Ординатура / Офтальмология / Учебные материалы / Ocular Traumatology Springer
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2.9.3.13.2 Tractional
The cause is vitreoretinal traction but in the absence of a retinal break. The progression from injury to retinal detachment is usually slow.
Regarding treatment, the traction must be addressed. Although in principle a buckle is also an option, vitrectomy is preferred because it is able to deal with not only the anterior (peripheral) but also with the posterior and subretinal traction.
2.9.3.13.3 Hemorrhagic
The retina is lying on a dome-shaped accumulation of blood, which may be truly subretinal36 or located between the RPE and the neuroretina (see above). This is a commonly underdiagnosed complication in ocular traumatology.
Regarding treatment, if the blood is under the macula and thick, it should be evacuated (see above). If the hemorrhage is very large, a retinotomy may have to be performed to allow direct access to the blood. The risk of PVR is significant.
2.9.3.14PVR
Scar formation is the most common cause of vision loss after successful retinal detachment surgery, and it has been reported to occur in up to 40% of eyes after serious trauma [11]. With current techniques and technology, the initial surgery aimed at reattaching the retina after an injury is almost always successful; operations for PVR have a dramatically lower anatomical and functional success rate. The surgeon must understand the risk factors (see Table 2.14.1), prophylaxis possibilities, and treatment of PVR.
The timing of PVR occurrence depends on the type of injury: it presents earliest after perforating injuries (1.3 months), followed by ruptures (2.1 months) and IOFBs injuries (3.1 months) [11].
2.9.3.14.1 Risk Factors
The following variables have been found to increase the PVR rate:
36 i.e., sub-RPE
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•Rupture [11, 49].
•Perforating injury [11, 49].
•IOFB injury (the incidence is as high as 21% [88]), especially if a deep impact has occurred [49].
•Vitreous hemorrhage [11].37
•Choroidal detachment [28].38
•Size of the retinal break [35].
•Extent of retinal detachment [35].
•Severe inflammation [35].
•Cryopexy [20].
•Incomplete PVD [10].
•Too early removal of silicone oil [77]: even if a longer tamponade does not reduce the PVR risk, it does improve the functional outcome39 [38].
2.9.3.14.2Prophylaxis
Since treatment of an established PVR has a poor prognosis, prevention remains the surgeon’s best hope. The following list shows certain surgeoncontrolled variables that may help reduce the PVR risk.
•Timing of surgery. Early vitrectomy in high risk eyes [18, 49] appears to reduce the PVR risk, probably by removing the inflammation-inciting elements from the eye.
•Foregoing cryopexy (see above) [9].
•Atraumatic surgery. Avoiding intraoperative complications such as hemorrhage or retinal damage (see above) eliminates certain PVR-in- citing factors.
•Complete surgery. Removal of all vitreous, i.e., posteriorly (PVD), anteriorly (vitreous base and retrolental area), and all proliferative membranes [1], reduces the medium/scaffold on which cells can proliferate.
•Destruction of RPE cells in certain high-risk injuries. Since these cells are the primary culprit in PVR development, their elimination in the
37Whether intraor postoperative.
38Whether intraor postoperative.
39By keeping the macula attached.
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Table 2.9.5 Pharmaceutical options in preventing/treating PVR |
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Drug (reference) |
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Experimentally |
Protein kinase-C inhibitor, melatonin [32] |
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All-trans retinoic acid [27] |
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Cholcicine [54] |
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Taxol [85] |
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Daunorubicin encapsulated in liposome [75] |
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(Radiation11 [53]) |
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Clinically |
Intravitreal corticosteroids [58, 67] |
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Daunorubicin [89] |
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Low molecular weight heparin, fluorouracil [3, 5]
Low molecular weight heparin and intravitreal corticosteroids [90]
11 Mentioned only for completeness; this is obviously not a drug.
affected areas appears crucial (“prophylactic chorioretinectomy”; see Chap. 2.13).
•Silicone oil use. It appears that complete filling (see below) reduces the PVR risk [94] by taking away the space in which cells could multiply, especially if heavy silicone oil40 is used [91].
•The true value of heavy silicone oil use is yet to be determined. The rationale is that it does not allow the accumulation of proliferative cells inferiorly, where PVR traditionally starts [82]. The early results of the efficacy of heavy silicone oil use are mixed [72, 82].
•Removal of the ILM during vitrectomy in eyes with high PVR risk may prevent the development of proliferative membranes in the macula, even keep the macula attached in eyes with otherwise total, PVR-re- lated retinal detachment.
•Pharmaceutical approach (Table 2.9.5).
