Ординатура / Офтальмология / Английские материалы / Ocular Pathology_6th edition_Yanoff, Sassani_2009

CAUSES OF ENUCLEATION

I. Causes of enucleation are many and varied.

II.As can be seen in Figure 5.1, trauma (surgical and nonsurgical) is the number-one cause of enucleations, accounting for 35% of all enucleations.

COMPLICATIONS OF

INTRAOCULAR SURGERY*

Immediate

Complications occurring from the time the decision is made to perform surgery until the patient leaves the operating room are considered immediate.

Cataract surgery of any type falls into the category of refractive surgery.

I.“Surgical confusion”

A.Misdiagnosis: not all cataracts are primary, but they may be secondary to such things as trauma, inflammation, neoplasm (Fig. 5.2), or metabolic disease. When opaque media are caused by a cataract, ultrasonography, magnetic resonance imaging, or computed tomographic scanning can be helpful in establishing whether a neoplasm or a retinal detachment is present behind the cataract.

*This section refers to a cataract or glaucoma incision that usually involves a wound to the limbal region so that conjunctiva, cornea, sclera, and iris can all be considered.

Many technical complications can be avoided by the use of topical and intracameral anesthesia, and a clear-cornea, temporal, no-stitch incision.

B.Faulty technique may result in and/or from:

1.Inadequate anesthesia

2.Perforation of the globe, which may occur at the time of the retrobulbar or peribulbar anesthetic injection or when a bridle suture is inadvertently placed through the sclera

The risk of perforating the globe during retrobulbar anesthesia is approximately 1 : 1000 if the eye is less than 26 mm in axial length, and approximately 1 : 140 in longer eyes. The main risk factor for perforation is a posterior staphyloma.

a.Localized, extreme scleral thinning can predispose to scleral rupture during strabismus surgery.

3.Increased intraocular pressure because of a retrobulbar hemorrhage or poorly placed lid speculum

4.Misalignment of the entering incision

If the corneal-entering incision into the anterior chamber is too far peripheral, iris prolapse may occur. If the incision is too far central, corneal striae and poor visibility may result. Ideally, the corneal-entering incision into the anterior chamber should be 1 to 2 mm into clear cornea.

5.“Buttonhole” of the conjunctiva (not serious in cataract surgery but may lead to failure in filtering procedures)

Fig. 5.1 Reasons for enucleation. In this study of the incidence of enucleation in a defined population, trauma was the number-one cause. (Modified from Erie JC et al.: Am J Ophthalmol 113:138. Copyright Elsevier 1992.)

6.Splitting o (stripping) of Descemet’s membrane from the posterior cornea (can lead to postoperative corneal edema; Fig. 5.3)

Most commonly, the stripping may occur at the time of the introduction of the phacoemulsifier or the irrigation– aspiration tip, the placement of the lens implant into the eye, during the injection of a viscous agent into the eye. Many detachments resolve spontaneously and do not require surgical repair. Intracameral treatment of Descemet’s membrane detachment with perfluoropropane gas has been successful.

7.Iridodialysis (although usually innocuous, may lead to anterior-chamber hemorrhage or problems with pupillary distortion)

8.Photic retinal toxicity (believed to occur from a too-strong surgical light, especially after a cataract is removed, the lens implant is in place, and the surgical light is focused on the macula)

After the lens implant is in place, if further surgery is indicated, it is advisable to place an opaque or semiopaque cover over the cornea, or an air bubble in the anterior chamber to reduce the effect of light focused on the posterior pole.

II.Anterior-chamber bleeding

A.This usually occurs from the scleral side of the cut edge of the wound, especially at the end of the incision.

B.It may also occur at the iridectomy site.

C.Bleeding invariably stops in a short time if patience and continuous saline irrigation are used.

III.Radial tear of the anterior capsulectomy (either capsulorhexis or “can-opener incision”), rupture of the posterior lens capsule, or a zonular dialysis

A.This makes surgery more di cult and leads to an increased incidence of vitreous loss, posterior displacement of lens nucleus or nuclear fragments into the vitreous compartment, retained cortex, and complicated wound healing.

