 's memberain and endothelium ( m ) ( table 1 ) . moreover , the sm exposure group was significantly different from normal and solution groups by means of number of meibomian gland 's cells in 2500 m , thickness of palpebral conjuctival epithelium ( m ) , number of palpebral conjuctival epithelial layers , thickness of epithelial of palpebral skin ( m ) , number of epithelial layers of palpebral skin , number of goblet cells in conjunctival sac in 1000 m ( table 1 ) . comparisons of mean  sem ocular morphometric characteristics between study groups bethamethazone group was significantly different from sm exposure group by means of number of keratocyte in 10000 m , thickness of cornea ( m ) , and thickness of corneal epithelium ( m ) ( table 1 ) . bethamethazone group was also significantly different from sm exposure group by means of number of meibomian gland 's cells in 2500 m , thickness of palpebral conjuctival epithelium ( m ) , thickness of epithelial of palpebral skin ( m ) , number of epithelial layers of palpebral skin , and number of goblet cells in conjunctival sac in 1000 m ( table 1 ) . the sm exposure group was significantly different from normal and solution groups by means of number of keratocyte in 10000 m , thickness of cornea ( m ) , thickness of corneal epithelium ( m ) , and number of corneal epithelial layers ( table 1 ) . it was also significantly different from normal and solution groups by means of thickness of limbal epithelium ( m ) and thickness of descemet 's memberain and endothelium ( m ) ( table 1 ) . moreover , the sm exposure group was significantly different from normal and solution groups by means of number of meibomian gland 's cells in 2500 m , thickness of palpebral conjuctival epithelium ( m ) , number of palpebral conjuctival epithelial layers , thickness of epithelial of palpebral skin ( m ) , number of epithelial layers of palpebral skin , number of goblet cells in conjunctival sac in 1000 m ( table 1 ) . bethamethazone group was significantly different from sm exposure group by means of number of keratocyte in 10000 m , thickness of cornea ( m ) , and thickness of corneal epithelium ( m ) ( table 1 ) . bethamethazone group was also significantly different from sm exposure group by means of number of meibomian gland 's cells in 2500 m , thickness of palpebral conjuctival epithelium ( m ) , thickness of epithelial of palpebral skin ( m ) , number of epithelial layers of palpebral skin , and number of goblet cells in conjunctival sac in 1000 m ( table 1 ) . according to the results of this study , bethamethazone can protect eyes from sm effect by decreasing changes in number of keratocyte in 10000 m , thickness of cornea ( m ) , thickness of corneal epithelium ( m ) , number of meibomian gland 's cells in 2500 m , thickness of palpebral conjuctival epithelium ( m ) , thickness of epithelial of palpebral skin ( m ) , number of epithelial layers of palpebral skin , and number of goblet cells in conjunctival sac in 1000 m . in line with the present study , previous studies have shown that steroids may be potential candidates for the pretreatment of ocular lesions following sm exposure.10 betamethasone is known to modulate the development and propagation of inflammation ; it not only decreases the production of inflammatory mediators ( cytokines and chemokines ) but also increases the synthesis of lipocortin and inhibits the production and decreases the induction of enzymes producing inflammatory mediators.11 betamethasone , therefore , attenuates both the initiation and the propagation of inflammation . with respect to sm exposure , steroids have been previously recommended for the treatment of sm lesions only after re - generabbition of the epithelium , or after the appearance of anterior chamber uveitis.11 it must be noted , however , that the mechanism of sm - induced injuries has hitherto eluded the scientific community and no effective drug is known against the local and systemic lesions begotten by sm.4 the best protection remains contact avoidance and in the event of contact , rapid decontamination or detoxification of the contaminated site.14 although the pharmacological response to topical steroids in rabbits may be different from that in humans , we believe that our findings are significant in emergency conditions , for example if people should enter area of known sm contamination . the present study carried out in vivo and to our knowledge there is no previous in vivo published document for the prophylactic use of betamethasone in sm - induced lesions . it should be noted that the mechanisms of the prophylactic effects of bethametazone in sm - induced eye lesions were not evaluated in this study . another limitation for this study was the use of a liquid solution of sm , not an aerosol exposure . although the primary route of corneal exposure would be to aerosolized sm , and not to direct instillation of a sm solution into the eye , it was prohibitively expensive for our research center to perform controlled aerosolized exposures , and this study should be considered as a pilot - study . given that humans can not be tested in future research and on the basis of the findings of the present study , betamethasone can be used as an effective prophylaxis against the hazardous effects of sm on the eye if the risk in an emergency can be justified . grk , mn , and shs carried out the design and coordinated the study . mn and kj participated in most of the experiments . shs provided assistance in the design of the study and participated in the revision of the manuscript .
background : the present study sought to evaluate the prophylactic effect of bethametazone on sulfur mustard ( sm)-induced ocular morphometric damage in the rabbit eye.methods:twenty five healthy new zealand white rabbits were divided into 4 groups of normal ( not exposed to sm or solution ) , solution ( exposed to solution ) , sm ( exposed to sm ) , and prophylactic bethametazone ( received eye solution of bethametazone then exposed to sm solution ; then treated for 2 weeks ) . on the day 14 after exposure , 
 five - micron sections were stained with haematoxylin and eosin for light microscopy evaluation . 
 the ocular morphometric characteristics in the study groups were compared to determine the prophylactic effects of the bethametazone.results:bethamethazone could protect eyes from sm effect by means of decrease in changes in number of keratocyte in 10000 m2 , thickness of cornea ( m ) , thickness of corneal epithelium ( m ) , number of meibomian gland 's cells in 2500 m2 , thickness of palpebral conjuctival epithelium ( m ) , thickness of epithelial of palpebral skin ( m ) , number of epithelial layers of palpebral skin , and number of goblet cells in conjunctival sac in 1000 m.conclusions:bethametazone may have a prophylactic effect on the early lesions of the eye of the rabbit due to sm exposure .