Dear Editor,

We have read with considerable interest the article entitled "Bilateral acute depigmentation of the iris (BADI): first reported case in Brazil", by Maestrini et al.⁽¹⁾. The authors describe a patient who was diagnosed as having BADI, which has attracted a lot of attention among ophthalmologists in recent years. We would like to thank the authors for reporting on this interesting case, and we want to contribute further by making the following three points.

Bilateral acute iris transillumination (BAIT) and BADI are both relatively new clinical entities and share some important features: an acute onset of severe photophobia and red eyes after a flu-like syndrome, pigment dispersion into the anterior chamber, and exclusive involvement of the iris. However, in patients who have BAIT the pigment discharge is from the iris pigment epithelium, whereas for those with BADI, the pigment discharge comes from the iris stroma. This leads to iris transillumination defects and mydriatic/atonic pupilla in patients with BAIT, but not in those who have BADI.

First, the authors report that there are two clinical sub-types of BADI. The first sub-type has a more benign course, a lower incidence of increased intraocular pressure (IOP), and reversibility of the iris changes without transillumination defects or pupil distortion. The second sub-type, BAIT, has diffuse iris transillumination and mydriatic/atonic pupilla or distorted pupil, occasional posterior synechiae, and increased IOP⁽¹⁾. Indeed, the first sub-type mentioned by the authors reflects the characteristic clinical features of the BADI⁽²⁾, and the second sub-type, referred to in the study as BAIT, shares some properties with BADI but has differentiating characteristic features⁽³⁾. In addition, BAIT was first described by Tugal-Tutkun et al. as being a probable distinct entity⁽³⁾, and several publications have subsequently reported it as being a distinct entity from the BADI^(4,5). It is not clear, therefore, whether BAIT is a sub-type of the BADI. It appears to be a different entity or an expanded spectrum of BADI, which makes it incorrect to describe BAIT as a sub-type of BADI.

In addition, Maestrini et al.⁽¹⁾ report that both conditions have a self-limited course and a good prognosis. However, BAIT cases may present with severe IOP rise, which is sometimes resistant to medical treatment and necessitates trabeculectomy surgery as in our case report⁽⁵⁾. Therefore, clinicians should be aware of a severe IOP rise in patients with BAIT during their follow-up.

Finally, although the exact etiopathogenesis of BAIT remains unclear, several publications have reported a relationship between BAIT and systemic use of moxifloxacin⁽⁴⁾, upper respiratory tract infections⁽³⁾, and a toxic effect following a fumigation therapy⁽⁵⁾. Maestrini et al.⁽¹⁾ reported the cause of BADI may be a viral etiology considering empirical antiviral therapy has provided some clinical improvement by reducing pigment dispersion into the anterior chamber. However, these authors should have taken an aqueous sample for viral analysis in order to conclude such a relationship. Therefore, further study is needed to include the aqueous tap for local antibody production against the virus, or to demonstrate the viral DNA to clarify the viral etiology in patients with BAIT.