Ординатура / Офтальмология / Учебные материалы / Ocular Traumatology Springer
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482Claude Boscher and Ferenc Kuhn
–Tissues and membranes located superiorly19 can be dissected under direct visualization by placing the endoscope in an inferior sclerotomy, or the area is approached tangentially by alternating the endoscope between the two superior sclerotomies.
–The membranes may be so thick and elastic as to allow true dissection at the level of the Wieger ligament or ciliary epithelium only if a flow-control vitrectomy machine is used. The cut rate and flow should be adapted to each individual case.
–Air or PFCL is often necessary to exert counter pressure on tissues to avoid iatrogenic injury to the ciliary epithelium or retina20 while performing complete dissection (see Chap. 2.9). The endoscope provides unique, high-magnification visual feedback.
–For the thick proliferative membranes the flow may have to be tripled to allow relieving at least some of the circumferential traction. The endoscope’s high magnification and access to any intraocular space offers the best chance of freeing the ciliary body from cyclitic membranes and subsequent hypotony/phthisis (see Chap. 2.19). Radial cuts into the membranes may be the only option if the en- doscope-relayed image shows that dissection is impossible. Radial cuts can also alleviate the need for a prophylactic encircling scleral buckle.
In addition to removal of the vitreous and peripheral membranes, EAV also allows performing virtually the entire arsenal of intravitreal maneuvers, including:
•Lensectomy/phacofragmentation
•Removal of EMPs and the ILM21
•Removal of subretinal membranes and blood
19i.e., between 11 and 1 o’clock.
20Especially if the retina is detached.
21Staining of the ILM is necessary.
DO:
•consider endoscopy/EAV in severely traumatized eyes if the cornea (AC, lens, pupil) interferes with visualization of the posterior segment
•create as many sclerotomies as necessary to do a complete job and avoid injuring a lens that would otherwise be preserved
•be thorough with the removal of vitreous, blood, fibrin, inflammatory debris, etc.
•make full use of the opportunity the endoscope offers to completely clean the vitreous base and ciliary body
DON’T:
•use the endoscope if you are inexperienced in both EAV and the vitrectomy management of severely injured eyes
•limit endoscope use to diagnostic purposes
•try to perform surgery on cases that would benefit from bimanual surgery
•operate blindly
Summary
Endoscopy provides a means to “bypass” a nontransparent anterior segment and thus allow for timely vitrectomy. The endoscope is not just a diagnostic tool: it can be utilized to perform virtually any and all
maneuvers the vitreoretinal surgeon using the microscope would carry out. Endoscopy-assisted vitrectomy (EAV) requires the ocular trauma tology expert to also be experienced in every aspect of endoscope use.
22 Cryopexy is to be avoided because of its risks of inducing PVR (see Chap. 2.9).
484 Claude Boscher and Ferenc Kuhn
References
[1]Boscher C (1998) Endoscopic vitreoretinal surgery of the injured eye. In: Alfaro D, Liggett P (eds) Vitreoretinal surgery of the injured eye. Lippincott-Raven, Philadelphia, pp 301−314
[2]Boscher C (2002) Endoscopy. In: Kuhn F, Pieramici D (eds) Ocular trauma: principles and practice. Thieme, New York, pp 414−418
[3]Hammer ME, Grizzard WS (2003) Endoscopy for evaluation and treatment of the ciliary body in hypotony. Retina 23: 30−36
[4]Koch FH, Luloh KP, Augustin AJ, el Agha MS, Guembel H, Ohrloff C, Grizzard WS, Hammer ME, Sinclair S (1997) Subretinal microsurgery with gradient index endoscopes. Ophthalmologica 211: 283−287
[5]Park S, Marcus D, Duker J, Pesavento R, Topping P, Frederick A, D’Amico D (1995) Posterior segment complications after vitrectomy for macular hole. Ophthalmology 102: 775−781
[6]Thorpe H (1934) Ocular endoscope: instrument for removal of intravitreous non magnetic foreign bodies. Trans Am Acad Ophthalmol Otolaryngol 39: 422−424
[7]Uram M (1992) Ophthalmic laser microendoscope endophotocoagulation. Ophthalmology 99: 1829−1832
[8]Boscher C (2001) Endoscopy for anterior PVR. American Academy of Ophthalmology Subspecialty Day, New Orleans
[9]Cuenca N, Martinez-Navarrete GC et al. (2004) Process of differentiation of retinal neurons from stem cells in the peripheral retinal margin of primates. Association for Research and Vision in Ophthalmology, Ft. Lauderdale
Section III
3.1 Chemical Injuries
Norbert Schrage and Ferenc Kuhn
3.1.1Introduction
Most chemical injuries cause only limited damage, and patients tend to rinse their eye themselves, usually with water. The duration of contact between eye and agent , and the agent’s characteristics, are the primary factors in determining the outcome.
3.1.2Evaluation
An acute chemical injury is one of the few conditions when virtually all patients voluntarily and immediately disclose the incident. A chemical burn is also an exception because the ophthalmologist should not appreciate his- tory-taking as his initial goal; instead, he must “shoot first and ask later”: details of injury are asked during or after the initial irrigation. Table 3.1.1 shows the questions the ophthalmologist should raise.
It is sensible to use this term rather than “mild,” reflecting that with delayed/improper treatment, a mild injury can rapidly become severe (see endophthalmitis classification in Chap. 2.17).
i.e., the time between injury and agent removal.
The terms “chemical injury“ and “chemical burn“ are alternatively used in this chapter, referring to the same condition.
488 Norbert Schrage and Ferenc Kuhn
Table 3.1.1 Taking a history in a patient with chemical burn
What happened?
When did it happen?
