Differential diagnosis of cataract and retinal detachment. Retina and optic nerve, pathologies Analysis of the retina in dogs

Authors): S.A. Boyarinov is a veterinary ophthalmologist at the IVC MBA, head of the treatment and preventive department of the SBBZh in Pushkino, graduate student of the department of the Federal State Budgetary Educational Institution FSBEI HE MGAVMiB - MBA named after. K.I. Scriabin, member of RVO, ESVO, Russian Geographical Society.
Organization(s): Federal State Budgetary Educational Institution higher education“Moscow State Academy of Veterinary Medicine and Biotechnology - MBA named after K.I. Scriabin" (FSBEI HE MGAVMiB - MBA named after K.I. Scriabin)
Magazine: №1 -2017

Introduction

The retina is a unique organ with a complex structure and functionality that provides visual perception of the surrounding world in dogs and cats. Since eye pathologies are often associated with various somatic diseases in animals, it is necessary to take into account the possibilities of primary diagnosis of pathology and, accordingly, prognosis. One of these visual diseases is retinal detachment (RD).

Normally, the retina of the eye is tightly adjacent to the underlying layers, the pigment epithelium (RPE) and choroid. This condition is due to the gentle pressure exerted on it by the vitreous body (VT), which holds the retina in a physiological position. The retina is attached tightly to the underlying layer only in a few places: along the dentate line and near optic nerve. In other areas, the connection is caused only by gentle pressing of the joint, which, accordingly, allows us to conclude that the likelihood of detachment developing in these places is the highest.

OS is an eye pathology in which there is a complete or partial separation of its 9 layers (neuroretina) from the RPE and choroid (choroid). Normally, these structures fit tightly together, providing trophic functions.

With OS of the eye in animals, vision decreases to the point of complete blindness, and in advanced cases OS leads to the death of the eye. That's why this pathology is an emergency and requires immediate attention veterinarian- ophthalmologist.

Etiology

This eye disease occurs in both dogs and cats, but often has different causes. For example, hypertensive retinopathy with both total and local OS of an exudative nature is most typical for cats.

Most often, the following factors and pathologies can lead to OS in dogs and cats.

• - Congenital malformations such as retinal dysplasia (RD), collie eye anomaly (CEA), and primary hyperplastic persistent TS syndrome (PHTVL/PHPV).
• - Eye injury leading to retinal rupture and hemorrhage.
• - Inflammatory processes (chorioretinitis), leading to accumulation of exudate or blood in the subretinal space.
• - Degeneration and dysplasia CT.
• - Neoplasms of the posterior segment of the eye, including the choroid.
• - Buphthalmos in glaucoma, leading to stretching of the membranes eyeball.
• - Pathologies leading to damage vascular bed: systemic hypertension, blood hyperviscosity syndrome, diabetes.

Based on the reasons leading to OS, several types of this pathology are distinguished.

Serous OS occurs as a result of the accumulation of fluid under the retina and, accordingly, its separation from the underlying layer. There are two types of serous detachment: the first is the exudative type, characterized by the accumulation of inflammatory fluid (exudate) as a result of infectious diseases, the second is the hemorrhagic type, characterized by the presence of blood under the neuroretina due to systemic arterial hypertension, coagulopathies, thrombocytopenia.

Tractional detachment occurs as a result of tension on the retina from the side of the CT, to which it fits tightly. This condition is possible due to posterior uveitis, the formation of moorings and cords during degeneration of the CT, as well as when it is displaced forward as a result of luxation of the lens and displacement of the iridolenticular diaphragm.

Rhegmatogenous OS is associated with thinning and formation of retinal breaks as a result of degenerative changes, especially in older animals. Through these breaks, CT can penetrate under the retina, leading to detachment.

Traumatic OS is the result of injury to the eyeball (contusion, penetrating injury). In these cases, trauma can lead to both acute detachment as a result of retinal rupture, displacement of the retina, subretinal hemorrhages, and to detachment in the long term (chronic inflammatory process, destruction of ST, hypotension).

It is also worth mentioning the possible iatrogenic OS after intraocular manipulations, in particular phacoemulsification of cataracts and vitrectomy. Thus, with phacoemulsification of 290 eyes in dogs and their three-year follow-up, postoperative complications in the form of OS amounted to 1–2%, although in the work of other researchers they range from 4 to 9%. Despite the small percentage of detachments after phacoemulsification of cataracts in dogs, it is necessary to regularly assess the condition of the retina using ultrasound at the immediate and late postoperative periods.

According to the degree of prevalence, it is customary to distinguish the following types of OS: local, total, subtotal.

