PATHOLOGY. 
St. purulentum: from flow of pus from an abfcefs 
in one of the membranes; pupil cloudy. By Plenck 
called onyx, when between the lamellse of the cornea j 
and hypopyum, when in the aqueous humour. 
y. St. complicatum; complicated with a rupture of 
the iris, and its protrufion upon the cornea ; conftituting 
a grape-like tumour; light aboliflied. 
13. Paroplis ftrabifmus, fquinting: optic axes of the 
eyes not coinciding on an objeCt. 
The optic axis is an imaginary right line palling from 
the centre of the vitreous humour, lens, and globe, of 
the eye, to the object of vifion. In perfeft vilion, the 
optic axis of the one eye is in unifon with thaf of the 
other, qnd confequently they converge or coincide at the 
fame point ; and the object, which would otherwife ap¬ 
pear double, as being feen by each eye, is contemplated 
as Angle. In order to this coincidence, the mufcles of 
each eye mull conllantly affume the fame direction, their 
pofition and configuration be precifely alike, and the 
fight be of an equal power and focus : a deviation from 
each of which poltulates mull: neceffarily produce fquint¬ 
ing, or an inaccordant aCtion of one eye with the other. 
From common and early habit we acquire an equal com¬ 
mand over the mufcles of both, and are able to give them 
any direction, and to fix them againft any objeCt we 
pleafe : and fuch is the power of habit, that at length they 
involuntarily aflbciate in the fame aCtion, and it is diffi¬ 
cult for us to give to the one eye a different direction 
from that of the other, or, in other words, to make their 
optic axes diverge inftead of converge. In perfons born 
blind, no benefit can be derived from this unity of ac¬ 
tion ; hence it is never attempted; and, the mufcles 
being never fubjeCted to difcipline, the eye-balls roll at 
random, and wander in every direction. And hence one 
of the moll difficult talks to be acquired by fuch perfons 
after obtaining fight, is that of keeping their eyes fixed, 
and giving the fame bearing or convergent line to each ; 
and hence, again, they fee things double at firll, and in a 
Hate of great confulion. When one eye is naturally 
ltronger, or of a more favourable focus, or more fre¬ 
quently employed than the other, as among watchmakers 
and jewellers, the latter from comparative negleCl re- 
lapfes into an undifciplined Hate, and lefs readily obeys 
the control of the will. Its mufcles do not affume the 
fame direction, and if they do, in the two former cafes, 
the objeCl appears double; and hence the negleCted or 
weaker eye wanders and flares at one or at various ob¬ 
jects, while the eye relied upon is fixed upon fome other. 
And it is this divergence of the optic axes, this inaccor¬ 
dance of direction, or looking at different objeCts at the 
lame time, that conftitures the difeafe called ftrabifmus, 
or fquinting. From the above-mentioned caufes, we 
divide the fpecies into three varieties. 
a. Str, habitualis, from habit, or the cuftom of ufing 
one eye and neglecting the other; whereby the latter 
grows gradually more unfteady, and the will has no 
longer an equal command over both. 
( 3 . Str. atonicus, from debility of the affeCted eye; 
whence the found eye poffeffes a different focus and power 
of vifion, and is alone trufted to : in confequence of 
which the w’eak or negleCted eye infenflbly wanders as 
above. 
y. Str. organicus, differently conftruCted in form or 
pofition : fo that the fituation or figure of one eye, or of 
particular parts of one eye, are inaccordant with thofe of 
the other; whence, as in the preceding varieties, one eye 
is chiefly depended upon, and the other negleCted. 
14. Paropfis eCtropium, everfion of the eye-lids : ever- 
fion of one or both the eye-lids; and confequent expofure 
of the red internal tunic. 
The oppofite affeCtion, or inverfion of one or both eye¬ 
lids, is denominated entropium. It is often a very trou- 
blefome complaint, from the irritation produced by the 
inverted eye-lafhes. But it is, perhaps, in every inftance 
3 fymptom or fequel of fome other diforder, as a tumour 
.*501 
feated on the affeCted lid, or a contraction of its inter¬ 
nal membrane from a cicatrix, or other caufe. 
