Publications

May 2000 Subscription Information Volume 26, Number 5


CONSULTATION SECTION

edited by Samuel Masket, MD

An active 78-year-old woman had seemingly uneventful cataract extraction with intraocular lens (IOL) implantation 2 months before seeking consultation. Per her history, surgery was performed using local anesthesia (sub-Tenon's), and a 6.0 mm acrylic IOL (AcrySof MA60BA, Alcon) was placed in the capsular bag through a superior limbal incision. One day after surgery, she was noted to have capsular bag distention with artificial myopia. The capsule block did not diminish by the second postoperative day, and 2 small neodymium:YAG (Nd:YAG) laser capsulotomies were created in the posterior capsule near the edge of the optic; the capsule block and the myopia resolved.

In addition, the patient developed a tonic pupil, contributing to significant postoperative disabling glare. Although the patient notes an improvement in visual acuity, she finds that she cannot drive at night as a result of undesired phenomena (e.g., light rings, streaks, halos). Unfortunately, she wanted surgery initially to improve vision for nighttime driving.

Present ocular examination demonstrates the following findings. Visual acuity in both eyes is 20/25. Intraocular pressures (IOPs) are 16 mm Hg bilaterally. The right pupil is irregular in shape, has serpentine pupillary reactions, and is enlarged to approximately 6.0 mm, whereas the left pupil is normally reactive and is 3.0 mm in ambient light.

Infrared pupillometry is recorded at 7.0 mm in the right eye and 5.0 mm in the left. Further findings in the right eye reveal a perfectly centered IOL inside the capsular bag with a 0.5 mm overlapping anterior capsule rim for 360 degrees (Figure 1). The posterior capsule is clear with 2 small openings 180 degrees apart adjacent to the optic edge. The left eye demonstrates minimal cortical cataract formation. Posterior segment examination is unremarkable in both eyes.

Figure 1.
(Masket) Dilated examination reveals a well-centered IOL. A triangular posterior capsulotomy is visible near the temporal edge of the optic.

The patient is intolerant of her current quality of vision and refuses a trial of a custom contact lens, given earlier failures with attempted contact lens wear. Pilocarpine 0.5% induces miosis but does not meaningfully reduce her symptoms. She requests correction of her condition. How would you proceed?


This patient represents a challenging therapeutic problem. Before discussing the therapeutic options, some important considerations must be taken into account (1) when dealing with a patient reporting glare after otherwise uneventful cataract surgery and (2) when evaluating the management of the capsular distention syndrome.

The treatment of capsular distention syndrome should be based on breaking the adhesion of the anterior capsule to the surface of the optic. In this patient, the pupil dilates quite widely, as shown in Figure 1. The anterior capsule rim overlaps the optic for 360 degrees. If the Nd:YAG laser is applied to the anterior capsule edge and extends to the edge of the optic, the block is remedied by the release of the retained proteinaceous fluid from behind the IOL forward into the anterior chamber. This preserves the posterior capsule and maintains compartmentalization of the eye.

Although a posterior capsule opening(s) relieves the block, future IOL manipulation becomes much more difficult. In cases in which the pupil does not dilate widely and the anterior capsule rim is not visible to the edge of the optic, consideration should be given to bringing the patient to the operating room where bimanual irrigation/aspiration (I/A) can be performed by breaking the adhesions between the anterior capsule and surface of the lens in mechanical fashion.

Glare is often thought to be caused by posterior capsule opacification (PCO), even when mild degrees are noted. It is important when evaluating glare that all potential etiologies are considered and the major source is confirmed. Possible etiologies include PCO, internal reflections from an IOL, edge glare from a tonic pupil, a physiologic large pupil that dilates larger than the diameter of the optic in dim light, or corneal abnormalities. The latter can usually be assessed by placing a rigid contact lens. If the symptoms disappear with the use of the contact lens, the cornea is the most likely etiology. Constriction of the pupil with pilocarpine can be used to determine whether an enlarged pupil is the etiology of the glare. If the pupil constricts to a diameter smaller than the optic size yet glare symptoms persist, the large pupil is not the entire explanation for the glare symptoms, and internal reflection from the IOL is the most likely etiology.

In the case presented, pupillary miosis did not eliminate glare; therefore, the etiology of the patient's symptoms is probably related to internal reflections from the IOL rather than from the tonic pupil. Treatment strategies should center around IOL exchange. This is made more difficult by the openings in the posterior capsule and the potential for vitreous prolapse during lens-exchange manipulations. Lens exchange would be easy if there were simply a split in the anterior capsule to the edge of the optic with an intact posterior capsule.

In this patient, I would recommend the following steps: Through a paracentesis opening, viscoelastic material would be used to fill the anterior chamber. With the blunt cannula or a Sinskey hook, adhesions between the anterior capsule and surface of the optic would be lysed, mobilizing the lens. Installation of a retentive viscoelastic material behind the IOL will create space for lens manipulation and tamponade the vitreous.