As a result of detachment of the neuroretina from the RPE and choroid, the following disorders occur:

Decreased metabolism in neuroretina; disruption of retinol transport from the RPE to the neuroretina; disruption of the blood supply to the neuroretina from the choriocapillaris; development of atrophy of the photoreceptor layer of the neuroretina; release of vascular endothelial growth factor (VEGF) by hypoxic neuroretina.

It should be noted that OS is a condition that requires emergency treatment by the animal owner to a veterinary specialist and provision of immediate assistance to the patient. In many cases, when treatment is timely, and depending on the type and cause of OS, the prognosis for vision can be favorable. However, the lack of treatment, the impossibility of diagnosing this pathology, as well as late application can lead to complications that can arise after OS - retinal atrophy, glaucoma, hemophthalmos, etc. In such cases, irreversible blindness develops and there is a high risk of losing the eye as an organ.

Risk factors

Risk factors for the development of OS in dogs and cats include the following:

High blood pressure (hypertension); old age; the presence of overripe cataracts; luxation of the lens; phacoemulsification of cataracts; genetics.

Clinical signs

Symptoms of OS in dogs and cats include partial or complete loss of vision (acute blindness), decreased or absent pupillary light response (PLR), the appearance of retinal floats and vessels visible without special equipment on a dilated pupil, ultrasound signs characteristic of OS - “gull wings” or the Latin letter V during ultrasound of the eyeball. OS can often be accompanied by hemophthalmos (accumulation of blood in the CT).

As already mentioned, OS in many cases can be a concomitant symptom of the underlying disease. Therefore, it is important to take this connection into account, even in the absence obvious signs OS.

Diagnostics

Confirmation of the diagnosis of OS is made on the basis of anamnesis, examination by a veterinary ophthalmologist and diagnostic studies.

Pet owners in most cases complain of dilated pupils and varying degrees of blindness. In cats, fibrin and blood may be present in the intraocular space.

For staging accurate diagnosis It is recommended to use a comprehensive diagnostic approach: conducting an ophthalmological examination (biomicroscopy, ophthalmoscopy, ultrasound), as well as assessing the somatic condition of the animal (clinical and biochemical analysis blood, testing for infections, cardiac examination, etc.).

A comprehensive ophthalmological examination provides a complete diagnostic picture of the disease, prognosis and choice of treatment tactics. If OS is suspected, it is necessary to assess the condition of the anterior chamber of the eye, iris and lens, and check pupillary reflexes.

Important diagnostic measure if OS is suspected, ophthalmoscopy is performed.

This procedure is possible in the presence of transparent light-refracting media of the eye (cornea, lens, CT) and allows you to visually assess the state of the OS: detection and localization of areas of detachment (vibrating gray-white areas of the retina), the presence of exudate and hemorrhages, the presence of retinal breaks of various configurations.

Ultrasound of the eye is the “gold standard” for diagnosis in animals with suspected OS. It is especially important that this study is relevant when it is impossible to perform ophthalmoscopy and when the optical media of the eye are opaque (hyphema, hemophthalmos, cataracts, corneal edema). With an ultrasound of the eyeball, it is possible to assess the degree and type of OS, the presence of exudate, blood, concomitant pathologies of CT (moorings, destruction) and choroid. When B-scanning, the OS is visualized as a film-like formation in the CT, usually having contact with the dentate line, and the optic nerve head (ONH) in the form of the letter V.

The detached neuroretina is mobile, and when the eye moves during ultrasound, it moves smoothly, as if floating. OS is often accompanied by posterior vitreous detachment (PVD) and is typical for older animals.

Treatment

Since OS is an acute condition leading to decreased vision and blindness, the speed of treatment and the urgency of the assistance provided play a decisive role in the further prognosis of the disease. Long absence medical care, as a rule, leads to disruption of the retina. This is due to the lack of contact between the detached neuroretina and the choroid (choroid) and a violation of trophism and metabolism between them. However, when emergency assistance it is possible to restore vision to a patient with detachment using both conservative and surgical treatment.

Drug treatment includes the use medicines aimed at stopping primary cause, which caused neuroretinal detachment. For example, cats with arterial hypertension, even without signs of retinopathy, should receive antihypertensive therapy aimed at normalizing blood pressure through the use of systemic antihypertensive drugs (amlodipine) and ACE inhibitors(enalapril), thus preventing OS. The use of antibacterial therapy is justified if a systemic infection is confirmed. At the same time, it is especially important to take measures in case of emergency admission of an animal to veterinary clinic in the form of diuretic drugs (in the absence of contraindications). The use of natural, and in the absence of contraindications, systemic corticosteroids (prednisolone), gives good results, especially in dogs.

