Surgery and complications - refractive surgery. Diffuse lamellar keratitis in keratorefractive surgery Clinical picture, classifications and treatment methods

Eye surgery – SURGERY.SU – 2009

Some of the most common complications of LASIK surgery include:

• Unrealistic expectations
• Incomplete correction of visual impairment,
• Overcorrection of visual impairment,
• Astigmatism,
• Dry eye syndrome,
• Hayes,
• Corneal erosion,
• Complications associated with corneal flap creation
• Epithelial ingrowth
• Regression,
• Diffuse lamellar keratitis,
• Infection or severe inflammation.

Unrealistic expectations

This is a very important problem and, rather, it can be attributed not to complications, but to features. The patient must understand that laser correction, despite the fact that it is a modern technology, cannot do everything. And, of course, the doctor himself should tell the patient about this. Even the most experienced ophthalmic surgeon cannot promise complete vision correction and getting rid of glasses or contacts. In addition, it is worth remembering that after 40 years of age, vision deteriorates due to the development of presbyopia. So, if you had your vision corrected when you were young, this is not insurance for you against senile farsightedness.

Some patients may even need to wear low-power glasses during activities that require maximum distance visual acuity, such as driving at night. It is best to think of the LASIK procedure as a way to reduce a patient's dependence on glasses or contact lenses, rather than to see it as a way to get rid of them completely.

Incomplete correction of visual impairment (hypocorrection)

Hypocorrection is an insufficient effect of LASIK surgery. LASIK surgery consists, roughly speaking, of polishing the surface of the cornea. However, different patients may have different reactions to the laser. Usually such a difference does not affect the visual result, but in some cases hypo- or hyper-correction may occur. Most often, hypocorrection is noted - incomplete correction of one or another refractive error. Moreover, such a small hypocorrection will not greatly affect vision, and for people whose age is approaching 40, it may even be desirable, given the development of presbyopia. In case of severe hypocorrection, repeated laser treatment is required.

Excessive correction of visual impairment (overcorrection)

Typically, hypercorrection goes away on its own within one month after surgery. If hypercorrection is observed during the treatment of farsightedness, then for a while you will become slightly myopic, while you will see a little blurry in the distance, but well near. If myopia was corrected, then, on the contrary, hypercorrection leads to the development of farsightedness and difficulty seeing near. These temporary effects may require weak glasses or contact lenses. Hypercorrection is observed less frequently than hypocorrection, and with pronounced hypercorrection, additional laser exposure may be required.

Induced astigmatism

The surgeon cannot always cut the corneal flap perfectly evenly, and it does not always fit perfectly evenly into place. Therefore, in very rare cases, after LASIK surgery there is a risk of developing astigmatism, resulting in blurry vision after surgery. This astigmatism is easily corrected with additional laser treatment. At small amounts, astigmatism can even improve your vision.

Dry eye syndrome

Sometimes after LASIK surgery, some patients may experience a gritty sensation in their eyes. Usually this condition goes away within the first 1 - 2 weeks after surgery. To reduce irritation, patients are recommended to use special eye drops to reduce symptoms and speed up vision recovery.

If the symptoms of dry eye syndrome do not go away after treatment, or they are severe, you may be offered a procedure for closing the tear ducts using miniature plugs. This procedure is painless and quick, as a result of which the rapid flow of tear fluid from the eye is stopped, and this leads to better wetting of the ocular surface.

Hayes

Haze is a cellular response of the cornea that can occur to interventions such as photorefractive keratectomy (PRK) and rarely to LASIK. In cases where haze is severe, it may require the use of special eye drops or laser therapy to remove it.

Corneal erosion

Erosion is a defect in the corneal epithelium. Even with adequate wetting of the eye with tear fluid and strict adherence to the rules of the surgical technique on the corneal epithelium, slight scratches of the epithelium may occur. Typically, such erosions heal quickly (within 2 - 3 days).

Complications associated with the flap

Complications associated with corneal flaps are rare among experienced surgeons. Typically, such complications occur during surgery. They may appear as a superficial corneal flap that is too thin or too small. Short and uneven flaps have also been described in the literature. In rare cases, there is a risk that the pedicle of the flap will be cut. After surgery, sometimes the flap may also move slightly. Therefore, it is very important for the first time after LASIK not to rub your eyes, not to squeeze them too tightly with your eyelids closed, and to maintain eye lubrication after surgery, especially in the first hours.

If the flap has moved, folds may form on it. When such folds are located in the center of the cornea, vision may deteriorate. In this situation, you have to re-operate on the patient, lift the displaced flap and put it correctly in its place. If the folds of the flap are smoothed out in time, they may disappear. In extremely rare cases, such problems can lead to permanent vision loss.

Although any complication associated with a corneal flap can result from decreased vision, most are easily corrected and do not have serious consequences.

Epithelial ingrowth

In rare cases, some cells of the surface layer of the cornea - the epithelium - can grow under the corneal flap, and less often, cause vision impairment. In such cases, this problem is radically solved by surgical removal of such overgrown cells.

Regression

Regression is a return of the state of visual acuity of the eye to what it was before the operation, i.e. to the original state. Most often, such a complication can occur with PRK, but is sometimes observed in patients after LASIK performed for a high degree of myopia, farsightedness or astigmatism.

If there is significant regression, the patient may undergo additional laser treatment to “improve” the effect of the first laser operation, if, of course, sufficient thickness of the cornea allows.

Diffuse lamellar keratitis

This is a condition in which there is inflammation between the flap and the underlying corneal stroma. The cause of this inflammation is unknown. Depending on the degree of this inflammation, the patient does not experience anything bad or experiences some blurred vision. Prevention of such a complication consists in preventing microscopic foreign bodies from entering the space under the flap.