Through the original wound or a new clear corneal incision, 3.5 to 4.0 mm in length, I would cut the haptics from the optic with an intraocular scissors. Every attempt should be made to minimize lens movement during these manipulations to avoid further stretching the capsule and extension of the existing posterior capsule openings. The severed haptics can then be removed by rotation. With the capsule distended, the haptics should be easy to remove.

A paracentesis opening should be made through clear cornea 180 degrees from the incision. With a cyclodialysis spatula through the paracentesis, the lens optic can be gently lifted anteriorly through the capsulorhexis opening, and a folding forceps can refold the lens in the anterior chamber under viscoelastic protection. The lens is removed.

If the 2 posterior capsule openings remain unchanged, I would recommend using a foldable silicone IOL to avoid the internal reflections from the squared edge of the acrylic lens. The IOL should be placed in the ciliary sulcus and the optic prolapsed through the anterior capsulorhexis, capturing the optic within the capsular bag as described by Neuhann. Should vitreous prolapse, a pars plana vitrectomy would be the most efficient way of removing the vitreous and preserving as much capsule as possible. The viscoelastic material can be removed with bimanual I/A to avoid overinflating the eye with aggressive irrigation inflow. Alternatively, a vitreous cutter could be used in a bimanual fashion to remove the viscoelastic agent.

If glare symptoms persist postoperatively, I would consider performing a purse-string closure of the pupil or the chronic use of a miotic. I would not, however, favor primary closure of the pupil as the patient's initial symptoms of glare seem to result more from the IOL than pupil size.

Stephen S. Lane,MD
Stillwater, Minnesota, USA


In this case, the contribution of the tonic pupil to this patient's problem has been decoupled from the contribution of the IOL by the diagnostic trial of pilocarpine. As pilocarpine 0.5% induces miosis but does not meaningfully reduce this patient's symptoms, her refusal of a trial of a custom contact lens is moot because the pilocarpine-induced miosis provides a more physiologic pupil aperture than a custom contact. Thus, the major culprit causing her disabling glare with inability to drive at night because of light rings, streaks, and halos must be entoptic phenomena resulting from the edge of the AcrySof MA60BA IOL.

The truncated edge design of AcrySof IOLs results from the manufacturing process (verbal communication, David Eister, Alcon Laboratories) and significantly contributes to the low rate of PCO with these lenses. 1 However, this advantage is offset to some degree by the entoptic phenomena attributed to this design. 2

The effect of IOL edge design on postoperative edge glare has been studied in an eye model using a 3-dimensional radiometric ray-tracing program. 3 Designs with sharp edges formed by "cropping" the anterior and posterior optic zones focus edge glare rays into distinct arc-shaped images whose peak intensity is an order of magnitude stronger than the peak intensity of the diffuse image formed by lenses with rounded edges. Intraocular lenses with truncated edge designs are thus much more likely to produce edge glare phenomena that can appear to the patient as a thin crescent or partial ring.

AcrySof lenses have also been found to result in higher chromatic aberration than poly(methyl methacrylate) (PMMA) lenses, 4 so some entoptic phenomena reported with these lenses may relate to the optical properties of the acrylic material. All currently available lens designs have relative advantages and disadvantages, and acrylic lenses are particularly advantageous with regard to minimizing postoperative inflammation, capsule contraction and opacification, and in cases anticipated to subsequently require vitreoretinal surgery.

I chose the MA60BM to implant in both of my father's eyes last month with great success. However, given this patient's presenting complaints at the time of her initial surgery, she might have been better served with an IOL style with a rounded edge. Of course, hindsight is 20/20.

In this case, I would exchange the IOL for a lens with a 7.0 mm optic with a rounded edge. Unfortunately, such a lens is not routinely available in a foldable material in the United States. Thus, it would be necessary to create a large wound to allow implantation of an all-PMMA IOL with these characteristics. A superiorly placed scleral tunnel using a frown architecture would minimize induced astigmatism. As a large wound would be required, it would not be necessary to cut or refold the acrylic lens inside the eye before explantation.

Preoperatively, I would extensively counsel the patient on the management options for tonic pupil. Because the pupil would cover the IOL edge in all but the most scotopic conditions, and as the anterior capsule remnant would be expected to rapidly opacify with a PMMA lens in the bag, an initial trial of conservative therapy would be recommended. The most likely scenario would be that the patient might initially require a drop of pilocarpine 0.5% before night driving; however, that requirement would probably diminish with time.

Should glare continue to be problematic, a 10-0 running polypropylene suture could be passed through multiple paracenteses and woven through the iris near the pupillary margin to perform an iris cerclage, producing a small, relatively round pupil. 5,6 Should the patient be unwilling to undertake a trial of conservative medical management for the tonic pupil, an iris cerclage could be performed at the same surgical sitting as the IOL exchange.