What is the name of the agent that caused the injury?
What characteristics (e.g., pH, concentration) does this agent have and how much got onto the eye?
Was this a work-related injury? If yes, was a witness present? Was a report filed? Was the injury self-inflicted or the result of assault1 [6]?
Was the eye irrigated after the injury? If yes, with what and for how long? What therapy has been employed for the injury so far?
How much pain is there now?
How has vision been effected?
It must be emphasized again that these questions are asked only during or after the initial irrigation, not beforehand (see text for more details)
1 Unfortunately, this is not uncommon in certain societies.
ZPearl
If the patient has a chemical injury, the taking of a detailed history should never precede the irrigation.
Pain may be a somewhat misleading symptom. The cornea is involved in nearly all cases, and the pain and severity of the damage are often inversely proportional .
ZCave
Severe chemical injuries tend to cause little pain because of the destruction involving the nerve endings. A lack of pain in an eye with severe morphological damage is therefore indicative of a very severe injury with poor prognosis.
Similar to that seen with mechanical injuries to the cornea (see Chap. 2.2).
3.1 Chemical Injuries |
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Following the initial irrigation, a penlight is used to search for remnants of the agent on the lids, in the palpebral fissure, and in the deep fornices; the latter requires double eversion of the upper lid (see Chap. 2.1). Slit lamp examination follows to determine the damage to anterior segment structures and grade the injury (Table 3.1.2). Since viability of the limbal vascular arcades has prognostic importance, this must carefully be evaluated. The visual acuity and the IOP should also be taken. Secondary glaucoma can rapidly develop and cause severe optic nerve damage. Checking the pH of the conjunctival cul-de-sac at the end of the initial rinsing period helps determining when the situation has been stabilized.
ZPearl
After a chemical injury, evaluation and irrigation may have to be alternated: if further rinsing is deemed necessary, the examination is interrupted and continued only after the irrigation has been repeated.
3.1.3Treatment
3.1.3.1Primary Intervention and Postirrigation Management
Certain aspects of the injury are beyond physician control: the agent starts causing tissue destruction upon contact. The ophthalmologist-controlled factors in determining the prognosis are the time from patient arrival to irrigation [9] and the quality of rinsing [3, 13] . If the irrigation is painful, topical anesthetics must be instilled without delay: brief rinsing with xylocain 2% eliminates the pain and doubles as an initial irrigation.
e.g., pieces of lime.
Applanation tonometry on the burnt cornea is not contraindicated.
See also Table 2.10.1.
i.e., the quality of the fluid used and how thorough the rinsing is.
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Norbert Schrage and Ferenc Kuhn |
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Table 3.1.2 Grading ocular burns |
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Grade |
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I |
II |
III |
IV |
Timing |
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Immediately |
Erosion, |
Erosion |
Erosion |
Deep ischemia, |
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hyperemia |
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involving >240° |
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Ischemia in |
Ischemia in |
Conjunctival |
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<120° |
120−240° |
necrosis |
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Chemosis |
Red chemosis |
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Turbid cornea |
Porcelain-white |
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cornea |
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Iris atrophy |
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Fibrin exudate |
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in AC |
Re-grading |
Regeneration |
Restored |
Persistent |
Anterior segment |
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on day 2 |
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circulation |
erosion |
melting |
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Regeneration |
Corneal ulcer- |
Proliferation |
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ation |
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Vascularization |
Large ulcerations |
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Scar formation |
Cataract |
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Glaucoma |
Diffuse scar formation
3.1 Chemical Injuries |
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ZPearl
Chemical eye burns require immediate rinsing, continued for at least 15 min . Any consumable solution suffices if it is not alcoholic or acidic; preferably, it should be of room temperature. Ophthalmologists are strongly encouraged to educate all ER personnel regarding the techniques of irrigation.
Typically, water or saline is used for rinsing. If available, a polyvalent, hypertonic, amphoteric compound, such as Diphoterine10 [4], is preferred, which is effective against acids, alkali, and agents with oxidative or redox activity. If both eyes have been burned, the irrigation must be done alternatively on both sides. Should the cornea be opaque and the iris discolored, the AC must also be irrigated with BSS (see Chap. 2.5). Irrigation improves the prognosis even if hours have elapsed since the injury [3].
3.1.3.1.1 Irrigation
The process of irrigation should proceed as follows:
•Explain to the patient what will take place. This is especially important in children who are scared and would not cooperate (see Chap. 2.16).
•Use anesthetics if necessary (see above).
•Carefully separate the lids. Placement of a lid retractor is preferred, although manual separation (see Chap 1.9) is also acceptable.
•Gently rinse the cornea and the fornices using an infusion line (Fig. 3.1.1); the infusion bottle should be 30−80 cm above eye level.
•Remove all particles11 with a cotton-tipped applicator or forceps.
•Proceed with the irrigation even if the injury is open globe. Closure with sutures should follow, not precede, rinsing.
•Rinse the palpebral conjunctiva and the fornices as well; the latter requires double eversion (Fig. 3.1.2).
ANSI-Standard Z358.1-2004.
10Prevor GmbH, Köln, Germany.
11These are usually calciferous.
492 Norbert Schrage and Ferenc Kuhn
Fig. 3.1.1 Rinsing the eye after a chemical injury. The flow of the rinsing fluid is low and soft, the eye is turned away from the stream, the lids are held open with fingers pressuring the bones not the eyeball, and a paper drain is used to try to keep the patient’s clothing dry
Fig. 3.1.2 Double eversion of the upper lid with a Desmarres retractor. The upper fornix is completely visible and accessible, making particle removal easy to perform. The patient is instructed to look straight downward, and his forehead is positioned low to permit free flow of the irrigation fluid