Optometry - Journal of the American Optometric Association
Volume 81, Issue 9 , Pages 432-436, September 2010

Bilateral phacomorphic angle-closure glaucoma in a highly myopic patient secondary to isolated spherophakia

  • Joseph Sowka, O.D.

      Affiliations

    • Corresponding Author InformationCorresponding author: Joseph Sowka, O.D., Nova Southeastern University College of Optometry, 3200 South University Drive, Fort Lauderdale, Florida 33328.
    • ,
  • Nadine Girgis, O.D.

Nova Southeastern University, Fort Lauderdale, Florida

published online 31 May 2010.

Article Outline

Abstract 

Background

Angle closure most commonly occurs in older hyperopic patients as a result of primary relative pupil block. Less frequently, angle closure occurs in highly myopic patients with conditions other than primary relative pupil block. This report presents the diagnosis, pathophysiologic mechanism, and management of a patient with both high myopia and bilateral advanced phacomorphic angle-closure glaucoma caused by isolated spherophakia.

Case

A 40-year-old asymptomatic man with very high myopic astigmatism presented with chronic angle closure and an intraocular pressure of 42 mmHg in both eyes. Additionally there was a nonmyopic fundus and 24-mm axial length, with a clear crystalline lens protruding through the pupillary plane in each eye, confirmed by B-scan ultrasonography. Gonioscopy and A-scan and B-scan ultrasonography identified the pathogenesis of intraocular pressure elevation, angle closure, and high myopia to be lenticular in origin. Initial medical therapy and subsequent laser iridotomy relieved the pupil block angle closure and successfully lowered intraocular pressure.

Conclusion

Angle closure can occur in highly myopic eyes. Careful gonioscopy and ultrasonography can lead to the correct diagnosis and tailored management for these eyes. Phacomorphic angle-closure glaucoma from spherophakia is associated with Weill-Marchesani syndrome as well as a few other uncommon syndromes. Isolated pseudophakia is a rarely reported cause of phacomorphic angle closure.

Keywords: Angle closure, Phacomorphic glaucoma, Pupil block, Isolated spherophakia

 

Angle-closure glaucoma typically affects older hyperopic patients.1 It occurs much less commonly in younger patients and highly myopic patients. When angle-closure glaucoma occurs in younger patients or highly myopic patients, it tends to occur from causes other than the relative pupil block mechanism common to the general angle-closure population and is typically associated with structural and developmental ocular anomalies.2, 3 Such structural and developmental abnormalities include plateau iris syndrome, iridociliary cysts, retinopathy of prematurity, uveitis, nanophthalmos, Marfan syndrome with lens subluxation, miotic-induced angle closure, phacomorphic glaucoma, and persistent hyperplastic primary vitreous.2, 3

Phacomorphic glaucoma is a form of secondary angle-closure glaucoma arising from pupil block typically secondary to an intumescent lens in an extreme stage of cataractogenisis.4 Phacomorphic glaucoma can also occur in the absence of a cataract. In these cases, spherophakia produces pupil block as a result of extreme lens curvature and/or weak zonules causing anterior lens displacement.2, 3, 5, 6

Spherophakia is associated typically with systemic disorders and syndromes such as Weill-Marchesani syndrome, Marfan syndrome, Alport syndrome, Klinefelter syndrome, Fanconi anemia, and homocystinemia.7, 8, 9, 10 It is uncommon to encounter isolated spherophakia and seemingly even less common to encounter patients with bilateral angle closure and high myopia with isolated spherophakia.7 This report details the diagnosis and management of a man with bilateral chronic angle closure and high myopia caused by isolated spherophakia.

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Case 

A 40-year-old white man presented for a comprehensive eye examination with complaints of mildly blurred vision at distance and near with his current spectacle correction. He also noted glare when driving at night but had no other visual complaints. He reported that he had worn glasses since childhood and had a very nearsighted prescription. He stated that he always had poor vision in each eye, even with glasses. He reported no ocular disease, trauma, or surgery. He had no significant or contributory medical history except for the fact that he was born with only 1 kidney. His last physical examination was 20 years earlier. He was of normal height and did not manifest brachydactyly. His family ocular history was significant only for paternal macular degeneration. He was using no medications and reported only environmental allergies.

