Ординатура / Офтальмология / Учебные материалы / Ocular Traumatology Springer
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2.13 Penetrating Injuries and IOFBs |
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Table 2.13.3 Factors to consider related to toxicosisa
Symptoms Signs
Chalcosis (chronic) [5]
Siderosis [19, 25, 27]
Treatment:
Deteriorating visual acuity
Kayser−Fleischer ring
Sunflower cataract
Greenish discoloration of the iris
Chronic uveitis
Glaucoma
Vitreous opacities
ERG changes
Brownish deposits on the corneal endothelium
Brownish discoloration of the iris (heterochromia9)
Dilated, nonreactive pupil10
Yellowish cataract with brown capsular deposits
Glaucoma
Pigmentary degeneration of the retina
Optic disc hyperemia, edema
ERG changes
Chalcosis or siderosis
Even in advanced cases, IOFB removal and the treatment of complications such as cataract extraction can bring improvement
9 The difference in color between the two irises is easily appreciated only if the iris had a light color originally. Since heterochromia may have been present since birth and the patient may be unaware, a pre-injury photograph may be needed for comparison.
10 Dissociation between reaction to light and accommodation, and hypersensitive reaction to weak miotics, may also be present.
a Also called metallosis.
380 Ferenc Kuhn
Table 2.13.4 Instrumentation for IOFB removal
Instrument Advantages |
Disadvantages |
EEM |
Simple to use; |
(Fig. 1.6.1) |
no need to enter |
|
the eye |
Effective only in acute cases, before encapsulation of the IOFB occurs
The intraocular flight path of the IOFB is beyond the surgeon’s control;11 the outcome is significantly worse if EEM, rather than IOM or forceps, is used [17, 26]
IOM |
The extraction |
None if the IOM is strong, its working distance is |
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is entirely under |
short, the magnetic pull force is directional, and the |
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the surgeon’s |
magnet’s power does not diminish with time13 |
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control12 |
|
Forceps |
Suitable for |
Depending on the IOFB characteristics,14 several dif- |
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removing non- |
ferent types of forceps may have to be available |
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magnetic IOFBs |
Extensive intraocular manipulations of the IOFB15 are |
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often needed, and the threat of iatrogenic retinal |
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injury is not negligible |
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If the extraction incision is not large enough, the |
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IOFB can get lost |
Snare [10] |
Able to grab |
If the IOFB has a long axis, its position must be |
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even large IOFBs |
adjusted so that the IOFB can be fed into a smaller |
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sclerotomy: this requires considerable intraocular |
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manipulations of the IOFB |
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Considerable intraocular manipulations of the IOFB |
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are often needed, and the threat of iatrogenic retinal |
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injury is not negligible |
11 Complications from unintentional IOFB impact during extraction are fairly common.
12 Unlike with an EEM, the instrument moves toward the IOFB; the path of the instrument and the IOFB is entirely determined by the surgeon.
13 If the magnetic pull force does diminish with time, the instrument needs to be remagnetized.
14 Size, shape, and surface texture
15 i.e., to ensure a firm grab (the IOFB’s position at the initial pickup is rarely a secure one) and to align it with the sclerotomy (so that the IOFB’s entry into the sclerotomy is with its smallest cross-section)
2.13 Penetrating Injuries and IOFBs |
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Table 2.13.5 Large series of eyes with IOFB injury: a comparison after a 5-decade interval (%). VA visual acuity
Variable |
555 cases, 1954 [22] |
567 cases, 2005 USEIRa |
Posterior IOFB |
35 |
53 |
Vitreous hemorrhage |
5 (5) |
48 (370) |
Retinal detachment |
2 (10) |
20 (23) |
VA <20/200 |
42 (?) |
31 (56) |
VA 20/200−20/25 |
34 (?) |
55 (39) |
VA 20/20 |
25 (?) |
14 (5) |
Enucleation |
20 |
8 |
Preoperative figures are in parentheses a Unpublished data
•The paracentesis should be 90−180º away from the IOFB at a convenient location to increase the ease of manipulations and to provide for maximal flexibility.
•The endothelium and the lens must be protected by injecting viscoelastics before removal.
•The pupil may have to be constricted. This helps protect the lens and bring an IOFB that is lying on the surface of iris (or is buried in it) to a more central location.
2.13.3.2.2 Lens
With regard to the lens:
•Extraction of the lens is not necessary if there is no cataract or the anterior capsule’s lesion appears to have healed (Fig. 2.13.3). Early cataract formation is not inevitable just because the capsule has been breached [21].
382 Ferenc Kuhn
•The IOFB’s enclosure by the lens does not necessarily imply that the eye is protected against siderosis [14].
•If the lens to be removed, lensectomy, ICCE, ECCE, or, in most cases, phacoemulsification, are all valid options; the decision is based on the individual case. The potential for vitreous prolapse should always be kept in mind (see Chap. 2.7).
•Concurrent IOL implantation is encouraged unless there is major damage to the posterior segment or it is impossible to preoperatively determine the correct IOL power.
