Glaucoma with diabetes

 Glaucoma for diabetes

Pathological changes in the body's vascular system are becoming a common cause of glaucoma in diabetics. Glaucoma with type 1 and 2 diabetes occur much more often than in people without diabetes. In the early stages of development, the disease is treated, and advanced glaucoma often leads to disability or complete blindness.

Etiology and pathogenesis of diabetes

Glaucoma - a chronic eye disease that results from stable or occasionally elevated intraocular pressure.

Regular metabolism in the body maintains the tone of the eyeball and ensures normal circulation of intraocular fluid - the main source of nutrition for eye structures. The outflow and inflow of fluid should be performed evenly, so when this balance is disturbed, the intraocular pressure also changes. If the pressure becomes high, then in most cases glaucoma develops, optic nerve atrophy, and changes in peripheral (lateral) vision occur. In diabetes, open and neovascular glaucoma is most often observed.

Open corner

A common form of the disease is open-angle glaucoma, which is characterized by gradual blockage of the drainage canals, resulting in excessive production of ocular fluid. The disease is found in both diabetics and people without diabetes, but, according to statistics, such disorders occur much more often among diabetics. This is due to high blood sugar, which leads to damage to the smallest vessels that pierce the retina. Vasoconstriction interferes with the normal circulation of fluid in the eyes and causes an increase in intraocular pressure.

neovascular

This type of glaucoma is directly related to diabetes. It occurs when abnormal blood vessels begin to grow on the iris, blocking fluid flow. As a result, the eyes do not receive the necessary nutrition, the circulation of intraocular fluid is disrupted, the pressure level rises and the destruction of nerve cells begins. These irreversible processes develop very quickly and lead to complete blindness. Diabetic glaucoma occurs in 32% of cases.

Symptoms of the disease

Until peripheral vision problems begin, many are unaware of the development of pathological processes due to the absence of pain, so they come to the doctor too late. Only an ophthalmologist can detect the disease at an early stage. Glaucoma usually develops gradually, but diabetes accelerates this process. When the disease has already developed, it is manifested by the following clinical symptoms:

• the appearance of multicolored circles around objects;
• the viel before the eyes;
• blurred contours;
• feeling of sand in the eyes;
• photophobia;
• headaches;
• pain in the upper arms and temples.

 Treatment of glaucoma of the eye in diabetes

The leading factor in the prevention, stabilization, and treatment of all visual organs for diabetes is a rational therapy aimed at regulating the metabolism of carbon, protein, fat, and water.

Drug therapy for diabetes with glaucoma will be successful if the disease is in its infancy. In such cases, eye drops are prescribed to lower the pressure of the intraocular chambers and supplement the diet of the retina and optic nerves, for example, Timolol, Betaxolol, etc. But, unfortunately, drug therapy takes a long time and is not effective in all cases. the pressure normalizes, but the optic nerves do not regenerate. Therefore, another, more productive treatment is used - surgery or laser surgery.

surgery

Deep impenetrable sclerectomy is an operation that allows you to quickly and painlessly normalize intraocular pressure with minimal risk of complications. The advantage of this method is that autopsy of the eyeball is not used here, so the probability of infection is minimal. 

However, given the predisposition of diabetic patients to postoperative infections and inflammatory reactions, some patients have been prescribed corticosteroids and nonsteroidal anti-inflammatory drugs, antibiotics to prevent secondary infections, vascular wall-strengthening agents, anti-sclerotic drugs, or vitamins during the rehabilitation period. If the cataract developed in parallel with glaucoma, then it implants an intraocular lens. Check out the best online casinos with sign-up bonuses.

Laser treatment

Laser exposure is a modern and effective treatment for glaucoma in diabetes mellitus, especially if there are concomitant diseases of the cardiovascular system or other diabetic complications. The principle of operation is that the laser beam penetrates freely into the eye, restores the drainage system, and ensures uniform circulation of intraocular fluid. If the disease does not start, then vision returns completely. The operation is easy to perform, fast and outpatient. Laser treatment of the eyeball does not subject to surgical intervention.

How to prevent the development of the disease?

To prevent the development of glaucoma in diabetes, simple but effective rules should be followed:

• Maintain normal sugar at all times.
• Avoid stressful situations.
• Avoid situations that cause an increase in intraocular pressure (alcohol baths or saunas, excessive exercise).

