individual still young. This variety of myopia offers an explanation of the curious phenomenon mentioned by most authors as occasionally occurring, the spontaneous return of the power of working without the use of convex glasses. But the acquired myopia may be complicated with amblyopia. The amblyopia in these cases is generally asthænic, although it is sometimes attended with cerebro-ocular congestion. The treatment, as in all cases wherein amblyopia is present, is difficult, and there is always danger of the affection becoming converted into permanent amaurosis. Absolute rest from occupations, with exercise of the eye on long distances in the open air, are indicated--the accompanying congestion or other diseased conditions being removed by appropriate means. All glasses must be interdicted. The amblyopia may in this way be removed even when approaching to amaurosis; but the myopia remains, diminished however, in proportion to the docility and the perseverance of the patient. At this period, the cautious use of convex glasses may be allowed during a portion of the day. We may quote some of Mr. Cooper's remarks upon the Preservation of the Eyes.

"Those whom circumstances compel to study in the evening, should select that kind of work which is least distressing to the eyes. They should especially avoid indistinct writing or small print. The Diamond Editions,' in which the print is extremely small, are very hurtful to the eyes. I have a volume of Burns' Poems thus printed, and if 1 attempt to read it, my eyes feel strained, and the appearance of muscæ volitantes is excited before I have perused half a page. Reading by fire-light, or simply gazing at the fire, when sitting alone, or in a contemplative mood, is highly injurious to feeble eyes, and should be avoided by all. It is not advisable to read by twilight: too little light is as pernicious as too much, yet many persons will, evening after evening, try their eyes in this way rather than burn a candle. It is injurious to the eyes to be long exposed to the reflection of a strong light, whether artificial or natural, such as the reflected sun-shine from of a book. page

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In reading and writing, just that amount and quantity of light, whether natural or artificial, should be allowed, which, while it thoroughly illuminates the object, feels grateful and pleasant to the eyes. This desideratum can never be attained without due regard to the position of the light. The light cast upon a book while the candle is in front, is by no means pleasant, and the glare of the flame is very trying to weak eyes. It will be found that, if the candle or lamp be placed behind the reader, a little elevated and slightly on one side, the pleasantest and least injurious effect is produced; for the light then reflected to the eyes is less distressing, and at the same time the eyes are perfectly protected from the heat and glare of the flame. It would be well if in our public buildings more attention were paid to the position of the lights: it is very distressing to sit in a gallery immediately opposite the glare of a gas-burner or lamp, for an hour or more; the eyes frequently do not recover from the irritation thus excited for several days. Not only might the evil be easily removed by employing lights of greater power and placed nearer the ceiling, but there would be a great advantage gained from the increased purity of the air.

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It cannot be too strongly urged upon any one about to use spectacles for the first time, that that power which will enable him to read without much exertion by candle-light, is the only power suitable for him. It is by candle-light only he should use glasses at first, and so soon as he finds that he stands in need of glasses by day as well as by candle-light, and the glasses he uses no longer afford him sufficient assistance by candle-light, it will be proper to use the next power for the evening, but the evening only, and to allow himself the use of the others—and their use

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only during the day. The greatest caution as to increasing the power of glasses should be observed, for persons who change their glasses unnecessarily, increasing the power each time, are exhausting the resources of art instead of economising them as much as possible. Optical aid can only be extended to a certain point, and the steps to that point should be as slow and as numerous as possible. By exercising prudent precautions, persons may often attain great age, and yet never require the aid of glasses beyond a very moderate power; others on the contrary, who from ignorance frequently increase the power of their glasses, may run through the whole assortment, and leave themselves only the most inconvenient resources to fall back upon-viz. the very highest powers.-Pp. 100-107.

This is very sound advice, and if more generally followed, would prevent much disappointment and vexation. It is precisely in accordance with that so emphatically reiterated by M. Sichel, but Mr. Cooper recommends a power (48 inches focus) which the former practitioner regards as far too high to commence with, and an augmentation of it, which he looks upon as not sufficiently gradual. We think the low powers recommended by M. Sichel from their conservative tendency are well worthy a trial. They are to be found in the opticians' shops of Paris, and would be soon procurable in London if sought for.

Myopia-Shortsightedness—Near-sight.—This subject will not occupy us long, as M. Sichel's observations upon it have not yet been published, and those of Mr. Cooper do not possess much novelty. He describes two varieties of the affection-1, that resulting from a too convex state of the cornea or lens, the too great distance between the cornea and the retina, or an undue density of the media. Any of these causes unduly increase the refracting power of the organ, and bring the rays to a focus before they can reach the retina. 2. Myopia resulting from the loss of the adjusting power of the eye.

Myopia from structural peculiarity is often discovered only by accident, a person casually observing the improved vision which is produced by his looking through a concave glass. Short-sighted persons also see better by holding objects very near their eyes, in consequence of the divergency of the rays which is thus produced and the greater distance backwards at which the image is formed.

"Distant objects appear large to near-sighted persons, because a distinct picture is formed only at the point of intersection of the rays proceeding from an object and as this point falls short of the retina in these persons, the retina receives the rays beyond the point of intersection, and consequently where they are more extended. Near-sighted individuals often write a very small hand; the proximity of the letters to the eyes increasing the visual angle subtended by them, and causing them to appear distinct enough. If a near-sighted person looks through a pinhole in a card, he can distinguish objects clearly at a greater distance than before; this is effected by excluding the circumferential rays, which by their too speedy conveyance, would tend to form foci before they reach the retina, and thus cause indistinctness of vision. The pupils of the eyes of myopic persons are generally large, and their habit of half closing the lids when looking at distant objects is upon the same principle, that is, for the purpose of excluding all but the central and direct rays."-P. 45.

Myopia may result from disease, as Hydrophthalmia, which is especially liable to occur in strumous children from inflammation of the cornea or of

the aqueous membrane. After the acute stage has subsided, the anterior chamber is observed enormously enlarged, the cornea protuberant, and the iris carried backwards and apparently concave. "In some cases there does not appear to be much alteration in the form of the cornea; it appears thinner, but does not assume the pointed form characteristic of conical cornea. The extra prominence is general." There is more affection of vision than the altered form of the cornea will explain, the retina being usually more or less impaired in its functions. The early stage of Conical Cornea may be mistaken for a mere myopic condition of the eye; and Mr. Cooper has met with a case of Congenital Cataract that was for many years treated as aggravated myopia.

Mr. Cooper cautions the myopic patient not to increase the power of his concave spectacles too rapidly, or to wear them constantly. He quotes Dr. Kitchener's excellent remarks upon this subject; and those of our readers who have not seen this eccentric but clever author's work, "The Economy of the Eyes," will do well to peruse it, containing as it does much valuable information, interlarded though this be with all kinds of extraneous observations. One or two of Mr. Cooper's cautionary remarks may be quoted.

"Dr. Wells, in his Experiments and Observations (London, 1818), states that he was informed by Mr. George Adams, an eminent optician, that he does not know a short-sighted person who has had occasion to increase the depth of his glasses if he began to use them in the form of spectacles; whereas he can recollect several instances where those have been obliged to change their concave glasses repeatedly for those of higher powers who had been accustomed to apply them to one eye only.'

"The above is a fact which ought to be more generally known, and is an argument against the use of single eye-glasses. Near-sighted persons are very apt to stoop while at their studies. To avoid a practice so injurious to the figure and the health, a high desk should be provided to read and write at, and such glasses should be used as are just sufficient to enable the parties to pursue their occupation at the ordinary reading distance, that of about 14 inches. In all cases of myopia, and especially in early life, or when the affection is just commencing, it is highly important that any tendency to an over-supply to the eyes should be counteracted by a proper quantity of bodily exercise. The adjusting powers of the eyes should also be daily exercised in the attempt to obtain a distinct view of objects at a distance."-P. 59.

Of the variety of Myopia dependent upon the Loss of the Adjusting Power of the Eye, much has been already said when treating of Presbyopia. The eyes when excessively exerted upon minute or near objects, become unable to adjust themselves for the due perception of the more distant ones. Mr. Cooper remarks the prevalence of the concave spectacles among the Germans, who are such hard students, and Mr. Ware found of 127 students at one of the Colleges at Oxford, 32 employed an eye-glass or spectacles. Mr. Cooper relates a few cases in which the employment of the eye upon minute objects gave rise to the production of a myopia, which was cured by rest of the organ, its exercise on distant objects, country air, and the abstaining from, or the cautious use of glasses.

Impaired Vision.-Hard reading, and a variety of occupations among the working-classes, give rise to this affection, the prevalence of which among

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the latter the author says may be judged of by the fact of no less than 329 of such cases having been relieved between Jan. 1842 and Jan. 1846, at the North London Ophthalmic Institution-a conclusion, however, not easily drawn in the absence of a statement of the total number of patients attending during this period.

