Bobby Jones* was a healthy, active 76-year-old retiree who had been diagnosed with glaucoma. Golfing was his primary form of exercise, but over the last few years the vision in his left eye would deteriorate for several hours as he trekked around the course. He had come to our glaucoma clinic for a second opinion because his game was suffering. "Every time I go and play golf, my vision gets foggy," lamented Mr. Jones.
His Medical History
Mr. Jones said things had been going along fine until old age caught up with him and, about three years ago, he had bilateral cataracts removed.
In the year before we saw him, the glaucoma in his left eye had progressed to the point that he required a trabeculectomy with mitomycin C. During this period, he was also told he had chronic uveitis in the left eye and early macular degeneration in both eyes. He continued to take bimatoprost in the right eye and prednisolone acetate drops in the left eye. Other than an aspirin a day and cholesterol medications, the rest of Mr. Jones’ history was unrevealing.
We Get a Look
On examination, Mr. Jones had BCVA of 20/25 in his right eye and 20/30 in his left. There was no afferent pupillary defect. His IOP by applanation was 14 mmHg in his right eye and 7 mmHg in his left, with average corneal thicknesses. Slit-lamp examination of the right eye showed mild hyperemia and a posterior chamber IOL. The right optic nerve was unremarkable.
Examination of the left eye revealed a diffuse superior bleb and fine pigment dusting on his central corneal endothelium and iris surface. A posterior chamber IOL was seen centrally, but on transillumination we were also able to see a portion of the haptic behind an area of atrophic iris nasally (Fig. 1). Gonioscopy of the left eye showed a heavy uniform layer of pigment covering his angle structures in contrast to the rather featureless open angle of his right eye. The left optic nerve had thinning of the neuroretinal rim inferiorly. This correlated with retinal nerve fiber layer thinning inferiorly by optical coherence tomography and a superior arcuate defect present on Humphrey visual field testing of the left eye. Review of prior visual fields showed definitive progression from a normal field three years prior, but no evidence of change since the trabeculectomy.
|Caption: (1) An examination of Mr. Jones revealed transillumination defects of the left eye with the edge of the IOL haptic apparent in nasal defect.|
It was apparent at this point that Mr. Jones had had a rapidly progressive glaucoma over the last three years with a concurrent chronic uveitis, and his anterior segment findings suggested the underlying reason.
While a differential for a secondary glaucoma with iritis might include Fuchs’ heterochromic iridocyclitis, Mr. Jones had none of the characteristic findings of heterochromia, stellate keratic precipitates or fine vessels of the angle.
Likewise, pseudoexfoliation could be entertained given the pigment and transillumination defects present. But the lack of signs in the right eye and the heavy, uniform pigmentation of the angle in the left eye rather than a "clumpy" pattern spoke against that.
Given the presence of the haptic in the area of transilluminated iris, the most likely diagnosis was a pigmentary dispersion glaucoma secondary to mechanical chafing of the iris by the IOL.
Signs of the classic pigmentary dispersion syndrome consist of Krukenberg’s spindle, midperipheral spokelike iris transillumination defects and dense uniform pigmentation of the trabecular meshwork. These signs result from the liberation of pigment by mechanical chafing of an anatomically susceptible iris pigment epithelium against the lens zonules. Pigment in the trabecular meshwork may result in acute spikes of IOP and, over time, trabecular dysfunction and glaucoma. In a pseudophakic eye, a similar mechanical process can occur between the iris and the IOL. The uveitis-glaucoma-hyphema syndrome described with the early anterior chamber IOLs can be considered a particularly extreme form in the spectrum of this process.
With the popularization of the posterior chamber IOL in the late 1970s and 1980s came reports of a pigmentary dispersion syndrome related to mechanical chafing of the iris pigment epithelium by the posterior chamber IOL.1 Contributing factors to this syndrome included coarse IOL manufacturing artifacts, lack of IOL posterior angulation allowing proximity of the iris and optic, and sulcus placement of the IOL again allowing close contact.
While pigment dispersion is possible with any IOL, of recent interest is the advent and widespread use of the AcrySof SA series (Alcon) one-piece, planar, square-edged posterior chamber IOL. When placed within the capsular bag as indicated by the manufacturer, the square edges of the optic and haptics of this one-piece IOL provide a barrier to migrating lens epithelial cells and decrease subsequent posterior capsular opacification. When placed or dislocated into the sulcus, however, its zero angulation and square-edged thick haptics and optic can traumatize the nearby iris, resulting in a secondary pigmentary dispersion syndrome with subsequent iris pigment epithelial atrophy, heavy pigmentation of the angle and ocular hypertension.2 When a symptomatic, unanticipated sulcus IOL is suspected, modern anterior segment imaging techniques—such as ultrasound biomicroscopy (UBM)—can confirm the diagnosis.3 UBM is an immersion B-scan ultrasonograph with a field of view 5 x 5 millimeters (lateral x axial) and a resolution up to 25 micrometers axially.
Caption: We performed ultrasound biomicroscopy of Mr. Jones’ IOL positions. (2) In his right eye, the MZ40 IOL is in the capsular bag and away from the iris. (3) In the left eye, the SA60AT IOL is in the sulcus and in contact with the iris.
We Check His Cards
We asked Mr. Jones for his IOL cards. These showed that an SA60AT lens had been placed in the left eye three years earlier, which is when his troubles began. UBM demonstrated haptic and optic contact with the iris pigment epithelium in the left eye (Fig. 3), confirming our clinical exam and suspicions.
As for Mr. Jones’ foggy vision while golfing, pigmentary dispersion syndrome is known to produce this phenomenon with exercise or pupillary dilation. We offered to surgically exchange the IOL, but he declined. Though he is still symptomatic, his risk of further glaucomatous damage is limited by the presence of an effective trabeculectomy.
In summary, an IOL-related secondary pigmentary dispersion syndrome should be considered in a pseudophakic patient with a subsequent, poorly responsive chronic uveitis. While we could not help Mr. Jones with his golf game, awareness and surgical treatment of the underlying mechanical cause of his uveitis can arrest the process and prevent progression to glaucoma and frank uveitis-glaucoma-hyphema syndrome.
* Patient name is fictitious.
1 Masket, S. J Cataract Refract Surg 1986; 12:252–256.
2 Micheli, T. et al. J Cataract Refract Surg 2002;28:1869–1872.
3 Piette, S. et al. Am J Ophthalmol 2002;133:839–841.
Dr. Noecker is vice chairman and director of glaucoma service. Dr. Kuo is chief resident. Both are at the University of Pittsburgh’s ophthalmology department.