Surgical treatment of OS in dogs and cats is relevant if the prognosis for vision is favorable, as well as the absence of contraindications for anesthesia. The procedure to restore the retina to its physiological position is called retinopexy. There are several types of retinopexy:

Laser surgery (photocoagulation);
cryopexy;
pneumatic retinopexy;
vitrectomy with replacement.

The principle of laser surgery and cryopexy is similar and consists in “welding” or “freezing” the retina to the underlying tissues by forming scars at the site of exposure.

Pneumatic retinopexy is somewhat simple to perform and consists of introducing a gas bubble into the CT, which puts pressure on the retina, pressing it to a physiological place.

Vitrectomy for OS is quite complex and requires expensive equipment and the skill of a microsurgeon. The meaning of this procedure is to remove the CT, straighten the OS and introduce heavy oil into the eye cavity (silicone tamponade of the vitreal cavity). Thus, the neuroretina is pressed against the RPE and choroid, providing anatomical and physiological fit.

Often enough surgical procedures in case of OS, they are performed in combination, for example, laser retinopexy and vitrectomy with replacement, to achieve a better result.

Each method has its own positive sides, and negative, as well as indications depending on the type and severity of OS.

Conclusion

In conclusion, I would like to note the importance of urgently contacting a veterinarian, the urgency of providing first aid emergency care, referral for ongoing treatment and monitoring to a veterinary ophthalmologist.

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Many of the diseases listed above, including corneal opacity, cataracts, inherited retinal diseases, and glaucoma, are discussed elsewhere in these works. The following is a discussion of the leading causes of acute blindness (not glaucoma).

1. Retinal detachment

Retinal detachment is the separation of the retina and choroid, more specifically between the retina and the retinal pigment epithelium). The result of this separation is ischemia of the visual receptors. If this separation is not quickly corrected and the blood supply restored, the cones and rods begin to die, leading to irreversible blindness.

There are 3 types of detachment, depending on the mechanism of its formation. Serous detachment is caused by the accumulation of fluid in the space under the retina, between the retina and the choroid. This fluid arising from the choroid may be blood or exudate.

Traction The detachment is caused by the force that pushes the retina away from the choroid. This force can be generated by forward movement of the vitreous (for example, after displacement of the anterior lens) or due to stretching by fibrin clots.

Rheumatogenous Detachment is caused by the penetration of liquefied vitreous humor into the space under the retina through holes in the retina.

Causes of fiber detachment

The list of possible causes of fiber detachment depends on the type of detachment.

□Rheumatogenic detachment may be caused by age-related changes, injury, or
inflammation (see below).

□Tractional detachment can be caused by lens luxation or inflammation (see below).
□Serous detachments are caused by bleeding or inflammation.

Causes of exudative (serous) detachment

The inflammation that leads to retinal detachment usually involves the choroid and retina (chorioretinitis or retinochoroiditis). As with anterior uveitis, it is possible that any ocular or systemic inflammation leads to chorioretinitis. However, chorioretinitis is usually inflammation caused by an infectious pathogen. This may be a viral infection (for example, canine distemper), rickettsiosis ( Ehrlichia canis ), protozoal diseases ( Leishmania, Toxoplasma ) or fungal infections.

Causes of hemorrhagic (serous detachment)

Any cause of systemic bleeding can lead to hemorrhagic retinal detachment. Common reasons include systemic hypertension, thrombocytopenia, ( Ehrlichia canis ), coagulopathy, increased blood viscosity, anemia and trauma.

Clinical signs of retinal detachment

□ Blind eye (no response to threat)

□ Fixed dilated pupil. When stimulating the contralateral eye, a friendly response is observed PLR.

□ When conducting an ophthalmoscopic examination, the doctor has difficulty trying to focus on the retina (since it is displaced from its natural location). A streak can be seen floating in the posterior chamber of the eye. This strip, which is the retina, may be clear, white (ie, swollen), or hemorrhagic, depending on the cause of the detachment. Blood vessels in the retina can be visible even without the use of an ophthalmoscope.

□ Ultrasound. Sensor with frequency 10 MHz can create an image of a detached retina. This image is called the "gull sign" because the detached retina usually remains attached to the eye - to the optic disc and to the serratus margin ( ora serrata ). Ultrasound examination especially useful when ophthalmoscopic examination cannot be performed due to severe corneal edema, hyphema, etc.

Treatment of retinal detachment

□Needs to be diagnosed main reason detachment and treat it. Therefore, systematic preparation must be carried out. Depending on the type of detachment, this preparation should be aimed at diagnosing cardiovascular or infectious diseases.

□Lens removal is indicated when detachment is secondary to lens displacement.