B.It also predisposes to malposition of the lens implant and irregular pupil.

IV. Loss of vitreous, which occurs in approximately 3% to 9% of cataract cases, leads to an increased incidence of iris prolapse, bullous keratopathy, epithelial downgrowth, stromal ingrowth, wound infection, endophthalmitis, updrawn or misshapen pupil, vitreous bands, postoperative flat chamber, secondary glaucoma, poor wound healing, neural retinal detachment, cystoid macular and optic disc edema, vitreous opacities and hemorrhage, expulsive choroidal hemorrhage, and “chronic ocular irritability.”

A.Modern surgical techniques can reduce the incidence of vitreous loss associated with cataract surgery in patients with pseudoexfoliation to that in una ected individuals.

B.Lens fragments retained within the vitreous compartment at the time of cataract surgery are associated with an increased incidence of inflammation, increased intraocular pressure,and cystoid macular edema (CME).

Vitrectomy to remove such fragments is associated with faster visual rehabilitation and better quality of vision.

V.Expulsive choroidal hemorrhage (Fig. 5.4; see also Figs

16.27 and 16.28).

A.This is a rare (it occurs in approximately 0.13% with nuclear expression and 0.03% with phacoemulsification), catastrophic complication and may result in loss of the eye.

Risk factors include glaucoma, increased axial length, elevated intraocular pressure, generalized atherosclerosis, and elevated systemic blood pressure

B.The hemorrhage usually results from rupture of a sclerotic choroidal (ciliary) artery or arteriole as it makes a right-angle turn crossing the suprachoroidal space from its scleral canal. The sudden hypotony after penetration of the globe straightens the sclerotic vessel and causes the rupture.

C.Although most hemorrhages are massive and immediate, occasionally they are delayed and may not occur for days to weeks.

Spontaneous choroidal effusion may occur during intraocular surgery and mimic expulsive choroidal hemorrhage.

D.Histologically, massive intraocular hemorrhage, a totally detached choroid and neural retina, and a gaping wound are seen. A ruptured ciliary artery may be found.

VI. Foreign bodies may be introduced into the eye at the time of surgery.

A.Cilia within the eye can have a variable response from endophthalmitis to prolonged periods of tolerance. Surgical removal of such foreign bodies is a clinical decision that must be individualized based on the patient response to the foreign material.

B.Material placed within the anterior segment to facilitate cataract surgery, such as indocyanine green (ICG) dye, may prove toxic if it migrates posteriorly to involve the retina.

C.Rarely, metallic foreign bodies may be introduced into the eye at the time of intraocular surgery and should be considered in the di erential diagnosis of recalcitrant postoperative inflammation. Nevertheless, frequently there is no inflammatory response, and removal is not necessary.

Postoperative

Postoperative complications may arise from the time the patient leaves the operating room until approximately 2 or 3 months after surgery.

I.Atonic pupil

A.Dilated, fixed pupil is rare, but when present, even with

20/20 acuity, can cause annoying, sometimes disabling, problems because of glare.

An atonic pupil develops in less than 2% of eyes after cataract surgery and posterior-chamber lens implantation.

B.The site of the lesion appears to be in the iris sphincter.

II.Flat anterior chamber*—most chambers refill within 4 to 8 hours after surgery.

Today, with phacoemulsification cataract surgery techniques and careful attention to wound construction and closure, including “no-stitch” closure, flat anterior chamber is quite rare. It is more commonly seen after filtration surgery than after cataract surgery.

*A flat anterior chamber is one in which the iris comes up against the posterior cornea and completely obliterates the anterior chamber. This must be di erentiated from a shallow chamber, in which some space is still present. If the chamber is flat for 5 days or more, peripheral anterior synechiae often develop on the posterior corneal surface (e.g., broad-based). With a shallow anterior chamber, synechiae take much longer to form.

A

B

Fig. 5.5 Poor apposition of wound edges. A, Poor apposition of posterior edges of wound after cataract extraction. Vitreous is seen in wound. B, Vitreous incarcerated in wound just in front of anterior synechia (periodic acid–Schiff stain). Fibrous ingrowth formation present deep to cut edges of Descemet’s membrane (see also Fig. 5.10B).

