Brief Answer: It can be pigmentation or nevus. Detailed Answer: Hello Welcome to healthcare magic I am Dr Dadapeer an OPHTHALMOLOGIST and I answer health problems related to eye. It seems from the history you have provided that your husband is havind a black dot on the iris. The black dot can be because pigmentation called as nevus. It is usually not harmful and does not require any treatment. This definitely requires treatment if it is increasing in size or associated with pain and redness. However this fist requires conformation of the above mentioned diagnosis. So if you can send me a photo of the eye I will have a look and confirm the diagnosis and then regarding next mode of treatment I can advice you accurately. Hope I have answered your query. Thank you

---