Best-corrected visual acuity was 20/40 in each eye through -15.00 – 2.50 x 030 in the right eye (O.D.) and -18.00 – 3.00 x 150 in the left eye (O.S.). Both corneas were approximately spherical keratometrically at 43.00 in both eyes (OU), indicating a slightly flat cornea. Pupils were sluggish but reactive to light without afferent defect in either eye. Abnormally constricted visual fields were elicited in both eyes by confrontation. Biomicroscopic examination was normal in each eye except for shallow anterior chambers with iris bombé OU. Peripheral anterior chamber depth was estimated by Von Herrick method to be grade 1 nasal and temporal in each eye. Both corneas were clear and nonedematous. Notably, the crystalline lens protruded slightly into the anterior chamber in each eye with the anterior lens capsule clearing the plane of the pupil bilaterally. There was no evidence of phacodonesis or lens subluxation. Intraocular pressure (IOP) by Goldmann applanation was 42 mmHg OU. Central corneal thickness was 549 μm O.D. and 535 μm O.S. Gonioscopy showed bilaterally closed angles in each eye with only anterior trabecular meshwork visible in one quadrant of each eye. There were no areas of obvious peripheral anterior synechiae (PAS). Bilateral iridodonesis was noted during gonioscopy. Because of the bilaterally closed anterior chamber angles, dilated fundus examination was deferred. Undilated examination with a 90-diopter lens and biomicroscope showed extensive glaucomatous damage to each optic disc. The cup-to-disc ratio was estimated to be 0.95/0.95 in each eye (see Figure 1). Most notably, there was no evidence of myopic conus, staphyloma, or myopic optic discs normally associated with refractive errors of the magnitude seen in this patient. Based on the bilaterally closed angles, apparent protrusion of the crystalline lens into the anterior chamber with subsequent pupil block, and the lack of degenerative myopic fundus findings in such a high myope, the patient had phacomorphic glaucoma secondary to spherophakia diagnosed. To ameliorate the IOP and relieve the pupil block, the patient was prescribed Combigan (brimonidine tartrate 0.2%/timolol maleate 0.5% fixed combination; Allergan, Irvine, California) twice a day OU and pilocarpine 2% 4 times a day OU. The nature of his condition was explained to him as well as the need for additional secondary laser therapy. He was referred for laser peripheral iridotomy (LPI).

The patient presented to the laser facility the following week as scheduled for the LPI, but did not feel that he fully understood the reason for the procedure and left the facility without being seen. He returned to our facility 1 week later. He reported using both medications with no adverse effects. Visual acuity was unchanged in each eye, and his pupils were bilaterally pharmacologically miotic and unreactive. IOPs were now 16 mmHg O.D. and 18 mmHg O.S. Gonioscopically, the right angle was unchanged and remained appositionally closed. However, the left anterior chamber angle now showed at least anterior trabecular meshwork in all quadrants with some quadrants open as far as posterior trabecular meshwork and others to the scleral spur. Iridodonesis was again noted bilaterally. The patient's condition was explained again and the need for LPI emphasized. The patient was urged to follow through with the surgical consultation and was scheduled for a subsequent progress evaluation in 3 months. The patient acknowledged his understanding and indicated that he would follow through as recommended in the near future for LPI.

The patient returned as scheduled for a progress evaluation and reported that he had undergone bilateral LPI without complications 2 months prior. The ophthalmologist discontinued pilocarpine postoperatively but continued the patient on Combigan bilaterally. The patient's visual acuity was unchanged, though he reported that he felt that he saw better after starting the medications and undergoing LPI. Biomicroscopy results showed patent LPIs bilaterally. Additionally, the anterior chamber appeared deeper, and iris bombé had been relieved. IOP was 20 mmHg OU. Gonioscopically, the right anterior chamber angle was now open to the posterior trabecular meshwork for 3 quadrants and to the scleral spur in the remaining quadrant. The left anterior chamber angle was open to the scleral spur for 3 quadrants and the posterior trabecular meshwork for the remaining quadrant. There was no residual PAS present; however, there was dense, irregular pigmentation to the trabecular meshwork throughout both eyes, likely caused by the previous appositional closure and broken subclinical PAS.

A-scan biometry showed an axial length 24.12 mm O.D. and 23.98 mm O.S., consistent with a slightly hyperopic eye. B-scan ultrasonography found a distinctly round crystalline lens in each eye clearly protruding through the pupil into the anterior chamber (see Figure 2). These findings confirmed the initial suspicion that the phacomorphic pupil block angle closure was caused by the lens shape. Additionally, it was clear that the patient's high myopia was not caused by globe elongation but by the refractive component of a highly spherical lens.

