a Application using a sterile strip, rather than the 25% solution, is preferred (see Chap. 1.9). The strip should be placed over the conjunctiva, never over the cornea a Application using a sterile strip, rather than the 25% solution, is preferred (see Chap. 1.9). The strip should be placed over the conjunctiva, never over the cornea
1 Fluorescein is also useful to show aqueous leakage from the anterior chamber in eyes with open globe injury: Seidel's test (see Chap. 1.9).
8 Such as that projected by a penlight
9 Such as that associated with erosion
Illumination beam opened wide, directed from 45 degrees slightly behind cornea, but microscope's focus is sharp on cornea; certain pathologies (scars, Descemet membrane irregularities) become visible; also useful if combined with staining
Narrowed Illumination beam's and biomicroscope's focus are sharp on cornea; pathologies reflecting light become visible
Illumination beam focused somewhere behind cornea but biomicroscope's focus is sharp on cornea; pathology interrupts reflected light
Illumination beam focused on limbus from wide angle; light travels within cornea and gets scattered if pathology interrupts it
Illumination beam at 45 degrees, bio microscope in front of cornea: area examined is lateral to illuminated one and receives illumination from neighboring area; helps detect microcystic edema and infiltrates in anterior cornea
Illumination heam at 50 degrees; high magnification and strong illumination; endothelial cells can be viewed in biomicroscope's ocular lens opposite to illumination
'Requires slit lamp with diffusing filters or with slit beam/microscope that can be focused separately
In this condition, the epithelial-cell cover over the basement membrane is partially or totally lost. The denuded area heals by peripheral cells migrating onto, and proliferating on, the denuded basement membrane; finally, hemidesmosomal attachments for strong anchorage develop. Limbal stem cells play an important role in the process, and their injury can lead to significant healing difficulties.
The symptoms are as follows:
• Severe and usually instantaneous11 pain (in milder cases foreign body sensation, irritation, or dryness may also be reported by the patient)
Injury severity and consequent pain in the cornea is typically inversely proportional: a tiny, fast-healing erosion is dramatically more painful than a sight-threatening laceration.
• Blurred vision (especially if the epithelial defect is in the visual axis)
• Significant photophobia
Fluorescein staining can reveal even small epithelial defects (Table 2.2.3). If the underlying corneal stroma has a granular appearance or edema is present, the injury is at least a few hours old.
10 Abrasion is another term used for the same condition.
11 A notable exception is welder's photokeratitis, caused by UV light; this is typically seen in those who perform/watch welding and do not wear proper eye protection. Symptoms take 6-10 h to develop.
Finding one pathology (e.g., erosion) does not mean that another one (e.g., occult scleral rupture) is not present; do not terminate the evaluation prematurely.
• Antibiotic ointment12 to cover the sensitive surface and to prevent infection.
• Corticosteroid13 drops to counter the consequences of inflammation" and to positively influence corneal metabolism .
• Cycloplegic drops to alleviate the pain resulting from reactive spasm of the sphincter muscle. The drug should be short-acting (cyclopentolate 0.5%) or mid-range (scopolamine hydrobromidei5  0.25%) to keep the pupil mobile, rather than long-acting (atropine 1%).
• Bandage soft contact lens may also be used; this does not interfere with the external oxygen supply or the patient's ability to use the eye during the healing process.
• The use of tight pressure-patching is not recommended as it interferes with the external oxygen supply, raises the surface temperature, and prolongs healing .
12 Topical antibiotics are toxic [30, 38]. Their use is nevertheless recommended because of the risk of infection via the denuded cornea, but the antibiotics should be discontinued as soon as possible.
13 These should be used for a few days but not past the first week if the erosion persists. The negligibly increased risk of infection due to local immunosupression is more than offset by the benefits from reduction of the inflammation, especially if antibiotics prophylaxis is used (see above).
14 Excessive edema in the short- and extensive scarring in the long term
15 Cave: may cause psychosis in elderly patients
Many patients prefer the eye to be patched for a corneal erosion; others want the patch removed. An individual decision should be made regarding patch use.
Most erosions heal rapidly, especially in younger patients. Conversely, the process is much slower in diabetics.i® The healing line appears similar to a dendrite; history helps in the differential diagnosis, and sensitivity is maintained in the injured eye.
Up to 8% of erosions recur . The original agent is most often a fingernail, a sheet of paper, or vegetable matter. Typically, the recurrence presents in the morningi7 upon opening the eyelids, and heals by midday. Large erosions may persist for several days.
