Comparison of the effects of topical levobunolol and timolol solution on the human ocular surface.
OBJECTIVE
To compare the effects of levobunolol hydrochloride and timolol maleate on tear volume, precorneal tear film stability, and corneal epithelial barrier function in normal human eyes.


METHODS
The study population consisted of 14 healthy volunteers. To obtain pretreatment baseline values, we determined the radius of the tear meniscus (RTM) by meniscometry; the noninvasive breakup time (NIBUT) of the precorneal tear film with a tear specular microscope; and corneal fluorescein uptake with a fluorophotometer. Levobunolol hydrochloride (0.5%) or timolol maleate solution (0.5%) was instilled twice daily for 4 weeks into 1 eye; the contralateral eye was treated with the other topical drug twice daily for the same period. At the end of the study period, the same tests were performed, and the pre- and posttreatment results were compared.


RESULTS
Timolol solution did, and levobunolol did not, significantly reduce NIBUT from the baseline values. RTM was significantly decreased by treatment with either timolol or levobunolol solution. Corneal fluorescein uptake was not significantly changed, although it was higher after treatment with both topical drugs.


CONCLUSIONS
Four-week treatment with timolol solution resulted in significant instability of the precorneal tear film. Both timolol and levobunolol solution significantly decreased tear volume on the ocular surface. These results indicate that levobunolol solution applied twice daily has equal effects on the tear volume and corneal epithelial barrier function as does timolol solution applied twice daily and that it affects precorneal tear film stability less than timolol solution.
Ishibashi
Takeshi
T
Department of Ophthalmology, Kyoto Prefectural University of Medicine, Japan. tishibas@ophth.kpu-m.ac.jp
Yokoi
Norihiko
N
Kinoshita
Shigeru
S
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D000328:Adult; D003287:Contrast Media / Q000493:pharmacokinetics; D003315:Cornea / Q000378:metabolism; D019573:Epithelium, Corneal / Q000187:drug effects* / Q000378:metabolism*; D005123:Eye / Q000187:drug effects*; D005260:Female; D019793:Fluorescein / Q000493:pharmacokinetics; D006801:Humans; D007509:Irritants / Q000008:administration & dosage; D002040:Levobunolol / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012996:Solutions; D013666:Tears / Q000187:drug effects / Q000378:metabolism; D013999:Timolol / Q000008:administration & dosage* / Q000009:adverse effects
D000319:Adrenergic beta-Antagonists; D003287:Contrast Media; D007509:Irritants; D012996:Solutions; D013999:Timolol; D002040:Levobunolol; D019793:Fluorescein