Deciphering unusual visual symptoms

Patients may not always be able to explain what’s wrong

Priscilla Lynch

Posted: Tuesday, October 2, 2018

Prof Patrick Lavin, Miss Patricia Logan and Mr Michael Burdon

Unusual, unexplained visual symptoms are sometimes a sign of a serious underlying disease but, on the other hand, can be completely harmless despite appearing alarming, the Irish College of Ophthalmologists 2018 Annual Conference heard.

Prof Patrick Lavin MD, Professor of Neurology and Neurosciences and Vanderbilt Headache Clinic Tennessee, US, presented a number of topics during the conference’s neuro-ophthalmology session.

One of his talks focused on patients who appear to be faking their symptoms but have real problems that may be misinterpreted because of the rarity or subtlety of the disorders. Making the correct diagnosis for these patients can be complicated by behavioural characteristics that might be misconstrued as real disease, or exaggeration of minor problems for financial gain, he noted.

Prof Lavin also highlighted unusual visual symptoms that can be normal but occasionally herald serious disease. These include entopic phenomena such as benign floaters, more serious floaters and migraine aura, which can be present in 25% of migraine attacks and are rarely harmful.

While visual hallucinations can be caused by drug and alcohol abuse, some may be the manifestation of serious health issues such as stroke, brain tumour, seizures (epilepsy) and the like, or certain psychiatric disorders, he noted.

Also, he discussed unusual visual conditions like palinopsia, the persistent recurrence of a visual image after the stimulus has been removed that can occur with certain medications; and synaesthesia, a perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway, e.g. words and numbers can appear to have certain colours for those with the condition.

Speaking to EuroTimes, Prof Lavin 
said that the key to determining the 
cause of unusual visual symptoms is taking a thorough patient history and system review.

“Listen to the patient who is trying to tell you what’s wrong and it is up to you to interpret the clues. Examine the patient based on their complaint, and, generally speaking, don’t get side-tracked by other issues, unless they are relevant. If you don’t know what is wrong, don’t be afraid to ask for help.”

Also speaking during this session was UK neuro-ophthalmology specialist Mr Michael Burdon, Consultant Ophthalmologist, Queen Elizabeth Hospital, Birmingham, who discussed how a small number of patients with unusual visual symptoms referred to his clinic were eventually diagnosed with Creutzfeldt-Jacob Disease (CJD).

Cortical blindness, dysmetria and hallucinations are among the visual issues that can signal a potential diagnosis of this very rare but devastating disease, 
he said.

“I also noticed very distinct anxiety in these cases. Patients experiencing visual loss are anxious, or depressed or worried but this acute anxiety of ‘I can’t see, I can’t see’, that repetitive concern on their vision I’ve never seen in any other neurological disease,” Mr Burdon 
told EuroTimes.

Another unusual visual issue he discussed was night vision blindness 
caused by vitamin A deficiency, which can often occur in patients who have had bariatric surgery.

During the neuro-ophthalmology symposium there was also an interesting paper study presented on ‘visual snow’, carried out by Emer Doolin MD under the supervision of the session’s chair Miss Patricia Logan MD, Consultant Ophthalmologist, Beaumont Hospital Dublin.

Although seldom recorded in the medical literature, visual snow can be distressing for patients and often lead to multiple unnecessary investigations and inappropriate treatments.

Visual snow is syndromically consistent from one case to the next and this phenomenon is reported by young and healthy individuals, with neither ophthalmic nor neurological disease, said Dr Doolin.

Her study of eight patients confirmed that all had normal ocular examinations, normal neuroimaging, and normal electrophysiological studies.

The study concluded that patients could be reassured that the condition, although sometimes disabling, is benign, i.e., does not lead to visual loss. Special investigations may still be required for patient reassurance but must be made on a clinical basis, the study found.

Patrick Lavin:
Michael Burdon: