Ординатура / Офтальмология / Английские материалы / Applied Pathology for Ophthalmic Microsurgeons_Naumann, Holbach, Kruse_2008

Fig. 2.7. Expulsive choroidal hemorrhage: The uveal effusion is associated with every phenomenon of vis a tergo particularly in young patients with arterial hypertension, and may induce a tear in the posterior ciliary vessels at the inner sclera entering the choroid. The resulting choroidal hemorrhage leads to a ballooning of the choroid filling the entire intraocular space and pushing the tissues of retina, lens, and iris into the wound opening anteriorly (PAS)

¸

Fig. 2.8. Pupillary and ciliary block leading to angle closure glaucoma: a Normal anterior chamber. b, c Pupillary block obstructs flow from the posterior into the anterior chamber by increased contact between the pupillary iris with the anterior lens capsule or, rarely, from luxation of the lens in the anterior chamber. This obstruction is increased by viscosity of the aqueous fluid, by paracentesis effect and hemorrhage. In pupillary block the position of the lens is unchanged; only the peripheral anterior chamber is occluded by the iris. d, e Ciliary block means obstruction of aqueous flow from the retrolental space into the posterior and anterior chamber. The contact between the ciliary body and muscle with the equator of the lens misdirects aqueous toward the vitreous, pushing the lens forward. With the forward position of the lens there is shallowing also of the central anterior chamber

2.2.5

Purulent Endophthalmitis

Theoretically every opening of the eye wall is at risk of an acute (bacterial) or chronic (mycotic) infection or inflammation. Acute infections are potentially devastating because of the small dimensions and irreversible damage (Fig. 2.9) particularly after foreign body entrance (Fig. 2.10).

In a recent interventional case series from the Wilmer Institute, it was shown that an inflow of extraocular fluid into the anterior chamber occurs frequently after phacoemulsification via a sutureless 2.8-mm corne-

a

b

c

d

e

al incision even after hydrosealing if located temporally. This aspiration may happen spontaneously and was observed after pressure release on the anterior chamber in all eyes! With minimal bleeding from the limbal capillaries this could easily be illustrated (Taban et al., 2005). In spite of all attempts at anti-infectious prophylaxis, the ciliae and glands located at the lid margins cannot be made completely free of bacterial coloniza-

Fig. 2.9. Purulent panophthalmitis may result from exogenous inflow of bacteria or fungi or endogenously from hematogenic sepsis. All intraocular tissues are involved. Bacterial endophthalmitis usually follows an acute course and is characterized by diffuse leukocytic infiltration of the vitreous. Mycotic endophthalmitis usually develops endogenously subacutely or chronically from a retinitis septica Roth or infected infusion fluid with multiple microabscesses. Optic nerve (O), Cornea (C), Ciliary body (CB) (PAS)

tion. Therefore it is not surprising that at the end of the procedure bacteria can be detected in the anterior chamber aqueous in about 30 % of all patients after extracapsular catardet extraction (Linda Ficker). We must assume that mechanisms exist to eliminate these minimal but common usually subclinical bacterial infections.

The rate of postoperative endophthalmitis following intraocular microsurgery apparently can be reduced by prophylactic intraccameral antibiotics (see also chapter 5.5 and Lundström et al., 2007).

2.2.6

Sympathetic Uveitis

Even with meticulous microsurgical techniques the catastrophe of a bilateral sympathetic uveitis cannot be excluded with certainty in intraocular microsurgery – although the incidence today is extremely low. It has even been observed following a surgical iridectomy with a small corneoscleral incision. One hundred years ago sympathetic uveitis after perforating ocular injury occurred so frequently that early enucleation of the traumatized eye was recommended as a prevention.

2.2.7

Diffuse and Cystic Epithelial Ingrowth

Diffuse and cystic epithelial ingrowth cannot be totally excluded following punctures or extensive wounds in the cornea, or the corneoscleral or conjunctivoscleral region (Fig. 2.11 – 13). Rarely a non-penetrating wound in the corneal limbus may induce an extensive deep conjunctival epithelial lined cyst containing mucus-produc- ing goblet cells, procing a sedimented horizontal level.

2.2.8

Hemorrhage from Vasoproliferative Processes

Hemorrhage from vasoproliferative processes (Table 2.2) into the anterior chamber and/or vitreous cavi-

ty is seen in retinopathia proliferans, cyclitic membranes and rubeosis iridis, which are all induced by a chronic focal or diffuse hypoxia of the retina or a localized trauma to the iris, ciliary body or retina (see Chap-

2.3

Choice of Anesthesia and Knowledge of Ophthalmic Pathology

Most intraocular microsurgery today is done using local anesthesia. However, there are indications for general anesthesia – aside from the necessity in children – in the following situations. (1) preoperative open eye: perforating corneal trauma, or ulcers;

(2) very thin sclera, e.g., scleral staphyloma: large globe in buphthalmus and high myopes; and (3) patients with an only eye. Local anesthesia today frequently is done with epibulbar drops and gels. However, if local anesthesia with parabulbar or retrobulbar injection is considered, the theoretical risk of

scleral perforation by periocular needle injection cannot be totally neglected.