For severe manifestations of diffuse lamellar keratitis, corticosteroid drugs are used in the form of eye drops. In more advanced cases, it may be necessary to wash the space under the flap in the operating room.

Infection or severe inflammation

Corneal infection is a rather dangerous complication, but fortunately it is quite rare. As in any other area of ​​surgery, to avoid infectious complications developing, you must follow the rules of asepsis. Usually, if infectious complications arise, they appear on the second or third day after surgery. Therefore, it is important to follow all the doctor’s recommendations after surgery, such as avoiding the use of eye cosmetics, hot baths, and swimming pools in the first week after surgery. As a preventive measure, it is important to instill prescribed antibacterial drops.

• Complications of LASIK surgery

Owners of patent RU 2294718:

The invention relates to the field of medicine, namely to ophthalmology, and can be used in the treatment of diffuse lamellar keratitis. Steroid drugs are prescribed and laser infrared thermotherapy of corneal infiltration is additionally used. Exposure parameters: wavelength 810 nm, radiation power 300-400 mW, spot diameter 3.0 mm and exposure for one minute. The impact is carried out along the edge of the corneal flap along the entire diameter, 7-8 pulses per 1-2 treatment sessions with an interval of 1-2 days. The method prevents clouding of the cornea, a shift in refraction towards hypermetropia, the development of irregular astigmatism, and ensures a reduction in rehabilitation time.

The invention relates to the field of medicine, namely ophthalmology, and can be used in the treatment of diffuse lamellar keratitis after laser in situ keratomileusis.

Diffuse lamellar keratitis is characterized by the formation of multiple infiltrates under the corneal flap. There are 4 stages of diffuse lamellar keratitis, which range from a moderate self-limited peripheral infiltrate that responds to local steroid therapy (stage 1) to a severe process that leads to stromal softening, scarring, resulting in irregular astigmatism and a refractive shift towards hypermetropia (4 stage).

There is a known method of treating diffuse lamellar keratitis, which consists of frequent instillation of corticosteroids (every two hours); in severe forms of the disease, oral corticosteroids are also used (see Balashevich L.I. Refractive surgery. - St. Petersburg: Publishing House SPbMAPO, 2002. - 285 pp.).

There is a known method of treating the disease, according to which, in the absence of positive dynamics, the flap is lifted and the interface is washed, followed by the administration of steroid therapy (see Balashevich L.I. Refractive surgery. - St. Petersburg: Publishing House SPbMAPO, 2002. - 285 p.).

The technical result of the proposed method of treatment is a reduction in rehabilitation time and a reduction in complications by reducing gross clouding of the cornea and the degree of hypermetropia.

What is new in achieving the stated technical result is that they additionally use laser infrared thermotherapy of the corneal infiltrate with a wavelength of 810 nm, a radiation power of 300-400 mW, with a spot diameter of 3.0 mm and an exposure time of one minute.

What is also new is that the effect is carried out along the edge of the corneal flap along the entire diameter, 7-8 pulses per 1-2 treatment sessions with an interval of 1-2 days.

Laser infrared thermotherapy of the cornea is a method of laser subthreshold photocoagulation, which uses a large area spot, low energy, long exposure of radiation. The radiation temperature increases by 4-9 degrees, so the method does not have a coagulating effect and does not increase corneal opacification caused by diffuse lamellar keratitis itself. The authors selected the optimal parameter values ​​to obtain the optimal therapeutic effect.

A comparative analysis with the prototype shows that the claimed method differs from the known one in that it additionally uses laser infrared thermotherapy of the corneal infiltrate with a wavelength of 810 nm, radiation power of 300-400 mW, with a spot diameter of 3.0 mm and exposure for a minute, while the impact is carried out along the edge of the corneal flap along the entire diameter, 7-8 pulses per 1-2 treatment sessions with an interval of 1-2 days, which corresponds to the “novelty” criterion.

The new set of features makes it possible to reduce the risk of developing complications such as corneal opacification, a shift in refraction towards hypermetropia, the development of irregular astigmatism, and reduce rehabilitation time, which corresponds to the criterion of “industrial applicability”.

The method is carried out as follows.

All patients, 1 day, 7 days, 1 month after the procedure, undergo visometry, refractokeratometry, biomicroscopy, and optical coherence tomography of the cornea. Before surgery, the patient is instilled with 1% mydriacyl, causing maximum mydriasis. Laser infrared thermotherapy of the cornea is carried out using an IRIDEX (USA) device along the edge of the corneal flap along the entire diameter, 7-8 pulses. Exposure parameters: laser radiation wavelength 810 nm, radiation power 300-400 mW, spot diameter 3.0 mm, exposure - 1 minute. 2 sessions are carried out with an interval of 1-2 days. In parallel, conservative treatment is carried out with the steroids dexamethasone and Flarex. When assessing the dynamics of the process, visual acuity, refractokeratometry data, corneal biomicroscopy are taken into account: corneal infiltration - diameter and depth, pachymetry data. After the first treatment session, all patients noted improvement in vision (reduction of “fog”). According to biomicroscopy, corneal infiltration decreased after just 1 session, and a month after the operation, a slight clouding remained in the optical zone, which did not cause a decrease in vision in patients. Optical coherence tomography of the cornea showed that mild stromal opacification persisted. The thickness of the cornea in the center corresponded to the calculated one after the operation.

The method is illustrated by the following clinical example.

Patient B. DS: high myopia, myopic astigmatism.

01/27/05 The operation was performed: laser keratomileusis OU, without complications.

