A rabbit model of age-dependant ocular hypertensive response to topical corticosteroids.
OBJECTIVE
To investigate the ocular hypertensive response to topical dexamethasone (DEX), rimexolone (RIM), loteprednol etabonate (LOT) and fluorometholone (FML) in rabbits of different ages.


METHODS
Seventy-five rabbits of three age groups (7 weeks, 6 months and 1-year old) received topical administration of 0.1% DEX, 1% RIM, 0.5% LOT, 0.1% FML or balanced salt solution four times daily for 1 month. Intraocular pressure (IOP) was monitored at regular time intervals. After a month, eyes were harvested for histological study with haematoxylin and eosin (H&E), periodic acid Schiff and Masson trichrome staining. Trabecular meshwork changes were graded by masked ocular pathologists.


RESULTS
Topical DEX caused the greatest increase in IOP, followed by RIM and FML. LOT caused the least IOP increase. Similar pattern of IOP response to the four corticosteroids was observed in the three studied age groups. Young rabbits (7 week) were the most responsive to corticosteroids among the age groups. Extracellular matrix thickening in the trabecular meshwork region and loss of trabecular meshwork cells were observed after DEX, FML or RIM treatments.


CONCLUSIONS
Young rabbits are more susceptible to steroid induced increase in IOP, even for milder steroids such as fluorometholone and rimexolone.
Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
Yi
Y
Qin
Shi
S
Lam
Gary Hin Fai
GH
Yam
Kwong Wai
KW
Choy
David Tai Li
DT
Liu
Thomas Yee Hang
TY
Chiu
Wai Ying
WY
Li
Dennis Shun Chiu
DS
Lam
Chi Pui
CP
Pang
Dorothy Shu Ping
DS
Fan
D000287:Administration, Topical; D000367:Age Factors; D000730:Androstadienes / Q000633:toxicity; D000818:Animals; D003907:Dexamethasone / Q000633:toxicity; D004195:Disease Models, Animal; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005469:Fluorometholone / Q000633:toxicity; D005938:Glucocorticoids / Q000633:toxicity*; D007429:Intraocular Pressure / Q000187:drug effects*; D000069559:Loteprednol Etabonate; D008297:Male; D009798:Ocular Hypertension / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D009883:Ophthalmic Solutions / Q000633:toxicity; D011245:Pregnadienes / Q000633:toxicity; D011817:Rabbits; D014065:Tonometry, Ocular; D014129:Trabecular Meshwork / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D000730:Androstadienes; D016326:Extracellular Matrix Proteins; D005938:Glucocorticoids; D009883:Ophthalmic Solutions; D011245:Pregnadienes; D003907:Dexamethasone; C013769:rimexolone; D005469:Fluorometholone; D000069559:Loteprednol Etabonate