2.13.3.2.3Intravitreal
ZPearl
If an IOFB is in the midvitreous and has not caused any posterior segment pathology, it may be removed with an IOM or a forceps without performing vitrectomy. If, however, vitreous hemorrhage or a retinal lesion is present, a complete vitrectomy is necessary in conjunction with IOFB extraction.
•Remove as much of the vitreous as needed until the IOFB is clearly visible.
•If the IOFB is visible, bring it into the midvitreous with the IOM or forceps. If the IOFB is hidden by vitreous hemorrhage, carefully remove the vitreous until the IOFB becomes visible.
•Withdraw the light pipe and use the vitrectomy probe to severe any vitreous attachment to the IOFB.
•Prepare the removal site (Table 2.13.2).
•Make sure that no vitreous remains attached to the IOFB.
•Remove the vitrectomy probe, put a plug in this sclerotomy, and gape the extraction sclerotomy with a tooth forceps.
•Slowly remove the IOFB.
•Put a suture in the sclerotomy to restore it to its original size.
i.e., the FB is completely intralenticular, not protruding.
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Fig. 2.13.4 Retinal impact sites. a The IOFB is lying on the retina surface. It has caused a fibrinous reaction, which must not be mistaken for endophthalmitis. Nevertheless the finding does require close observation for the first 24 h. A much larger area of retinal opacification is also seen. This may eventually develop into a contusion retinopathy. A tiny amount of retinal hemorrhage is visible at 12 o’clock from the IOFB. Since a retinal break (laceration) has not occurred, laser prophylaxis does not appear to be indicated around the current position of the IOFB, and neither is it likely to be needed at the margin of the opaque area. b A typical deepimpact IOFB with chorioretinal bleeding. The lesion has been surrounded by laser spots; these may be helpful in keeping the retina attached as far as the retinal break is concerned, but they take several weeks to reach full strength. The real danger, however, is scar formation, against which the laser does not offer protection. Prophylactic chorioretinectomy, performed within a few days, should be considered (see Chap. 2.14)
•Complete the vitrectomy.
•Search for retinal impact site(s) and determine whether they require laser treatment (Fig. 2.13.4).
:Controversial
Laser treatment for an impact that is purely retinal is unnecessary if all the vitreous has been removed and the traction potential has been eliminated [1]. Conversely, properly executed laser retinopexy does not increase the risk of complications and may help the surgeon sleep better. (“I’ve done all that’s possible to prevent retinal detachment.”) An individual decision should be made (see Chap. 2.9).
i.e., not involving the choroid and the sclera, and not causing a subretinal hemorrhage. Such complete vitreous removal is possible posterior to the equator but not anteriorly.
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•Examine the peripheral retina with scleral indentation; obviously, the equator must also be inspected, especially in young people.
•Consider endolaser cerclage even in the absence of a visible retinal break (see Chap. 2.9).
•Carefully weigh the benefits and disadvantages of gas tamponade.
2.13.3.2.4Retinal
With regard to retinal IOFB injury:
•Complete the vitrectomy first; it is especially important no to leave any vitreous at the IOFB site. If the vitreous is impossible to detach, circumscribe it at the impact site, leaving only a “stump” over the IOFB (see Chap. 2.9).
•Make sure that the IOFB is free and mobile. If it is not, use a sharp instrument to break all its connections from the retina and/or to open the fibrous capsule if one has already formed. Never use a magnet or blunt dissection to break the IOFB free.
ZPearl
The danger during sharp tissue dissection is hemorrhage, which can be prevented with diathermy. The danger during blunt dissection is that it is the tissue the “decides” where to separate: it is much less under the surgeon’s control than during sharp dissection (see Chap. 2.5).
• The remaining steps of surgery have been described above.
2.13.3.2.5Subretinal
With regard to subretinal IOFB injury:
•Complete the vitrectomy first; it is especially important not to leave any vitreous at the IOFB site.
Even if extreme caution has been used, it is not unusual to find a break just posterior to the extraction sclerotomy.
2.13 Penetrating Injuries and IOFBs |
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•If the retina is detached, create a retinotomy in the midperiphery in an area where a PVD exists or has been created. If possible, select one of the superior quadrants. The retinotomy should be as far away from major vessels as possible, and it should not be too large. Retinal elasticity permits passage of an IOFB whose cross-section is larger than the area of the retinotomy itself. Use an IOM if the IOFB is ferrous; insert it through the retinotomy and carefully remove the IOFB.
•If the IOFB is under an attached retina, the ideal retinotomy site is right on top of the IOFB. No fibrous capsule is expected to occur, and the IOFB is usually quite free: if pushed from one side through the retina, it will actually move. If subretinal blood is present, it may have to be irrigated first. The retinotomy should be large enough10 to comfortably let the IOFB pass through11.
•If the IOFB must be moved in the subretinal space before extraction,12 a small retinal detachment, incorporating the IOFB and the retinotomy site, must be created first. It is preferable to use viscoelastics than BSS for this purpose: the viscoelastic provides protection for the photoreceptors and the size of the detached area is easier to control. The viscoelastic can be aspirated after IOFB removal to reattach the retina.