Joel K. Shugar, MD

References

1.
Peng Q., Visessook N., Apple D.J. et al. Surgical prevention of posterior capsule opacification, Part 3: intraocular lens barrier effect as a second line of defense. J Cataract Refract Surg. 2000; 26: 198-213.
2.
Masket S., Consultation Section, J Cataract Refract Surg. 1998; 24: 1554-1561.
3.
Holladay J.T., Lang A. and Portney V., Analysis of edge glare phenomena in intraocular lens edge designs, J Cataract Refract Surg. 1999; 25: 748-752.
4.
Nagata T., Kubota S., Watanabe I. and Aoshima S., [Chromatic aberration in pseudophakic eyes], [Japanese] Nippon Ganka Gakkai Zasshi. 1999; 103: 237-242.
5.
Ogawa G.S., The iris cerclage suture for permanent mydriasis - a running suture technique, Ophthalmic Surg Lasers. 1998; 29: 1001-1009.
6.
Behndig A., Small incision single-suture-loop pupilloplasty for postoperative atonic pupil, J Cataract Refract Surg. 1998; 24: 1429-1431.

Joel K. Shugar, MD
Perry, Florida, USA


Before we can help this patient, we must clearly understand the source of her symptoms. She had implantation of a 6.0 mm acrylic IOL (AcrySof MA60BA, Alcon). Although this IOL enjoys a reputation for a low incidence of PCO, it is also well known to cause intracameral reflections from the IOL edge design, which contributes to symptoms of halos and rings, particularly at night. This may occur with perfect implantation and a normal pupil.

We are presented with an anterior segment photograph that demonstrates an irregularly enlarged pupil and informed it has serpentine pupillary reactions, is enlarged to 6.0 mm in ambient light, and is recorded at 7.0 mm with infrared pupillometry. The patient is described as having developed a tonic pupil, possibly from the sub-Tenon's anesthesia (resulting in damage to the ciliary ganglion).

The question arises: Are the symptoms related to the tonic pupil or the AcrySof IOL? Depending on the answer, the treatment options can differ. We are told that pilocarpine 0.5% induced miosis but did not meaningfully reduce the symptoms. It would be useful to know how much miosis was induced and whether the symptoms would have persisted with a 4.0 mm pupil.

A trial with a custom diagnostic contact lens with a 4.0 mm central clear zone and opaque periphery would be helpful. If this adequately eliminates her symptoms, she can be offered 1 procedure to resolve the problem; that is, a pupilloplasty using the same method as that to correct postoperative atonic pupil in aphakic or pseudophakic eyes. This procedure should work equally well for a pseudophakic tonic pupil.

If this diagnostic test or a course of stronger miotics shows that the symptoms persist despite eliminating the pupil as the source of the problem, our options change and any course of action must consider an IOL exchange. I sense that the problem is likely a combination of the AcrySof IOL and the tonic pupil. Assuming this is the problem, I would proceed in this fashion after obtaining an endothelial cell count.


Option 1

Perform an A-scan and calculate for a foldable silicone IOL (Chiron LI61U), 1 for capsular bag placement and a backup calculation for sulcus placement. I would choose this IOL because it allows planar injection through a small incision, which facilitates implantation in the event of extension of the pre-existing capsule openings. Although it is not my routine, I would consider intracameral lidocaine or an anesthetic block for this patient, depending on how cooperative she was during the preoperative evaluation.

I would dilate the eye preoperatively with only 1 drop of phenylephrine hydrochloride 2.5% (Neo-Synephrine®) because a small pupil is required for stage 2 of the surgery. I would sit temporally and perform 2 diametrically opposed stab incisions close to the limbus, angled slightly down.

Next, I would make a 3.5 mm temporal 2-plane clear corneal incision. I believe that corneal incisions larger than 3.0 mm should be biplanar for better sealing; otherwise, I use a single-plane incision. I would use an easily removable viscoelastic material because there are 2 capsule openings, and I do not want to hydrate the vitreous excessively at the end of the case while trying to remove the viscoelastic agent.

Next, I would attempt to use 2 Lester lens rotators to mobilize the IOL into the pupillary plane, cut the IOL, and remove it in longitudinal pieces through the 3.5 mm incision with a forceps. At 2 months postoperatively, it is unlikely the AcrySof cannot be mobilized. If it could not, I would cut the haptics, remove the optic in pieces, and leave the haptics in place. If the bag is preserved and inflatable, I would place the LI61U in the bag. Otherwise, I would place the appropriately calculated LI61U in the sulcus. Next, I would inject acetylcholine chloride (Miochol®) and perform small incision single-suture-loop pupilloplasty 1 to treat the tonic pupil.