But the main preventive method is a regular visit to an ophthalmologist and endocrinologist. It is best to undergo an ophthalmological examination for diabetics several times a year because glaucoma in diabetes develops very quickly. Timely diagnosis will allow for quick treatment and help maintain vision.

Treatment of glaucoma for diabetes

Glaucoma develops much more often in diabetes than in the absence of this disease. Due to the fact that all structures of the eye are affected, the manifestations of this disease are diverse. And treatment, in this case, should start immediately.

With the development of retinopathy in diabetics, iris rubella, a network of newly formed blood vessels, develops in the iris. The result of this procedure is the closure of the angle of the anterior chamber of the eye and, accordingly, the disruption of the drainage system. 

Glaucoma associated with blood vessel proliferation is called “secondary”. It is a common cause of vision loss in patients with diabetes. This condition is accompanied by severe pain due to optic nerve damage with an increase in intraocular pressure.

As you know, any damage to the eye structures caused by glaucoma is irreversible. Therefore, if eye drops have failed to reduce intraocular pressure, it is necessary to resort to surgical treatment, namely creating a way to drain intraocular fluid or bypass surgery.

Glaucoma medications

It contains 3 main areas:

1. Therapy that improves blood flow to the inner mucosa of the eye and optic nerves.

2. Antihypertensive therapy to reduce intraocular pressure.

3. Therapy that normalizes tissue trophism and metabolic processes.

Glaucoma surgical treatment

Often with diabetes glaucoma is combined with cataracts. With such combined pathology, surgeries are performed with simultaneous lens removal and intraocular lens establishment.

The laser approach also produces satisfactory results. It works very well in the early phases of development. But even in more advanced cases, the laser can provide an invaluable service. This surgery is painless, less traumatic to the eye, and is indicated for patients who have common diseases, for example, diseases of the cardiovascular system.

Eye glaucoma and diabetes - a feature of danger and treatment

Diabetes mellitus is a very serious disease that can be complicated by various pathological conditions. This is due to the loss of basic pancreatic functions, which are insulin synthesis. This substance is responsible for regulating blood glucose levels.

With the progression of diabetes mellitus, the functioning of pancreatic beta cells is gradually interrupted, leading to constant jumps in blood glucose concentration. Moreover, complications of the disease are mainly associated with vascular problems. This leads to an increase in blood pressure and intraocular pressure.

The cause of glaucoma in patients with diabetes

If a person has diabetes, then the risk of developing glaucoma is 5 times higher. With a prolonged rise in blood sugar, retinal damage occurs, which is accompanied by changes in the vascular network and nerve fibers.

In this case, the wall of the vessel changes and its diameter decreases. This causes an increase in intraocular pressure as well as the development of pathological abnormalities in the iris and fundus structure.

.Features of glaucoma in diabetes

Due to the destruction of the vascular wall under the influence of high glucose concentrations, the so-called protective mechanism is activated. Thanks to this, new vessels began to develop. 

But unlike their predecessors, the newly formed vessels do not have a strong enough wall, and therefore do more harm than good. These veins can develop into the iris of the eye, disrupting the normal outflow of aqueous fluid and causing elevated intraocular pressure.

In case of violation of the outflow of intraocular fluid, the drainage system, located in the anterior chamber of the eye, closes. As a result, secondary neovascular glaucoma developed. Unfortunately, without adequate treatment, this type of glaucoma leads to complete and irreversible blindness.

The effectiveness of treatment is largely determined by the stage of the disease and the replacement of diabetes (maintenance of normal glycemia). Once the disease has been diagnosed, treatment should be started immediately, otherwise, atrophy of visual function will occur.

Principles for the treatment of glaucoma in diabetes

Several basic approaches are used to treat glaucoma. It is important to pay attention to the early diagnosis of the disease because in this case, the results of glaucoma are much better. Of the drugs, beta-blockers are most often prescribed, which include Betaxolol, Timolol, as well as Latanoprost. In this case, the therapy should be chosen only by a doctor, because all these drugs can have side effects.

Glaucoma drug therapy

This approach has three main areas:

• Specific therapy that improves the processes of blood supply and nutrition of the optic nerve and other structures of the eye.
• Antihypertensive treatment that normalizes the level of intraocular pressure.
• Drugs that stimulate metabolic processes in the body, as well as slow down reactions leading to dystrophy of ocular structures.

