of constantly changing, the two should be combined as bi-focal glasses. The upper portion of the bi-focal corrects the distant, and the lower the near vision, and in the best form the division between the two is invisible. When properly fitted these bi-focals prove the greatest boon to the presbyope.
Anisometropia (Odd Sight) is a condition in which the refraction of the two eyes is different. There are three varieties. (1) Binocular vision exists. As a rule a very small difference is present, and the difference is generally in the astigmatism; consequently eye-strain is very commonly manifested, and the correction by suitable glasses is imperative. (2) The eyes are used alternately. For instance, one eye may be hyperopic or emmetropic, and the other myopic; in such a case the former will be used for distant and the latter for near vision, and although binocular or stereoscopic vision is lost, glasses may never be required and any attempt at a correction of the defect may be useless. However, if eye-strain is present, the attempt should be made. (3) One of the eyes is permanently excluded. When the difference between the eyes is great the most defective eye is little used and tends to become amblyopic (partially blind), if it is not so already. This condition is very common in squint, and the treatment in such cases consists in providing the defective eye with its correcting glass, completely covering up the good eye and practising for certain periods every day, and thus forcing the defective eye to work. This eye may never take its share in binocular vision, but it may become very useful, especially if disease or damage should affect the good eye; and the improvement of the vision of the eye materially assists the treatment of the squint. When one eye is irremediably lost, the other should be very carefully tested, and if any error exists it ought to be corrected and the glass worn always.
Aphakia is the absence of the crystalline lens through dislocation, or removal by operation, or injury. A strong convex glass has to be worn in front of such an eye in order to obtain clear vision even for distance, and a still stronger one for near vision; after cataract operation astigmatism is generally present and the convex glass must be combined with a cylinder: these glasses are best worn in the form of bi-focals (see Presbyopia, above).
Eye-Strain.—Eye-strain is a symptom, or group of symptoms, produced by the correction, or attempt at correction, by the ciliary muscle of an error of refraction, or a want of balance between the external muscles of the eye (heterophoria). Where gross errors exist either in the refraction or in the muscular equilibrium, the correction cannot be made, and consequently no attempt is made to correct the defect, and eye-strain is not produced. The smaller the error the more likely is the eye-strain to be present, and also, unfortunately, the more likely is it to be overlooked. It is important to recognize what may be the different manifestations of eye-strain. They may be grouped under three headings: (1) manifestations on the eye and lids, such as conjunctivitis, blepharitis, iritis, cyclitis, glaucoma and cataract. (2) Peripheral irritation: (a) with pain: headaches and megrim; (b) without pain: epileptic attacks and choreiform movements of the facial muscles: vertigo, nausea, vomiting. (3) Nerve waste: nerve exhaustion, neurasthenia, brain-fag. This last form of eye-strain is as common as it is subtle. It is subtle because the sufferer never suspects the eyes to be at fault; all his waking hours he is unconsciously correcting a low degree of astigmatism, or anisometropia, or heterophoria, which means a constant nerve waste; and when he begins near work he starts with a big deficit, and further strain results.
Insomnia is a prominent symptom of eye-strain; this leads to depression, which in its turn may lead to the alcoholic or morphia habit. There is no form of functional nerve disorder that may not be caused by, or aggravated by, eye-strain.
The treatment of eye-strain consists in correcting all errors of refraction (and in the case of astigmatism and anisometropia, even the smallest) and in wearing the correction always. A small amount of heterophoria will generally, in a short time, disappear when the error is corrected; if not, it must be corrected by prisms or decentring. (E. C.*)
VISITATION (Lat. from visitare, frequentative form of visere, to look at, go to see, visit, videre, to see), an act of visiting, or going to see, a formal visit. The use of the word for an act of divine retributive justice, or generally of an occurrence of grave import, such as a plague or famine, is due mainly to Biblical phraseology, as in “the day of visitation” (Isa. x. 3). For the duty of bishops of the Roman Church to visit periodically the tombs of the apostles Peter and Paul at Rome, the Visitatio Liminium Apostolorum, see Bishop. The specific application of the term is to a formal periodical visit paid by a superior authority to an institution or to a district for the purpose of investigation, examination or the like. There are three classes of such visitations: ecclesiastical, charitable and heraldic. Ecclesiastical visitations, originally the periodical journeys of personal inspection to ascertain the temporal and spiritual condition of each parish, form part of the functions of an archbishop, a bishop and an archdeacon. All charitable corporations are at law subject to visitation; the functions of the “visitors” have been largely taken over by the Board of Charity Commissioners. Colleges at a university are regarded in law as charitable institutions, and each college has a “visitor” whose duty it is to represent the founder and see that his wishes are carried out. Heraldic visitations were perambulations made by a king-at-arms or other high heraldic officer with a commission under the Great Seal to examine into pedigrees and claims to bear arms. The results of these visitations were entered in “Visitation Books,” which are in the nature of official records; their admissibility as evidence, though claimed, is judicially questioned as containing merely experts' statements from the families to whom they refer (D'Arcy de Knayth Peerage Case, 1901). These heraldic visitations ceased about 1686.
In addition to these specific meanings may be mentioned the festival of the “Visitation of Mary,” in commemoration of the visit of the Virgin to Elizabeth, mother of St John the Baptist, celebrated in the Roman, Greek and other churches on the 2nd of July, and the office of the English Church, the “Visitation of the Sick,” ordered for the spiritual comfort and benefit of sick persons.
For the international law relating to the right of belligerent vessels to “visit and search” neutral vessels in time of war, see Search, Right of.
VISITING CARDS. The use of cards of personal identification for social purposes is generally supposed to have had its origin at the court of Louis XIV. of France, that centre of the etiquette of the 17th century. But there appears to be little doubt that, in a rougher and ruder form, this mark of intercourse dates from much earlier times, and that the Chinese, and possibly other Oriental nations also, had in bygone ages employed such mediums of communication on calling at the houses of absent friends. When and where visiting cards first came into vogue in Europe is a matter of some uncertainty. It is probable, however, that they were first used in Germany—and as early as the 16th century. A German visiting card recently discovered in Venice bears this inscription: Johannes Westerholt Westphalus scribebat, Patavii, 4 Martii 15 x 60. Concerning this, Professor Dr Kirmis (Daheim, September 30th, 1905) remarks that the German students in Padua were wont, on quitting the university, to pay farewell calls at the houses of the professors, and, in the event of not finding them within, to leave their names on paper billets; and he adds that the custom must, until that time, have been unknown in Italy, for this card of the student Westerholt was sent by Professor Giacomo Contarini on the 15th of January 1572 to Venice as a curiosity. Under the reign of Louis XIV., however, the fashion appears to have become firmly established in France. Small strips of paper were at first employed for the purpose of the communication, but gradually they attained a more elaborate finish and execution. Ladies especially seem to have been the pioneers in this direction, and to have embellished their cards with hand drawings, sometimes taking the form of “hearts” and other amorous tokens of affection. Under Louis XV., the reign of exquisite extravagance