Option 2

Perform an A-scan and calculate for a PMMA Morcher aniridia IOL type 67G (12.5 mm overall length/5.0 mm optic) for in-the-bag placement and an aniridia IOL type 67S (13.5 mm overall length/5.0 mm optic) for backup sulcus placement. These IOLs have black PMMA surrounding the clear portion of the optic to help the aniridia. The drawback is that a much larger clear corneal incision requiring wound suturing would be used.

I would work temporally because the keratometric changes are less than with a superior approach. Once the aniridia IOL is implanted, in the bag or in the sulcus, the surgeon must make certain that the black PMMA extends beyond the edge of the scotopic, pharmacologically unaffected tonic pupil. The surgeon can be certain of this only if careful preoperative documentation of the pupil edge is done under scotopic illumination. Appropriate consent must be obtained to use this IOL.

Which option to use would likely depend on discussions with the patient. Option 2 is less surgically demanding and requires less intraocular manipulation. Cosmetically, it may not look as good as option 1. If the patient has an endothelial cell count close to 1000 or less, this would probably be the more appropriate approach. Either option offers a viable solution.

Omar F. Almallah, MD

References

1.
Behndig A., Small incision single-suture-loop pupilloplasty for postoperative atonic pupil, J Cataract Refract Surg. 1998; 24: 1429-1431.

Omar F. Almallah, MD
Toms River, New Jersey, USA


This 78-year-old woman who had uneventful cataract surgery, other than the capsular block syndrome that was relieved with Nd:YAG laser capsulotomies, must have had an immediate postoperative IOP spike that created the postoperative atonic pupil, known as Urrets-Zavalia syndrome. At the time of cataract surgery, this could not be predicted; therefore, the option of using endocapsular rings to serve as a pseudo pupil was not a consideration. At present, it is still not a consideration as extensive intraocular surgery would be required to place the endocapsular rings, which function as an artificial pupil.

I think the easiest and best solution for this patient is to perform a pupilloplasty, which can be accomplished through a superior and an inferior clear corneal paracentesis at the 12 and 6 o'clock positions. Passing from temporal to nasal, an Ethicon 10-0 polypropylene (Prolene®) suture (#17136 on an STCG straight needle) would be used to grasp the pupil margins.

After the suture was cut, both ends of the suture would be retrieved and brought through the 12 o'clock paracentesis with an iris hook, where they could be tied outside the eye to suture the pupil. This would next be accomplished in a similar manner inferiorly, passing the needle through the peripheral clear cornea, grasping the edge of the pupil, and then regrasping the edge of the pupil on the opposite side and passing through the nasal clear cornea. The suture would be cut and the 2 cut ends retrieved through the inferior paracentesis. If adequate closure of the pupil was not evident, 2 additional sutures could be placed in a similar manner. This should improve the patient's optical symptoms.

Stephen F. Brint, MD
Metairie, Louisiana, USA


The fact that the anterior capsule overlies the AcrySof lens is the major factor in favor of this patient having a reasonable outcome. Two months postoperatively, there is little opacification. However, within another 2 to 3 months, the rim of anterior capsule will likely opacify more, and in particular, there would be quite considerable opacification where the anterior and posterior capsules fuse at the lens margin. This will help greatly with her symptoms, and I would suggest continuing with the pilocarpine while waiting.

The only other long-term solution is to use the technique described by Osher and colleagues and place, in effect, an artificial iris to reduce the disabling symptoms caused by the edge effect of the lens.

Helen Seward, FRCS, FRCOphth
Surrey, England


This does not appear to be an eye with a fixed pupil, which may appear after a postoperative IOP rise. This could be a case of Addie's pupil, especially if the patient is responding well to pilocarpine 0.5%. Nevertheless, the mydriasis left is too great for normal night function. As the patient is intolerant to pilocarpine, I would consider suturing the pupil to approximately 4.0 mm. This is easily done with 1 or 2 10-0 Prolene sutures placed in each side, at the 3 and 9 o'clock positions. I would advise peribulbar anesthesia for this procedure.

Hamilton Moreira, MD
Curitiba, Brazil


The patient had retained viscoelastic material and most likely had a pressure spike with ischemia to the iris, resulting in permanent pupil dilation. If the patient can not wear a contact lens that is tinted in the periphery, the iris can be sutured to close the pupil with multiple modified McCannel sutures using a CTC needle and 10-0 Prolene suture supplied by Ethicon (#9090G).

The procedure would involve filling the eye with viscoelastic material and pharmacologically constricting the iris. The needle would then be placed through the cornea, through the iris border, and then again through the iris border about 2.0 mm away and then out through the cornea. An incision is made through the cornea, and both arms of the Prolene suture are pulled out through the peripheral incision. The knot is tightened and cut flush. The procedure would be repeated 6 to 8 times to produce a smaller pupil.

Walter J. Stark, MD
Baltimore, Maryland, USA