Intravitreal steroid for refractory diabetic macular edema

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The majority of eyes with diabetic macular edema (DME) and impaired
vision despite previous laser treatment that initially experienced
improvement in visual acuity following intravitreal triamcinolone
acetonide (IVTA) maintained their gain after 5 years of follow-up,
according to a new study.

Macular edema is the most common cause of reduced visual acuity in
diabetic retinopathy, which in turn is the leading cause of blindness
in North America. The treatment of macular edema, standardized by the
Early Treatment Diabetic Retinopathy Study (ETDRS), demonstrated that
focal laser treatment reduces the risk of moderate visual loss (3 or
more lines of visual acuity) from 24% to 12%. Unfortunately, not all
patients respond to focal laser treatment, stimulating the
investigation of other treatments such as grid laser photocoagulation,
pars plana vitrectomy, antivascular endothelial growth factor therapy,
and intravitreal triamcinolone.

Although important issues such as the optimal dose and retreatment
regimens still need to be addressed, it does seem that intravitreal
triamcinolone acetonide (IVTA) can be efficacious for advanced
diabetic macular edema (DME), at least in the short-term. An important
question that remains unanswered, however, is whether treatment with
IVTA is safe and efficacious for more extended periods. Another
unanswered question is whether the duration of macular edema at the
time of treatment affects the anatomic and functional response.

Methods and Results

This study was a prospective, double-masked, randomized clinical
trial. After completing the 2-year visit, all eyes, including those
initially randomized to receive placebo, received IVTA.

A total of 69 eyes (41 patients) were entered into the study, with 34
eyes initially receiving active treatment (which consisted of
intravitreal injection of 0.1 ml of 40 mg/ml triamcinolone acetonide
with adjunctive laser therapy where appropriate) and 35 eyes receiving
placebo. Five-year data were available for 44 of 67 eyes (66%). For
the 23 eyes with missing 5-year data, of which 13 received placebo and
10 received IVTA, the last observation was carried forward.

Improvement of best-corrected logarithm of the minimum angle of
resolution visual acuity by ≥5 letters after 5 years compared with
baseline and 2 years, and incidence of adverse events. Secondary
outcome was the change in central macular thickness.

Improvement of ≥5 letters after 5 years was found in 14 of 33 eyes
(42%) initially treated with IVTA compared with 11 of 34 eyes (32%)
initially treated with placebo. Foveal thickness decreased by 30
µm less in the initial-IVTA group than in the initial-placebo
group at 5 years; 5 of 11 eyes (45%) from the initial-IVTA group that
were phakic at commencement of the third year required cataract
surgery. A similar number of eyes from each group required ongoing
treatment from the third year onward with both laser and IVTA,
indicating that IVTA treatment for 2 years does not lead to reduction
in the risk of recurrent edema.

Discussion and Conclusions

In this report presents the longest term data available concerning the
safety and efficacy of intravitreal injections of IVTA for DME. We
found that the initial beneficial effect of treatment continued to
hold up in most eyes with respect to the primary outcome, with 42% of
eyes in the initial-IVTA group gaining 5 or more letters since
baseline after 5 years compared with 56% after 2 years.

The safety profile of IVTA was acceptable in the third to fifth years
of the study. Surgery had been performed in 55% of initially treated
eyes in the first 2 years of the study, mainly in the second year.
Thereafter, another 4 cataracts were removed from the 11 eyes in the
initial-IVTA group that were still phakic at the beginning of the
third year of the study. Glaucoma medication continued to be required
at a similar rate in those receiving IVTA treatment. Glaucoma surgery
was required by 9% of eyes in the initial-IVTA group over the 5 years
of the study.

Cataract surgery was associated with poor outcomes in some eyes in
this study. Three of 4 eyes that became unresponsive to treatment with
IVTA did so after cataract surgery. These 3 eyes each lost more than
10 letters and developed marked macular edema, thereby affecting the
mean values for the entire group. Although it was standard practice to
inject IVTA at the time of surgery in this study, we have since formed
the impression that injection of IVTA approximately 4 weeks before
surgery may result in better outcomes. The management of
steroid-induced cataract in eyes with advanced DME has been poorly
studied and warrants further research.

In conclusion, this study suggests that the beneficial effect of IVTA
in eyes with DME persists for up to 5 years in most eyes without a
large increase in steroid-related adverse events. A 2-year delay in
instituting treatment did not seem to affect outcomes adversely.
Removal of steroid-induced cataract in eyes with advanced DME may be
associated with poor outcomes in a minority and warrants further
research. The researchers state that treatment with IVTA may still be
considered in carefully selected cases of impaired vision caused by
advanced DME that is not responding to other interventions.

Ophthalmology. 2009 Nov;116(11):2182-7

http://www.ncbi.nlm.nih.gov/pubmed/19796823

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