I SEE A CLOUDY BLACK HALO

Dr. Carolina Valdivia answers a question from a man complaining about seeing a black halo in his field of vision.

Thank you for reading this. Since grade school (about 20 years ago) I have noticed a strange phenomenon in my left eye. If I close or cover my right eye, viewing only out of my left, and stare at something, like this WORD, after about 5-10 seconds, the following happens:

A cloudy black halo develops around the item I am focused on. It is like a slow moving blob and I see only the WORD inside it. Now I can see stuff outside the black halo, since it only takes up around the size of the top of a soda can (at a distance of 2 feet, from my eyes to the screen). The black halo vanishes after a few seconds or when I change my focus. Then it reappears when I fixate on something else. Over the years this black halo problem has not gotten worse and it only occurs with my right eye closed.

I was in an accident when I was in the second grade and wound up in the hospital intensive care unit with a head concussion. I cannot recall if this issue predates that accident, but I do remember being amused at the occurrence of the black halo as a kid. I have searched for this issue online, and found scotoma, pigmentosa, etc. What do you think this could be, doctor? I have solid vision (correctable with glasses) and my last eye exam was in August. The doctor said my eyes look fine in terms of structure. Do you think I have a scotoma?

I had an MRI recently. It seems to show (and this has not been reviewed by a doctor yet), a white band/mass behind what I assume is my left eye area. Certainly interesting, but I do not know what to make of it. Please help me figure this out.

Thank you.



Thank you for your question and for your interest in glaucoma-eye-info.com!

The phenomenon you describe is something that you have experienced for around 20 years but apparently it has not been a progressive problem (gotten worse over time). Instead, the black halo that you describe is a transient phenomenon (it comes and goes) and occurs only under certain conditions – for example, when you are looking at something intently or when you are viewing nearby objects, such as your computer. The fact that it is not a progressive condition is good news for you, although I understand that it nonetheless is annoying and perhaps disturbing to you.

You mentioned that you were evaluated by a doctor. I would like to emphasize that the person evaluating you should be an ophthalmologist. An ophthalmologist is a medical doctor with a significant amount of specialty training specific to the eye. An ophthalmologist will be able to look at your problem from a systemic perspective in order to determine what the problem may be.

The eye problems about which you have been concerned, such as retinitis pigmentosa and scotoma do not correspond to the phenomenon that you have described. A scotoma is an area in the visual field where there is little or no visual perception. A scotoma is like a stain in the visual field that is present all of the time. Retinitis pigmentosa is a disease that is present in both eyes and is progressive in all cases.

Although it is great that you have taken the initiative to learn about the eye and various eye conditions, I would like to suggest that you exercise caution in trying to self diagnose your problem. I understand that the process can drag out and be frustrating, but it is better to leave the diagnosis part to your ophthalmologist.

Of course, not being able to examine you places me at a distinct disadvantage in interpreting what is going on with your eye. However, I am listing a few ideas below that you can discuss with your ophthalmologist during your next visit. These are lens accommodation problems, an entoptic phenomenon, and an optical illusion.

1. When we switch from focusing our line of sight on one image to another, minor adjustments are made in the lens of the eye to bring the new image into focus. This process is called lens accommodation. It is possible that the eye with which you are having problems could be lagging behind in the lens accommodation process. A problem with lens accommodation is supported by your report that the black halo goes away and then reappears when you change your focus to a different point.
2. It may be what we call an entoptic phenomenon that has appeared spontaneously and persisted or, as you note, could be the result of trauma experienced in the past. An entoptic phenomenon refers to situations in which light entering the eye reflects on structures within the eye itself. An entoptic phenomenon usually appears as shadows in the visual field.
3. It is possible that it could be an optical illusion. I do not mean this in the popularized sense of the term but rather in a medical sense. Sometimes after head trauma or disease, people report seeing with good visual acuity but at times the image is distorted. I know that this does not match precisely what you described, but optical illusions can manifest in a variety of ways.

It is important that you understand that problems with lens accommodation, an entoptic phenomenon, and optical illusion are not diagnoses, but rather represent possibilities for you to discuss with your ophthalmologist. Finally, without being able to examine the MRI results myself, I cannot comment on them. I am sure that your ophthalmologist will review them with you or you can specifically request that they do so.

I hope that this helps.

Carolina Valdivia, MD

REFERENCES:

Crick RP and Khaw PT. A Textbook of Clinical Ophthalmology, 3rd Ed. River Edge, NJ: World Scientific Publishing Co. Pte. Ltd, 2003:88.

Elkington AR, Frank HJ and Greaney MJ. Clinical Optics, 3rd Ed. Oxford, UK: Blackwell Science Ltd, 1999:107-112.

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