□Fibrin clots and fibers can be dissolved by injecting tissue plasminogen activator (TPA) into the eye, thereby preventing tractional detachments.

□Treatment of exudative serous detachment involves drainage of fluid under the tissue. This can be accomplished using hyperosmotic factors. Systemic carbonic anhydrase should also be considered. If the cause of the exudate is an inflammatory process, systemic steroids are prescribed.

□Specialized centers may perform retinal attachment or retinal reattachment surgeries.“clogging” of holes in the retina.

2. Sudden acquired retinal degeneration ( SARD)

It is an acquired disease of unknown etiology, usually occurring in middle-aged female dogs. There is a sudden onset of blindness. Typical patients are lap dogs. Many dog ​​owners report lethargy, weight gain and PU/PD over the past few months.

Examination reveals a blind eye with a fixed, dilated pupil. During the first few months the bottom looks normal. Degenerative changes may appear on late stage (after several months). ERG flat, indicating insufficient retinal activity.

There are currently no treatments SARD . We hope that once the cause is identified, treatment can be offered.

3. Optic neuritis

A. Cause

Inflammation of the optic nerve caused by: D Meningitis of any etiology D Infections - canine distemper, fungal diseases (for example, Cryptococcus), toxoplasmosis,

bacteremia, etc. Many systemic diseases may cause eye complaints. D Neoplasia, trauma, or abscesses in areas where the optic nerve passes (especially when

chiasme!)

□CNS diseases - GME , reticulosis, etc.

□Idiopathy - perhaps the most common cause

B. Diagnostics

□Blind eye with a fixed, dilated pupil.

□ERG normal, since the retina is not affected (thus, optic neuritis is differentiated from SARD)

□The optic disc appears normal or inflamed, depending on which part of the nerve is involved. If the proximal part of the optic nerve is involved, then when examining the fundus, swelling of the optic nerve nipple and blockage of blood vessels are visible.
As the disease resolves, optic disc atrophy is observed. Inflammation of more distal portions of the nerve may occur when the disc appears normal.

C. Treatment

Treatment is based on identifying and eliminating the underlying cause. If no systemic cause is found, systemic steroids should be prescribed. The forecast is cautious.

Ophthalmic examination

An eye exam doesn't have to be scary! Although it must be recognized that interpretation of data can be difficult at times, the examination itself follows a logical anatomical order. In addition, it does not require expensive equipment. In fact, the most important things needed for an examination are those that are nonophthalmic in nature: a room that can be darkened, a good source of focal light, and a magnifying loupe. A hand lens, an ophthalmoscope, a Shiotz tonometer and some consumables (paints, solutions, etc.) complete the list of basic equipment.

As with any other system, the doctor must pay Special attention for signs. Many eye diseases can be related to breed or age. Because many ocular disorders may be a manifestation of systemic lesions, a complete medical history and a comprehensive physical examination should be performed. Likewise, if neuro-ophthalmological abnormalities are present (blindness, strabismus, anisocoria, etc.), it should be examined nervous system, since the above disorders may be signs of a disease of the nervous system.

1. Quick Look

The patient should be observed when he enters the room, since this is an unfamiliar environment for him, which may reveal poor eyesight; this should be analyzed later. After the anamnesis and physical examination begins assessment of the visual system through careful observation behind the patient from a distance, without touching him (as this may cause distortion of the palpebral fissure). As you observe, ask yourself:

□ Are both eyes open normally? Are there any signs of pain or photophobia? Does the animal blink normally?

□ Do they have eyes? normal size and location? Are there any signs of exophthalmos or buphthalmos? Are the pupils the same size?

□Is the shape of the eyelids normal? Are there any signs of entropion or ectropia (usually the lower eyelid)? Is there any loss of the upper eyelid? Is the third eyelid raised?

□Is there any discharge from the eyes? What character? The orbital area is then palpated to identify any cracks, abnormal swelling, etc. Take the opportunity to apply pressure to the eyeball through upper eyelid. This both serves as a test of retropulsion (indicating the presence of a retrobulbar mass) and causes exophthalmos of the third eyelid, allowing inspection of the outer surface of the eyelid. This is NOT effective way determination of intraocular pressure (IO).

Take a quick look at your eyelids. Examine the surface of their skin, the mucocutaneous border and turn them slightly outward to see the conjunctiva of the eyelids and the 2 eversions of the lacrimal punctum. Take the opportunity to test the blink reflex in response to touching the skin of the canthus. Continue by examining the conjunctiva of the eyeball and the surface of the cornea.