• Topical hyperosmotics (e.g., 2.5 or 5% sodium chloride drops during the day and ointment at bedtime), applied for 2 months^: this reduces the epithelial edema and helps the epithelium to adhere to Bowman's layer.
• Autologous serum applied topically .
• Extended-wear bandage contact lens, changed weekly and worn day and night for up to 6 months.
• Surgical debridement to remove the loose epithelium and scrub the basement membrane without damaging Bowman's layer. Remove any hypertrophy using a cotton-tip applicator, a blade, or a diamond burr .
16 For this reason, the epithelium should be removed during vitrectomy only as a last resort in diabetic patients (see Chap. 2.9).
17 Due to a lack of evaporation during sleep, the tear film becomes hypotonic, making the corneal epithelium edematous; it is wiped off with the first blinks of the day.
18 If one therapy fails, turn to the next option.
19 Recurrence of the erosion should start a new treatment cycle.
• Stromal micropunctures to create anchors for the epithelium by using a small hypodermic needle to penetrate into the anterior corneal stroma20 .
• YAG laser treatment of Bowman's layer .
• PTK: excimer laser to ablate the basement membrane/Bowman's layer .
Corneal FBs are the second most common form of eye trauma ; they represented 17% of all ocular injuries in a recent war  and 1.8% of all injuries seen in an ER in one study . Although the spectrum is wide from superficial FBs to those penetrating the cornea deeply (see Fig. 1.1.2a), most FBs do not reach Bowman's layer.
The symptoms usually present acutely and are similar to those seen with erosion, but the pain is less intense. Unless the FB is completely transparent or nonreflective,2' it is easily recognized with a penlight or - especially - at the slit lamp. Multiple FBs are occasionally present, especially if the etiology is explosion.
It may appear paradoxical that an FB lying on the hypersensitive corneal surface causes less pain than an FB lodged in the much less sensitive tarsal conjunctiva; however, the latter scratches the corneal epithelium with every blink, causing multiple vertical lines of erosion.
20 Be careful not to penetrate too deeply.
21 Changing the slit lamp's angle of illumination is helpful to detect reflection (e.g., in case of a glass fragment).
• The cornea must be properly anesthetized with drops.22
• Superficial FBs are best removed using a cotton-tip applicator; outside the office, even the tip of a clean handkerchief or paper tissue will suffice. Rust rings, which can develop as early as within a few hours , should also be removed, using a diamond burr or a sharp needle. Once the FB has been extracted, the condition is treated as an erosion.
• Deep FBs, whether or not protruding into the AC, require considerable skill to remove.23 The patient should be seated at the slit lamp, and his head must be secured by an assistant and/or a tight strap. This is especially important if the patient is less likely to cooperate (e.g., a young child or a mentally challenged adult).24 The potential complications of pushing the FB into the AC are severe. If the risk is high,25 FB removal may have to be done in the OR. A fine-tipped forceps, a small probe, or a strong IOM  if the FB is ferrous, can be used.
If the operating microscope does not have a built-in slit lamp, depth perception is more difficult, and a transparent FB, easily recognizable at the slit lamp, may all of a sudden become invisible. Careful prior mapping (drawing, marking) is highly recommended.
22 Anesthesia is not absolutely necessary if the FB is very superficial and no rust ring is present.
23 If the FB is embedded in the cornea so that it does not protrude in either direction, is of inert material (e.g., glass, plastic), and does not cause symptoms, it may be left in situ, especially if the wound is of a shelving type. Organic material that can be irritating (e.g., tarantula hair) should always be removed .
24 It is not only the uncooperative patient whose treatment calls for caution; those willing to cooperate may also reflectively move their head away from the slit lamp bar. Asking them to "come back against the bar" can cause the tool in the ophthalmologist's hand to penetrate into an approaching cornea deeper than intended. This is why presence of an assistant is crucial, to assure that the patient's head is always pressed forward.
25 Regardless of whether this happens due to improper maneuvering by the ophthalmologist or forward head movement by the patient
Direct trauma to the cornea by a blunt object26 can lead to:
• Fractures in Bowman's layer/stroma, especially in eyes with previous RK surgery.
• Edema due to endothelial damage . The edema can interfere with visualization of the eye's deeper structures during evaluation or surgery.
Treatment varies from observation to DSAEK  or even PK (see below). If PK is performed on a recently traumatized eye, it is advisable to leave viscoelastics in the AC to keep the angle open, fight synechia formation, and maintain chamber depth.