01/29/05 Complaints of “fog” before the eyes, OU calm. The flap is stable. Over the entire area of ​​the cornea OS>OD, infiltration is greater in the central optical zone. Treatment was prescribed: Flarex - 8 times, physiotherapy, dexazone under the conjunctiva.

01/31/05 OD-0.1

Complaints: “fog” before the eyes. OU are calm. The flap is stable, with infiltration over the entire area. In the central optical zone there is up to 2 mm of turbidity.

02.02.05 Complaints: “fog” before the eyes OD

The patient underwent laser infrared thermotherapy OS at a laser power of 310 mW, wavelength 810 nm, exposure for 1 minute, spot diameter - 3.0 mm over the entire diameter of the flap, 8 pulses.

02/04/05 OD-0.1

Vis=OS-0.2 with correction -1.5=0.4

OU are calm, the flap is stable, transparent along the periphery, there is no infiltration, in the central zone there is up to 1.5 mm of opacity, with clearing gaps OD

10.03.05. OD-0.3 n.k.

Vis=OS-0.5 n.c.

There are no complaints, both eyes are calm, the cornea is transparent, the flap is stable, gentle intrastromal opacities in the central zone.

The patient was discharged for outpatient observation.

A method of treating diffuse lamellar keratitis by prescribing steroid drugs, characterized in that it additionally uses laser infrared thermotherapy of the corneal infiltrate with a wavelength of 810 nm, radiation power of 300-400 mW, with a spot diameter of 3.0 mm and exposure for one minute, while the impact is carried out along the edge of the corneal flap along the entire diameter, 7-8 pulses per 1-2 treatment sessions with an interval of 1-2 days.

Similar patents:

The invention relates to ophthalmology, namely to surgical methods for correcting refraction, and is intended for performing refractive-correcting excimer laser intrastromal keratectomy (REIK) in patients wearing contact lenses.

24-10-2011, 06:36

Description

Complications after laser correction?

And they told me...

LASIK- laser, superficial, outpatient, but surgery. And therefore, like all operations, there are complications.

LASIK- one of the safest surgical operations in the world.

The vast majority of LASIK complications can be reversed. Of course, the patient must be warned about this before the correction. Because everything the doctor says after the correction is considered as an excuse for his own unprofessionalism.

But there are more serious complications of LASIK that reduce visual acuity. The probability of their occurrence is many times less than one percent, but they exist. That's what we'll talk about now.

This low rate of complications is phenomenal for surgery. Therefore, it is not customary to talk about these complications to patients, which, of course, places a large burden of responsibility on the shoulders of the surgeon. There are the following opinions on this question.

There is an opinion among doctors that the patient should not know all the nuances of treatment, since he can evaluate them incorrectly and subjectively.

And he will refuse treatment, dooming himself with a much higher probability to a more sorrowful fate. Not to mention the need to instill optimism in the patient to create a positive emotional background for treatment. Legally, this is a very precarious position, since according to the law on consumer protection, the patient has the right to know all the nuances.

On the other hand, the health insurance system, which came to us from the West, forces the doctor to familiarize the patient with the possible complications of a surgical operation against signature. There, the doctor does not so much fight for the health and life of the patient using all available methods, but rather carries out the algorithm prescribed to him in this case by the insurance companies. He is only trying to protect himself and the insurance company from the patient’s legal claims. This is the price for high salaries of health workers. Just like the lack of masterpieces is the price to pay for the large budgets of Hollywood films. So we came to this system. So far only in excimer laser and cosmetic surgery.

Refractive surgeons did not hide the complications of laser correction, but did not advertise them either, trying to justify the promises of advertising with their professionalism. However, now even medical management is coming to the need for broader coverage of these issues. Because the response to the silence was the unbridled growth of rumors about the dangers of LASIK. Just look at the forums on the Internet about laser correction. A mixture of ignorance and prejudice. True, several professional websites have now appeared that explain and answer questions from future patients.

Public opinion is inert, and if the growth of mistrust in laser surgery is not broken now, then it will be difficult to justify it later. I hope this book will help to objectively assess the capabilities of excimer laser surgery and determine its place in the provision of medical services.

Complications of PRK

There are different classifications of complications. By time of appearance, by reason of occurrence, by localization. Apparently, in this book the most appropriate classification is based on the degree of influence on the result of laser correction.

Complications that worsen (extend, make uncomfortable) the healing period, but do not affect the final result of correction:

Delayed reepithelialization;

Filamentous epitheliokeratopathy;

Corneal edema;

Allergy to medications used;

Dry eye (mild form).

Complications that require intensive drug treatment to eliminate them, and sometimes repeated intervention to eliminate the consequences:

Exacerbation of herpetic keratitis;

Dry eye syndrome (severe degree);

Corneal opacification (in other words, haze, subepithelial fibroplasia, or fleur) (mild);

Bacterial keratitis.

Incomplete removal of the epithelium;

Decentration of the ablation zone;

Undercorrection;

Hypercorrection of myopia;

Regression of the refractive effect;

Corneal opacification (in other words, haze, subepithelial fibroplasia or fleur) (severe degree).

Complications of LASIK

Complications that worsen (extend, make uncomfortable) the healing period, but do not affect the final result of the correction:

Damage to the corneal epithelium by an eyelid speculum or during marking;

Temporary ptosis (some drooping of the eyelid);

Toxic effect on the epithelium of the dye or coloring of the subflap space after marking;

Debris (remnants of tissue evaporated by the laser under the flap, invisible to the patient and dissolving over time);

Ingrowth of the epithelium under the flap (not causing decreased vision or discomfort);

Damage to the epithelial layer during flap formation; marginal or partial keratomalacia (resorption) of the flap; dry eye syndrome (mild form).

