THE ORBIT AND ITS DISEASES

Anatomy of the Orbit

The orbit is an osseous hollow in a form of quadrangular pyra­mid which has four osseous walls.

The optic foramen which continues into the optic canal is on the bottom of the orbit. Its length is 8-9 mm, its diameter is nearly 6 mm. The optic nerve and ophthalmic artery pass there too. Besides the optic foramen there are two fissures in the orbit. Superior or­bital fissure (fissura orbitalis superior) leads to middle cranial fos­sa. All the oculomotor nerves, the first ramus of the trigeminal nerve and superior orbital vein, which opens into cavernous sinus (sinus cavernosus) pass through it. The maxillary nerve and zygo­matic nerve pass through inferior orbital fissure. A posterior part of the inferior orbital fissure connects the orbit with the pterygoid fossa, and the anterior one — with the temporal fossa. There is an orbital muscle innervated by sympathetic nerve inside the lumen of the fissure.

The orbital walls are covered with tiny periosteum. It passes into the dura mater of the optic nerve near the optic foramen, and into periosteum of the adjacent parts of the face at the orbital margins.

The tarso-orbital fascia which protects the orbital cavity from the external harmful influences (infection, etc) serves as the ante­rior orbital margin. The tarso-orbital fascia is in close connection with the Tenon's fascia at the orbital margins. It divides the orbit into 2 areas: anterior and posterior. The eyeball and the muscles which pass through the Tenon's fascia and are attached to the scle­ra are in the anterior area; the optic nerve, muscles, vessels, nerves, the orbital fat are in the posterior area. The eyeball is separated from the orbital fat by the Tenon's fascia which dresses its poste­rior area as the articular bursa. A narrow capillary fissure is be­tween it and the eyeball; it is connected with a suprachoroid space from one side; and with an intermembranous space of the optic nerve from the other side.

The orbit is closely connected with the cranial cavity, that is why not only the oculists but also the doctors of other special­ties must be acquainted with clinical course of the orbital diseas­es because they threaten not only the sight but also the patient's

Inflammations of the Orbit

Inflammations of the orbit are manifested by pains in the orbit, headache, general anxiety, and elevation of the body temperature, sleep disorders and loss of appetite. The pains increase in the eye ' motions. Depending on the localization of the inflammatory proc­ess and its intensity exophthalmos appears, the eyeball is displaced and its mobility decreases, it results in diplopia. These changes are caused by oedema, infiltration, haemorrhages in the soft tissues and, also by the periostitis and caries of the orbital walls or by changes in the vessels. The inflammatory processes in the orbit occur mostly in a form of phlegmon or tenonitis in children. Pe­riostitis, caries, thrombophlebitis, empyema of the paranasal cav­ities are mostly observed in adults and elderlies nowadays. Not infrequently periostitis and caries are the consequence of inborn syphilis and osseous tuberculosis. These processes are accompa­nied by changes revealed in roentgenological (tomography) and laboratory investigations besides the symptoms which are char­acteristic of phlegmon. As all the inflammatory processes in the orbit have a similar clinical picture, for treatment it is necessary to use, first of all, sulfanilamide preparations and the broad-spec­trum antibiotics.

Orbital phlegmon. Phlegmon of the orbit is characterized by quick development of oedema and palpebral hyperemia which spread on the area of its edge and nasal wall, the cheek or the whole half of the face on its side. The orbital fissure is closed; there are exophthalmos and chemosis of the conjunctiva. The eyeball mo­bility in all sides is limited; a total ophthalmoplegia (immobiliza­tion) is sometimes observed. The patients complain of severe dull pain behind the eye which increases in the attempt to look at the side or on pressure on the eyes. However, definite pain points which appear when periostitis or sinusitis are not revealed. The pains are not also revealed on pressure on the osseous orbital mar­gins.