A.Secondary to hypotony

Most of the complications that cause hypotony are reduced or negated by clear-cornea, temporal, no-stitch phacoemulsification technique.

1.Faulty wound closure (Fig. 5.5): faulty apposition of the wound edges can lead to poor wound healing and a “leaky” wound. Hypotony and a flat anterior chamber result.

2.Choroidal detachment (“combined”choroidal detachment) is not a true detachment, but rather, an e u- sion or edema of the choroid (hydrops), and is always associated with a similar process in the ciliary body.

This complication occurs much more commonly following glaucoma surgery than following cataract surgery.

a.The choroidal detachment, instead of causing the flat chamber, is usually secondary to it; a leaky wound is the cause.

b.Once choroidal hydrops occurs,however,slowing of aqueous production by the edematous ciliary body and anterior displacement of the iris lens diaphragm by the increased volume within the vitreous compartment or by ciliary body “detachment” may further complicate the flat chamber and hypotonic eye.

c.Histologically, the choroid and ciliary body, especially the outer layers, appear spread out like a fan, and the spaces are filled with an eosinophilic coagulum.

Frequently, the edema fluid is “washed out” of tissue sections and the spaces appear empty.

3.Iris incarceration (Fig. 5.6; iris within the surgical wound) or iris prolapse (iris through the wound into the subconjunctival area) acts as a wick through which aqueous can escape, resulting in a flat chamber.

Other ocular structures such as ciliary body, lens remnants, vitreous, or even choroid and retina can become incarcerated in, or prolapsed through, the wound and lead to a flat chamber. All these structures are more likely to enter the wound after nonsurgical trauma than after surgical trauma. Rarely, a lens implant loop may prolapse through the surgical wound.

4.Histologically, iris (recognized by heavy pigmentation) may be seen in the limbal scar, in the limbal episclera, or in both areas.

5.Fistulization of the wound (Fig. 5.7) is usually of no clinical significance, but on occasion, it may be marked and lead to a large bleb, hypotony, flat chamber, corneal astigmatism, and epiphora.

6.Vitreous wick syndrome consists of microscopic-scale wound breakdown leading to subsequent vitreous prolapse, thus creating a tiny wick draining to the external surface of the eye.

a.In some cases, severe intraocular inflammation develops and resembles a bacterial endophthalmitis.

b.Infection can gain entrance into the eye through a vitreous wick.

7.Poor wound healing per se, without an identifiable cause, can lead to aqueous leakage, a filtering bleb, or a flat chamber.

B.Secondary to glaucoma

Aphakic glaucoma, or glaucoma in an aphakic eye, is almost never seen today because intracapsular cataract extraction is so rarely performed. The glaucoma in the postoperative period is usually caused by a pupillary block mechanism.

b.Histologically, posterior synechiae form between the iris, lens capsule, and lens implant (or lens remnants, including cortex). In eyes that have had an intracapsular cataract extraction, synechiae form between the posterior pupillary portion of the iris and the anterior vitreous face.

2.A choroidal hemorrhage can occur slowly rather than abruptly and cause anterior vitreous displacement, resulting in an anterior displacement of the iris or iris lens implant diaphragm. The hemorrhage may remain confined to the uvea or may break through into the subretinal space, the vitreous, or even the anterior chamber.

An unusual hemorrhage is one in which blood collects in the narrow space between the posterior lens implant

surface and posterior capsule (endocapsular hematoma) in an “in the bag” implant.

3.Sodium hyaluronate trapped within the vitreous compartment at the time of cataract surgery complicated by posterior capsule tear has resulted in intractable glaucoma.

III.Striate keratopathy (“keratitis”)

A.Damage to the corneal endothelium results in linear striae caused by posterior corneal edema and folding of Descemet’s membrane.

B.Vigorous bending or folding of the cornea during surgery was the usual cause in the days of intracapsular cataract surgery.

