Open-angle glaucoma

Congenital Glaucoma or Hydrophthalmos

There are distinguished three clinical forms of congenital glau?coma:

1. The classical or simple form ? develops as a result of an in?complete resorbtion of the mesodermal tissue in the angle of the anterior chamber.

2. Congenital glaucoma with anomaly of the anterior part of the eye (aniridia, coloboma of the iris). It is caused by the abnor?mal development of the angle of anterior chamber.

3. Congenital glaucoma with neurofibromatosis and angioma?tosis of the head (encephalotrigeminal angiomatosis, Sturge ? Weber ? Dimitry's syndrome).

Sclera, cornea, limbus of the child's eye are very elastic, they stretch, the eye enlarges in the size and at the final stages reaches a considerably large size. Such condition is known as buphthalmos (a "bovine" eye). In 75% hydrophthalmos is bilateral. The disease is easy diagnosed within first days after birth in 90% of affected children.

Diagnosis methods of congenital glaucoma:

? lateral illumination, biomicroscopy (limbus, cornea, their size, transparency);

? keratometry;

? tonometry (under general anaesthesia or during deep physio-'ogical sleep);

? US-biometry (length of eye axis, depth of anterior chamber);

? ophthalmoscopy.

Clinical course. The following signs are typical for hydrophthalmos:

? stretched limbus (up to 2-3 mm, normal ? 1 mm);

? large cornea (the norm ? before 1 year ? 9 mm, at 1 year ? 10 mm);

? deep anterior chamber (the norm ? 1.5-2 mm in newborns, 3-3.5 mm ? in adults);

? enlargment of the eye size;

? increase of IOP;

? lowered vision;

? glaucomatous atrophy of the optic nerve (displacement of the vascular bundle, glaucomatous excavation, pale optic nerve).

Then the eye stretches and ruptures of discemetic membrane appear, thus permitting fluid to enter the corneal stroma with sub?sequent loss of transparency, lacrimation, photophobia, blepharos?pasm, redness. In later stages of glaucoma the leucoma of the cor?nea forms, it may be dystrophy of the cornea up to trophical ul?cer.

Hydrophthalmos has 4 stages.

1. The initial stage.

Diameter of the cornea is 12-12.5 mm, length of eye axis is in?creased by 1.5-2 mm. Fundus of the eye is normal.

2. The developed stage.

Diameter of the cornea is 13-14 mm, the length of axis of the eye is increased by 3-4 mm. There are glaucomatous excavation of the optic nerve, partial atrophy of the optic nerve in the fundus of the eye.

3. The late stage.

Diameter of the cornea is more than 14 mm. Axis of the eye is more than 24 mm. There are atrophy of the optic nerve and glau?comatous cup in the fundus of the eye.

4. The terminal stage.

Absolute blindness, staphilomas of the sclera and the cornea, the corneal leucoma, complete atrophy of the optic nerve with glau?comatous cup (excavation).

Treatment is only surgical: goniotomy and goniopunctura, la?ser surgery, sinusotrabeculotomy, reconstructive microsurgery of the angle of the anterior chamber.

An operation should be performed early, as soon as the diag?nosis has been established.

Acquired Glaucoma

Primary glaucomais the multifactorial condition with the threshold effect. It develops owing to combination of a few unfa?vourable to IOP regulation factors, each of which doesn't cause glaucoma, but association of some of them exceeds the compensa?tive possibility of IOP regulative mechanism.

These factors are:

? anatomical peculiarities of the anterior chamber angle;

? local vascular changes, which may be the signs of general vascular pathology (atherosclerosis, hypertonic desease, diabetes mellitus);

? diseases of the connective tissue, which cause sclerosis and degeneration of trabecular meshwork (collagenosis);

? neuro-vegetative alterations, which cause hypersecretion of aqueous humor.

Methods of diagnosis consist in functional and objective exami?nations.

Functional examination includes visometry, adaptometry, peri?metry, campimetry.

Objective examination uses the method of lateral illumination, biomicroscopy, gonioscopy, ophthalmoscopy; measurement of IOP (diurnal and hourly tonometry, tonography, elastotonometry).

Classification of primary glaucoma

The forms of primary glaucoma are open angle glaucoma, nar?row or closed angle glaucoma and mixed glaucoma.

Open-angle glaucoma

Pathogenesis ? sclerosis of trabeculum or constriction of Schlemm's cannel due to endocrine, vascular diseases (atheroscle?rosis, hypertension, diabetes mellitus). The angle of the anterior chamber (gonioscopically) is wide, open, can be pigmented.

Clinical course. As a rule, glaucoma is bilateral, but in 80% is asymmetric: damage of one eye is more than other ones.

It arises and progresses slowly, unwittingly for the patient. The first simptoms are loss of visual acuity and visual field. At exter?nal examination the eye has normal appearance; only at a biomi?croscopy it is possible to find distrophical changes of the iris. An angle of the anterior chamber has normal sizes. There may be pig?mentation of trabecula. The first objective sign is periodic or con?stant rise of IOP more than 27.0 mm Hg.

There are the typical changes of the optic nerve, revealed with using of ophthalmoscopy.

The first manifestation is displacement of vascular bundle to a periphery edge of the optic disc. Then extension of physiological excavation up to the edge of the disc with an inflection of vessels. In the last stage the optic disc pales up to the white ? grey colour with the edge excavation.

The patients, as a rule, do not notice the first changes of visual functions, they are discovered only at inspection by the ophthal?mologist. These are decrease of the dark adaptation, extension of a blind spot, appearance of paracentral absolute scotomas, con-straction of peripheral borders. It is typical the contraction of the visual field from the nasal side. When considerable loss of visual field takes place, the central vision decreases. Without treatment the process results in complete blindness (VIS=0).

Date: 2016-06-12; view: 203