Dilated fundus examination was performed without complications. Biomicroscopically, both lenses had distinctly spherical shapes. In the dilated state, lens zonules were clearly seen biomicroscopically. This was attributed to the extremely spherical shape of the lens because there was no evidence of lens subluxation or dislocation. There appeared to be no loss of zonular integrity. In the absence of zonular rupture or lens displacement, the iridodonesis was ascribed to the extreme spherical nature of the lens with minimal midperipheral iris-lens apposition (see Figure 3). The remainder of the examination showed a normal retinal periphery in each eye. There was no evidence of fundus changes associated with high or degenerative myopia. The optic discs showed significant glaucomatous compromise. Based on the advanced degree of glaucomatous disc damage OU, Travatan Z (travoprost 0.004%/SofZia; Alcon, Fort Worth, Texas) was added O.S. at bedtime as a monocular trial and Combigan twice a day OU was continued. The patient was reappointed for re-evaluation of IOP and threshold perimetry.

The patient returned as scheduled 1 month later and reported no changes. He claimed good medical compliance and reported no adverse effects from the recently added travoprost. IOPs were 20 mmHg O.D. and 13 mmHg O.S., indicating an excellent additive effect of travoprost. Threshold perimetry using 24-2 and 10-2 SITA Standard test strategies showed marked visual field compromise bilaterally. Travoprost was prescribed bilaterally along with Combigan for optimal IOP control. He was also advised to discontinue driving because of his marked visual field constriction. He was referred for low vision rehabilitation evaluation and for university-based counseling to assist his acceptance of vision loss and lifestyle changes. The patient continues to be followed up at appropriate intervals with excellent control of IOP.

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Discussion 

Spherophakia is an anomaly in which the crystalline lens assumes a distinctly spherical shape with an increased anteroposterior diameter.7, 11, 12 Common features of spherophakia include phacodonesis, iridodonesis, lens protrusion through the plane of the pupil, pupil block, visibility of the lens equator on dilation, zonular rupture, and lens dislocation. Not all features occur in every case.5, 7, 11, 12 Phacodonesis and iridodonesis occur most commonly from zonular frailty and rupture with subsequent lens dislocation. When zonules are intact and the lens is not dislocated, there is no phacodonesis, and iridodonesis can then be attributed to minimal irido-lenticular contact in the midperipheral iris region.5

In cases of spherophakia with reduced equatorial diameter, the term microspherophakia applies.7, 11 Microspherophakia tends to be associated with systemic disorders and syndromes, especially the Weill-Marchesani syndrome.9, 11 Weill-Marchesani syndrome, a rare connective tissue disorder, has alternately been referred to as spherophakia-brachymorphia syndrome and congenital mesodermal dystrophy.9 The prominent features and diagnostic criteria include short stature, brachydactyly, and microspherophakia.9 Ectopia lentis, severe myopia, and glaucoma can also occur but are variable and are not required to diagnose this syndrome.13 There are few familial cases of Weill-Marchesani syndrome reported, although autosomal dominant and recessive inheritances have been described.14 It is theorized that there is a developmental abnormality involving mesodermal tissues such as those of the ciliary body, lens, and epiphysis of the bones.9 Subsequently, the spherical fetal lens is never subjected to tractional forces by the ciliary body and lens zonules and thus retains its spherical shape into adulthood.9, 15

High myopia occurs commonly as a result of spherophakia with and without associated syndromes. Although axial myopia can occur, the axial length in eyes with myopia secondary to spherophakia are typically normal.5, 11, 12, 16, 17, 18, 19, 20 Normal biometric measurements and lack of characteristic fundus changes associated with high myopia implicate the lens as the source of myopia in these cases.2

Lens forward dislocation from zonular rupture combined with increasing anteroposterior lens thickness from lack of zonular support is often the cause of the myopia. When lens zonules are intact, it is the extreme lens curvature that accounts for the myopia.

