PRIMARY IMPLANTATION OF A SCLERAL

FIXATED POSTERIOR CHAMBER LENS

When the posterior capsule is compromised during cataract surgery, capsular support may be inadequate to safely place a PC IOL. Careful and thorough vitrectomy is necessary to remove all vitreous from the anterior segment of the eye and within the posterior chamber. This is often best accomplished using a pars plana technique. A small conjunctival peritomy is performed 3 mm from the limbus, and bipolar cautery is utilized to attain hemostasis. A sclerotomy opening is made by pointing the tip of the blade toward the optic nerve. A lance type of blade—mi- crovitreoretinal (MVR) blade—is best for this incision. It is necessary to visualize the blade within the pupillary space before extracting it. Using a butterfly needle, an anterior chamber maintainer, or some other type of infusion through the paracentesis anteriorly, a posterior vitreous cutter (with a no irrigation sleeve) is placed through the sclerotomy. Vitreous is accessed easily from within the pupillary space and the subincisional area. Small capsular tags can also be removed. Care should be taken to retain as much capsule as possible. Once the vitreous has been removed and the anterior segment swept with a cyclodialysis spatula to be sure that no residual vitreous is present, the sclerotomy site can be closed using an X 10-0 nylon suture. If enough residual capsule is present, the new PC IOL can be placed over the residual capsule. In many cases it is possible to place the haptics within the ciliary sulcus and prolapse the optic through an intact anterior capsulorrhexis despite the posterior capsule being absent. This assures excellent fixation and centration. If there is more significant loss of capsular support, a transsclerally fixated PCL can be placed as described above. On occasion, adequate residual capsule is present in one area but absent elsewhere. Under these circumstances one haptic of a transsclerally fixated lens can be placed over the area of intact capsule while the opposite haptic can be transsclerally fixated with a suture. This lends itself nicely to stable IOL fixation.

COMPLICATIONS OF TS PCLS

Erosion of the external prolene suture through conjunctival flaps has been reported to vary between 5 and 50%.25–27 External erosion of sutures initially placed under scleral flaps has been reported to range from 5 to 17%.27,28 Erosion of 9-0 and 10-0 Prolene suture knots through scleral flaps, but not externally, was seen in all patients in two reviews.26,29 Minimizing the incidence of external erosion of transscleral sutures is important because the full-thickness su-

ture tract allows for the potential intraocular spread of microorganisms or epithelial cells from the surface. Exposed external polypropylene sutures or barbs can be successfully managed in a stepwise fashion including trimming the sutures with Vannas scissors, application of cautery to melt and blunt the end of the suture, revision of the knot with placement in an episcleral tunnel, revision of the conjunctival flap, and placement of a scleral or corneal patch graft over the knot or barb.

There have been three case reports of endophthalmitis associated with TS PCLs. The first case occurred as a result of erosion of a 9-0 polypropylene suture under conjunctival and scleral flaps 6 years postoperatively.26,29 In the second case Haemophilus influenzae endophthalmitis was seen 5 months following the procedure. A 9-0 polypropylene transscleral suture had eroded through a conjunctival flap.30 Another report involved loss of an eye to Streptococcus viridans endophthalmitis 1 month following placement of a lens secured by 10-0 polypropylene sutures under conjunctival flaps that subsequently eroded31 (Fig. 22–7).

LENS TILT

The incidence of lens tilt with TS lenses has been reported to be between 5 and 11%.32,33 A lens with a reduced overall length is more anatomically correct and hence more reliably and accurately placed in the ciliary sulcus when compared to standard lenses of 13.0 mm or greater overall length. Procedures performed on cadaver eyes, modified to allow visualization of the ciliary sulcus from the posterior aspect of the globe, have demonstrated the difficulty of placing large lenses, 13 mm in length or greater, in the ciliary sulcus.16 Histopathology of iris-supported and TS PCLs support these observations, where 10 of

FIGURE 22–7 Clinical photograph demonstrating erosion of a 10-0 polypropylene suture through the conjunctiva 6 months following placement.

12 haptics were not placed accurately in the sulcus despite the surgeon’s attempt to do so.1,27 Asymmetric haptic placement has been cited as a contributing cause of lens tilt in one study.32 Recommendations have been made to use a one-piece all-PMMA lens because its rigidity at the haptic optic junction minimizes lens tilt. Double eyelets on the haptics have been reported to decrease the incidence of lens tilt.

