Retinal detachment - Preventive treatment

Retinal tears

When conditions are favorable for retinal detachment, any break is considered dangerous, but some are particularly dangerous. The main criteria for selecting patients for preventive treatment are: the type of break, other features.

Type of break

• Ruptures are more dangerous than holes because they are accompanied by dynamic vitreoretinal traction.
• Large ruptures are more dangerous than small ones due to increased access to the subretinal space.
• Symptomatic ruptures are more dangerous than those detected incidentally, as they are accompanied by dynamic vitreoretinal traction.
• Superior retinal tears are more dangerous than inferior ones because the retinal fluid can move faster.
• Equatorial breaks are more dangerous than those in the serrated line area and are often complicated by retinal detachment.
• Subclinical retinal detachment involves a break surrounded by a very small amount of SRH. In some cases, the SRH can spread and the retinal detachment becomes "clinical" in a very short time.
• Pigmentation around the tear indicates that the process has been going on for a long time with a low risk of developing retinal detachment.

Other features

1. Aphakia is a risk factor for retinal detachment, especially if there was a loss of vitreous during surgery. Although relatively safe, small peripheral round holes after cataract surgery can in some cases provoke retinal detachment.
2. Myopia is the main risk factor for retinal detachment. Myopic breaks require more careful monitoring than non-myopic breaks.
3. The single eye with the rupture should be monitored carefully, especially if the cause of vision loss in the fellow eye was retinal detachment.
4. Heredity sometimes plays a role; patients with tears or degenerative changes, in whose family there are cases of retinal detachment, need to be observed especially carefully.
5. Systemic diseases with an increased risk of developing retinal detachment include Marfan syndrome, Stickler syndrome, and Ehlers-Danlos syndrome. These patients have a poor prognosis for developing retinal detachment, so prophylactic treatment is indicated for any breaks or dystrophies.

Clinical examples

• in case of extensive equatorial U-shaped breaks accompanied by subclinical retinal detachment and localized in the superior temporal quadrant, prophylactic treatment is indicated without delay, since the risk of progression to clinical retinal detachment is very high. The break is located in the superior temporal quadrant, so early leakage of SRH into the macular region is possible;
• in eyes with symptomatic, acute posterior vitreous detachment, extensive U-shaped breaks in the superotemporal quadrant require immediate treatment due to the high risk of progression to clinical retinal detachment;
• in case of a rupture with a "cap" that crosses the vessel, treatment is indicated due to the fact that constant dynamic vitreoretinal traction of the crossing vessel can lead to recurrent vitreous hemorrhages;
• a rupture with a free-floating "lid" in the inferotemporal quadrant, detected by chance, is quite safe, since there is no vitreoretinal traction. In the absence of other risk factors, prophylactic treatment is not required;
• A U-shaped tear in the lower part, as well as a tear surrounded by pigment, discovered by chance, are classified as long-term changes with low risk;
• degenerative retinoschisis, even if there are breaks in both layers, does not require treatment. Although this change is a profound defect in the sensory retina, the fluid in the "schisis" cavity is usually viscous and rarely shifts into the subretinal space;
• Two small asymptomatic holes near the serrated line do not require treatment; the risk of retinal detachment is extremely low, since they are located at the base of the vitreous. Such changes are found in about 5% of the world's population;
• Small holes in the inner layer of the retinoschisis also pose an extremely low risk of retinal detachment, since there is no connection between the vitreous cavity and the subretinal space.

Peripheral retinal dystrophies predisposing to retinal detachment

In the absence of associated ruptures, lattice dystrophy and snail-track dystrophy do not require prophylactic treatment unless they are accompanied by one or more risk factors.

• Retinal detachment in the fellow eye is the most common indication.
• Aphakia or pseudophakia, especially if there is a need for posterior laser capsulotomy.
• High degree myopia, especially if it is accompanied by pronounced “lattice” dystrophy.
• Established cases of retinal detachment in the family.
• Systemic diseases known to predispose to the development of retinal detachment (Marfan syndrome, Stickler syndrome, and Ehlers-Danlos syndrome).

