Commentary: An option for treating resistant pseudophakic cystoid macular edema

Pseudophakic cystoid macular edema (PCME) can cause considerable angst to the patient and the surgeon. When it occurs after uncomplicated cataract surgery, it becomes all the more difficult for the surgeon to explain the cause of the “blurred vision” to the patient, advise additional treatment, and reassure them of a good outcome in due course of time.

Traditionally, a step-wise approach is followed in treating pseudophakic CME.[1] Topical nonsteroidal anti-inflammatory agents with or without topical carbonic anhydrase inhibitors lead to the resolution of the PCME in most cases.[2] Topical, periocular, or intraocular steroids are used in refractory cases and so are anti-vascular endothelial growth factor (VEGF) agents. Vitrectomy and oral carbonic anhydrase inhibitors being other options to manage resistant cases.

In this issue of the Indian Journal of Ophthalmology, an interesting therapeutic option to treat PCME has been explored by the authors.[3] The authors have used topical interferon (IFN) alfa-2b as a viable treatment option to treat PCME. This small case series comprises cases responding to traditional treatment, a few resistant to it, and a couple of them needing a switch due to complications associated with traditional therapy (steroid-induced glaucoma). Topical IFN has recently been used to treat ocular surface squamous neoplasia and is reasonably safe and hence this line of treatment for PCME is likely to be safe as well.

The advantages of considering IFN as a treatment option are as follows:

1. Yet another noninvasive therapeutic option to treat resistant cases

2. Appears to be reasonably safe (one patient in the reported series developed papillary conjunctivitis)

3. Alternate to treating steroid responders with PCME

4. Less expensive when compared with anti-VEGF agents

Disadvantages of IFN therapy to PCME are

1. At 1,600 INR/month, it is considerably more expensive than traditional topical therapy (NSAID, topical steroids)

2. IFN drops need temperature-controlled storage, which can limit their utility

3. Though an early therapeutic response has been demonstrated by the authors, cessation of therapy has resulted in recurrences and hence a long-term treatment may be necessary for some patients

4. Considering that it is not an over-the-counter medication, it has to be specially prepared and dispensed by the treating physician

5. Rare side effects such as a flu-like syndrome may occur and long-term side effects are yet to be known.

To summarize, although the authors need to be congratulated for exploring a new avenue of treatment for PCME, its role may remain limited considering the existence of proven, safe, cost-effective therapies that need no special dispensing versus that of the topical IFN. However, it may find its role as rescue therapy in treating resistant PCME cases.