One side effect of cycloplegic drops is that they often have BAK as a preservative ingredient, which, with daily use, can erode the tear shield:

At each administration of an eye drop containing benzalkonium chloride, its detergent effect disrupts the lipid layer of the tear film. This cannot be regenerated and can no longer protect the aqueous layer of the tear film, which evaporates easily. In these circumstances, the cornea is exposed and eye dryness occurs. In addition, benzalkonium chloride has a cellular toxicity on caliciform cells, entailing a reduction in the amount of mucin, an additional reason for disrupting the tear film. In fact, none of the cycloplegic drops used to treat Spasm of Accommodation in the United States are available without BAK. This unfortunately makes treatment much more difficult as the side effect of dry eyes and corneal damage can occur. France, Australia, Canada, and the United Kingdom do have limited availability of BAK-free eye drops available in unidose, and they must be imported to the United States with a physicians letter to the FDA enclosed with the imported prescription. Due to the high potential of tear shield damage with long-term use and the associated dry eye condition caused by cycloplegic eye drops with BAK (preservative), many physicians do not recommend cycloplegic eye drops.
Unfortunately, these are not standardized for routine use, and some centres have reported persistent PCR positivity after clinically successful treatment, fuelling the controversy about the existence of prolonged chronic brucellosis.Other laboratory findings include normal peripheral white cell count, and occasional leucopenia with relative lymphocytosis. The serum biochemical profiles are commonly normal. Prevention
Surveillance using serological tests, as well as tests on milk such as the milk ring test, can be used for screening and play an important role in campaigns to eliminate the disease. Also, individual animal testing both for trade and for disease-control purposes is practiced. In endemic areas, vaccination is often used to reduce the incidence of infection. An animal vaccine is available that uses modified live bacteria. The World Organisation for Animal Health Manual of Diagnostic Test and Vaccines for Terrestrial Animals provides detailed guidance on the production of vaccines. As the disease is closer to being eliminated, a test and eradication program is required to eliminate it.The main way of preventing brucellosis is by using fastidious hygiene in producing raw milk products, or by pasteurizing all milk that is to be ingested by human beings, either in its unaltered form or as a derivative, such as cheese. Treatment
Antibiotics such as tetracyclines, rifampicin, and the aminoglycosides streptomycin and gentamicin are effective against Brucella bacteria.