Methotrexate reduces the complications of endophthalmitis resulting from intravitreal injection compared with dexamethasone in a rabbit model.
OBJECTIVE
The incidence of infectious endophthalmitis associated with intravitreal injection (IVI) of steroid has been reported to be as high as 0.87%. This study was designed to investigate whether the antimicrobial activity of intravitreal methotrexate (MTX) alters the incidence or course of bacterial endophthalmitis associated with IVI in a rabbit model.


METHODS
A rabbit model of endophthalmitis induced by Staphylococcus epidermidis (S) was established. Six groups of rabbits had IVI of sterile balanced salt solution (BSS), MTX (400 microg), dexamethasone (Dex, 200 microg), S, S and MTX (S-MTX), or S and dexamethasone (S-Dex). On days 0, 1, 3, 6, 10, and 14, total intraocular inflammation was measured in each animal. Vitritis was graded by the degree of vitreal haze. An intravitreal tap was performed on two animals from groups S, S-Dex, and S-MTX. A histopathologic study was performed on day 14.


RESULTS
No endophthalmitis was observed in the control groups BSS, MTX, and Dex. Group S-Dex had the highest and group S-MTX had the least total ocular inflammation and vitritis scores from days 3 to 14. The difference in total inflammation and vitritis among groups S, S-Dex, and S-MTX is significant (P = 0.046 and P = 0.001, respectively). Live bacteria were isolated only from groups S and S-Dex. Pathology revealed severe ocular destruction in groups S and S-Dex and intact structures in group S-MTX.


CONCLUSIONS
MTX appears to reduce the risk of development of bacterial endophthalmitis and ocular destruction associated with IVI compared with Dex. IVI of MTX may be a safer alternative than steroid injection in treating noninfectious uveitis.
Department of Ophthalmology and Visual Sciences, College of Medicine, University of Illinois at Chicago, 60612, USA.
Sophie X
SX
Deng
Susan
S
Penland
Sumit
S
Gupta
Richard
R
Fiscella
Deepak P
DP
Edward
Howard H
HH
Tessler
Debra A
DA
Goldstein
D000818:Animals; D015169:Colony Count, Microbial; D003907:Dexamethasone / Q000627:therapeutic use*; D004195:Disease Models, Animal; D009877:Endophthalmitis / Q000188:drug therapy* / Q000382:microbiology; D015818:Eye Infections, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D005493:Folic Acid Antagonists / Q000627:therapeutic use; D005938:Glucocorticoids / Q000627:therapeutic use; D007267:Injections; D008727:Methotrexate / Q000627:therapeutic use*; D008826:Microbial Sensitivity Tests; D011817:Rabbits; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000302:isolation & purification*; D014822:Vitreous Body
D005493:Folic Acid Antagonists; D005938:Glucocorticoids; D003907:Dexamethasone; D008727:Methotrexate