When conducting complex treatment it is almost always possible to do without surgical intervention.

Surgical treatment of glaucoma in diabetes

Several surgical approaches are currently used in the treatment of glaucoma patients:

• A deep impenetrable sclerectomy allows you to restore the balance of aqueous humor. This technique is very effective and does not lead to permanent eye damage. Thinning of the affected membrane is sufficient for its implementation.
• Lens implantation helps to immediately eliminate two diseases (glaucoma and cataracts). At the same time, during the intervention in the eyeball, an additional path of outflow of the water cavity is created, at the same time implanting the lens.
• Laser therapy is one of the most effective and minimally invasive techniques. Success can also be achieved in the treatment of patients with stage III disease. During laser treatment, general anesthesia is not required, so this type of exposure is suitable even for patients with concomitant diseases of the kidneys, heart, liver.

Prevention of glaucoma for diabetes

Patients with diabetes should visit an ophthalmologist and be examined twice a year. It will also allow you to notice signs of other eye diseases (diabetic retinopathy, cataracts) in time. The effectiveness of treatment depends on the timely diagnosis of the disease. Sometimes treatment is not necessary at all, and it is enough to keep blood glucose levels at a normal level. If all these conditions are observed, then the development of glaucoma does not threaten you in the near future.

Why does diabetes develop glaucoma? 

 There is a threat of serious deterioration of vision and even complete loss. Glaucoma in diabetes is not mandatory, but in diabetics, it is observed 5 times more often than in those who do not suffer from this disease. In the early stages, the process can be controlled very successfully.

pathogenesis

How can pancreatic dysfunction affect vision? The fact is that sharp drops and rises in blood sugar, typical of diabetes, affect the condition of blood vessels. In particular, the vessels of the retina. Their pathological changes are called rhinopathy.

Externally, the syndrome manifests as the pinkish sclera, which is explained by numerous ruptured capillaries. Violation of the outflow of fluid from the eyeball leads to a periodic or permanent increase in intraocular pressure. Ultimately, this causes optic nerve atrophy and leads to loss of vision ability.

Diabetes medications can also affect glaucoma. For example, insulin can stimulate the excessive production of aqueous humor.

At the same time, drug therapy prescribed for diabetes reduces the risk of glaucoma. This applies to statins and hypoglycemic drugs.

Features of diabetic glaucoma

The development of the disease in diabetes has its own characteristics. Most often, diabetes is characterized by open-angle glaucoma, in which there is a violation of the circulation of ocular fluid in the absence of structural changes in the tissues.

The most dangerous form of the disease is neovascular, in which new blood vessels form on the surface of the iris. This phenomenon is called iris rubeosis. The mechanism of its occurrence is related to the fact that the body tries to create new instead of damaged eye vessels. However, they are fragile and prone to destruction.

As a result, bleeding occurs and a hyphema (accumulation of blood inside the eye) is created. As it grows, the vessels form a so-called trabecular meshwork, which prevents the outflow of fluid from the eyes, contributing to the development of glaucoma of the second angle of closure. This form of the disease is accompanied by pain and deformity of the pupil, therefore requiring surgical intervention.

symptoms

You may suspect glaucoma in the following signs:

• vision has lost clarity;
• flies appear, long circles before the eyes;
• painful sensations appeared in the eye;
• optic nerve death leads to the appearance of tunnel vision with a lack of peripheral vision;
• poor adaptation of the eyes to darkness;
• deviations in color perception;
• vessel burglaries are visible.

Manifestations of glaucoma can be acute:

• the person experiences nausea, accompanied by vomiting;
• heart rate may decrease (bradycardia);
• feeling anxious;
• chest pain.

The complex of these symptoms indicates increased intraocular pressure, which is manifested in the hardness of the eyeball when pressed.

Unfortunately, glaucoma often starts without severe symptoms, so it is not diagnosed in time. Treatment is started only in the later stages when the probability of a positive prognosis is small.

Diagnostic

For diagnostic purposes it is necessary:

• Measure the intraocular pressure.
• Examine the outflow of intraocular fluid.
• Explore the fields of vision.

Intraocular pressure (IOP) is measured by tonometry with a special tonometer. Indicators should generally be the same for both eyes. It is also an informative measurement of daily IOP fluctuations, which should usually be negligible. Significant fluctuations in the indicators may indicate glaucoma.