2. Vision assessment

A. Threat Response: This involves making sudden threatening gestures that are supposed to should reveal the blink reflex. The centripetal path of the reflex includes the retina, axons optic nerve, as well as optic tract and irradiation. The efferent component of the response includes the cerebral cortex, cerebellum and nucleus and nerve YII cranial nerve (facial nerve).

It is important to note that the threat response involves cortical integration and interpretation and is therefore not a reflex. Rather, this reaction of the cerebral cortex, which requires everything peripheral and central visual pathways, as well as the integrity of the visual cortex and facial nerve center. Also, remember that the threat response is a very rough test of vision and actually requires only 6 out of 600 visual activity!.

Threat response should be assessed in one eye at a time while the other eye is covered.... Be careful not to touch the patient's eyelashes/fur or cause a breeze as this may result in a "false positive" reaction; make threatening gestures behind a glass partition. “False negative” results are also possible (lack of reaction to a threat in sighted animals). One possible cause is facial nerve palsy, which eliminated through the use of the blink reflex. There is no reaction to threat in very young (<10-12 недель) животных, и на нее так же может воздействовать психическое состояние пациента.

b ) Additional Vision Testing: Vision can also be assessed through the use of an obstacle course. You must be consistent in choosing the obstacle course, and make sure it can be completed by normal animals! Assess patients in bright and dim lighting while covering one eye.

Another test is the visual placement response, which is useful when the strip resultsobstacles and responses to threats are questionable. This is done by lifting the animal towards the table; at the same time he is allowed to see the approaching surface. A normal animal extends its paw toward the surface before the paw touches the table.

3. Examination in the dark.

After the light goes out, pupil dilation should increase. Use dim light (to prevent constriction), and stand at a distance so you can see both pupils at the same time using tapetal reflection. Tapetal reflection also serves to reveal (through retro-illumination) any visual opacity, especially of the lens or vitreous.

Next, use bright lighting to assess the pupillary light reflex ( PLR ). Unlike the reaction to a threat, PLR - This is a subcortical reflex. Therefore, he does NOT test vision, and normal PLR a subcortically blind animal can be detected. Besides, PLR usually present (although it may be reduced or delayed) in animals suffering from retinal degeneration ( PRA ), cataracts and other causes of subcortical blindness. Nevertheless, PLR is a very important test that helps localize the damage causing vision loss.

If one of the pupils does not respond to light or cannot be seen (for example, in cases of severe corneal edema or hyphema), the agreed PLR . Alternatively, you can test the blinding reflex. It is also a subcortical reflex that manifests itself as a bilateral partial blink in response to bright light.

For the next stages of the examination, magnification is required. The eyelid margins, conjunctiva, and corneal surface are again examined. Use magnification to check for distorted eyelashes (trichiasis, distichiasis); this can be seen on the white background of the conjunctiva by lightly pressing the eyelid. Following the anatomical order, the anterior chamber of the eye (detecting the opacity of the aqueous humor), the surface of the iris and the anterior segment of the lens are then examined.

4. Ophthalmoscopy

This is the part of the examination that doctors usually dread the most. In part, this undoubtedly stems from the wide range of normal variations in fundus appearance in dogs (and to a lesser extent in cats). It is common knowledge that if you are not accustomed to examining the fundus, it will be difficult for you to diagnose deviations from the norm. Therefore, you should make it a habit to examine the fundus, however, briefly, of every patient you see. Your customers will appreciate the extra touch, and so will you. achieve the necessary professionalism.

Due to the high cost of reverse ophthalmoscopy, direct ophthalmoscopy is used in most general clinical practice. This tool provides a high degree of magnification (x16 for medium-sized dogs). An unfortunate consequence of high magnification is a small field of view (4o), which increases the time required to fully fundus examinations. A quick fundus examination can be achieved by using bright light source and hand lenses (20-30 D ), which provides reverse monocular ophthalmoscopy capabilities. Direct ophthalmoscopy is characterized by several features:

□Ocular grid - used to compare the size of the lesion in the optic disc
nerve.

□Red free filter (emits green light) - Helps evaluate hemorrhages and blood vessels that appear black.

□Holes of different diameters - the largest one that matches the patient's pupil is used.

□Changing lenses allows the doctor to determine the depth/height of the lesion or to examine more anterior structures, such as the lens. The identified lesion is brought into focus by adding convex magnifying lenses (+). The vitreous depression/coloboma comes into focus with the addition of concave diverging lenses (-). In dogs, each diopter you add is equivalent to 0.28 mm.

