Objective and Methods: Intravitreous aminoglycosides are widely used f
or the treatment and prophylaxis of endophthalmitis. Because the toxic
ity of 0.4 mg of gentamicin sulfate is well documented, many surgeons
now use amikacin sulfate or low-dose gentamicin to reduce the risk of
macular infarction. A survey of retinal specialists has suggested that
amikacin or low-dose gentamicin can also cause macular toxic side eff
ects. To further investigate this issue, the critical details of the c
ase histories, findings, and course of 13 patients who received intrav
itreous injections of 0.2 to 0.4 mg of amikacin sulfate or 0.1 to 0.2
mg of gentamicin sulfate for prophylaxis or treatment of endophthalmit
is are summarized. For several patients, complete case histories and a
fluorescein angiogram are provided. Results: These cases suggest that
amikacin and low-dose gentamicin, similar to gentamicin sulfate at a
dose of 0.4 mg, can cause macular infarction. The causative dose canno
t be ascertained in any of the cases, but doses were prepared by hospi
tal pharmacists using typewritten protocols, a practice that helps to
prevent dilution errors. Several of these cases differ from previously
reported cases of aminoglycoside toxicity in that the involvement of
the macula was quite discrete. Most of the patients suffered severe vi
sual loss, but two patients, in whom most of the nonperfusion was adja
cent to the macula and in whom some of the perifoveal capillaries were
spared, recovered 20/50 visual acuity.Conclusions: These cases emphas
ize the potential hazards of the intravitreous use of aminoglycosides.
A toxic reaction can occur even when injection of low doses is intend
ed and precautions are made to avoid dilution errors. A localized incr
ease in concentration in dependent areas of the retina may play a role
in aminoglycoside toxicity. If some of the perifoveal capillaries are
spared, retention of some central vision is possible. Consideration s
hould be given to substituting ceftazidime for aminoglycosides for the
treatment and prophylaxis of endophthalmitis.