Ординатура / Офтальмология / Учебные материалы / Ocular Traumatology Springer

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ZPearl

Surrounding a retinal break with laser scars makes clinical sense if vi­ treoretinal traction is present or expected to develop, or the vitreous cannot be completely removed in the vicinity25. If, however, true PVR with strong traction evolves, adhesion provided by the laser (cryo) scars rarely have the strength to prevent retinal detachment.

If a break is treated, laser is the preferred option since cryopexy has a much greater tendency to incite inflammation, which is a known precursor to PVR [9]. If cryopexy is used,26 its power must be kept to the minimum necessary27 and placement must be carefully controlled (Fig. 2.9.5).

2.9.3.10Macular Hole

Although macular holes caused by injury may close spontaneously, delaying surgery is not without risks. Even if serious additional damage in the macular area is present (e.g., contusion maculopathy, choroidal rupture), surgery may improve vision [51]. The OCT allows following the patient with a posttraumatic macular hole in more detail than what biomicroscopy can provide.

Regarding treatment, complete vitrectomy should be performed. Removal of the ILM is strongly advised. Staining of ILM makes the surgery less traumatic to the retina and less frustrating to the surgeon. Table 2.9.3 shows the various methods of ILM staining; Table 2.9.4 provides an overview of ILM removal techniques and instrumentation.

25i.e., in the periphery: here the vitreous is shaved rather than removed. Conversely, full-thickness retinal lesions can be left without “pexy” in the posterior retina where a complete PVD has been accomplished.

26e.g., because media opacity interferes with laser delivery or there is a substantial amount of subretinal fluid present.

27Stop the cryo application as soon as the retina starts turning white. If the retinal detachment is high, never try to freeze the fluid over and wait for the retina to turn white; watch the RPE closely instead and stop the cryopexy as soon as the RPE becomes pink.

Fig. 2.9.5  Cryopexy or laser treatment of a retinal break. a The properly placed cryopexy spots are confluent and are in normal retina. The base (“RPE floor”) of the break is spared of any cryopexy. Although ideally the entire lesion is to be surrounded, the most important areas to be treated are inferiorly and centrally from it. b It is technically easier and faster to apply a few large (and thus strong) spots. This, however, is dangerous and contraindicated. It leads to intraoperatively visible dispersion of RPE cells and dramatically increases the postoperative PVR risk.1 c Laser scars surround this horseshoe-spaded break, the shape of which reveals that there is residual traction, which at the moment is weaker than the strength of the laser-in- duced scars. The light reflex is an artifact

1  It is not uncommon to read a note in the patient’s chart, stating that: “PVR developed despite the good cryopexy scars.” The note should read instead: “PVR developed due to the too good cryopexy scars.”

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Table 2.9.3  Methods of intraoperative staining of the ILM in eyes with a traumatic macular hole1  

1   Other dyes, such as sodium fluorescein, Chicago blue, Patent blue, etc., are also under investigation; staining the tissue during surgery is becoming more prevalent, increasingly effective, and even has its own name: “chromovitrectomy.”

Table 2.9.3  (continued) Methods of intraoperative staining of the ILM in eyes with a traumatic macular hole

2  The barb is made by pressing, not hitting, the tip of the MVR blade against a metallic object. The barb should be small and its angle is ideally around 45º.

3  Performing surgery using illumination from a slit lamp attached to the microscope is of great help.

4 The drug must be filtered through a Millipore filter (0.45 µm) and then diluted to its original concentration with BSS.

Table 2.9.4  Internal limiting membrane removal techniques and instrumentation: an overview

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Table 2.9.4  (continued) Internal limiting membrane removal techniques and instrumentation: an overview

occurs. Once the ILM is lifted, it is removed with any type of forceps. The FILMS technique should not be employed in eyes with unhealthy macula (e.g., CME)

5  Similarly to a cataract surgeon using a sharp, pointed instrument to perform capsulorhexis. The ILM must also be flipped as it is being dialed around.

6  e.g., Storz #E 1964 (Bausch and Lomb, St. Louis, Mo.)

7  Ideally, the two actions: pressing down onto the retina and grabbing the ILM are separated in time, not done simultaneously.

8  e.g., DORC #1286 (Zuidland, The Netherlands)

9  e.g., Alcon #641.21 (Fort Worth, Texas)

:Controversial

The use of ICG in eyes with a macular hole has been found by some authors to cause toxic damage to the RPE; Table 2.9.3 presents some alternatives and technical advice.

•After the ILM has been peeled, gas tamponade should be used and the patient should be informed about the importance of positioning.

2.9.3.11Retinal Hemorrhage28

The condition in itself rarely justifies treatment; if the bleeding is under the ILM in the macula (submembranous hemorrhagic macular cyst [64]), however, surgical evacuation is advised. YAG laser may also be used to puncture the ILM and drain the cyst if other pathologies do not interfere [4].

2.9.3.12Subretinal Hemorrhage

The photoreceptors may start dying as early as within 24 h [36], and early photoreceptor death ensues if the blood is not evacuated [57]. Late subretinal scarring is another threat that should force the ophthalmologist to consider fairly acute intervention if the blood is thick and submacular.