Tomography is used to determine the indicators of intraocular fluid outflow. During the method, extended tonometry is performed using special instruments.

The field of view is examined by various perimeter methods. The most informative is computer perimetry.

A blood sugar test helps test a hypothesis about the diabetic nature of glaucoma. If there is a connection between an increase in its content and damage to vision, it means that we are talking about rhinopathy, the cause of which is diabetes.

General principles of treatment

There are two approaches to treating glaucoma - medical and surgical. The first of these involves solving the following problems with the help of medication:

• restoration of ocular blood circulation (special treatment);
• reduction of intraocular pressure (antihypertensive therapy);
• inhibition of ocular tissue dystrophy due to improved metabolism in them.

Often the first thing prescribed to glaucoma patients is adrenergic blockers (usually 0.25% or 0.5% solution of timolol in drops under various names). They help the tissues of the eyes to get rid of excess moisture and thus help to reduce the pressure in them. Unfortunately, these drugs have many side effects.

Alternatively, they may be carbonic anhydrase inhibitors and alpha2-adrenergic antagonists. They also reduce the production of eye fluid and help lower blood pressure.

Other medications prescribed for glaucoma include cholemetimetics, sympathomimetics, and prostaglandins. Although their action is built on different principles, they solve the same problem - to clean the eyes of excess fluid. Unfortunately, side effects are also noticed here. Therefore, the choice of medication is individual - especially taking into account the fact that the patient suffers from diabetes.

Surgical treatment of glaucoma is prescribed if conservative treatment does not give the desired results. There are several types of surgery for this disease.

The most important are the following three:

• Deep impenetrable sclerotomy. It involves mechanical intervention in the structure of the eye but is less traumatic. It aims to thin the peripheral region of the cornea. This contributes to a better discharge of fluid from the eyes.
• Laser action on the cornea and drainage system of the eye. This operation is the least traumatic, the patient recovers quickly.
• Electrocautery - cauterization of trabecular mesh tissue with electric current to remove obstacles to fluid outflow.

But sometimes more serious surgical intervention is needed. For example, if glaucoma is accompanied by cataracts. In this case, the implantation of an artificial lens is required.

prevention

Preventive measures are mandatory for people with diabetes, regardless of age. Experts recommend that people who are at risk visit an ophthalmologist every six months.

Of course, quality medical care is not available to everyone today. But those who can afford frequent clinic visits should not shift all responsibility for their health to doctors.

It is worth, for example, adhering to a special diet that helps to avoid hyperglycemic spikes. This is a diet that should generally be followed in diabetes but helps avoid glaucoma as well as other complications. Its essence is as follows:

• calculate the daily calorie rate based on age, gender, activity, and individual characteristics of metabolism;
• reduce calorie intake gradually, without sudden jumps;
• eat properly: keep a balanced ratio of protein, fat, and carbohydrates in food which is expressed in a ratio of 10-16% / 20-35% / 45-60%;
• it is better to consume complex carbohydrates that are absorbed more slowly (cereals, vegetables, fruits).

Thanks to the advent of portable blood glucose meters, it has become possible to conduct self-monitoring at home. Such devices show blood glucose and draw conclusions about their condition.

To date, there are many ophthalmic drugs for preventive purposes. These are basically vitamin complexes that are based on natural components to improve the regeneration of eye tissues. They are available in the form of suspensions and tablets. There are also special preventive drops with a different principle of action. As for their use, you should always consult an expert, because otherwise, you can only hurt yourself.

The prognosis for different types of treatment

The consequences of glaucoma treatment in diabetes mellitus depend on several factors. First, the stage of disease development plays a huge role. Second, the correctness of the choice of medical procedures.

An important role is played by the patient's awareness, adherence to diet, work and rest regime, rejection of bad habits (alcohol and smoking), as well as other nuances.

It is believed that it is impossible to completely get rid of glaucoma, but it is quite realistic to keep it under control. The main principle is not to let the disease bounce back. Here are the main measures for "managing" the problem: regular visits to the ophthalmologist, cooperation with him, taking prescribed medications, and, in case of their poor effectiveness - the search for a more suitable replacement. Alas, after the detection of glaucoma, the application of drugs will constantly monitor the patient, abandonment of drugs or self-medication threatens vision loss.

