My One Eyed Wonder- Feline Iris Melanosis
Image description: A black and white cat with one eye sits calmly on a bed, its fur contrasting the soft fabric. The missing eye adds character to its alert, curious gaze. Despite its injury, the cat’s tranquil posture shows trust and comfort, reflecting resilience and quiet dignity.
Dali’s Story
Dali had a small freckle on her eye for about seven years. She had been seen by several vets for routine vaccinations and there were a few different diagnoses given ranging from a problem with her eye lid to a possible vitamin D deficiency. I had decided to monitor her eye by taking photos every few months to check for any growth or changes. In January 2025 when she went for a routine check-up I raised concerns that the freckle on her iris had grown considerably and the vet suspected that she may have iris melanosis; Dali had some simple in-house tests which confirmed this but there was no evidence it had become malignant.
I was referred to a specialist whom I saw in April 2025; Dali underwent some more tests, this time under anaesthesia to give a more detailed assessment of her eye including ultrasounds to determine whether there was evidence that cancer was present in other areas of her body. Very fortunately there was no evidence of this and her organs looked healthy. I was then given a choice that no pet owner wants, do I choose to remove her eye to protect her other organs or leave things as they are and hope that she has more time before the iris melanosis becomes cancerous?
Image description: A black cat with green eyes lying in a playful posture on a white bed
The vets were wonderfully supportive but unfortunately the only diagnostic test to see if there is a malignant tumour is by removing the eye. I agonised over the decision; quality of life is the most important thing to me and I hated that there wasn’t a better option. Dali is 12 years old so technically a senior cat (although we don’t like to think of her that way!) but the chances of her developing other health problems are higher at this age. I kept wondering about how she might cope losing an eye and honestly how I would cope if she did.
Cats have been shown to do remarkably well with one eye, as they are brilliantly designed predators their vision is so forward facing that losing one eye only lessens their vision by around 30%. However, it can affect their depth perception which may make jumping up onto surfaces harder. To do the operation now instead of waiting a few years also gives her a higher chance of adapting to this change as the older an animal gets the more likely arthritis and other age-related issues may interfere. On the other hand, Dali lives in a busy household (with a rather mad dog) so I was worried she may become stressed and struggle to find quiet space to recover. There just didn’t seem to be a good solution.
Six weeks later I noticed that the pigment in her eye had changed again, this time it appeared to have spread and I could see free floating flecks of it in other parts of the iris. This raised alarm bells and I knew it was time to make the call. I booked Dali in for a consultation with the London Vet Specialists in their brand-new Hammersmith centre; walking in it was like being greeted by the most luxurious doctors you could imagine; the whole team were incredible and helped me and Dali feel as at ease as one could in this situation. I knew deep down it was time to take the plunge. 24 hours later I brought her in and holding back tears I left her to have the operation.
Thankfully it went well and after spending a night at the vets it was time to bring her home. I expected her to take a couple of weeks before she had adjusted enough to start jumping onto furniture and climbing stairs, how wrong I was! Just 15 minutes after she came out of her carrier she jumped onto the bed (cone of shame and all!) her resilience astounded me and I felt a huge sigh of relief, she was still my Dali, chatty and playful as ever. One week later I got the results back from the biopsy, her eye had become malignant and I had caught it just in time. I couldn’t believe our luck!
A few months on she has healed really well and I’ve not noticed any difference in her behaviour. Sadly, I have spotted a new freckle on her remaining eye. It is rare for cats to develop iris melanosis in both eyes so I hadn’t known this would be a potential issue. I am continuing to monitor it with the assistance of a vet and I am hoping for many more years before it presents as a bigger issue.
What is Iris Melanosis?
Iris melanosis in cats is generally a benign change of pigment in the iris that may look like a brown freckle. It should be monitored closely as it may progress to a melanoma (a malignant tumour) that can be detrimental to the eye (causing inflammation and glaucoma) and has the potential to metastasize (spread to other parts of the body). The difficulty with this disease is determining at which point the benign melanosis changes to the malignant melanoma.
Characteristics of iris pigment masses that often raises concern include:
Rate of progression (quick progression is more concerning)
Whether pigment extends into the iridocorneal (drainage) angle of the eye
A velvety appearance to the pigment
Development of dyscoria (abnormal pupil shape)
Presence of free-floating pigmented cells within the iris
When the drainage angle of the eye becomes clogged, it can lead to fluid backup in the eye and cause increased pressures, known as glaucoma. This is painful and may feel similar to a migraine. Historically, cats that already have glaucoma due to an intraocular melanoma are at higher risk of having metastatic disease, and therefore may have a shorter overall survival time.
If you suspect your cat may have iris melanosis it would be my advice to book a consultation with your primary vet where they can look at your pet’s eye and give you some guidance on whether they feel it would be optimal to refer you for further investigation. It is very helpful to monitor your cat’s eye by taking photos every month or so; zoomed in and with flash on and look out for any changes in appearance.
