To the Editor:

We read with interest the article regarding diffuse unilateral subacute neuroretinitis by Dr. Nelson Sabrosa and Dr. Fernando Arevalo (Retinal Insider, February, p. 58). In the discussion regarding treatment, there was a recommendation that laser photocoagulation be used to prompt movement of the worm away from the macula and towards an area of the fundus, where vital structures would not be threatened by laser ablation.

Our clinical experience, however, suggests that such a tactic should only be employed using extreme caution, as the organism is capable of migrating at a surprising speed in terms of retinal anatomy. One should also take into account the possibility of some, though much more limited, migration of a worm after apparently successful laser. In one case, we applied focal laser in an attempt to kill a subretinal nematode (See Figure). The following day, it was noted that the nematode was not killed but had migrated from the area where the laser was applied (upper arrow) to a region closer to the fovea (lower arrow). The application of additional laser was followed by absorption of the organism over weeks. As an alternative to using laser photocoagulation to stimulate worm movement, the treating physician can use the light from the slit lamp in order to prompt migration of the nematode into an area where definitive laser treatment can be safely applied.

Sincerely,

Jon Wender, MD, and Everett Ai, MD

San Francisco