40e.g., Densiron (Geuder GmbH, Heidelberg, Germany), Oxane (Bausch and Lomb, Rochester, N.Y.)
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!Pitfall
It appears that a long list of drugs is effective against PVR experimentally, but their efficacy in clinical use is limited at best [12].
2.9.3.14.3 Treatment
For a discussion of treatment, see Sect. 2.9.5.
2.9.3.15Macular Pucker41
Seeding of the retinal surface in the macula by proliferative cells42 leads to wrinkling of the ILM. Collagen production by these cells then results in focal traction with partialor full-thickness folds, and (cystoid) macular edema. Traumatic EMP usually occurs after contusion, and it is more common after vitreous hemorrhage, retinal detachment, or incomplete vitrectomy (i.e., if PVD was not achieved). Inflammation is another contributing factor. The risk of EMP is lower in patients over 50 years of age. The condition may take years to develop.
2.9.3.15.1 Symptoms
•Decreased visual acuity
•Metamorphopsia, which is best followed by M-charts [60]43
•Aniseikonia (micropsia or macropsia)
•Diplopia (monocular or binocular) due to foveal dragging [23]
The most important diagnostic tools are slit lamp biomicroscopy44 and OCT (Fig. 2.9.1).
41EMP is discussed here because, although a much less serious condition, it is reasonably perceived as a “mini PVR”.
42Mostly fibrous astrocytes, RPE cells, fibrocytes, myofibroblasts, and macrophages; the same as in PVR.
43Serial Amsler grid testings are inappropriate to determine progression.
44Use of a contact lens is necessary to detect early cases.
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2.9.3.15.2 Treatment
The definite solution is vitrectomy; spontaneous EMP separation [26] is extremely rare. The indication (i.e., when to intervene rather than to observe) should primarily rest with the patient (see Chap. 1.4). The recommended surgical steps are shown on Fig. 2.9.6.
ZPearl
Intentional removal of the ILM in EMP surgery reduces the recurrence rate from at least 5% to virtually zero.
2.9.4Visibility and Vitreoretinal Surgery
Detailed discussion of this topic is beyond the scope of this book; only a few helpful suggestions are made here:
•Use a wide-angle viewing system. Conditions45 that would otherwise make surgery much more difficult if not impossible lose at least some of their importance if a panoramic viewing system is used.
•Corneal edema is very common after corneal trauma and can be exacerbated by scleral indentation. The edema may be epithelial or stromal.
–Scraping of the epithelium can dramatically improve visibility; however, it increases the postoperative edema and infection risk, and healing may be protracted and painful, especially in diabetics.
–Alternatives to scraping include topical glucose (40%) and glycerin (50−95%). The solutions are applied by soaking a small piece of cotton, which is the placed on the cornea for a few minutes.
–If Descemet’s membrane is folded, the AC can be pressurized with viscoelastics. Filling the AC with viscoelastic is also helpful if BSSfluid exchange or silicone oil implantation is performed in an eye that is pseudophakic or has weak zonules.
45 i.e., corneal edema, small pupil, lens opacity
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< Fig. 2.9.6 Flowchart: surgical tactics for EMPs
•If the surface of the IOL is dirty because of the settling of inflammatory debris on it, the surface can be cleaned by the Tano membrane scraper.46
•If there is fluid condensation on the back surface of an IOL47 during BSS-air exchange, dispersive viscoelastic should be injected onto the IOL to coat it and wipe off the condensed fluid.
•Even though the wide angle system is helpful to overcome the visualization difficulties caused by a small pupil, good mydriasis dramatically increases surgical ease. If intracameral adrenaline does not help, iris retractors need to be used.48
•The use of strong illumination is particularly useful if the media are hazy and/or small gauge vitrectomy is performed.49 The dangers of such a powerful light source must always be kept in mind (see Chap. 3.2).
46Synergetics, East Windsor Hill, Conn
47The eye already underwent a posterior capsulectomy.
48Most iris retractors are made of plastic, not metal. It is not possible to bend them intracamerally. It is therefore crucial to aim well with the paracentesis (using a 27-g needle). The needle should be directed so that it is somewhere between where the pupillary margin is and where it needs to be. Too deep a path makes it very difficult to catch the iris; too shallow a path makes the iris tent. The parallaxis phenomenon must be taken into account when the angle of the needle path is made: objects appear closer to the cornea than they are in reality.
49e.g., such as provided by the Photon (Synergetics, East Windsor Hill, Conn.)