LENS DECENTRATION

Lens decentration has been estimated to occur in 3.5% of cases in one series.33 Decentration can occur if sutures are not securely or symmetrically attached to the haptic. If sutures are both secure and symmetrically placed, lens decentration can still occur if the transscleral passages are not 180 degrees apart from each other. Haptic tips with end bulbs can prevent loss of the suture from the haptic and dislocation, but do not prevent suture slippage along the haptic with subsequent decentration of the lens. Use of a radial marker dipped in gentian violet externally will assure success of placing the transscleral sutures 180 degrees apart when applied at the limbus.

LENS DISLOCATION

Dislocation of transscleral fixated lenses could theoretically occur if the transscleral suture is either inadvertently, or by intention, removed postoperatively. Lenses placed posterior to the sulcus on ciliary body processes in some cases have shown minimal fibrosis when examined histologically 6 months following placement.27 Lenses placed on the anterior pars plana and ciliary body have dislocated following removal of the transscleral Prolene suture 5 and 9 months following their respective placement.27,33 We believe it more prudent to keep transscleral sutures intact postoperatively to provide added stability. However, transscleral sutures have been successfully removed without dislocation of the sulcus fixated lens.18 In one report, fibrotic haptic fixation within the sulcus was so strong it impaired the ability of the surgeon to remove the lens postoperatively.34

VITREOUS HEMORRHAGE

The increased intraoperative time required for sutured lenses may raise the risk of intraoperative choroidal detachments. One of 47 patients in one study35 and 2 of 56 in another33 developed intraoperative choroidal detachments. One additional patient in the latter study developed a hemorrhagic choroidal detachment.

The incidence of vitreous hemorrhage has been reported at 8% with passes of sutures presumably

through pars plicata and exiting 2 mm posterior to the surgical limbus.35 The currently recommended more anterior passage of suture through the ciliary sulcus with external exit 0.5 to 1.0 mm posterior to the surgical limbus avoids the vascular ciliary body and reduces the risk of bleeding.28 Hyphemas have been seen in 5 to 14% of patients,32,33 but have been believed to be related to lens removal and anterior reconstructive surgery rather than transscleral suture passage. Occasionally episcleral bleeding occurs with wicking of blood along the suture back into the eye. This can be avoided by thorough cauterization prior to suture passage.

Based on the clinical and laboratory studies described above, specially designed PC IOLs have been developed for transscleral fixation techniques to optimize lens stability, simplify lens placement, and minimize complications.

CONCLUSION

Transscleral fixation of secondary PC IOLs has widespread applicability. The technique described eliminates the need for scleral flaps, thereby minimizing time, bleeding, and complications related to performing scleral flaps. It is important to note that, even if the exposed knot is covered by a scleral flap, the knot will eventually erode through the scleral flap over time.

Transscleral PCLs are technically more difficult to implant than either ACLs or sulcus-supported PCLs. However, complications related to their implantation have been minimized with the use of proper IOLs and implantation techniques. There is no conclusive evidence that one lens type—ACL, PCL, or TS PCL—is better than any other because no randomized studies have been performed to date.

Sizing issues are critical when considering implantation of ACLs. Because of the prevalence of PCLs in ophthalmic surgery, most IOL manufacturers have limited sizing availability, restricting ACL lengths to 12, 13, and 14 mm. Consequently, complications may occur in eyes that do not adequately match the sizes available.

Although most ophthalmologists would agree that a sulcus-supported PCL is the ideal IOL in patients with capsular compromise but adequate support, the ideal lens and best procedure for patients without capsular support are still in question. The PC IOLs and techniques described will preserve the advantages of a PCL while eliminating many of the complications previously reported with this technique (Table 22–1). External erosion of the polypropylene suture has been seen30 and can result in inflammation31 and endophalmitis.32 Eyelets on the haptics allow for the creation of a continuous transscleral loop with a knot