Striate keratopathy occurs less commonly and is milder after phacoemulsification. In this setting it is most commonly secondary to endothelial injury resulting from aqueous turbulence, or from direct endothelial trauma by nuclear or instrument contact or from nuclear particles. Nevertheless, striate keratopathy is not uncommon after nuclear expression or intracapsular cataract extraction.

C.Striate keratopathy is usually completely reversible and disappears within a week.

C

IV. Hyphema (Fig. 5.9)

A.Most postoperative hyphemas occur within 24 to 72 hours after surgery.

B.They tend not to be as serious as nonsurgical traumatic hyphemas, and usually clear with or without specific therapy.

V. Corneal edema

A.Causes

1.“Traumatic” extracapsular cataract extraction

a.Pseudophakic or aphakic bullous keratopathy can develop after traumatic (complicated) extracapsular cataract extraction and anteriorchamber lens implantation, or no lens implantation, respectively.

b.The bullous keratopathy may be associated with operative rupture of the posterior lens capsule and vitreous loss, followed by significant intraocular inflammation.

2.Glaucoma, usually pupillary block glaucoma (pseudophakic glaucoma)

3.Vitreous (Fig. 5.10) or iris adherent to the surgical wound or within it or adherent to the corneal endothelium

4.Splitting of Descemet’s membrane from the posterior cornea (Descemet’s membrane detachment)

(see Fig. 5.3)

5.“Aggravation” of Fuchs’ corneal dystrophy. The result is a combined endothelial dystrophy and epi-

thelial degeneration accompanied by guttata formation on Descemet’s membrane.

6.The scleral tunnel incision for cataract surgery is associated with less postoperative endothelial damage than clear corneal incisions, probably because of the more posterior location of the clear corneal incision.

7.Idiopathic causes (i.e., unknown)

B.Histologically (see Figs 8.45, 8.50, 16.26, and 16.27), the basal layer of epithelium is edematous early.

1.In time, subepithelial collections of fluid (bullae or vesicles) may occur.

2.Ultimately, a degenerative pannus may result from

fibrous tissue growing between epithelium and Bowman’s membrane.

VI. “Acute” band keratopathy

T is mayh develop when materials that contain excess phosphates, especially improperly bu ered viscous substances, are placed in the eye during surgery. It has been postulated that the use of phosphate bu ered irrigating fluid in the treatment of chemical eye injury may result in acute calcium phosphate deposition in some instances. Similarly, corneal calcification has occurred following intensified treatment with sodium hyaluronate artificial tears, which have a high concentration of phosphate.

VII. Subretinal hemorrhage

It is usually secondary to extension of a choroidal hemorrhage.

A

B

Fig. 5.10 Vitreous. A, Vitreous comes through pupil and touches posterior cornea, producing corneal edema (left). Slit-lamp view (right) shows thickening of cornea in area of vitreous touch. B, Histologic section of another case (see also Fig. 5.5B) shows vitreous in posterior aspect of corneal wound. (A, Courtesy of Dr. GOH Naumann.)

Hemorrhage is frequently found, however, in the vitreous inferiorly after intraocular surgery. The cause is unknown; however a careful search for retinal holes is mandatory in such cases.

VIII. Viscoelastic materials, and even air introduced into the anterior chamber, can cause a transient elevation of intraocular pressure that rarely lasts more than 24 to 48 hours.

Although now only of historical interest, α-chymotrypsin used during intracapsular cataract surgery was associated with glaucoma in the early postoperative period.

IX. Inflammation

A.Endophthalmitis (see Fig. 3.1)

The incidence of postoperative endophthalmitis is about 0.128%.

1.In the first day or two after surgery, the disease is usually purulent, fulminating (i.e., rapid), and caused by bacteria frequently from contaminated solutions or intraocular lenses introduced during the surgical procedure (see also section on toxic anterior-segment syndrome (TASS), below, for a simulating condition).

A bacterial infection is also a possible cause in a delayed endophthalmitis, especially with less virulent bacteria such

as Staphylococcus epidermidis and Propionibacterium acnes

(see later, p. 121). A delayed endophthalmitis, however, also suggests a fungal infection.

2.A form of aseptic endophthalmitis of unknown cause may be seen during the first few weeks after surgery.

