A man is 55 years old. Ten years ago he began to suffer from blurred vision just like looking straight at the sun. His optic nerve is normal and nothing has been found abnormal in his eyes. He has a history of drug abuse. What may cause his blurred vision?
Sahar M Elkhamary: Thank for your reply. What do you think is the possible diagnosis?
Sounds like a cone degeneration with severe after image scotomata. Does not sound like optic nerve disease.
To make a diagnosis it will be helpful to do electrophysiological testing - ERG ( electroretinogram0 to check function of the rods and cones and VEP -visual evoked potential. Obtaining results we continue our discussion.
Good luck !
Dear Dr. Baisakhya,
Regarding your diagnosis solar retinopathy , we need to clarify with the author of the question, since as was stated " just like looking straight at the sun"., but NOT AFTER LOOKING AT THE SUN
Hello. How was the retina in both his eyes? What was the drug abused? Can do an electroretinogram to look for Cone Dystrophy.
Dear Dr. Saurabh,
As was noted in the primary information " His optic nerve is normal and nothing has been found abnormal in his eyes".
A history of drug abuse can be associated with miicro-vascular pathology in the superior posterior parietal area that can giving rise to competitive simultanagnosia.
The reason for suggesting this less common diagnosis is that the assumption is made that all other evaluations have been normal.
This can present with 'blurred vision' which is worst in crowded environments and looking into the distance, because the further away things are, usually the more there is to see (except when looking out to sea for example). As posterior parietal function is non-conscious, simultanagnostic dysfunction is experienced as blurring, as the affected person is not aware of the elements that he does not see. The condition is therefore not describable by the patient and a history from a close friend or relative reveals the anosognostic elements of impaired visual search and clumsiness.
Even if MRI appears normal on close scrutiny, structured history taking for difficulties finding clothes in a pile, items in the fridge and finding a friend in a crowd, assist in making the diagnosis. As can asking the patient to look straight ahead and to lift the foot until it can be seen. This may be lifted much higher than others do, in this condition, because the superior optic radiation is periventricular, but no visual field tests investigate out to this very peripheral degree. Tripping, walking off pavement edges, difficulty going down stairs and bumping into low obstacles may be present.
If the foot is only seen when extended a long way, then vertical static perimetry can reveal lower sensitivity in the lower visual field.
Examination of eye movements can reveal apraxia of gaze, probably because the affected person is unable to look at the elements of the visual scene that are not evident. Assessment of the 'in flight' gap between the fingers as the hand is used to pick something up using visual guidance of movement can reveal that it is wider on account of optic ataxia (impaired visual guidance of movement).
If all are present then there is evidence of pathology in the spectrum between 'dorsal stream dysfunction' and the full blown 'Balint syndrome'.
Tests of visual attention can reveal the diagnosis but may direct one's attention to frontal pathology, when in fact it is posterior parietal.
This condition is said to be rare, but in our experience it is common but rarely diagnosed.
A basic review can be found in: Cognitive vision, its disorders and differential diagnosis in adults and children: knowing where and what things are. Eye 2003; 17: 289-304
If this does turn out to be the somewhat esoteric diagnosis there is a lot one can do to help. This is outlined in the above paper.
I would be fascinated to learn if this unusual diagnosis turns out to be correct.
Gordon N Dutton: I am an Obstetrics docter. The patient is my friend. I will take him to an oculist whom I will tell your suggestion. If there is a diagnosis, I would like to inform you. Thank you very much.
A pleasure
This condition is arguably best understood and diagnosed by a neuro-ophthalmologist and the oculist may consider referring accordingly.
Could you please tell to the ophthalmologist also my suggestiones
To make a diagnosis it will be helpful to do electrophysiological testing - ERG ( electroretinogram0 to check function of the rods and cones and VEP -visual evoked potential. Obtaining results we continue our discussion.
Good luck !
Interesting! I My colleagues here have given excellent differentials and explanations. I am not able to add anything because there are lots of other ophthalmological details in terms of history, clinical examination and investigations that are required before coming even close to such cases.
It would be worthwhile doing Spectral domain OCT and autofluorescence of macula to rule out any macular pathology. ERG and VEP may be done following this, if necessary.
Dear Marianne Levon Shahsuvaryan: Certainly , I would like to tell the ophthalmologist my suggestiones. Thank you very much!
Dear Marianne Levon Shahsuvaryan: Certainly , I would like to tell the ophthalmologist my suggestiones. Thank you very much!
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