TABLE 22–1 COMPLICATIONS ASSOCIATED

WITH TRANSSCLERALLY SUTURED POSTERIOR

CHAMBER INTRAOCULAR LENSES

Suture-related complications

External erosion of polypropylene suture25,28,29,32,33 Endophthalmitis26,30,31

Episcleritis

Lens-related complications

Tilt29,33

Decentration32,33

Dislocation following suture removal30

Hemorrhage

Hyphema28,32,33

Vitreous hemorrhage32,35 Choroidal hemorrhage29,32,33,35

Retinal detachment25,33,35

Cystoid macular edema (CME)32,33

Peripheral anterior synechia (PAS) formation33

Glaucoma25,29,32,33

Graft rejection/failure25,32,33

that can be buried. Because of this rotation of the knots, erosion of the polypropylene knot or barb has been eliminated. Lens tilt, decentration, and dislocation have been reported with previous techniques.33 Eyelets on each haptic, 12 to 121⁄2 mm apart, allow for a secure, symmetric, and reproducible attachment of sutures to the lens, and facilitate the placement of haptics in the ciliary sulcus that anatomically measure 12 mm in diameter. The large optic of these lenses reduces postoperative edge glare, and the mild degree of posterior angulation of the haptics minimizes iris chafe (and hence the potential for CME), and peripheral anterior synechia. This more physiological PC IOL design maintains stable fixation without evidence of postoperative IOL movement. Continued long-term follow-up of patients with transsclerally fixated PCLs is needed, ideally by means of a randomized study comparing transsclerally fixated PCLs with ACLs to determine the best approach for patients without adequate capsular support. Nonetheless, transscleral fixation of PCLs using techniques described here and other similar techniques has found widespread success and is a viable alternative for patients lacking adequate capsular support.

REFERENCES

1.Apple DJ, Mamalis N, Loftfield K, et al. Complications of intraocular lenses: a historical and histopathological review. Surv Ophthalmol 1984;29:1–54.

2.Kraft MC, Sanders DR, Lieberman HL. Monitoring for continuing endothelial cell loss with cataract extraction and intraocular lens implantation. Ophthalmology 1982;98:30–34.

3.Busin M, Arffa RO, McDonald MB, et al. Intraocular lens removal during penetrating keratoplasty for pseudophakic bullous keratopathy. Ophthalmology 1987;94:505–509.

4.Smith PW, Wong SK, Stark WJ, et al. Complications of semiflexible, closed-loop anterior chamber intraocular lenses. Arch Ophthalmol 1987;105:52–57.

5.Waring GO, Stulfing RD, Street D, et al. Penetrating keratoplasty for pseudophakic corneal edema with exchange of intraocular lenses. Arch Ophthalmol 1987; 105:58–62.

6.Speaker MG, Lugo M, Laibson PR, et al. Penetrating keratoplasty for pseudophakic bullous keratopathy: management of intraocular lens. Ophthalmology 1988;95:1260–1268.

7.Waring GO. The 50-year epidemic of pseudophakic corneal edema. Arch Ophthalmol 1989;107:657–659.

8.Insler S, Kook MS, Kaufman HE. Penetrating keratoplasty for pseudophakic bullous keratopathy associated with semi-flexible, close-loop anterior chamber intraocular lenses Am J Ophthalmol 1989;107:252–256.

9.Koenig SB, McDermott ML, Hyndluk RA. Penetrating keratoplasty and intraocular lens exchange for pseudophakic bullous keratopathy associated with a closedloop anterior chamber intraocular lens. Am J Ophthalmol 1989;108:43–48.

10.Korhmehl EW, Steinert RF, Odrich MG, et al. Penetrating keratoplasty for pseudophakic bullous keratopathy associated with closed-loop anterior chamber intraocular lenses. Ophthalmology 1990;97:407–414.

11.Murphy GE. A technique for suturing the Shearing posterior chamber implant to the iris. J Am Intraocul Implant Soc J 1981;7:167–169.

12.Drews RC. Posterior chamber lens implantation during keratoplasty without posterior lens capsule support. Cornea 1987;6:38–40.

13.Wong SK, Stark WJ, Gottsch JD, et al. Use of posterior chamber lenses in pseudophakic bullous keratoplasty. Arch Ophthalmol 1987;105:856–858.

14.Soong HK, Musch DC, Kowal VS, et al. Implantation of posterior chamber intraocular lenses in the absence of lens capsule during penetrating keratoplasty. Arch Ophthalmol 1989;107:660–665.

15.Apple DA, Price FW, Gwin T, et al. Sutured retropupillary posterior chamber intraocular lenses for exchange of secondary implantation. Ophthalmology 1989;96: 1241–1247.

16.Price FW, Whitson WE. Visual results of suture fixated posterior chamber intraocular lenses during penetrating keratoplasty. Ophthalmology 1989;96:1234–1240.

17.Busin M, Brauweiler P, Boker T, et al. Complications of sulcus-supported intraocular lens with iris sutures, implanted during penetrating keratoplasty after intracapsular cataract extraction. Ophthalmology 1990;97: 401–406.

18.Maus M, Sivalingam E. Alternative method for sulcus fixation of posterior chamber lenses in the absence of capsular support. Ophthalmic Surg 1989;20:476–479.

19.Aray EN. A technique for fixing posterior chamber intraocular lenses to the iris through a corneoscleral incision. Am J Ophthalmol 1990;109:488–489.

20.Campbell D, Davis R, Ferguson JG. Ciliary sulcus anatomical dimensions. Invest Ophthalmol Vis Sci 1988; 29:34(suppl: ARVO abstracts).