3.An increased prevalence of endophthalmitis is seen in diabetic patients.

B.Uveitis

1.This may occur as an aggravation of a previous uveitis, a reaction to a noxious stimulus, or de novo, and may be chronic granulomatous or nongranulomatous.

2.Granulomatous reaction (mainly inflammatory giant cells) on the lens implant often is associated with a nongranulomatous anterior uveitis.

If acute iritis or anterior uveitis occurs in the first 5 days after cataract surgery, it is usually caused by (1) bacterial endophthalmitis or (2) aseptic iritis (see discussion of TASS later in this chapter). Bacterial endophthalmitis usually results in permanent vision impairment. Other causes of aseptic iritis include inert foreign materials and trauma. A common form of aseptic iritis caused by an inert foreign body was the UGH (uveitis, glaucoma, and hyphema) syndrome, most often associated with an anterior-chamber lens implant. The incidence of this syndrome has been greatly reduced by modern intraocular lens implant designs. Aseptic iritis may heal completely without any problems, may lead to complete blindness, or anything in between.

3.Nodular episcleritis, peripheral corneal ulceration, wound necrosis, and even wound dehiscence may be related to sutures that were used in cataract surgery, especially virgin silk sutures; however, modern synthetic monofilament sutures have made this complication very rare.

4.Uveitis secondary to non-Hodgkin lymphoma has presented after blunt trauma with the trauma possibly leading to the migration of atypical cells into the eye.

C.Toxic anterior segment syndrome (TASS) and toxic endothelial destruction syndrome (TEDS).

1.TASS is an acute, sterile, postoperative inflammation that manifests itself in the first 12 to 48 hours following surgery.

2.Possible causes that have been cited include intraocular solutions with inappropriate chemical composition, concentration, pH, or osmolality; preservatives; denatured ophthalmic viscosurgical devices; enzymatic detergents; bacterial endotoxin; oxidized metal deposits and residues; and factors related to intraocular lenses such as residues from polishing or sterilizing compounds.

3.In some cases of TASS, an oily substance has been noted in the anterior chamber of a ected individuals and possessed the same gas chromatograph–

mass spectrometry characteristics as the ointment used postoperatively, thereby strongly suggesting intraocular migration ophthalmic ointment instilled at the end of the surgical procedure as a likely source for the inflammation. Poor wound construction and tight surgical dressings have been postulated to contribute to the entrance of the ointment into the anterior chamber.

4.Impurities in an autoclave steam mixture have also been cited as causing one outbreak of TASS.

5.An iris-supported phakic intraocular lens has been associated with TASS.

6.Some authors di erentiate TASS from TEDS based on the less prominent corneal edema in TASS, and its more prominent inflammation in comparison to TEDS. Moreover, corneal edema, timing, impairment of iris sphincter function, and increased intraocular pressure to a level between 40 and 70 mm Hg also are said to help di erentiate

TASS from endophthalmitis.

X.Intraocular lens implantation

A. Lens implant subluxation and dislocation (Fig. 5.11)

1.The posterior-chamber lens implant may subluxate nasally, temporally, superiorly (sunrise syndrome), or inferiorly (sunset syndrome).

a.Bilateral spontaneous dislocation of intraocular lenses within the capsule bag has been related to the presence of retinitis pigmentosa, gyrate atrophy, and intermediate uveitis.

b.The lens implant may also dislocate into the anterior chamber partially (iris capture) or completely (rare), or into the vitreous compartment. Dislocation into the anterior chamber may be associated with pseudophakic bullous keratopathy.

c.Blunt trauma may result in the expulsion of an intraocular lens through a clear corneal wound.

d.The loops of the implant may prolapse through the corneoscleral wound or into the anteriorchamber angle.

e.Other forms of implantable devices, such as endocapsular tension rings, that are being utilized as adjuncts to cataract surgery, may also become dislocated into the vitreous compartment, or even into the anterior-chamber angle.

2.Anterior-chamber lens implants may dislocate posteriorly into the posterior chamber or vitreous compartment.

3.Dislocation of a posterior-chamber intraocular lens under the conjunctiva secondary to blunt trauma