In the treatment of this affection, rest of the eyes, at the least for a while, is of the first importance; and those persons whose occupations forbid this, should at all events intermit them repeatedly and apply cold water to the eyes, working as little by artificial light as possible. If there is marked congestion of the retina, as shown by brilliant spectra, photophobia and deep seated pain, cupping from the temple is indicated. Successive blisters to the brow are very useful also; or the following rubefacient may be applied upon a piece of flannel to the forehead for two or three minutes every or every other night: R. Liquor. ammon. fort. 3 ss., Sp. rorism., Sp. camph. āā 3 j., Sp. v. r. 3 ss. M. The bowels are to be kept duly regulated, and an alterative course of mercury often proves of great service in arresting disease in the retina. When general debility is present, tonics, in combination with counter-irritation, and especially bark and iron, are the appropriate medicines, duly regulating the bowels by means of aloes and myrrh, and carefully watching the condition of the various secretions. In these subjects, cold ablution, followed by active friction with a rough salted towel and a horse-hair or Indian flesh-glove, is a very invigorating procedure. When there is weight or oppression of the head the showerbath should be employed, highly sensitive persons even well bearing the shock it occasions if they stand the while in hot water. The due regulation of the diet, and the removal of disorders of the digestive organs, in such who suffer from them, are of great importance.

Artificial Light.-Every one is aware of the great superiority of daylight over any kind of artificial light. Here are some of the reasons for

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"When the eye is exposed to light in which the red and yellow rays prevail, the colours in excess produce, first an excitement, and afterwards a degree of debility of the retina. Consequently that light which approaches the nearest to white is best suited to the eyes, and that which partakes most of red, the worst. Another cause of the injurious effects of artificial light is the direct and concentrated manner in which it acts upon the eyes. The rays from a candle or lamp fall direct upon the object which a person is regarding (the page of a book or sheet of writing-paper for instance), and are thence reflected into the eyes, carrying with them a considerable quantity of heat, which irritates and inflames the external coats of the eyes, and the lining membranes of the lids. great portion of the heat which accompanies the sun's rays is absorbed during the repeated reflections from the atmosphere and clouds, or from the surface of the earth, which the light undergoes before it reaches the eyes. Another cause of the distress produced by artificial light upon some eyes, is the fact of the rays not falling in parallel but divergent lines upon the object, from which they are reflected in equally divergent lines; consequently, indistinctness of vision results from the want of definition of the object: whereas the rays of the sun, owing to its immense distance from the earth, may be regarded as parallel. The unsteadiness of artificial light is another serious evil to persons suffering from weak eyes. One great superiority of day-light over artificial light is its perfect even

ness. It is some inequality, either in the current of air, or in the supply of combustible material, that renders the common flame unsteady and varying."-P.

167.

Among the various kinds of artificial light, Mr. Cooper disapproves of that from gas, owing to its yellow colour and heating power, these rendering it injurious to the eyes when employed upon minute objects. It evolves carbonic acid also in large quantities, and some of the gas escapes unconsumed; so that it should never be employed in apartments unless some special means for their ventilation is also in operation. The Camphine lamp burns with a pure flame possessed of great power of illumination; but it should not be brought too near the book, or ordinary candle-light will in future be found insufficient. "By the injudicious employment of too brilliant a light, for the purpose of study, the sensibility of the retina may be blunted by slow and imperceptible degrees, without the patient being alarmed by any sudden impairment of vision, or marked difference in his sight." The light of a well-constructed Argand Lamp is of a very superior description. Mr. Cooper recommends wax candles for those who employ their eyes by night, as affording sufficient illumination without fatiguing or heating the organs. "I find, from experience, that the light they afford enables me to write longer with less distress to the eyes, less irritation of the lids, and a greater amount of general comfort than any other." Composition candles formed of stearine and wax, also give an excellent light, and are less expensive. As artificial light proves injurious from an excess of the red and yellow rays, much of its inconvenience may be obviated by surrounding it with a shade coloured blue in its inner side, which reflects a whiter or purer light. The same object may be attained by using a pale blue glass chimney for the lamp, or allowing the light to pass through a bluish fluid. Contrivances of this kind are to be preferred to wearing shades or spectacles.

Although, as we have stated, we do not approve of the system of morselling an entire subject, the account of Mr. Cooper's work we have given shows it to be one of considerable merit.

Dr. Littel's "Manual" will be found useful to those who are too much engaged, or, as is too often the case with the degenerate students of the present day, too indolent to consult more elaborate works. The descriptions are faithful, and the directions for treatment judicious. Their conciseness, however, and our want of space, prevent our giving a more detailed notice of its contents. We may remark, however, that Dr. Littel disposes of the operation for Strabismus in too off-hand a manner for our taste. That its efficacy has been ridiculously and mischievously exaggerated, and that sometimes from the most sordid motives, we admit : but, well knowing the advantageous issue which has attended certain carefullyselected cases, we should indeed feel sorry in joining Dr. Littel in absolutely proscribing so simple a remedy for so grievous a deformity.

In our next number, we shall probably enter at considerable length into the subject of Diseases of the Eye, as M. Desmarres' and Mr. Wharton Jones' new works upon Ophthalmic Medicine will then be in our hands.