28The term refers to bleeding into the retinal layers. Blood that originates in the retinal vasculature but accumulates elsewhere (e.g., subhyaloidal, intravitreal) is discussed elsewhere in this chapter.

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:Controversial

Being able to preoperatively determine whether the blood is under or in front of the RPE would be very helpful to the ophthalmologist. If the hemorrhage is sub-RPE, evacuation is probably not necessary; if it is under the neuroretina, removal is indicated. The OCT may be helpful in some cases, but the exact location of the blood is more difficult to determine in the context of large traumatic hemorrhage than in a small one caused by age-related macular degeneration.

The following options are available:29

•Intravitreal gas injection (e.g., 0.3 ml pure SF6) and positioning.

•Laser (argon) retinotomy and positioning. Once the retina is perforated and the patient is upright, a nonclotted hemorrhage may “ooze” out [24].

•TPA. A subretinal injection of 0.1−0.2 ml of (12.5 μg/0.1 ml) of (recombinant) TPA subretinally helps liquefy the clotted blood, which can be displaced by positioning or surgery [13]. One of the disadvantages of the procedure is a long waiting period30 while the drug takes effect, although a preoperative intravitreal injection (100 µg) may alleviate this problem.

•Surgical evacuation.

–If the blood is still fluidic, one31 small retinotomy is made at a convenient location and the subretinal space is irrigated with BSS. The flow must be kept low. Since the blood is drained into the vitreous, it obscures the surgeon’s view and requires removal as well as repeated entries into the subretinal space. The desire to do a complete irrigation must be balanced with the need to minimize trauma to the photoreceptors and RPE cells.

29The treatment modalities listed here may also be combined with each other.

30Up to 45 min

31There is no real advantage to creating two retinotomies (one for BSS entry, the other for the exit of BSS and blood): as soon as the view is lost due to the intravitreally “leaked” blood, the subretinal cannula must be withdrawn, the vitreous cavity irrigated, and then the entire procedure can be repeated.

•If the blood is still clotted, either TPA is injected and then irrigation performed as described above, or a slightly larger retinotomy is created and the blood clot is removed with forceps. The retina is very elastic, as is the clot: surprisingly, a large clot can be removed through small a retinotomy. Forceps use for removal of subretinal hemorrhage is not without risk; complications include unintentional grabbing of the retina or RPE, injury to the choroid, and extraction of large areas of RPE.

ZPearl

It is mandatory to remove all vitreous from the retinal surface before a retinotomy is performed; if so, there is no need to surround the site with laser. The retinotomy is virtually impossible to detect the following day.

If the retina is detached over a large area because of the blood, this must be considered a hemorrhagic retinal detachment (see below).

2.9.3.13Retinal Detachment

Traumatic retinal detachment is a prime example showing how proper (and timely) surgery can improve the prognosis after an injury: in one study ambulatory vision was achieved in 75% of eyes undergoing vitrectomy for retinal detachment after open globe injury, as opposed to only 37% of eyes without vitrectomy [56]. There are several types of posttraumatic retinal detachment; these may present alone or in combination. During the preoperative evaluation, it is insufficient to focus on break localization; if possible, the type of traction should also be investigated.

One of the consequences of retinal detachment is increased uveal aqueous outflow. Removal of the retina is a last resort in lowering the IOP (see Chap. 2.18).

2.9.3.13.1Rhegmatogenous

A retinal break (see above) is present, which may have been caused by the injury or by the surgeon (see Chap. 2.7). The time from injury to retinal detachment development varies from hours to years, depending on the type, location, and size of the break as well as whether vitreous hemorrhage is also present.

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Regarding treatment, even in the presence of a retinal break, the most important factor in the development of a retinal detachment is traction. Unless the vitreoretinal traction is addressed, therapy is likely to fail.

In terms of countering traction, vitrectomy and scleral buckling are the two main weapons:

•A buckle achieves its goal by shortening the distance between the endpoints of the traction force.32 Since the traction forces may also act at different locations on the peripheral retina, a circumferential, rather than a segmental, buckle is preferred in the context of trauma. The buckle must carefully calibrated: if too broad and too high, anterior segment ischemia may follow.33 The buckle is much more efficient in eyes with stationary34 traction; less so if the traction is dynamic35.

•Vitrectomy achieves its goal by eliminating the traction. It has the added benefit of allowing the treatment of the additional intraocular pathologies that may have occurred. Vitrectomy is able to address both stationary and dynamic tractions.

ZCave

Vitrectomy for retinal detachment should always be complete; if vitreous (i.e., traction) is left behind, there is now more room for intraocular fluid movement (currents) and for vitreous movement (dynamic traction). The fluid can then easily enter through the retinal break, which is held open by the residual traction force.

•Creating a chorioretinal adhesion around the break: the retinopexy is delivered by laser or cryo (see above).

32Thereby lessening or eliminating the power of the pulling force exerted on the retina.

33It is not possible to analyze in great detail the advantages and disadvantages of each procedure. The reader is referred to appropriate textbooks specifically dedicated to these topics.

34The traction is present continually and is not influenced by eye or head movement.

35With sudden eye or head movement, the mobile vitreous, due to inertia, also moves. This movement is transmitted to the retina at the site of vitreoretinal adhesion and presents as a powerful traction force. Without head or eye movement, the traction disappears or at least greatly subsides.