□Use a narrow beam that allows you to identify the depressions and elevations of the fundus lesion. Ophthalmoscopy should be performed in a dark room after dilation of the pupil. Initially, determine the tapetal reflex at a distance to identify any biconvex or vitreal opacities. As you approach the patient, focus on the more successful posterior structures - the cornea, iris, lens and vitreous - until you focus on the fundus. Carefully examine the fundus as a whole, looking for changes in the lining layer, blood vessels and optic nerve head. It is best to maintain the same position and allow the patient's eye movements to bring the structures closer to you, rather than chasing them.

5. Additional tests

□Srimer's tear test is used to evaluate tear production and diagnose

keratoconjunctivitis. It should be carried out at an early stage of the examination, since anyvisual manipulations can cause the tear reflex to be indicated.

□Fluorescein staining is used to diagnose corneal ulcers. Superficial ulcers
can be painted with pink bengal paint.

□Specimens for bacteriology, mycology and cytology may be collected as indicated. The first two should be taken before any drops are put into the eye, since ophthalmic solutions often contain preservatives.

□Nasolacrimal patency is determined by the passage of fluorescein from the eye to the nose, through catheterization of the nasolacrimal system and through dacryocystorhinography.

□Ultrasound is often used in ophthalmology. The main indications are
images of the retroburbal area and images of the posterior segment when this is not possible
see (for example, due to hyphema or cataract). ST and MRI can be
used in certain cases.

□Tonometric measurement of intraocular pressure for the diagnosis of glaucoma.

□Additional tests, including gonioscopy (measuring the iridocorneal angle as part of the diagnosis of glaucoma) and electroretinography (recording the retina's electrical response to flashes of light to determine retinal function), may be available in specialized centers and are discussed elsewhere in these works.

Good vision is important not only for people, but also for their pets. Unfortunately, there is a huge list of ophthalmological diseases that can not only lead to deterioration of the visual system, but also completely deprive the pet of the ability to see. An example is retinal atrophy.

The most severe pathology in which death of photosensitive receptors in the retina. In most cases, the disease develops simultaneously in both eyes. The pathological process does not cause pain to the animal. Many veterinarians suggest that retinal atrophy can rightfully be called a hereditary disease (this is indirectly confirmed by the fact that the pathology is predominantly found in purebred animals).

Outbred pets get sick much less often, but their crosses “based on” purebred ones get sick more often. This is explained by the presence of a recessive gene and poor breeding work, when many breeders actually have no idea what characteristics even the immediate ancestors of the sires they used had.

Clinical picture, mechanism of pathology development

With atrophic phenomena in the retina, the rods are affected, that is, night vision is the first to be affected. The first and quite obvious symptom is sudden onset of night blindness, which is especially noticeable in the case of cats. In addition, the pupils of a sick animal are often and strongly dilated, and the eyes themselves seem to “shine,” which is explained by a lower degree of light absorption. In mild cases, your pet may go completely blind, but this will only occur at night and in thick twilight. If the process proceeds according to the most severe scenario, the animal completely loses vision in any situation. Unfortunately, if you don’t treat your pet at all, then about a year after the first clinical signs appear, he will become completely blind. Alas, in some cases, owners bring almost blind pets to the clinic when retinal atrophy in a cat or dog has reached the terminal (final) stage.

Read also: Wolfarthiosis in dogs: symptoms and treatment methods

To this day, the disease is considered incurable, but recent research by veterinary pharmacists gives hope that the intensity of photoreceptor death may be significantly slowed down. Unfortunately, there is still no talk of a complete cure, since the pathology (which we have already written about) belongs to the category of genetic. So, how does the atrophic process in the retina develop?

As we have already noted, with this pathology one of the types of photoreceptors, that is, rods, dies. They are responsible for night and twilight vision. Cones (the second type of receptor) are practically not affected by the disease. They provide “standard” daytime vision. There are about 150 million receptors in the dog's retina, of which... only 1.2 million are cones.

Thus, With retinal atrophy, more than 96% of all animal eye receptors die! In cats, whose night vision acuity is known to everyone, the disease is even more severe. A logical question arises: “Why, if only the “night” receptors atrophy, does the pet see nothing even during the day?”

When rods die, there is a lot of “leftover”, excess oxygen that can no longer be used by the dead photoreceptors. Free oxygen is a powerful oxidizing agent, and even more so in such volumes. It begins to destroy the cones. It is on knowledge of these processes that the only more or less effective treatment of atrophy is based: the sick animal is prescribed special antioxidants, which significantly reduce the activity of free oxygen and save at least part of the daytime photoreceptors. The sooner therapy is started, the greater the chance of maintaining an acceptable quality of life for the animal.