Surgery gives very good results, especially in the early stages of the disease. The percentage of patients who have completely normalized intraocular pressure is quite high - 80-90%. True, this condition in most surgeries lasts about 5-6 years (with less traumatic interventions - longer), and then the pressure continues to rise. Therefore, another operation may be needed. However, such measures make it possible to maintain vision for the rest of one's life is about 75% of cases.

But, unfortunately, about 15% of glaucoma patients lose sight in one or both eyes during various decades of the disease for various reasons.

Given all this, diabetics should keep in mind that they represent a major risk group for the development of glaucoma and must take all measures in advance to prevent this or at least detect it early.

Treatment of glaucoma for diabetes: vision problems in diabetics

Glaucoma in diabetics

When you look at the face of a loved one, his portrait appears on the retina of your eye. To get deeper into the brain, to see it in reality, you need an optic nerve. Glaucoma strikes him.

The optic nerve can be compared to an electrical cable consisting of many wires. Glaucoma destroys individual wires (nerve fibers), and black spots appear at the base of the eye.

First, peripheral vision is impaired - we can clearly see the center of the image, and the edges are dark. So the field of vision narrows, but it happens very slowly, so we don’t notice the changes for a long time.

Glaucoma does not give other symptoms, so it is not possible to see it without an ophthalmologist's examination. Clearer symptoms appear only when the disease is already progressing when the number of destroyed fibers increases. Then we see only the middle of the picture, and to see the others, we have to turn our heads.

Important: Glaucoma can occur in a diabetic patient who has already developed serious lesions in the eyeballs. The appearance of new blood vessels in the iris diaphragm causes circulatory disorders in the corner of the anterior chamber of the eye, resulting in increased pressure in the eyeballs.

The symptoms are burning and pain in the eyeballs. Drops are used to treat intraocular pressure.

Glaucoma and diabetes

Diabetes mellitus is one of the complicating factors of glaucoma. Often it is this disease that causes changes in the eyeball, which lead to the death of the optic nerve. According to statistics, in patients with diabetes, the probability of developing glaucoma is 5 times higher than in healthy people.

The fact is that diabetes adversely affects the condition of the entire vascular system. The vessels become fragile, the blood supply to the organs is disrupted. The retina is especially affected, which consists of the intertwining of small veins.

How is the disease?

Vascular problems in the eyeball are exacerbated by the fact that the mass formation of new capillaries begins instead of destroyed ones (iris rubella). But at the same time, young vessels do not have sufficient working capacity and cannot cope with their tasks. Therefore:

The optic nerve does not receive proper nutrition. Intraocular fluid outflow is reduced. The IOP is growing.

All this accelerates the destruction of nerve cells. Secondary neovascular glaucoma developed. Fondus pati, vascular system, iris. There are pathological and usually irreversible changes that quickly lead to blindness. The difficulty is that glaucoma in diabetes is characterized by a rapid course. If measures are not taken in time, it will be almost impossible to stop the destruction process.

The symptomatology of such changes does not differ from the usual course of the disease: headaches appear, various visual effects begin, and vision decreases. This happens already in stages 2-3 when the process of destruction has gone quite far.

Treatment

The tactics a physician chooses are based on an integrated approach. It is impossible to get rid of glaucoma, and the main cause of this disease remains unchanged. Effective therapy allows you to:

lower blood sugar; reduce intraocular pressure; restore optic nerve nutrition; establish metabolic processes in the eyeball.

Due to the intake of vitamins and special medications, it is possible to partially restore the lost visual functions. But one should not hope for a complete restoration of vision. If the disease is detected in a timely manner and effective measures are taken, then you can do without surgery.

When eye glaucoma in diabetes is overly advanced or conservative treatment is unsuccessful, resort to surgical methods. They are possible in several ways:

Laser therapy Notches are created to remove excess fluid. Deep sclerectomy is a thinning of the eye membrane, which helps to compensate for the pressure difference. Artificial drainage implantation.

The ophthalmologist selects the method of surgery based on examination and clinical indications. The safest and fastest way is laser therapy which is painless and gives immediate results. However, in some cases the effect is short-lived and after some time the intraocular pressure increases.

Attention! Glaucoma is often complicated by diabetes and cataracts - fogging of the lens. In this case, a lens is implanted to replace the lens. At the same time, measures to reduce IOP.