Complications that require intensive drug treatment to eliminate and sometimes repeated intervention to eliminate the consequences:

Keratitis.

Complications that require repeated intervention to eliminate:

Incorrect placement of the flap;

Decentration of the optical zone of laser ablation;

Undercorrection;

Hypercorrection;

Folding the edge of the flap;

Flap displacement;

Ingrowth of the epithelium under the flap (causing decreased vision and discomfort);

Debris (if located in the center of the optical zone and affects visual acuity).

Complications for which other treatment methods are used:

Poor-quality cut of the flap (decentred, incomplete, thin, torn, small, with striae, full cut of the flap);

Traumatic damage to the flap (tear or tear of the flap);

Dry eye syndrome (chronic form).

A few words about those complications that can be eliminated through repeated intervention.

Debris and epithelial ingrowth under the flap

During the process of laser ablation, that is, the evaporation of the corneal substance, tiny particles are formed, most of which become airborne. This is where the “burning” smell comes from. But a small amount of these particles settle back on the cornea. Of course, the cornea is washed, but some laser ablation products, along with the detached meibomian glands (glands on the edges of the eyelids), talc from the surgeon's gloves, etc., may remain under the corneal flap. This “garbage” is called debris. Most often, it does not affect vision in any way or bother the patient and gradually resolves. If the debris is large enough, is located close to the center of the optical zone of the cornea, and the patient notices it as a speck in the field of view, then the subflap space is washed and the flap is repositioned. Nothing special. The same is done when the epithelium (the surface cellular layer of the cornea) grows under the flap.

Ingrowth occurs due to insufficient adherence of the corneal flap, its uneven edges, or due to the entry of cells under the flap during surgery. Cells trapped during surgery dissolve on their own. The epithelium, which grows under the edge of the cornea, has a connection with the main layer and receives constant recharge. Therefore, it can grow quite far. This causes local elevation of the flap, a feeling of a foreign body in the patient, and a change in refraction towards increasing astigmatism. There is no need to further correct this astigmatism. When this ingrowth is removed, most of the astigmatism will also go away. But relapse is quite possible. The fact is that under an operating microscope the epithelium is mostly invisible. Therefore, it is quite difficult to remove all of it. There are various techniques to exclude relapse, in particular, the use of dyes (which permanently stain the entire subflap space), washing the subflap space (interface) with a weak solution of dexamethasone, and thoroughly cleansing the site of ingrowth. At the site of epithelial ingrowth, it is necessary to de-epithelialize a small area of ​​the cornea. The edge of the flap should not be torn, but smooth and, therefore, fit more tightly to the corneal bed.

Incorrect placement, edge tucking, or flap misalignment

If the surgeon is insufficiently experienced, the flap may be placed incorrectly (unevenly, unevenly). Or the patient may accidentally touch the eyelid and tuck or displace the edge of the corneal flap. In such cases, re-installation is also carried out.

Poor quality flap cut

If the flap is of poor quality, the possibility of laser ablation is assessed. If a sufficient area of ​​the corneal bed is exposed, then you can proceed as usual. If there is not enough space, then the flap is carefully placed in place (you can put a contact lens on top for a couple of days for fixation) and after 3-6 months a new cut and a new correction are made. All this applies to decentralized, incomplete, thin, torn (botton hole and other options), small flaps and full cut flaps.

Flap with striae- This is a flap that has folds. Folds can appear both due to non-standard operation of the microkeratome or the peculiarities of the condition of the cornea, and due to mechanical effects on the eye in the first days. If the flap has been moved from its place, then, of course, it must be repositioned, but the remnants of the folds (striae) will remain. Striae can lead to a decrease in the quality of vision due to aberrations (more on this in the next chapter). The second stage of laser correction will help improve the situation.

If you want to avoid all sorts of problems after laser surgery, diseases, node corrections and poor-quality flap cuts, then you can restore your vision in a proven and reliable way. Allowing you to get rid of vision problems once and for all without the help of glasses, lenses or contact surgery.

Michael Richardson's method has helped many people say goodbye to glasses and contacts and see better without glasses than with glasses.

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Decentration of the optical zone of laser ablation.

Undercorrection. Hypercorrection

Everyone has heard about nanotechnology. Scientists create miracles by manipulating substances at the molecular level. Super apparatuses are required to work on such a miniature scale. Nanotechnology opens the way to the future for humanity.

But when carrying out laser correction, it is necessary to evaporate the cornea with an accuracy of 1000 nanometers. And for this purpose, equipment is used that is close in complexity to spacecraft. That is why the accuracy of the excimer laser is checked several times a day - calibration is carried out.

Yet such precision is not enough. Each person is too individual. There are several hypotheses that explain the occasional small discrepancies between the planned and obtained results of laser correction.

For example, hydration in human tissue varies over a fairly wide range. You yourself know about this. Some people's faces may swell after sleep. By evening, your legs may swell, especially for those who stand in one place all day. Worse than that. One person has a loose constitution, the tissues are saturated with water, while the other has a dry, thin constitution, and he almost never experiences edema. And everyone’s cornea is different. And water absorbs ultraviolet radiation, including the ultraviolet excimer laser. Therefore, with the same calculated dosage of laser radiation, a person with a loose, watery cornea may experience undercorrection, since water will “eat up” a lot. And in a person with a low density of water in the cornea, a hypercorrection may occur, evaporating more micrometers of thickness than planned.

Or there are, for example, scientific works that prove at the histological level the difference in the reaction of the cornea to LASIK. When forming a corneal flap and evaporating the corneal tissue, part of the connective tissue microfibers - collagen fibrils (of which the cornea mostly consists) is removed. Some of the remaining fibrils, having lost one of their attachment sites, shrink and thicken. This process is centrifugal in nature and can lead to a slight, 1-2 micron, thickening of the periphery of the cornea, which has almost no effect on its curvature. Almost. It is impossible to predict the degree of this influence and the severity of this process individually in each case.