The phacomorphic glaucomatous mechanism occurring from spherophakia is pupil block with subsequent angle closure (both acute and chronic) caused by the lens dislocation and forward movement when zonules are not intact. In cases in which the zonules are intact, the anterior lens curvature, increased anteroposterior thickness, and forward positioning of the lens allow for iridolenticular apposition and pupil block with resultant phacomorphic glaucoma.7, 12, 17, 18 Ultrasound biomicroscopic findings in spherophakia support this pathogenesis, revealing a shallow anterior chamber, a very steep anterior lens curvature, iridolenticular contact, elongated zonules, and an increased distance between the lens equator and the ciliary processes.21

Secondary forms of pupillary block are often seen in Weill-Marchesani syndrome caused by spherophakia and in Marfan syndrome caused by defective lens zonules, allowing for increased lens curvature and increased anteroposterior lens thickness.6, 7, 8, 11, 20, 22 It is unusual, however, to find isolated spherophakia unrelated to any systemic syndrome as a cause of pupil block. Glaucoma associated with isolated spherophakia is not well known or as recognized and much less commonly reported.7, 9, 12, 23, 24

Management of phacomorphic glaucoma secondary to spherophakia initially involves establishing communication between the anterior and posterior chambers through the use of LPI to break the relative pupil block by allowing equilibration of the IOP.25, 26 This treatment is generally effective for both chronic and acute cases of phacomorphic glaucoma. However, despite the presence of patent LPI, the anterior chamber angles may remain closed or occludable because of forward displacement of the lens.2, 11 In cases of acute and chronic angle closure with continued angle closure after LPI for phacomorphic glaucoma, argon laser peripheral iridoplasty (ALPI) can be used as an ancillary treatment or before lens extraction.27, 28 This laser-induced iridoretraction procedure assists by physically pulling the iris away from the trabecular meshwork.

Should LPI and/or ALPI, combined with topical glaucoma medications, relieve pupil block and successfully lower and stabilize IOP, patients with phacomorphic glaucoma secondary to spherophakia could be followed up without further intervention. However, it is not uncommon that lensectomy is necessary to fully treat these patients. It should be recognized that potential surgical complications exist in patients with spherophakia-induced glaucoma. Vitreous loss, late-onset bleb leaks, endophthalmitis, and hypotony have been reported in patients undergoing lensectomy, trabeculectomy, and combined procedures.11, 12

The chronic complicating factor in managing phacomorphic glaucoma secondary to spherophakia is residual IOP elevation after LPI, iridoplasty, and lensectomy. In most cases, this is caused by residual PAS or trabecular damage developing from appositional angle closure.11, 29 In such cases in which residual PAS remains a causative factor, goniosynechialysis can potentially restructure the aqueous outflow route.11, 30 Additionally, glaucoma drainage implant devices can assist in IOP control and are a viable option.31 In that glaucoma surgery in phacomorphic glaucoma compared with that in open-angle glaucoma has a higher rate of complications, chronic medical therapy after LPI appears to be the safest and most efficacious manner in which to manage IOP elevation.11, 12 Although most glaucoma medications will have a beneficial effect in these cases, numerous studies have noted an exceptional effect of prostaglandin analogs in managing the IOP of patients with chronic angle-closure glaucoma after LPI.32, 33, 34

Miotics, however, should be used with caution both before and after LPI in these patients, as miosis also produces ciliary contraction with forward movement of the lens and possible increase in pupil block.12, 26

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Conclusion 

Primary relative pupil block is the most common cause of angle closure in older and hyperopic populations and is substantially less common in younger and highly myopic patients. Indeed, angle closure in highly myopic patients is uncommon and may not be correctly identified because gonioscopy may not be appropriately performed in these patients because of a misperception that an elongated myopic eye would be incapable of angle closure. When angle closure does occur in highly myopic patients, there is likely an underlying secondary cause that must be identified. In cases of angle closure in a highly myopic eye, especially in the absence of characteristic myopic fundus findings, biometry and B-scan ultrasound scan may identify the underlying mechanism. In this case, a 40-year-old highly myopic man presented with chronic angle-closure glaucoma and a fundus devoid of myopic appearances. Ultimately, the angle closure was attributed to phacomorphic glaucoma from isolated spherophakia, a rarely reported condition. Additionally, in the presence of a normal globe axial length, it was determined that his high myopia was lenticular in origin. The presence of angle closure in a highly myopic patient should raise the suspicion of spherophakia as a possible cause.

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References 

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PII: S1529-1839(10)00089-8

doi:10.1016/j.optm.2010.02.010

Optometry - Journal of the American Optometric Association
Volume 81, Issue 9 , Pages 432-436, September 2010

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