If a patient develops glaucoma as a result of diabetes, it does not necessarily mean that surgery will be performed. This can be avoided by following simple rules:

• people with diabetes should visit an ophthalmologist once every six months. This will help identify glaucoma and other ocular pathologies in the early stages and take action quickly.
• it is necessary to conduct a complex therapy of the underlying disease and monitor blood sugar levels. After all, it is this injury that leads to other serious consequences.
• all factors that contribute to increased pressure in the eyes will need to be ruled out. Get rid of bad habits, do not overload yourself with physical work, and at the same time do sport.

Treatment of glaucoma for diabetes

With diabetes, the development of glaucoma occurs 4-5 times more often than in the absence of this disease. Moreover, all structures of the eye suffer to one degree or another. Therefore, the ocular manifestations of diabetes are very diverse. Treatment should be started immediately, otherwise, it will be impossible to restore visual function.

Features of the disease

When a diabetic develops retinopathy, in some cases the network of newly formed vessels begins to grow in the iris. This condition is called "iris rubella". As a result, the main path of outflow of fluid inside the eye is closed - the angle of the anterior chamber with a special drainage system located in it.

Such glaucoma in the doctor is called secondary, associated with new blood vessels. This type of glaucoma is one of the most serious problems of patients with diabetes, which often leads to blindness. In this case, the intraocular pressure rises greatly, the optic nerve is affected, severe pain occurs in the eye. There is such an expression: "Everything that glaucoma takes away never returns."

If the intraocular pressure does not return to normal after the medication is inserted into the eye, surgery will be required. The purpose of the operation will be to reduce the intraocular pressure by creating a new route of outflow of intraocular fluid.

General aspects of treatment

Unlike cataracts, treatment of moderate to moderate intraocular hypertension can prevent further development of glaucoma. Adrenoblockers - betaxolol, and timolol - are used as a medicine.

Advice! Also, such drugs as latanoprost, pilocarpine, etc. Timolol drops (0.25% or 0.5%), which have more than 30 trade names in the pharmacy network, are commonly used. For example, arutimol, okomed, gmol, okumol, timolol-akos, optan-timolol, fotil, etc ..

Mild reactions (itching and burning in the eyes, tearing) may occur during the administration of timolol. Systemic reactions are also possible: slowing of the pulse (bradycardia), lowering of blood pressure, bronchospasm, difficulty breathing, dizziness, shortness of breath, weakness, etc.

Pressure reduction and bradycardia are improved if taken orally due to concomitant arterial hypertension of systemic calcium antagonists or adrenergic blockers.

Drug treatment

It contains 3 main areas:

• Special therapy that improves the blood supply to the inner lining of the eye and optic nerves.
• Antihypertensive therapy - focuses on the normalization of total intraocular pressure.
• Therapy in which, in order to influence the processes of dystrophy characteristic of glaucoma, metabolic processes in the eye tissue are normalized and visual function is restored.

surgery

It is performed in patients with diabetes to restore vision.

A deep impenetrable sclerectomy (GNSE) allows you to restore fluid balance in the eye. A feature of the operation is that a passage hole is not created to facilitate the outflow of fluid from the anterior chamber cavity of the eye. 

The peripheral area of ​​the affected corneal membrane is only thinner, and only this area has a natural moisture permeability. Surgery can be combined with the implantation of collagen drainages that prevent degeneration of the outflow tract. Glaucoma in diabetes is often combined with cataracts (lens fogging). 

For such cases, a surgical method of treatment has been developed in which anti-glaucomatous surgery is performed simultaneously with cataract removal and intraocular lens implantation. The laser technique in the treatment of glaucoma in diabetics is the most modern and effective, especially in the early stages of development.

 The laser is effective in some cases in third-degree glaucoma. However, this issue is resolved only during the examination and mandatory consultation with an expert. Such a procedure is absolutely painless, less traumatic to the eye, and is indicated for patients with common diseases (diseases of the blood vessels, heart, joints, and internal organs).

Laser treatment of diabetes with glaucoma is the safest and most effective way to restore vision. Treatment will be more successful the sooner it is started and diagnosed correctly. Therefore, people after the age of 40 are recommended to be examined by an ophthalmologist once a year for a complete ophthalmological examination.