Moreover, modern data confirms that sometimes impressive successes can be achieved. Even animals that were brought to the clinic almost blind, after the administration of antioxidants, retained the ability to see at least something for a long time. The mitochondrial antioxidant SKQ1 performed best. Some animals receive it for more than seven years, and even if they have developed atrophy (by the time they go to the clinic), they have not become completely blind during all this time.

Read also: Uveitis in dogs - causes, symptoms, treatment

If you do nothing at all, There are two possible scenarios: either the pet “simply” goes blind within a year completely, or in both his eyes huge cataracts form(which also leads to complete loss of vision, and also threatens the loss of the eye altogether).

Additional troubles

Don't give up if your pet is diagnosed with retinal atrophy! It is no longer a completely hopeless disease. It is advisable that the animal O was examined by a veterinary ophthalmologist who can identify the presence/absence of concomitant pathologies. The sooner he does this, the better. Pets that have been diagnosed with progressive retinal atrophy should under no circumstances be allowed into the breeding process! Moreover, you need to notify the breeder from whom you bought the cat/dog about the presence of a defective gene in its producers.

An additional danger of atrophy is severe cataracts that develop against the background of oxidative processes in the retina. A huge amount of released oxygen oxidizes the lens tissue. In addition, deteriorating photoreceptors release many toxic metabolic products, which also does not add health to the eyeball. Even if some of the cones and rods remain intact, the toxins successfully finish them off, and the resulting cataract completely and completely blinds the animal! So retinal atrophy in a dog or cat is a “multifaceted” and very dangerous process.

All the same antioxidants can not only slow down, but, in some cases, completely stop this pathological process. Even if the lens begins to become cloudy, SKQ1 helps maintain it in a “sane” state, preserving the remaining vision.

Unfortunately, in advanced cases, it is unlikely that anything will help the animal: Even surgical intervention in such a situation is completely pointless, since the root cause of vision loss cannot be corrected. Yes, a good ophthalmologist will be able to replace the lens with its synthetic analogue, but he will still not be able to capture the light of the eyes!

The thin, delicate retina lining the back of the eye records images of the outside world. It converts image light into coded impulses and transmits them along the optic nerves to the brain. Behind the retina is the choroid layer, which contains pigment and is rich in blood vessels that deliver nutrition to the retinal cells. The upper half of the posterior surface of the eye is lined with a reflective layer of cells - tapetum lucidum.

In most cases, retinal dysplasia is congenital. Breeds predisposed to this pathology include: American Cocker Spaniel, Australian Shepherd, Beldington Terrier, Puli, English Springer Spaniel, Golden Retriever, Labrador Retriever, Sealyham Terrier.

In some cases, retinal dysplasia develops as a result of a viral infection: herpes, which is the cause of puppy decline syndrome, and adenovirus, the cause of infectious canine hepatitis and kennel cough. Other causes include certain medications, vitamin A deficiency, and intrauterine injury to the fetus.

Diagnosis and treatment
The diagnosis is made based on a visual examination of the dog's eyes. No treatment has been developed.

Veterinarian advice
Never ignore visible eye changes in your dog. Cloudiness of the eye may indicate irreversible changes. Enlargement of the eye is an important sign of glaucoma, which, if diagnosed early, can be successfully treated. It is necessary to conduct regular eye examinations of your dog by specialists using appropriate diagnostic equipment.

The congenital disorder, also called congenital retinal degeneration, occurs in more than 90 breeds. With PAS, gradual atrophy of retinal cells and sclerosis of the blood vessels of the choroid layer are observed, which leads to a gradual deterioration of vision.

Usually the first sign of vision deterioration is night blindness. With further development of PAS, the dog's insecure behavior becomes obvious. Over time, complete atrophy of the retina is observed and blindness develops.

Diagnosis and treatment

Prevention measures
As in the case of hereditary cataracts, certificates have been developed which indicate that dogs intended for breeding should not show signs of PAS.

This disease is similar to PAS, but affects only the central part of the retina of both eyes; Peripheral vision in affected animals is preserved: the ability to distinguish between stationary objects is lost, but the ability to see moving objects is retained. The disease occurs mainly in old dogs.

Diagnosis and treatment
The diagnosis is made on the basis of an ophthalmological examination. No treatment has been developed.

Trauma, congenital or hereditary diseases can cause detachment of the retina from the choroid layer. There is deterioration in vision, but complete blindness does not develop.

Diagnosis and treatment
The diagnosis is made on the basis of an ophthalmological examination. A detached retina can be put back into place using laser surgery.

This disease develops in collie dogs. All layers of the back surface of the eye are affected, resulting in the formation of a pale spot on the retina. In more complex cases, there is a change in the distribution of blood vessels in the choroid layer, retinal detachment, and loss of vision.