Treatment methods

Selecting a method

Preventive treatment methods include: cryotherapy, slit lamp laser coagulation, laser coagulation with indirect ophthalmoscopy in combination with sclerocompression. In most cases, the choice is made depending on individual preferences and experience, as well as the availability of equipment. In addition, the following factors are taken into account.

Localization of dystrophies

• In case of equatorial dystrophies, both laser coagulation and cryotherapy can be performed.
• In case of postequatorial dystrophies, only laser coagulation is indicated if there are no conjunctival incisions.
• In dystrophies near the "serrated" line, either cryotherapy or laser coagulation using an indirect ophthalmoscopy system, in combination with compression, is indicated. Laser coagulation using a slit lamp system is more difficult in such cases and may lead to inadequate treatment of the base of the U-shaped rupture.

Transparency of the media. When the media are cloudy, cryotherapy is easier to perform.

Pupil size. Cryotherapy is easier to perform with small pupils.

Cryotherapy

Technique

• anesthesia is performed with a swab soaked in amethocaine solution or a subconjunctival injection of lignocaine, respectively, in the quadrant of dystrophy;
• in postequatorial dystrophies, it may be necessary to make a small conjunctival incision to better reach the required area with the tip;
• During indirect ophthalmoscopy, gentle compression of the sclera is performed with the tip of the handpiece;
• the dystrophic focus is limited to one row of cryocoagulants; the effect is completed as the retina becomes pale;
• The cryotip is removed only after complete defrosting, since premature removal can cause choroidal rupture and choroidal bleeding;
• A bandage is applied to the eye for 4 hours to prevent the development of chemosis, and the patient is advised to refrain from significant physical activity for a week. For approximately 2 days, the affected area is pale due to edema. After 5 days, pigmentation begins to appear. At first, it is gentle; later it becomes more pronounced and is associated with varying degrees of chorioretinal atrophy.

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Possible complications

• Chemosis and eyelid edema are common and harmless complications.
• Transient diplopia if the extraocular muscle is damaged during cryocoagulation.
• Vitreite may result from exposure to a wide area.
• Maculopathy is rare.

Reasons for failures

The main reasons for unsuccessful prevention: inadequate treatment, formation of a new rupture.

Inadequate treatment may be due to the following reasons:

• Insufficient limitation of the rupture during laser coagulation in two rows, especially at the base of the U-shaped rupture, is the most common cause of failure. If the most peripheral part of the rupture is inaccessible for laser coagulation, cryotherapy is necessary.
• Insufficiently close placement of coagulants during coagulation of extensive ruptures and tears.
• Insufficient excision of dynamic vitreoretinal traction with extensive U-shaped tear with explant insertion and failed attempt to use explant in an eye with subclinical retinal detachment.

Formation of a new gap is possible in the zones:

• Inside or near the coagulation zone, often due to exceeding its dose, especially in the area of "lattice" dystrophy.
• On a retina that appears “normal” despite adequate treatment of the dystrophy that predisposes it to rupture, which is one of the limitations of preventive treatment.

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Violations that do not require prevention

It is important to know the following peripheral retinal dystrophies that are not dangerous and do not require preventive treatment:

• microcystic degeneration - small bubbles with unclear borders on a grayish-white background, giving the retina a thickened and less transparent appearance;
• "snowflakes" - shiny, yellowish-white spots that are diffusely scattered on the periphery of the fundus. Areas where only snowflake-type dystrophies are detected are safe and do not require treatment;

However, snowflake dystrophy is considered to be of clinical importance because it is often accompanied by lattice dystrophy, snail-track dystrophy, or acquired retinoschisis, as mentioned earlier.

• cobblestone dystrophy is characterized by discrete yellowish-white foci of localized chorioretinal atrophy, which, according to some data, is normally found in 25% of eyes;
• honeycombing or reticular degeneration - an age-related change characterized by a fine network of perivascular pigmentation that may extend to the equator;
• Drusen or colloidal bodies are represented by small pale clusters, sometimes with hyperpigmentation at the edges.
• Perioral pigmentary degeneration is an age-related change characterized by a band of hyperpigmentation along the "dentate" line.