These are just a couple of hypotheses that attempt to explain the likelihood of undercorrection or overcorrection occurring. There are many more such hypotheses.

However, in practice, such complications are extremely rare and, if they occur, they will not ruin the rest of your life. Your vision will improve after correction in any case. And the second stage of laser correction will help you achieve a 100% result.

As for decentration, much depends on the subtleties of the diagnostic manipulations performed and the individual characteristics of the location of the optical axis of the eye. The appearance in excimer lasers of tracking systems for the position of the eyeball and new aberrometers with the function of determining not only the center of the pupil and the center of the cornea, but also the localization of the optical axis has almost led to eliminating the possibility of decentering almost completely.

Decentering is best corrected with an excimer laser, which can eliminate higher order aberrations.

Dry eye (chronic)

It would seem like a small thing. But this little thing sometimes causes a lot of trouble. It’s no wonder that so many ophthalmologists have been looking for a solution to this problem in the last five years.

Causes of dry eye syndrome comes out a lot. Ecology, air from air conditioners, stress, increased dryness of indoor air, working at a computer and, of course, increased visual stress.

With prolonged visual concentration, whether driving a car or watching TV, a person actually blinks less often. This is how nature intended it. And this condition of “drying out” the eye and reducing tear production becomes chronic. And then there is air. And then there is laser correction, which somewhat disrupts the nervous regulation of tear production. Temporarily. But if you had dry eye syndrome before the correction, it will not go away even after. And for some time it will intensify.

You will have to instill artificial tear preparations; fortunately, addiction to them does not develop (but still try to take more breaks when using them).

Keratitis

Keratitis- inflammation of the cornea, accompanied by pain, decreased vision, severe photophobia and lacrimation. Keratitis can be traumatic, bacterial, viral, neurotrophic and of unknown etiology (cause). Like many other diseases, no one is immune from keratitis. It can occur in those: who wear contact lenses; who has the flu; who was blown away; who got garbage in their eyes; who has a toothache; who has sinusitis; who got wet in the rain or froze in the cold.

In academic terms, the etiological factors for the development of keratitis are divided into general and local. Common causes that can cause keratitis include colds (acute respiratory infections, acute respiratory viral infections), diseases of the paranasal sinuses, caries, tuberculosis, syphilis, etc. Local causes of keratitis are conjunctivitis, small foreign bodies of the cornea, improper use of contact lenses, trauma and etc.

After laser eye correction- a weak point and any infection that is in the body can trigger the development of keratitis. The main thing is to diagnose keratitis in time and treat it well. Therefore, before correction it is necessary to undergo a general blood test, RW, Hbs Ag, HIV. It is advisable to consult a dentist, otolaryngologist and others. In the presence of sluggish chronic diseases (from chronic pyelonephritis to stomatitis), the patient should warn the surgeon about them and, if necessary, carry out preventive treatment.

Keratitis that occurs immediately after laser correction is treated with drops and tablets and has no consequences for vision. Usually. But there are also exceptions.

Herpetic and fungal keratitis are difficult to treat. If you have had herpetic keratitis before and are planning to undergo laser correction, then warn your doctor and begin preventive treatment on the eve of the operation. The herpes virus, once settled in our body, almost never leaves it. After all, a cold on the lips can only be an infection transmitted from someone for the first time. And the second time, and all other times, it’s often just an exacerbation of the disease due to decreased immunity. The same thing happens to the eye - the ultraviolet light of the laser can activate the herpes virus that was dormant in the past focus of inflammation in the cornea. In such cases, laser correction should be carried out under the cover of appropriate medications (at a minimum).

As for the treatment of fungal infections, in addition to standard treatment, modern drugs of general antifungal therapy (for example, flucostat) should not be neglected. Invaluable assistance in early diagnosis can be provided by the patient himself, who promptly admitted the presence of chronic fungal diseases that can be localized in any part of the body (otomycosis, mycosis of the feet, etc.).

Complications of LASIK that can significantly and irreversibly reduce vision

Now in more detail about those complications of LASIK that can irreversibly reduce vision. The likelihood of each of them occurring is measured in tenths and hundredths of a percent, and the likelihood of irreversible vision loss is even less. But this possibility exists.

Traumatic flap injury

Serious traumatic injuries after LASIK are extremely rare. During the first month after LASIK, patients try to adhere to restrictions and avoid even light touching the eye area. As a rule, they succeed.

In the world ophthalmological scientific literature there are descriptions of the loss of a corneal flap due to injury. Of course, emergency hospitalization is indicated for a patient who has lost a corneal flap. Such an extensive corneal wound takes a long time to heal and is painful. After the end of a long healing process, such a patient has large “plus” diopters - induced, or rather, iatrogenic hypermetropia. And a serious decrease in the quality of vision. Further treatment consists of implanting the patient instead (or together, that is, phakic IOLs) with an intraocular lens (artificial lens, IOL). The intraocular lens is selected in such a way as to cover the resulting deficiency in diopters and eliminate iatrogenic farsightedness. A similar operation is performed during cataract surgery. This, of course, is an abdominal operation. But this is a way out of the situation in case of loss of a corneal flap.

Diffuse lamellar keratitis (DLK)

Keratitis has already been discussed above, but DLK should be separated into a separate group.

Diffuse lamellar keratitis (DLK) It is insidious in that no one reliably knows the cause of its occurrence and cannot predict and prevent it. On the 2-4th day after LASIK, minor discomfort appears, accompanied by some decrease in vision and fog in one eye. Then the gradual progression of these symptoms begins.

