A gentleman, aged 36, librarian to one of our medical colleges, has communicated to me the particulars of his own case in the follow ing words : " A few years ago I noticed that on getting out of bed, and looking at a new carpet which had been laid down but a short time, I was unable to distinguish the colours, though I could clearly make out the pattern, which appeared simply black and white. I felt rather alarmed, and asked my wife if it was the same carpet. She assured me it was, and inquired my reason for putting the ques tion. On telling her, she at once suspected I had taken some bad wine at a public dinner I had attended over-night. I may add that I have invariably experienced the same effects after dining out, more especially if I take more than one kind of wine ; and of this I take hut little, in consequence of the severe illness I experience on the following morning. If I take grog or punch, the symptoms, including the loss of power of seeing colours, are still more severe." Simple congestion of the head and eyes, especially when accompanied with fatigue, is also an exciting cause of achromatopsy. Ruete states, that a girl suddenly lost the faculty of distinguishing colours as a conse quence of congestion ; and we have known instances produced by exhaustion.
A clergyman, 45 years of age, of full habit, but enjoying good health, was performing Di vine service in the month of June, 1851, and felt fatigued and oppressed by heat and the close atmosphere of the church. At the con clusion of the service, on rising from the kneeling posture, he was alarmed at finding that the crimson velvet cushion and hangings of the pulpit appeared of a dark violet hue, and that other familiar objects which he knew to be red, had likewise changed to bluish green ; there was at the same time some gid diness and discomfort in the head. Having rested in the vestry about ten minutes, the symptoms gradually passed away, the crimson objects becoming less and less blue, and the red objects gradually resuming their proper colour. Aperient medicine, &c., was pre scribed, and we are not aware of any other attack having been experienced.
Another case occurred during the great Exhibition in Hyde Park. A stout plethoric farmer, aged 52, visited London, and had undergone much fatigue and excitement in seeing the various objects of interest. On the third day, after spending some hours in the exhibition, he felt giddy and oppressed, and remarked that the crimson hangings appeared of a dull brownish green. This led him to notice other objects, and he ascertained that he could no longer discern the difference be tween reds and greens generally, though yel lows and blues retained their proper colour. On his leaving the building, the uniform of the fbotguards and the colour of the foliage of the trees, nearly assimilated. When he reached home, he slept for three hours ; and on awaking, was much relieved at finding that the power of discerning colours had re turned.
The extraordinary variety and glare of co lours at the exhibition was sinvularly dis tressing to the eyes, and numerous persons suffered from congestion of the choroid in consequence.
According to M. Cunier, temporary achro matopsy almost always constitutes one of the symptoms of congestive amblyopia in per sons affected with hemorrhoids and venous congestion of the abdomen. The confusion between the sensations of red and blue, takes place every time that the encephalo-ocular turgescence is augmented by the effect of a lively emotion, anger, a rapid walk, too great application of the eyes, That eminent oculist relates the following case. He was consulted by an officer of artillery, who suffered in a slight degree from congestive amblyopia. Every time that he performed manoeuvres, and fatigue increased the cerebro-ocular con gestion, the men appeared dressed entirely in blue ; the white waistbelts he distinguished, hut the red worsted epaulets, the red tuft of the shako, the facings of the coat and red stripes down the trowsers, appeared blue. He could see that the shako and trowsers were of black cloth. A brief repose, with cold water to the eyes and forehead, soon re stored natural vision.
An interesting example of temporary achro matopsy, doubtless the effect of congestion, is related by Professor Wartmann. 111 Thury, an ex-professor of botany in the academy of Lausanne, had walked during the night from Geneva to Nyon to witness a magnificent aurora borealis, which shone on the night of the 17th and 18th of November, 1848. To his great surprise and disappointment, he could not discern any difference between the blue of the sky and the magnificent blood colour of the aurora, which was viewed with rapture by.all around. Singular to say, another lady of Geneva, a septuagenarian, presented precisely the same peculiarity, though both she and the professor had distinctly seen many previous auroras.
The following case, which occurred under our own observation, is an example of tem porary achromatopsy caused by vitiated blood circulating through the brain and retina, and disturbing the functions of those organs :— Mr. H., a solicitor aged 37, of a spare make and melancholic temperament, is fre quently subject to attacks of congestion of the liver followed by vomiting and purging of bile. These attacks are ushered in by dull pain in the head and tenderness of the eye balls, rendering motion of them distressing. At such times he is quite incapable of dis tinguishing colours, all objects being simply divided into two classes, black and white with their intermediate shades of grey. The vision of objects continues perfectly distinct, but it is not until the portal system has been relieved that the perception of colours is recovered, and then yellow is the first dis tinguished. If however he takes five grains of calomel, the attack is cut short and the power of discriminating colours at once re stored. There is nothing whatever unusual about • his eyes, and under ordinary circum stances he possesses perfectly natural vision.