In analogy to severe contusion, scleral perforation occurs most easily at the three “loci minores resistentiae” of the sclera (Fig. 2.16, 2.17): (1) between the scleral spur and Schwalbe’s line at the limbus cornea, (2) at the equator of the eye, where the sclera is thinnest underneath the insertion of the straight rectus muscles, (3) at the exit of the optic nerve through the lamina cribrosa, and (4) immediately adjacent to the optic disc margin in front of the insertion of the meninges of the optic nerve and Elschnig’s scleral rim. A thin sclera is often associated with large globes such as in buphthalmus or high myopia (> 26 mm optical axis). Scleral thinning is also evident as staphyloma following scleritis, blunt

b

trauma and incomplete rupture of the globe, cryocoagulation or diathermy of the ciliary processes to reduce aqueous inflow or as part of retinal detachment surgery. Small caliber needles with sharp tips more easily engage with and perforate the sclera. Pronounced obe-

Table 2.4. Potential indications for general anesthesia

1.Children

2.“Wide open eye”: perforated trauma, perforated corneal ulcers, penetrating keratoplasty, block excisions, direct surgery of ciliary body

3.Thin sclera – large globe: buphthalmus, high myopia (> 26 mm), scleral staphyloma

4.Clotting defects and arterial hypertension

5.“Oculus ultimus”

6.Choice of patient (cost)

c

Fig. 2.16. c Weakness at the margin of the optic disc, Elschnig’s spur (arrow):

(1) lamina cribrosa with exit of axons and (2) juxtapapillary sclera between scleral spur and liquor space (LS). The sclera here is only half as thick as the rest of the sclera. Arteficial retinal detachment (ARD). MASSONstain

Table 2.3. Advantages and disadvantages of local and general anesthesia

Although regional anesthesia appears at first glance convenient, the patient population often suffers severe comorbidity, making the perioperative management challenging. Whether regional or general anesthesia is preferable should be discussed in advance, with both the patient and the anesthesiologist. General anesthesia provided by a dedicated anesthesiologist can provide a good framework in which to perform faultless surgery without undue haste. If regional anesthesia is chosen, the anesthesiologist must be available to stabilize cardiopulmonary function immediately if necessary (Ulrich Beese, MD, personal communication, 31.12.06).

Finally: all microsurgical interventions in and around the eye can theoretically result in complications. Patient counselling following the “4R rule” – Recognition, Regret, Responsibility and Remedy – requires knowledge of the ophthalmic pathology pre-, intraand postoperatively!

2.4

Instrumentation and Physical Principles Are not the Subject of Our Book

two exceptions to this rule: “non-mechanical trephination techniques for penetrating keratoplasty with the excimer laser along a metal mask” (Chapter 5.1) and “direct surgery of the ciliary body” (Chapter 5.4) because the ciliary body until recently was considered a taboo zone. Our own experience with procedures involving the ciliary body is encouraging if certain principles and limits are respected (see Chapter 4, “minimal eye” and Chapter 5.4).

The morphologic elements of ocular disease and particularly those that are relevant for microsurgery do not change significantly over time – except for the complication of newer procedures.

In contrast, the instrumentation and technology for most ocular microsurgical procedures are undergoing dramatic and revolutionary innovations almost on a weekly basis.

Particularly the miniaturization demands an ever more detailed knowledge of the details of structural – and functional – alterations that are the target “attacked” by new microsurgical tools using both mechanical and non-mechanical principles.

a

Fig. 2.17. a Deformation of globe with blunt trauma leading to defects in the weak areas shown in

Fig. 2.16. b Rupture of the globe at the limbus from contusion (arrows). Cornea

(C), sclera (S), ciliary muscle b (CM)

Fig. 2.18. Proximity of osseous orbital wall and globe: narrowest distance at 12 and 6 o’clock

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Bialasiewicz AA, Ruprecht KW, Naumann GOH. Staphylokok- ken-Endophthalmitis nach Schieloperation. Klin Monatsbl Augenheilkd 1990; 196: 86 – 88

Chang D, Campbell JR. Intraoperative Floppy Iris Syndrome (IFIS). J Cataract Refract Surgery 2005; 31:664 – 673

Gieler J, Heuser D. Verschiebungen des Iris-Linsen-Diaphrag- mas unter Einfluss vasoaktiver Pharmaka. Vorläufige Mitteilung tierexperimenteller Befunde. In Naumann GOH and Gloor B loc. cit.

Hellmund K, Frühauf A, Seiler T, Naumann GOH. Sympathische Ophthalmie 50 Jahre nach perforierender Verletzung. Eine Kasuistik Klin Monatsbl Augenheilkd 1998; 213: 182 –185

Henke V, Naumann GOH, Gierth K. Intraokulare Operationen an “letzten” Augen (Bericht über 145 Eingriffe). Fortschr Ophthalmol 1988; 85: 385 – 389