21.Duffey RJ, Lindstrom RL, Holland EJ. Anatomic study of transsclerally sutured intraocular lens implantation. Am J Ophthalmol 1989;108:300–309.

22.Lane SS, Agapitos PJ, Lindquist TD. Secondary intraocular lens implantation. In: Lindquist TD, Lindstrom RL, eds. Ophthalmic Surgery: Loose-Leaf and Update Service. St. Louis: Mosby Yearbook; 1990:1–17.

23.Lane SS, Schwartz GS. IOL exchanges and secondary IOLs: surgical techniques. Focal Points, American Academy of Ophthalmology 1998;16.

24.Sugiura T, Minami N, Miyake K. Ciliary sulcus pad. Video presentation, ASCRS, San Diego, April 10–14, 1998.

25.Lane SS, Lindquist TD, Spigelman AV. Scleral fixationcomplications. Invest Ophthal Vis Sci 1990;31(suppl): 573.

26.Epstein E. Suture problems. J Cataract Refract Surg 1989;16:116.

27.Lubniewski AJ, Holland EJ, Woodford S, et al. Histologic study of eyes with transsclerally sutured posterior chamber intraocular lenses. Am J Ophthalmol 1990;110:237–243.

28.Stark WJ, Gottsch JD, Goodman DF, et al. Posterior chamber intraocular lens implantation in the absence

of capsular support. Arch Ophthalmol 1989;107:1078– 1083.

29.Solomon K, VanMeter W, Gussler J. Incidence and management of complications and suture of sutured posterior chamber lenses. Final Program of the 95th Annual Meeting of American Academy of Ophthalmology, 1991;18:144.

30.Heilskov T, Joondeph BC, Olsen KR, et al. Late endophthalmitis after transscleral fixation of a posterior chamber intraocular lens. Arch Ophthalmol 1989;107: 1427.

31.Schachter RJ. Suture-wick endophthalmitis with sutured posterior chamber intraocular lenses. J Cataract Refract Surg 1990;16:755–758.

32.Lindquist TD, Agapitos PJ, Lindstrom RL, et al. Transscleral fixation of posterior chamber intraocular lenses in the absence of capsular support. Ophthalmic Surg 1989;20:769–775.

33.Heidemann DG, Dunn SP. Visual results and complications of transsclerally sutured intraocular lenses in penetrating keratoplasty. Ophthalmic Surg 1990;21: 609–614.

34.Lane SS. Haptic Fibrosis Following Transscleral Fixation of Posterior Chamber IOLs. Seattle, WA: ASCRS; 1999.

35.Johnson SM. Results of exchanging anterior chamber lenses with sulcus-fixated posterior chamber IOLs without capsular support in penetrating keratoplasty. Ophthalmic Surg 1989;20:465–468.

The cornea, even though it is the window to the eye, like Rodney Dangerfield, often gets little respect! Ignorance is bliss until the cornea is not clear preoperatively, in which case doing surgery through a “dirty window” can be difficult, indeed; and, if the cornea is unclear after surgery, it may be too late to consider what damage might have occurred at the time of surgery. In fact, it is fair to say that the best phacoemulsification that could possibly be done is meaningless if permanent corneal damage occurred. In this era of technically advanced phacoemulsification, pseudophakic bullous keratopathy is almost considered a problem of the past; however, it continues to be a leading indication for penetrating keratoplasty,1 and surprisingly it can be easily induced among the unwary. Those of us who specialize as “window cleaners” may have a few pieces of advice worthy of consideration for any phacoemulsification surgeon. To appreciate these problems a general review of corneal anatomy may be helpful.

CORNEAL ANATOMY2–4

The cornea measures 12 mm horizontally and 11 mm vertically. The thickness varies from 1 mm at the periphery to 0.5 mm centrally. Viewed from the front it appears elliptical with an average radius of 7.8 mm; viewed from behind, it appears circular with an average radius of 6.8 mm.

Centrally the cornea consists of five layers:

Epithelium: The corneal epithelium is stratified, squamous, nonkeratinized epithelium five to seven

cell layers (50 m) in thickness. The deepest layer

166

of cells are the basal cells, which are arranged in a single layer. They have flat bases and rounded heads with large oval nuclei lying near the head.

The basement membrane lies between the basal cells and Bowman’s membrane. It is thin and difficult to visualize, but plays an important role in epithelial cell adhesion. The basal cells adhere to their basement membrane by a combination of desmosomes, adherens junctions, tight junctions, and gap junctions.

Bowman’s membrane: This membrane is an acellular connective tissue layer composed of thin collagen fibrils aligned randomly in a ground substance. It will merge into the highly organized corneal stroma. It is 10 m thick.