Many patients come for laser correction from populated areas, sometimes far away. There is no need to rush to go back. Even if your doctor allows you to. Stay near the clinic where you had LASIK for about a week. And for any unpleasant symptoms, consult a doctor.

If DLK is not treated on time with intensive courses of hormone therapy, then you can lose several lines of visual acuity. It is quite difficult to remove the developed cloudiness under the corneal flap in the optical center of the cornea without consequences.

For DLK, it is necessary to instill dexamethasone (preferably oftan-dexamethasone) or 1% prednisolone acetate into the eye 4-6 times a day (sometimes every hour). The same dexamethasone should be administered under the conjunctiva. Sometimes even general hormonal therapy is indicated. In a specialized clinic, a single rinse with dexamethasone under the corneal flap is possible.

For the prevention of DLK, there is only one piece of advice so far - it is advisable for allergy sufferers to take prophylactic antihistamines (Kestin, Zyrtec, Erius, Claritin, Loratadine, etc.) on the eve of laser correction and after it for 10-14 days.

There are suggestions that the cause of DLK may be debris, microkeratome lubricant, or talc from the surgeon’s gloves that got under the flap during LASIK, but no direct connection with these factors has been found. However, it is better for the surgeon to play it safe and not take risks.

Article from the book:

A review of the literature is presented regarding the etiopathogenesis, frequency, clinical picture, classifications and treatment methods of one of the serious postoperative complications of LASIK surgery, which is diffuse lamellar keratitis (DLK). Early detection and adequate treatment of DLK continues to be an urgent problem in keratorefractive surgery.

Diffuse lamellar keratitis in keratorefractive surgery

Review of the literature concerning etiopathogenesis, incidence, clinical features, classification and treatment of diffuse lamellar keratitis (DLK) - one of the most severe post-LASIK complications - was reviewed. Early detection and adequate DLK treatment stays on being topical problem in keratorefractive surgery.

The development of excimer laser surgery using the LASIK technique, including in the form of Femto-LASIK, has now almost reached its technical perfection. However, despite undoubted technical progress and the introduction of new technologies, the prevention and control of intra- and postoperative complications remains relevant. One of the serious postoperative complications of LASIK surgery is diffuse lamellar keratitis (DLK). You can also find other names for this condition in the literature: “Sands Of Sahara” syndrome or SOS, since on biomicroscopy the picture of DLK resembles the landscape of desert dunes, “diffuse intralamellar keratitis”, “interface keratitis”, “nonspecific diffuse lamellar keratitis". This work is a review of the literature with an analysis of possible etiopathogenetic factors in the development of DLK, the clinical picture, its stages, and consideration of various approaches to treatment.

Frequency, etiology, pathogenesis

This complication was first described by Smith and Maloney in 1998 as a non-infectious inflammatory reaction occurring at the interface within a week of LASIK. However, cases of the occurrence of DLK 3-6 months after the initial LASIK operation or a repeat additional correction procedure have been described, while DLK was not recorded in the first days of the postoperative period. There are reports of the development of DLK after additional correction of LASIK using the corneal flap lift method. There have also been cases of the occurrence of DLK in the early postoperative period after cross-linking in patients for iatrogenic keratectasia 4 years after primary LASIK.

DLK is a process that can be triggered by one or a combination of several factors. Considering etiopathogenetic factors, some researchers attribute a certain role in the development of DLK to intraoperative epithelial erosion.

J.D. Johnson et al. indicate that epithelial defects that arise during LASIK predetermine the development of DLK in 38.9% of cases. It has been noted that cases of DLC develop more often in patients with dystrophy of the corneal basement membrane and in patients with a history of recurrent corneal erosions. Moreover, the occurrence of DLC in patients with intraoperative epithelial erosion does not exclude the presence of subclinical dystrophy of the corneal basement membrane.

Currently, most authors agree that DLK is a multi-etiological disease. Possible inducing factors for the development of DLK after LASIK are considered, such as: microkeratome lubricant, silicone and talc from surgical gloves, metal fragments from instruments, bacterial endo- and exotoxins, meibomian gland secretions, povidone-iodine, corneal markers damaged by laser and thermal energy of corneal cells with the formation of antigenic cellular fragments, erythrocytes.

Femtosecond technologies, currently represented by at least five commercial laser models, have many advantages over classical LASIK technology, but they do not guarantee a reduction in the risk of developing DLK. There are data on cases of DLK after the use of femtosecond technologies. The incidence of DLK was noted to be up to 12% when using IntraLase FS15, which is slightly lower in cases of using the high-frequency femtosecond laser IntraLase FS60. It has also been reported that lowering the femtosecond laser energy level reduces the frequency of DLC.

Other studies show that there is no significant difference in the incidence of DLK among patients after i-LASIK surgery with the IntraLase laser FS15, FS30 and FS60. When comparing the IntraLase FS15 femtosecond laser with the Moria M2 microkeratome, the incidence of DLK was significantly higher in the femtosecond laser group (17%) than in the mechanical group (0%). R Gil-Cazorla et al. also revealed a similar pattern. In general, it is noted that with the advent of Femto-LASIK, the incidence of DLK has increased. On average, the incidence of DLK after the use of a mechanical microkeratome is estimated at 0.4-7.7%. For comparison, the incidence of DLK after Femto-LASIK is 0.4-19.4%. Nevertheless, the advantage of using femtosecond lasers is associated with more accurate dimensions of the corneal flap and a lower incidence of complications during its formation. Thus, interest in the use of femtosecond lasers to create corneal flaps in LASIK has not been overshadowed by the increasing incidence of DLK.
In cases where Z-LASIK surgery is performed using the Femto LDV laser (Ziemer), complications in the form of DLK also occur. The severity of symptoms and the area of ​​damage to the cornea with DLC is less compared to the same process after using IntraLase FS60. When performing LASIK with a femtosecond laser, Visumax DZ Reinstein shows 0.4% of cases of DLK in up to 3 months. after operation .