Diplopia and sight failing can sometimes appear. The slight con­gestion phenomena but more often the neurotic changes of the op­tic disc (papillitis) can be observed on the eye fundus. A half of the patients are not revealed any pathology on the eye fundus even at the height of the process development. The orbital phlegmon can have a course without any signs of the eyelid inflammation and mucous membrane in early infant age, only a slight exophthalmos is observed.

The causative agents of orbital phlegmon are mostly staphylo­coccus albus and aureus, streptococcus haemolytic or viridans, rarely Friedlander's pneumobacillus, Frenckel's diplococcus and colon bacillus. Spreading of the infection into the orbit occurs most­ly by means of metastazation and contact way, rarely the infec­tion develops as a result of the orbital wound or it is caused by the other causes.

Treatment of orbital phlegmon is started by the parenteral in­take of the loading doses of the new broad spectrum antibiotics. In presence of the sinusitis the patients are hospitalized immedi­ately into otorhinolaryngologic hospital where they are performed opening of the cells of ethmoidal labyrinth in the fist hours and days, puncture of the maxillary sinus with the following washing of it and snapping off of the anterior half of the middle nasal con­cha. The oculist performs the incision of orbital phlegmon with a following drainage of the wound canal by means of a turunda sat­urated with antibiotics.

Dehydration therapy is performed (the solutions of magnesi­um sulfate and glucose intravenously, daily or every other day) and antihistaminic, antisensitizer, antiedemic preparations are administered for a prophylaxis of the changes of the eye fun­dus.

Tenonitis is an inflammation of the eyeball vagina (Tenon's cap­sule); it is manifested by pains when the eye moves, a feeling of "bulging" of the eye from the orbit. Gradually exophthalmos ap­pears and increases, decrease of the eyeball mobility appears, a slight hemosis develops. As a result of exophthalmos and decrease of the eyeball mobility diplopia develops. Mostly there are no changes on the eye fundus. The general condition of the patient in tenonitis is satisfactory compared with phlegmon. The process de­velops during 3-4 days. The appearance of tenonitis is caused, as a rule, by eye inflammation, injury of the eyeball vagina in trau­ma or operation on the muscles, as well as erysipelatous inflam­mation, flu, rheumatism, epidemic parotitis, etc. Serous or puru­lent inflammation appears in the episcleral (Tenon's) space under the influence of any of such causes.

Treatment of the tenonitis includes the application of antibiot­ics, sulfanilamide, antisensitizer, salicylate preparations, dehydra­tion preparations, ultraviolet radiation.

Tumours of the Orbit

The main symptoms of the orbit tumour are:

1) exophthalmos, sometimes with a displacement of the eye to a side which depends upon where the tumour presses on it;

2) limitation of the eye mobility; the eye mobility does not suf­fer when the tumour is formed inside the funnel formed by the mus­cles;

3) diplopia which develops in the eye displacement;

4) absence of the eye reposition under the pressure.

It is necessary to mark the following types of tumours:

Benign Tumours

Dermoid cysts are formed at the external orbital wall. The cyst grows slowly.

Cerebral hernia (encephalocele, meningocele) is an inborn con-vexion of the part of the brain or only cerebral membrane through the unadherent cranial suturae, mostly among the frontal and eth­moidal bones. If hernia preserves a connection with the cranial cav­ity, then the cranial phenomena (vomiting, nausea, slow pulse) ap­pear under the pressure on it. One can confuse it with dacryocys­titis, dermoid.

A mucous cyst of the paranasal sinuses (mucocele). A passage of the frontal sinus or ethmoidal labyrinth into the nose is obstruct­ed, and it causes stretching of the labyrinth wall and displacement of the eyeball; it is accompanied by exophthalmos. Pains are ab­sent. Roentgenological and rhinological investigations are impor­tant for the diagnosis.

Angioma is a benign tumour. The tumour is inborn, it grows slowly. They are formed mostly in the funnel of the muscles. It is diagnosed with difficulty.

Date: 2014-12-21; view: 1255