•In most cases, the IOFB has entered the subretinal space through the retina, not from the scleral side. The site of this retinal lesion should be identified; this and the extraction retinotomy may have to be treated with laser (see above).
•The remaining steps of surgery have been described above.
i.e., in cases of a detached retina., the retinotomy can be slightly smaller than the size of subretinal IOFB.
Not that this is recommended: the photoreceptors and RPE would be injured in the process.
10This larger retinotomy reduces the risk of causing a iatrogenic retinal detachment.
11i.e., in cases of an attached retina, the retinotomy should be slightly larger than the size of subretinal IOFB.
12e.g., because it is under a major blood vessel or is subfoveal.
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2.13.3.2.6Choroidal/Scleral (Deep-impact IOFBs)
In most acute cases, there is subretinal/choroidal bleeding and the retina is initially attached. There are two majors risks associated: first, the creation of an iatrogenic retinal detachment and reopening the posterior wound intraoperatively; and second, severe PVR developing postoperatively. Careful surgery is needed to avoid the first risk; prophylactic chorioretinectomy is recommended for the second (see below and Chap. 2.14). If prophylactic chorioretinectomy is not performed, the rate of PVR in eyes with the IOFB injuring the choroid (“deep impact”) reaches 38%.13
•If the IOFB causes a major retinal impact and especially if deeper tissues (choroid, retina) are also involved, the vitreous may be “burned” into this impact site, making its detachment impossible. In such cases the vitreous must be circumcised here, rather than forcefully detached, which would risk creating a retinal break and detachment (see Chap. 2.9).
:Controversial
It may be technically difficult to remove an IOFB that is embedded deeply (“stuck”) in the sclera. Leaving a ferrous IOFB behind presents a siderosis risk, even if the IOFB is encapsulated [23]. Conversely, if the IOFB has perforated the sclera, forced removal can reopen the wound, which is a difficult-to-control complication (see Chap. 2.14). An individual decision must be made.
•If the IOFB is very difficult to mobilize, the surgeon probably has to leave it in situ for the time being and address the problem later. The risks vs benefits of observation with the potential of siderosis development vs reoperation at a later date must be discussed in detail with the patient, from whom the decision preferably comes (see Chap. 1.4). The probability of successful IOFB removal is not necessarily higher during a subsequent attempt, but the risk of wound reopening may be smaller.
13 Unpublished study, Gregory L., Birmingham, Alabama, based on USEIR data.
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Fig. 2.13.5 The need to adjust the IOFB’s position if a forceps or a snare is used. a,b The initial grab: the IOFB is grasped in its mid section to allow for maximal stability and control. c For the actual extraction, the IOFB has to be grabbed at its end. This means that the grab is insecure, but the length of the extraction sclerotomy can be short
•As in all eyes with choroidal and scleral involvement, the risk of PVR is sufficiently great to warrant at least consideration of prophylactic chorioretinectomy to prevent a developing scar from incarcerating the retina and lead to tractional retinal detachment (see Chap. 2.14).
•The remaining steps of surgery have been described above.
2.13.3.3Nonmagnetic IOFBs
For the roughly 20% of IOFBs that are not ferrous, the forceps or the snare are available as extraction tools (see above; Fig. 2.13.5). An epiretinally located IOFB can also be floated up by PFCL and then removed.
!Pitfall
If PFCL is used to bring an epiretinal object closer to the sclerotomy, there is always a danger that the heavy liquid will be layered on top of, rather than underneath, the object (see Chap. 2.7). If an IOFB with a sharp edge must be removed, an additional danger is that the PFCL will first push it sideways, causing a retinal lesion.
DO:
•despite a negative slit lamp examination, assume that a wound is present if the injury was caused by a sharp object; even if the visual acuity is good and the media are clear, a retinal injury may be present, making it certain that a scleral wound has occurred
•consider immediate surgery to remove the IOFB and the infected medium if the injury poses a high risk of endophthalmitis; otherwise, an individual decision regarding the timing of the intervention must be made
•consider prophylactic chorioretinectomy if the IOFB has caused a deep impact
DON’T:
•forgo ordering a CT if the slightest doubt exists about the possibility of a retained FB
•let the magnet’s power to rip the IOFB free from a capsule or even to “cut through” the choroid; controlled opening of the capsule and choroid with a sharp instrument is much less traumatic or risky
•use an EEM to extract a ferrous IOFB; a strong IOM provides complete surgeon control and reduces the risk of iatrogenic damage substantially
Summary
Penetrating and JOFB injuries have a lot in common, but the latter cause vastly more concern to the patient – and to the ophthalmologist – because of the presence of a foreign object in the eye. Although these
injuries have an increased risk of endophthalmitis their prognosis is relatively good, presumed the recommended rules of management are followed.
References
[1]Ambler J, Meyers S (1991) Management of intraretinal metallic foreign bodies without retinopexy in the absence of retinal detachment. Ophthalmology 98: 391−394
[2]Boldt H, Pulido J, Blodi C et al. (1989) Rural endophthalmitis. Ophthalmology 101: 332−341