DLC is more likely to develop in eyes with thinner corneal flaps (p=0.09), a trend noted by J. Javaloy et al., who showed that corneal flaps less than 120 µm thick had a higher opacity index measured using confocal microscopy. This is explained by the activation of a larger number of keratocytes located in the anterior stroma. Keratocyte necrosis associated with femtosecond laser flap formation likely contributes to the increased level of inflammatory response after LASIK, especially when the level of absorbed energy is high.

The pathophysiological model of the disease, according to B.R. Will, presumably looks like this: corneal opacification and hypermetropic shift are caused by an increase in negative pressure in the corneal stroma, which in turn leads to intense stromal edema, which appears “white” on biomicroscopy. Model of Dr. B.R. Will suggests that the occurrence of stromal edema is due to the loss of the ability to control interstitial fluid movement by keratocytes that are damaged by surgery. Next, the liquid is “sucked” into the interface along with white blood cells. As a result of central corneal edema, the flap swells, the cornea expands forward and sideways, and may become wrinkled and corrugated. The hypermetropic shift is associated with a local expansion of the central zone of the flap, which somewhat aligns the corneal ablation zone.

R.K. Maloney et al. It is recommended to carry out a differential diagnosis with central toxic keratopathy (CTK). According to the authors, the similar clinical picture between DLK and CTK can lead to confusion - DLK does not affect the patient’s refraction because the corneal tissue does not change its shape. CTK, on ​​the contrary, causes a noticeable hypermetropic shift due to the destruction of stromal collagen with necrosis and disintegration of corneal tissue. According to R.K. Maloney, treating patients with CTK with long-term instilled steroids is a mistake because it increases the risk of developing glaucoma.

Clinical picture, classifications and treatment methods

Depending on the localization and concentration of small-point inclusions in the E.J. interface. Linebarger and co-authors identify 4 stages of development of DLK:

Stage I - white inclusions appear along the periphery of the flap, visual acuity does not decrease (frequency 1:25); Stage II - granules and inclusions are found in the central parts of the cornea, including in the optical zone, visual acuity decreases slightly (frequency 1:2000); Stage III - cloud-like or flocculent inclusions throughout the interface with a more intense reaction in the central zone. At this stage, along with a significant decrease in vision (more than two lines), patients may complain of pain, photophobia (frequency 1:5000); Stage IV - severe lamellar keratitis, white inclusions in the form of flakes are distributed throughout the interface, swelling of the flap is noted in the center, and the nearby stroma is also involved. In severe cases, areas of softening and melting of the flap appear. At this stage, visual acuity may decrease significantly. The patient complains of pain, photophobia, foreign body sensation, and decreased vision. The frequency of this stage of development of complications is 1:10000.

Currently, in clinical practice, the most widely accepted approach to diagnosing DLK is according to the classification of E.J. Linebarger et al. . Classically, DLK begins on the first or second postoperative day with a mild sterile infiltration of inflammatory cells along the edge of the flap at the interface (stage I). This stage may progress through diffuse migration of inflammatory cells into the interface into more central zones (stage II). If the pathological process progresses, then aggregation of inflammatory cells in the optical zone is often associated with a subjective decrease in visual acuity (stage III). In rare cases, corneal melting may occur, followed by scarring, severe hypermetropic refractive error, and significant loss of best-corrected vision (stage IV)

. In turn, T.D. Azar proposed a classification of DLK based on the prevalence of inflammatory cell migration at the interface:

type I A - not affecting the optical zone, single foci;

type I B - not affecting the optical zone, conglomerates of foci;

type II A - affecting the optical zone, single foci;

type II B - affecting the optical zone, conglomerates of foci.

According to E.M. Nakano et al., the stages of development of DLK are as follows: Stage I occurs in 2-4% of cases after LASIK, develops on the first day after surgery. At the periphery of the flap, bright white, granular cells are found at the interface; visual acuity does not decrease during this period. Stage I can spontaneously end on the 7th–10th day, but can also progress to stage II. The treatment uses 1% Prednisolone every hour in combination with a fluoroquinolone antibiotic 3 times a day. Stage II usually develops 2-3 days after surgery and occurs in 0.5% of cases. Inflammatory cells begin to accumulate in the central optical zone, which affects visual acuity. Treatment is the same as in stage I. Stage III (“threshold of DLK”), as a rule, occurs on the 2nd–3rd day and occurs in 0.2% of cases. There is a more pronounced aggregation of inflammatory cells; they appear as white, dense, sticky particles in the optical zone. At the periphery, the corneal flap is transparent. Subjectively, patients complain of fog, vision deteriorates by 1-2 lines according to the Snellen chart. If treatment is not carried out at this stage, permanent scarring may occur. Treatment should be more massive. The corneal flap is raised and the stromal bed is washed with BSS solution. Washing reduces the inflammatory response and collagen activity of granulocytes. The use of long-acting steroids can increase IOP levels, which can contribute to the transition to stage IV (“DLK syndrome”), which occurs in 0.02% of cases. Aggregation of inflammatory cells is pronounced, collagen is released, fluid accumulates with the formation of a bullous surface. As a result, the stroma melts and permanent scars form. The patient's visual acuity decreases, irregular astigmatism and hypermetropic refraction appear. At this stage, treatment includes lifting the corneal flap with irrigation, followed by the use of 1% Prednisolone every hour in combination with a fluoroquinolone antibiotic 3 times a day. Mandatory monitoring of IOP levels is required to prevent “DLK syndrome”.

