At the beginning, glaucoma develops entirely unnoticed. Only a preventive check-up can detect the incipient disorder or detect the risk factors, such as increased intraocular pressure. It is only then, when the glaucoma develops, that the patient may experience at first unnoticeable failure in the visual field. Later, obvious failure in peripheral vision occurs, along with blurry vision on the edges of the vision field. If the patient comes to the doctor at a late stage of glaucoma, medicine cannot fully restore the eye's capability.
The principle of this disorder is damage to the optic nerve. It is usually caused by the impact of high intraocular pressure. There may be many causes – infection, failure in the regulation of intraocular fluid production, or blockage of drainage canals. Higher intraocular pressure does not necessarily have to be the only cause of glaucoma, as there are cases of glaucoma in patients with normal intraocular pressure.
In addition to the standard complex eye examination, (see dioptric defects) your intraocular pressure will be measured by contact free tonometer, as higher values of intraocular pressure are one of the main causes of glaucoma occurrence. The examination is short and will not cause any discomfort. You will be seated in front of a device that will blow air into your open eye. The equipment will measure the extent to which the cornea of your eye flattens.
The doctor will also examine the optic nerve by the means of ophthalmoscopy - direct or indirect. In both cases, this examination will not cause any difficulties or significant discomfort. Direct ophthalmoscope is a handheld device with a built-in light and the doctor will shine the light into your eye. For indirect ophthalmoscopy the doctor will wear a binocular device with a source of light on his or her head.
Another more advanced imaging technique is optical coherent tomography. You will be seated in front of the device and it will allow the doctor to see a cross-section of retina, the height of the swelling, the type and depth of the defect. Corneal thickness will be measured by a doctor with a so-called pachymeter. The device does not touch the eye and therefore the procedure is pain-free. It will detect the scope of your field of vision; and the scope of the peripheral vision will be measured by a perimeter. During the examination, you will look into a semi-lit hemisphere. You will focus on a central spot while light spots appear at the edges of the hemisphere. You push a button whenever you see a flash of light.
The physician usually begins non-surgical treatment of glaucoma with a prescription of eye drops or tablets (called antiglaucomatics), which facilitate and accelerate the drainage of intraocular fluid and therefore reduce the pressure inside the eye. Currently, eye drops applied only once daily (usually at night) are already available. The correct technique is important – the drops must be applied on the cornea and conjunctiva, not on the eyelid skin. This will ensure that the eye receives the maximum amount of effective substance.
If drug therapy fails to reach the targeted value of intraocular pressure, surgical treatment will be undertaken. Probably the most widely used operation for treating glaucoma is trabeculectomy. An alternate duct for intraocular fluid drainage is created during this filtering procedure. The doctor will gradually carry out the preparation of individual layers of the eye sclera just above the cornea. He will then make an opening inside the eye to form a deferent duct for the intraocular fluid. Individual layers will be sutured back again. The aim is to create a permanent filter between the eye chambers and beneath the conjunctiva space in which a so-called filter pad is formed. This outpatient surgery is performed under local anesthesia and usually takes 15-30 minutes.
Drainage implant surgery
Patients with very complicated glaucoma, when reducing of intraocular pressure cannot be achieved by conventional filtration surgery, can undergo drainage implants. These drain the intraocular fluid from the anterior chamber or vitreous space. Implants usually are surgically inserted on the outside of the eye and are covered by the conjunctiva. They consist of very small plates (the body of the implant) which regulate intraocular pressure. They are connected to a tube (cannula) that helps the fluid to drain. The implants can be of different shape and size and are usually named after their creator or manufacturer (e.g. Ahmed valve implant, Molteno implant, etc.).
In advanced glaucoma, which does not respond to drug therapy or laser or surgical treatment, the doctor is forced to proceed to the destruction of the part of the ciliary body that produces intraocular fluid. Cyclo-cryo-coagulation is one of the cyclo-destructive methods. The destruction of the ciliary body is carried out by freezing at several points by a probe set at temperatures of -60 to -70° C.
It is one of the most frequently used instruments for measuring intraocular pressure. It works on the following principle: a puff of air which flattens the cornea is blown into the patient’s open eye The device monitors the extent to which the cornea "deforms" - the more it flattens the greater the flexibility of the eye and therefore the lower the intraocular pressure. This contact-free method does not require eye anesthesia and therefore the risk of transmitted infection is reduced. The device used in our clinic is from the Nidek Company.
This device is designed for ultrasound measurement of the corneal thickness in its entirety without the necessity of attaching (touching) the test probe to the eye. Local eye anesthesia is therefore not necessary and the risk of transmitting infection is reduced. Our clinic uses the contactless pachymeter of the Nidek Company.
This is a computer-operated device designed to examine the scope of the visual field and its potential failures. It is a hollow hemisphere in which light spots flash with variable intensity in different places. The patient must press the joystick if he or she sees a spot of light. The device monitors the patient’s responses and evaluates the results. Our clinic uses the device of the Carl Zeiss Company.
OCT device (optic coherent tomography)
This is a modern diagnostic device used for a detailed, pain-free examination of the eye background, individual retina layers, nerve fibers and the optic nerve without taking a surgical sample abstract and without direct eye contact. Sometimes drops are administered to dilate the pupil to enable better visualization. OCT is an optic device operated by a computer. It generates colorful, cross-sectional images with a very high resolution of the individual structures and layers (in micrometers) of the examined tissues by means of infrared (IR) radiation, which uses a short coherent wavelength. It even permits 3D images and spatial relevance of the examined eye to be evaluated. We use device from the Carl Zeiss Company in our clinic.