10
Freeman, Cataract Surgery and Age-Related Macular Degeneration
in all three studies, although these estimates were not statistically significant (combined OR=1.4,
95% CI 0.8-2.4) (Table 4).
In the two datasets (SEE and BES) that had information on time since cataract surgery
(Table 5), the prevalence of late AMD increased as time since surgery increased. Results from
the combined analysis showed that those who reported surgery >=5 years ago had 2.1 times the
odds of late AMD (95% CI 1.0-4.6) (Table 5). Those who reported surgery <5 years ago had a
modestly elevated odds of late AMD, although it was not statistically significant (OR=1.4, 95%
CI 0.7-2.6) (Table 5). Sensitivity analyses were done to see how the eyes in SEE that were
missing dates of cataract surgery might bias the results. Those eyes that were missing date of
cataract surgery were less likely to have AMD (0.8% versus 2.2%). A minimum odds ratio was
estimated by assuming that those eyes that had cataract surgery but were missing the date of
cataract surgery were in the group that had surgery >=5 years ago. The odds ratio was
dramatically reduced and was no longer statistically significant suggesting that surgery >=5
years ago was likely not associated with late AMD in the SEE data set (OR=1.2, 95% CI 0.5-
2.8). The combined odds ratio for surgery >= 5 years ago was also attenuated and no longer
statistically significant (OR=1.5, 95% CI 0.8-2.6). Therefore, it does not appear that the
prevalence of late AMD increases with time since cataract surgery.
A higher prevalence of early AMD 1 (the definition that includes drusen of the smaller
size) was found in those who had cataract surgery >= 5 years ago in SEE (OR=1.7, 95% CI 1.1-
2.4) (Table 6). The prevalence of early AMD 1 was not different in those who were missing
dates of cataract surgery compared to those who had information on date of cataract surgery
(46% versus 44%). Thus, it is unlikely that the missing data would have changed these results.
In the BES study and in the combined analysis, though, previous cataract surgery was not
