Head, cataracts, eyes and nose

I’ve been aware for a long time about our inter-connecting senses and how they can influence and impact each other, or so I thought... 

Unexpected cataracts

Two months ago I arrived at work and laughingly said “I can’t see very well today”. I’m short sighted, and sometimes this just happens and usually rights itself with a clean of my glasses or a cup of tea. On this day, two hours later, I still couldn’t see very well. By lunch time I was getting worried and made an appointment with my optician.

It turned out I had Posterior Subcapsular Cataracts. These are fast growing cataracts which form on the back of the eye with a snowflake-like pattern. They more usually affect people with diabetes, who use steroids, or are extremely short sighted. One had started to form in my right eye four months previously and the left eye had been compensating. Once the left eye cataract started to form, my vision was impacted almost instantly due to the way this type of cataract scatters light. I struggled to see everything from my computer screen to people’s faces and even dull light caused pain. Of course it caused havoc with every aspect of life and work, but the experience was also fascinating.

Two weeks later, I was having my left eye operated on, to remove the bad lens and replace with a clear new one. Cataract surgery is the most common and safest operation in the world, I wasn’t worried - just keen to see well again. My surgeon warned me I would be ‘unhappy’ for the four weeks in between my left and right eye operations. Apparently people who are short-sighted and young with this condition have a different experience than most others.

In between eyes and bad smells

Fast forward a few days and my new eye could see! I didn’t realise white was so white. My prescription glasses had to have the left lens popped out to make way for my new world view. The light sensitivity was so bad I needed to wear light blocking dark glasses over my prescription glasses. My children eventually remembered not to turn the lights on when I was deliberately sitting in the dark at home.

I started to experiment, right eye closed left open and then the opposite, what did they see? My new eye saw colours very differently to my old eye, old brown was new purple. Objects were 20% different in size from one eye to the other. Every day the world looked a bit different; in part due to the healing process improving the vision in the new eye and the old eye degrading or perhaps becoming less relied upon.

Interpreting visual information was a big challenge. My work involves making sense of large amounts of complex information quickly, something I’ve been able to do all my memorable life. I could no longer scan text; each word on a screen was read at the speed of a child learning. Depth perception was tricky, walking needed to be much more deliberate- especially with stairs. Meetings were uncomfortable, I couldn’t take notes nor read previous notes. It even seemed harder to speak, it was disorientating in every way.

I also noticed my sense of smell was very different. Several people commented they expected my sense of smell would have got better, due to problematic vision. This was not the case for me. There appeared to be less odour around me, familiar smells were odd, food and drink were strange, I couldn’t differentiate and articulate smells. I was using prescribed eye drops 7 times a day and one set left a bitter taste in my mouth. I wondered if there was some interaction between the drops and my sense of smell?

How would I be coping if all my work was smell based, as in the days when I was a full time Perfumer? I did remind myself, it’s the brain that’s trained, not the nose, but felt quite unsettled.

After eyes

Four weeks after the first operation and it was time for the second. ‘Let’s even you up’ my surgeon said. Within 2 days, I felt so much better! It wasn’t so much that my eyes could see better (there’s still a bit of laser work to do as the scar tissue creates its own little cloud) but my brain could work so much better! 

By day four my sense of smell returned to normal. The contrast with its absence made everything smell great, such a joy and also a relief. Oranges smell of oranges again, but brighter and fresher. I could smell the fabric conditioner evidence of clean clothes; could again judge flavours of food as I cooked, and properly enjoy the smells of the outdoors as I walked. It seemed my sharper vision was echoed in my sense of smell.

Maxed out

With recovery came the realisation that my brain had been on max capacity for several weeks, just trying to interpret what my eyes saw. The ongoing subtle changes between the eyes meant my brain was constantly trying to adjust, never reaching a settled place.  

My sense of smell hadn’t really altered but my available brain capacity certainly had. My brain was just too busy with other things to take proper notice of what my nose sent it, even when I deliberately tried to smell. Temporarily my sense of smell was insensitive and untrained. I would never have predicted such a shift in my ability to ‘smell’. I wondered, is this how my sense of smell used to be, before joining the fragrance industry nearly 30 years ago? Has my brain been trained in that time to recognise, differentiate, predict and articulate in the language of odour? Almost certainly! Is my recent experience a glimpse into how ‘untrained’ people smell?

Research

As is in my nature, I did some research. 80% of all the sensory data received from the environment is visual. The processing power required by the brain is huge. In the retina 130 million light sensitive cells convert the visual information into electrical signals, processed in the brain into information about what we are observing, where it is and what is happening. Even the most powerful computers cannot compete with human visual interpretation. We can differentiate, discriminate and transform in an instant.

Multi-sensory research shows many ways in which our vision usually wins the sensory battle in influencing us. The ventriloquists skill in making puppets talk is a key example. We’ve learned over years that the mouth moving is providing the voice - our eyes fill in the gaps. The McGurk effect demonstrates we hear a different sound, depending on the mouth shapes of the apparent speaker. With eyes closed we would hear ‘ba, ba, ba’ but with eyes open we perceive ‘fa, fa, fa’ because that’s what the apparent speaker seems to say and our brain gives more weight to the visual information.

Smell can influence vision in many ways

1. We can find an object faster in the presence of a congruent odour. For instance we can find an image of an orange more quickly in the presence of the smell of an orange, versus without the orange smell.
2. When presented with a face with a neutral expression we are influenced by pleasant odours to perceive the expression more positively, and by bad odours to perceive the expression negatively.
3. When we smell within a group, the visual clues given by others influence our experience. The piriform cortex is stimulated before we sense an odour and gives us an expectation about how something is going to smell based on subtle clues from rest of the group.

What's really going on?

One of my favourite quotes is ‘the sense of smell is the canary in the coal mine of human health’. It comes from research which showed ‘Olfactory Dysfunction Predicts 5-Year Mortality in Older Adults’. Until now, my interpretation of this was that the chemical interactions responsible for olfaction were one representation of the chemical interactions responsible for everything else in the body. Therefore, decline in olfaction represented the body’s decline overall. Now I’ve experienced the impact of temporary visual impairment and the effect on my sense of smell, I think there could be even more to it.

I’ve found out that when people have a stroke, approximately 60% of survivors have vision problems. Many of them also have other sensory problems with smell and taste. Although these sensory problems are attributed to damage in the brain, my recent experience makes me wonder if they may also relate to the vision problems. I’m now looking for a study which compares the improvements in vision alongside improvements in smell or taste in stroke patients.

As always, comments very welcome!

Best wishes, Penny

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With special thanks for help with In Cosmetics, Paris

Dr Barbara Brockway , Cassandra Browning, Virginie Daniau, Roger Duprey, Hannah Patton and Richard Osborne

References

Sense of smell canary

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0107541

Sensory problems after stroke

https://www.stroke.org.uk/effects-of-stroke/physical-effects-of-stroke/sensory-problems

Taste and smell disorders in Acute stroke

https://www.ahajournals.org/doi/full/10.1161/01.STR.0000173174.79773.d3

1.. Smell can influence vision

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4107342/

2. Facial expression modulation with odour

https://www.frontiersin.org/articles/10.3389/fnhum.2015.00661/full

3. Piriform cortex and visual influence on perceived smell

https://news.rub.de/english/press-releases/2017-08-24-neuropsychology-how-emotions-others-influence-our-olfactory-sense