Genus II. Paracufis, [wapa>tcn? of Hippocrates, from 
mapa,, bad, and axaiv, to hear.] Senfe of hearing vitiated 
or loft. There are fix fpecies. 
1. Paracufis acris : hearing painfully acute, and into¬ 
lerant of the lowed founds. A fymptom of increafed 
nervous excitement, as in cephalitis, epilepfy, &c. When 
idiopathic, i.e. when a merC nervous difeafe of the part, 
and unconnected with general plethora or general exalta¬ 
tion of the cerebral fundion, it will require the fame 
treatment as in other local irritations; that is, the fub- 
duCtion of noife, opening medicine, and, in violent and 
diftrefiing cafes, the belladonna may be ufed. 
2. Paracufis obtufa : hearing dull and confufed, and 
demanding a clear and modulated articulation. Hard- 
nefs of hearing is divided into, 
as. Organica; from organic defeCl. 
| 3 . Atonica, or nervous deafnefs ; from local debility. 
This, which arifes from deficient energy of the auditory 
nerves, is much relieved by eleClricity. 
y. A meatu obftruCto ; from obftruftion in the au¬ 
ditory tube or paffage ; as by mucus, wax, forties, 
an infeCt, or any other extrinfic body. When any 
fubftance is lodged in the part, it muff: be extracted 
by fyringing; and in fome cafes, as where the Euftachian 
tube was clofed in confequence of inflammation, tire tym¬ 
panum has been fuccefsfully punCtured by Sir A. Cooper. 
For the mode of performing this operation, fee the arti¬ 
cle Surgery. 
3. Paracufis perverfa, perverfe hearing: the ear only 
fenlible to articulate founds when excited by other and 
louder founds intermixed with them. 
Of this extraordinary difeafe, Sauvages has collected 
various examples from unqueftionable authorities. The 
firft cafe is that of a woman who could never underftand 
what was fpoken to her unlefs a drum were beating clofe 
to her at the fame time ; and who, on this account, kept 
a drum always in the houfe, which was conllantly played 
upon while ftie was converfing with her hulband. Ano¬ 
ther cafe is that of a bell-ringer, who could never diftin- 
guilh fpeech except while the bells were ringing. A 
third cafe relates to a perfon who was always deaf except 
when travelling in a carriage ; during which time, from 
the rattling of the wheels, he was perfectly capable of 
hearing, and engaging in converfation. Sauvages inge- 
nioufly afcribes this difeafe to torpitude or parefis of the 
organs of the external ear, which require this additional 
ltimulus to route them into aCtion, fo as to convey the 
proper' founds addreffed to them beyond the tympanum. 
And he clofes with the following illuftrations : “ Sic 
fomnolenti oculos non aperiunt, nec proinde aptant ad 
vifum, nifi magna lux oculos commoveat; lie organa ge¬ 
nitalia ganeonum a torpore excitantur quandoque per 
flagra, de quorum ufu in rea venerea fcriplit Meibomius.” 
Tom. I. 757. 
4. Paracufis duplicata, double hearing: the aCtion of 
the one ear inaccordant with that of the other: founds 
heard doubly and in different tones or keys. 
Sauvages has given two or three very curious exam¬ 
ples upon this laft affeClion : A mufician, while blow¬ 
ing his flute, heard two diftinCt founds at every note. 
The founds were in different keys, and confequently not 
in harmony; and, as they were heard fimultaneoufly, the 
one could not be an echo of the other. This Angular 
affeClion feems to have been the refult of a catarrh, and 
ceafed on its termination. On another occafion he was 
confulted by a perfon who for feveral months antecedent¬ 
ly had been troubled with a hearing of two diftinCl 
voices whenever he was fpoken to : tire one at leaft an 
oCtave higher than the other, but not in unifon with it, 
and hence producing a harlh and infupportable difeor- 
dancy. Tom. I. 7 56. 
5. Paracufis illuforia, imaginary founds : internal 
fenfe 
1 