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2.9.5Surgery for Eyes with PVR-related Retinal Detachment: Technical Issues
2.9.5.1Timing
Selecting the optimal time for vitrectomy is not straightforward. Several factors need to be considered:
•PVR cycle. It appears that the proliferation takes a certain amount of time50 before it spontaneously stops. This cycle is independent of whether surgery is performed during the cycle.
:Controversial
If vitrectomy is performed before the PVR cycle is complete, retinal redetachment is virtually assured.51 Conversely, early surgery with silicone oil implantation is usually able to keep at least the macula attached and prevent, in most cases, the development of a closed funnel.
•Presence of silicone oil tamponade. Silicone oil slows down the progression of the retinal detachment and makes reoperation less urgent.
•Condition of the macula. If the macula is on (and especially if there is silicone oil in the eye), the intervention can be deferred virtually indefinitely52. If the macula is off or the retinal detachment is rapidly threatening it, surgery should not be delayed.
2.9.5.2The Goals of Surgery
All traction exerted on the retina should be eliminated, whether caused by pre-, intra-, or subretinal forces. The risk of traction recurrence should also be reduced. In addition to the factors already mentioned,53 the surgeon should follow certain principles:
50Usually several weeks.
51Surgery is also much easier if the PVR membranes are established since they are visible.
52i.e., depending on the complications caused by the silicone oil
53See under PVR prophylaxis.
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•Remove all vitreous, both posteriorly and anteriorly. In the periphery, scleral indentation must be used to assure that no residual vitreous is present. If the surgeon feels that the lens prevents completion of this task, the lens must be sacrificed (see below).
•The injection of trypan blue54 is very useful to demonstrate the presence of membranes that are immature or difficult to notice.
•If the retina is shortened because of intrinsic traction, either a scleral buckle should be used55 or a retinotomy be performed.
•When considering retinotomy,56 the surgeon must be aware that if the retina is cut from its peripheral insertion, it can quickly “roll up like a rug” if traction persists/recurs centrally. Retinotomy should therefore be performed only if the PVR recurrence risk is low.
•The retinotomy may be carried out with scissors or the vitrectomy probe, but either should be preceded by sufficient diathermy to prevent bleeding.
•The peripheral retina should be removed with the vitrectomy probe (retinectomy).
ZPearl
If retinotomy is performed, the surgeon should err on the side of “too much,” not “too little.” A common cause for failure is residual traction at the edges of the retinotomy if retinal shortening is present.
2.9.5.3 Lens-related Issues
Lens-related issues are as follows:
•If the lens interferes with the completeness of vitrectomy, it must be removed; however, “feathering” of the lens may also occur, especially
54i.e., VisionBlue, DORC, Zuidland, The Netherlands
55Encircling band (with a tire if necessary). Care must be taken not to make the band too tight so as to avoid anterior segment ischemia (see above).
56This is circumferential retinotomy, followed by retinectomy, i.e., removal of the peripheral retina. Relaxing retinotomy, a radial cut, must also be considered; this is usually not followed by retinectomy.
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if the eye is filled with air (gas). This is a temporary phenomenon, and sacrificing a lens in a patient who still has accommodation is an unne cessary price to pay.
•If the lens is removed, its posterior capsule should also be taken (see Chap. 2.7).
•If the eye is pseudophakic, the IOL is usually preserved.
•A posterior capsulectomy is often necessary since the capsule tends opacify faster in these eyes, especially if silicone oil tamponade is used.
•If the IOL is made of silicone and silicone oil is used, this makes subsequent silicone oil removal very difficult: the oil droplets tend to adhere to the IOL very strongly. Either the IOL must be removed or at the conclusion of silicone oil removal, an intraocular forceps holding a piece of cotton can be employed as a “window wiper” to collect the droplets or at least push them toward the periphery of the IOL (see Chap. 2.7).
2.9.5.4 Selected Retina-related Issues
Some retina-related issues are as follows:
•If a giant tear has caused the retinal detachment, implanting a scleral buckle does not improve the success rate, but it does increase the slippage risk (Table 2.9.2). Conversely, if PVR develops later, a scleral buckle should be considered during reoperation.
•Subretinal strands are often found in eyes with PVR.
–If they are encountered in an eye without a prior retinal break, which would allow convenient access to the strands, it must first be determined whether the strands interfere with retinal reattachment, because not all strands do. A fluid−gas exchange must be performed to observe how the retina behaves; if reattachment easily occurs and the retinal contour is smoothly concave, the strands are best left behind.57
57Both retinotomy and retinectomy increase the risk of PVR; they should be avoided unless their benefit exceeds the risk they pose.