Based on the classification of D.R. Hardten and R.L. Lindstrom, in stage I DLK (frequency 1:50), as a rule, on days 1–3 after surgery, white granular cells begin to accumulate on the periphery of the interface. Application of 1% Prednisolone every hour leads to complete recovery in most cases. In stage II (frequency 1:200), a diffuse distribution of cellular infiltrate occurs throughout the entire length of the corneal flap. Careful observation, along with intensive use of corticosteroids (1% Prednisolone), is preferred at this stage. Stage III DLK is characterized by central condensation of inflammatory cells (frequency 1:500). Inflammatory mediators and collagenolytic enzymes are released from aggregated polymorphonuclear cells (granulocytes), which can subsequently lead to melting of the stroma (stage IV DLK). Recommended treatment for stage III DLK is lifting a corneal flap, taking tissue for microbiological analysis, careful irrigation of the stromal bed with 1% Prednisolone, and use of the fourth generation of fluoroquinolones. During these activities, it is extremely important to avoid aggressive effects on the stromal bed, because Excessive loss of necrotic tissue can lead to pronounced topographic changes and hypermetropic shift.

Treatment, according to B.R. Will, should include management of corneal edema. Surgeons must immediately respond to increased osmotic pressure by using 99.5% glycerol solution, one drop every 10 minutes for 30 minutes, followed by 5% NaCl drops. He also suggested the non-steroidal anti-inflammatory drug Ketorolac instilled four times daily and 1000 mg of vitamin C daily. Early use of glycerin in treatment can quickly remove swelling and improve the patient's morale.

There are reports that prophylactic use of the antihistamine Loratadine reduces the incidence of DLB. Keratorefractive surgeons in Tehran aim to control the occurrence of DLK flares by using different microkeratome blades for different patients, paying attention to the choice of solutions used during surgery (Ringer's solution instead of BSS), irrigating the stromal bed with steroids during surgery, and advising avoidance of ultrasound and chemical sterilization instruments, use talc-free gloves, and regularly clean autoclaved systems. Although steroids (local or systemic) were used preoperatively for prophylactic purposes, there is no evidence that they can have an inhibitory effect on DLK.

According to domestic authors, at the 1st stage conservative treatment is possible, at the 2nd and 3rd stages surgical treatment is required: the corneal flap is raised, the intralamellar space is washed with a solution with steroids, then placed in place, the flap is carefully straightened. At the 4th stage, in the presence of areas of softening and melting, treatment is only conservative, followed by layer-by-layer keratoplasty. According to R.S. Hoffman, treatment of severe DLK with high-dose oral corticosteroids produces excellent results without corneal flap elevation and interface flushing.

Symptoms of DLK may be confused with microbial keratitis. However, with microbial keratitis, the inflammatory process can be combined with ciliary pain, infiltrates appear on the posterior or anterior surface of the stroma, and hypopyon may appear. Meibomian gland secretion can also mimic DLK, but meibomian gland secretion has a shiny, oily, irregular film, in contrast to the flat, white infiltrates of DLK. Cases have been described that can be called pseudo-DLK. In most cases it was secondary glaucoma caused by steroid use. After LASIK, pressure increases at the interface of the corneal flap, giving a ground glass appearance on biomicroscopy. In many cases, this phenomenon is diagnosed as “chronic” DLK, but the use of corticosteroids in treatment further worsens the condition. One should also pay attention to those cases of DLK that do not respond to treatment with steroids and corneal flap elevation.

Based on our clinical practice, we recommend starting the prevention of DLK already during examination 30-40 minutes after surgery, by instilling an anesthetic and a combination drug containing a vasoconstrictor and histamine H1 receptor antagonist Betadrin or Spersallerg or one vasoconstrictor Tetryzoline. Next, it is necessary to carefully examine patients the day after LASIK surgery. Excessive irritation - irritation of the eyeball should be regarded as an increase in the risk of developing DLK. In this case, we recommend increasing the frequency of Dexamethasone instillations to 6 times a day for 2-3 days. The patient should be notified of his condition, and if the irritation does not decrease, he should immediately contact the clinic. For more severe symptoms, when examination reveals flare in the interface, we practice subconjunctival administration of Dexamethasone in a volume of 0.3-0.5 ml, with the additional prescription of Solcoseryl eye gel 5-6 times a day. With an even more pronounced clinical picture of incipient DLK, parabulbar administration of prolonged forms of corticosteroids is possible. In the absence of pronounced positive dynamics, we recommend discontinuing both corticosteroids and instilled antibiotics due to their high epitheliotoxicity and cytotoxicity against keratocytes. The required doses of corticosteroids are administered by injection, while massive keratoreparative therapy is carried out: Balarpan - 5-6 times a day, Solcoseryl - 5-6 times a day in the form of an eye gel. As a rule, with this treatment regimen, a fairly rapid regression of the symptoms of DLK is observed; not a single case of loss of best-corrected visual acuity, corneal opacities, or stromal melting was observed.

Conclusion

Thus, despite technical innovations in the LASIK surgical technique, early detection and adequate treatment of DLK continues to be an urgent problem in keratorefractive surgery.

O.S. Kuznetsova, I.A. Remesnikov

Volgograd branch of the MNTK Eye Microsurgery named after. acad. S.N. Fedorov" of the Ministry of Health of the Russian Federation

Kuznetsova Olga Semenova - ophthalmologist, ophthalmology department for correction of refractive errors

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