Stroma: The stroma constitutes 90% of the corneal thickness. It is highly ordered and is composed of layers of cylindrical collagen fibrils embedded in a ground substance. The fibrils are arranged parallel to Bowman’s membrane and crisscross at right angles interlacing only slightly. Between the lamellae are two types of cells, keratocytes (fixed cells), and wandering cells, which appear to be phagocytic.

Descemet’s membrane: This membrane is a highly ordered network of very thin homogeneous collagen filaments about 10 m thick in adults. It is slightly thicker in the periphery than centrally. The thickness increases with age. It is the basement membrane for the endothelium.

Endothelium: The endothelium is a single cell layer 3m thick. Each cell is anchored to its neighbor by interdigitations of the cell surfaces. Due to the close binding of cells, the endothelium can be stripped off in a sheet.

LIMBAL ANATOMY2–4 (FIG. 23–1)

The limbus, approximately 1 mm wide, marks the transition between the cornea and sclera. It is important anatomically because a wide variety of surgical incisions pass through this structure. The cornea joins the sclera in a curved margin, leading to confusion in the nomenclature used for the true limbus. For the purposes of this discussion, the limbus will be defined as extending from a line drawn between the end of Descemet’s and Bowman’s membranes to the point where corneal stroma merges into sclera.

As the epithelium transitions from cornea to conjunctivae, it thickens rapidly to 10 or more layers. There are interdigitations of loose connective tissue papillae 1 to 2 mm apart running from the sclera to the cornea, where they are lost in the clear cornea. Blood vessels and lymphatics run in these papillae. The stroma loses the regular orientation of the cornea and resembles ordinary connective tissue.

The limbus is abundantly supplied by the superficial marginal plexus of blood vessels created by episcleral branches of the anterior ciliary vessel and conjunctival vessels. Lymphatics run in the same distribution.

Sympathetic nerve fibers supply the vascular plexus at the limbus. In addition, sensory fibers from the ophthalmic division of the trigeminal nerve enter

Scleral spur (thin white line)

Schwalbe's line

Corneal stroma

Trabecular meshwock

Limbus 1 mm

Posterior border of limbus

Schlemm's canal

Conjunctiva

Tenon's fascia

Aqueous vein

Scleral spur

FIGURE 23–1 The anatomic relationships of the cornea and limbus.

the limbus from the perichoroidal space and, after losing their myelin sheaths, branch into the corneal stroma, penetrating Bowman’s membrane and ending as naked fibrils between epithelial cells.

Viewed through the surgical microscope, with the conjunctiva reflected so that the limbus is visible, the posterior limbus is visualized as a line of demarcation between the bluish semitransparent limbal stroma and the opaque white sclera. An incision made perpendicular to the surface of the stroma at this junction will be in avascular limbal stroma, entering the anterior chamber in front of Schlemm’s canal and just behind the termination of Descemet’s membrane, passing through the anterior aspect of the trabecular meshwork. An incision made perpendicular to the cornea at the junction of the corneal and conjunctival epithelium will enter the anterior chamber, penetrating Descemet’s membrane and the endothelium anterior to the trabecular meshwork.

VISUALIZATION DIFFICULTIES

So, what is the problem? If the cornea is densely scarred, a corneal transplant needs to be done before cataract surgery or at the time of cataract surgery; if the scarring is minimal, adequate visualization should not be a problem. Generally, if the expected postoperative visual acuity is 20/30 or better due to corneal problems, why do a transplant if cataract surgery alone can result in exceedingly quicker and more guaranteed visual rehabilitation? The line to draw for visual acuity as an indication for keratoplasty is variable depending on the pathology (stable or getting worse) and is patient specific. At 20/60 or worse corneal acuity, a transplant is usually needed. Certainly, a corneal problem that will allow good visual acuity shouldn’t be difficult in the hands of an experienced phacoemulsification surgeon.

There is a new twist to consider, however. In a combined procedure a limbal or corneal self-sealing incision at the same time but prior to the penetrating keratoplasty is increasingly being seen as a better way to proceed. Expulsive hemorrhage, a frequent complication associated with prolonged open-sky techniques, is totally avoided by a closed, sealed phacoemulsification. Furthermore, an intact capsulorrhexis with a perfect placement of an in-the-bag intraocular lens is also immensely easier in the closed phacoemulsification system. Probably the biggest problem associated with open-sky surgical technique is the collapse of the capsular bag around the cortex and the difficulty in getting a complete cortex cleanup, often in the face of a bulging posterior capsule. This also is avoided by a closed system, which opens the capsular bag and makes cortex removal much simpler. Combine this