Whether caused by the original injury or the treatment (i.e., silicone oil touch), the endothelium may fail even if the anterior corneal layers are intact. In addition to PK, several new surgical options are available today to restore the endothelial layer (deep lamellar endothelial keratoplasty , Descemet's membrane endothelial keratoplasty , and posterior lamellar keratoplasty ).
Careful slit lamp examination can confirm the presence of this condition; the Seidel test (see Chap. 1.9) may be necessary to rule out the existence of a full-thickness wound. The decision whether closure is necessary is not always straightforward:
• Non-self-sealing wounds should be sutured.
• Small, self-sealing, clean wounds require no intervention other than prophylactic antibiotics and mild cycloplegics for a few days.
26 Concussions are also caused by blunt objects, but the impact is elsewhere and the energy transfer is via shockwaves. Common consequences include cell loss [26, 33].
• Flaps: if undisplaced, prophylactic antibiotics and mild cycloplegics applied for a few days suffice; if displaced, they need to be repositioned and sutured in place. If there is epithelial undergrowth, this must be removed prior to reposition.
• Larger, self-sealing, clean wounds need a bandage contact lens or gluing. Various glues are available (cyanoacrylate , fibrin )27 or under investigation (chondroitin sulfate aldehyde ) to close partial- or even full-thickness wounds. Cyanoacrylate glue prevents collagenase activity and has bacteriostatic capability. Before applying the glue, the epithelium should be removed and the surface dried. If both suture and glue are used, the two must not come into contact with each other. Proper glue application avoids inadvertent dripping, prevents epithelial downgrowth and endothelial toxicity, and provides a smooth surface . Amniotic membrane and glue use can also be combined .
If patient noncompliance is a risk of (e.g., rubbing of the eye likely before complete wound healing), closure with suture and/or glue is recommended.
The slit lamp (occasionally employing the Seidel test) is used to confirm the diagnosis. Unless the wound is firmly self-sealing, surgical closure is recommended.
Unnecessary suturing of a self-sealing wound may be inconvenient; but to forgo suturing and suffer endophthalmitis, tissue prolapse, or ECH as a result is a disaster.
27 One of the many differences between these two glues is that cyanoacrylate works on the surface while fibrin (e.g., Tisseel, Baxter, Deerfield, 111.) works between the wound edges as well; the latter is FDA-approved.
28 Laceration or rupture
The goal of surgery is not limited to the reestablishment of ocular wa-tertightness. The eye may need additional operations, and proper wound management is aimed at minimizing the interference of the corneal injury with subsequent surgical intervention/s on the posterior segment. The surgeon must understand:
• The effects of the wound and of the sutures on corneal anatomy and function.
• The basic concepts of how sutures work.
• The importance of a conscious planning of suture introduction.
Before actual wound closure, all elements of strategic thinking (see Chap. 1.8) must be considered, as should the implications and requirements of any additional tissue pathology caused by the injury. The variables involved in corneal suturing are discussed in Tables 2.2.4-2.2.6 and Figs. 2.2.2-126.96.36.199 Clinical examples are shown in Figs. 2.2.11-2.2.15.
Chapter 2.11 provides further details on managing eyes with corneal wounds, and present the similarities and differences between eyes with corneal vs scleral wound.
• In addition to the use of full-thickness sutures, intense topical cortico-steroid therapy is the other crucial factor in hastening edema resolu-tion.3'
• Antibiotics should also be used for a few days.
29 The author is greatly indebted to Bowes Hamill, M.D., for his invaluable contributions in developing the approach to suturing full-thickness corneal wounds as presented in this chapter.
30 The use of full-thickness sutures is somewhat controversial; this is discussed in Table 2.2.5.
31 In most cases, the combination of full-thickness sutures and intensive postoperative corticosteroid treatment allows the surgeon to perform vitreoretinal surgery within a few days and without having to compromise in the timing and completeness of vitrectomy due to cornea-related visualization difficulties.
Causes change in corneal curvature (i.e., refractive error and possibly AC shallowing): radial wounds flatten the cornea adjacent and 90° away; the flattening effect increases as the visual axis is approached
Causes change in corneal curvature [flattening of the dome and uneven-ness (astigmatism)]; loose limbal sutures cause flattening adjacent to the wound and 180° away; tight limbal sutures cause flattening 90° away
Makes wound watertight
Minimizes postoperative edema
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