Diagnosis and treatment
The diagnosis is made on the basis of an ophthalmological examination. No treatment has been developed.

The disease has been described only in dogs of the Alaskan Malamute and Miniature Poodle breeds; congenital pathology of the retina causes daylight blindness. In affected dogs, vision is partially preserved in dim light.

Diagnosis and treatment
No treatment has been developed.

On the back surface of the eye is the approximately circular optic disc. This is the area where the optic nerve fibers leave the retina and travel to the brain. All pathologies that can affect vision can also affect the optic disc and nerve. Inflammation, nerve atrophy, and congenital malformation may occur. For example, in a collie, the optic disc becomes scarred.

Cataract, glaucoma, retinal detachment

All these diseases are quite common in dogs, especially older ones. Cataract is accompanied by clouding of the lens; externally, the disease is expressed in clouding of the eye, which acquires a matte gray-bluish, light gray or milky gray color. There are no discharge or other symptoms of conjunctivitis and keratitis.

In addition to old age, the cause of cataract formation can be diabetes, toxicosis and trauma. Treatment boils down to instillation of vita-iodurol-triphosadadenine, viceine and vitamin preparations into the eye, 1-2 drops 2-3 times a day. Therapy is long-term and only slows down the development of the disease.

Cataract

Surgeries on the lens for cataracts in dogs are possible, but are rarely used in practice.

Glaucoma is characterized by a constant or periodic increase in intraocular pressure from 30 (normal) to 70 mm Hg. Art. The most common type of glaucoma in dogs is secondary (in addition to this type of disease, congenital and primary glaucoma is also found). The causes of the disease are quite varied: deep keratitis, displacement or swelling of the lens, hemorrhages in the vitreous body and anterior chamber of the eye, as well as contusions of the eye and penetrating wounds from trauma.

The disease is expressed by clouding of the lens, atrophy of the iris, and sometimes changes in the shape of the pupils. The dog's eyes are cloudy, gray-blue in color; when palpated, the eyeball is compacted and enlarged in size. When treating glaucoma, the drug method is primarily used, and only if this does not give visible results, surgery is used. Increased intraocular pressure in dogs can be cured by instilling a 1% solution of pilocarpine 5-6 times a day, as well as GLP with the same drug once a day. A solution of phosphakol at a concentration of 0.02% is also used 2-3 times a day.

Treatment of glaucoma should be started in a timely manner to avoid complications, the most dangerous of which is hemorrhages in the space between the choroid and the retina and, as a consequence, its detachment.

In addition to complications with glaucoma, retinal detachment can be caused by trauma, atrophy of the vitreous, or large accumulation of exudate in the chambers of the eye. With this disease, the animal’s vision suddenly deteriorates greatly, up to the onset of blindness, the pupils dilate, and there is no reaction to light with a rapid change in its intensity. The final diagnosis is made by a veterinarian when examining the dog's fundus.

With a complete retinal detachment, it is not possible to cure a dog: the dog becomes completely blind. Partial detachment can be treated with subconjunctival injections of 0.1-0.2 ml of hydrocortisone with novocaine every 3-4 days. At the same time, 0.3-0.5 ml of dexazone is administered daily. Atropine at a concentration of 1% or 2% dionine solution is instilled into the conjunctival sac.

This text is an introductory fragment. From the author's book

Cataract This disease is characterized by clouding of the lens. In some cases, cataracts are clearly visible to the naked eye as whitish lumps that give the lens a milky-gray or bluish-white mottled appearance behind the pupil. Cataracts are observed in any

From the author's book

Cataract Cataract is clouding of the lens. Some scientists consider it a widespread eye disease in dogs, mostly older than eight years of age. Typically, cataracts are easily visible to the naked eye as a white, cloudy spot in the

From the author's book

Cataracts, glaucoma, retinal detachment All these diseases are quite common in dogs, especially older ones. Cataract is accompanied by clouding of the lens; externally, the disease is expressed in clouding of the eye, which acquires a dull gray-bluish color,

From the author's book

Cataracts, glaucoma, retinal detachment These diseases are quite common in dogs, especially older ones, and can deprive the pet of his vision. Cataract is accompanied by clouding of the lens; externally, the disease is expressed in clouding of the eye, which becomes dull

From the author's book

Cataracts, glaucoma, retinal detachment All these diseases are quite common in dogs, especially older ones, and can deprive the pet of vision. Cataract is accompanied by clouding of the lens; externally, the disease is expressed in clouding of the eye, which acquires

From the author's book

Cataracts Cataracts are considered the second most common eye disease in dogs. Juvenile cataracts can appear in purebred dogs at a very early age. There are two forms of this disease - absorbable and non-absorbable. In the first case