Spark ImageWise 10 – Glaucoma

Pigmentary Glaucoma 

Dr Swati Mishra, Dr Vinay Nangia, Dr Sarang Lambat, Dr Prabhat Nangia
Suraj Eye Institute, 559 New Colony, Nagpur 

Case Description
A female, 42 years of age, presented  with complaints of progressive visual loss in both eyes since 9  months. Her best corrected visual acuity (BCVA) was 6/18, N12 in the right eye (RE) and 6/6, N6 in the left eye (LE) with a correction of –2.50 DS with +1.25 DC in RE and -1.75 DS with +1.00 DC in LE. The IOP was 56 mmHg in RE and 52 mmHg in LE. Her central corneal thickness was 537 micron and 521 micron in RE and LE respectively. Axial length in RE was 24.55 mm and LE was 24.29 mm.

Figure 1: Diffuse illumination image of anterior segment showing pigment dispersion throughout the endothelium. (Yellow arrows) 
Figure 2:
Direct focal illumination image showing deposition of iris pigments on endothelium. (Yellow arrows)
Figure 3: Indirect Gonioscopic examination of superior angle showing open angle with pigmented trabecular meshwork (yellow arrow). Concave configuration of the  iris can be appreciated (green arrow). 
Figure 4:
Notice the bend in the light beam over iris indicative of a  concavity. (green arrow).

Figure 5: Perimetry of right eye showing advance glaucomatous damage with global field loss (black arrow). 
Figure 6: Perimetry of left eye showing moderate glaucomatous loss in with superior and nasal field loss (black arrow).
Figure 7: Right eye fundus examination revealed vertical cup-disc ratio of 0.9:1 with bipolar rim thinning.
Figure 8:
Left eye fundus examination showed g with a vertical cup disc ratio of 0.7:1 with inferior rim thinning.
Figure 9: RE RNFL OCT showed significant RNFL loss in each sector and also globally (blue arrow in fig 9c). The flooring effect associated with reduced RNFL thickness is associated with a saw tooth appearance as seen in Figure 9b and 9d (red arrows).
Figure 10: LE RNFL OCT showed RNFL loss in temporo superior sector (blue arrow in Fig 10c) and global RNFL loss. Note the presence of  RNFL Retinoschisis (red arrow) in figure 10b.

She was started on combination eye drop (brimonidine tartrate and timolol maleate) BD and tablet acetazolamide 250 mg ½ tablet BD. 
On 2 week follow up her IOP was 24 mmHg and 26 mmHg in RE and LE respectively. She was advised to undergo trabeculectomy for IOP control in RE and Yag-PI in LE.
She underwent  Yag-PI in the LE followed by  trabeculectomy in the RE. Post surgery she had a large cystic bleb and an IOP of 22 mmHg which came down to 9 mmHg,  8 months post surgery. Her IOP in LE was 33 mmHg post Yag-PI on combination eye drop brimonidine tartrate + timolol maleate BD.   Patient was advised to undergo trabeculectomy in LE for better IOP control

Discussion

Pigment dispersion syndrome (PDS) is an ocular condition characterized by dispersion of iris pigment throughout the eye. PDS can be associated with ocular hypertension (OH) or glaucoma (PG) and is usually bilateral. Among several theories regarding the etiology of PDS, the hypoperfusion and iris hypoplasia, mechanical contacts and rubbing of the iris against the zonular bundles, and the reverse pupillary block are most important(1). Campbell found a close correlation between the proximity of the anterior zonular bundles with the mid-peripheral transillumination defects, suggesting mechanical rubbing of the posterior iris pigment as the cause of PDS(1).The most probable mechanism causing PDS is the reverse pupillary block. Karickhoff reported that higher aqueous pressure in the anterior chamber might cause a backward bowing of the iris as the posterior chamber collapses(2). Physiological events such as blinking, accommodation, ocular movements, and exercise trigger the reverse-pupillary block. Eyes with PDS have a more extensive irido-lenticular contact area, favoring the rise in the AC aqueous humor pressure. The relative higher pressure in the anterior chamber will lead to a reverse pupillary block with subsequent pigment dispersion(2).

The syndrome is characterized by the deposition of pigment on the posterior corneal surface, wide open angles on gonioscopy with uniform and heavy pigmentation of trabecular meshwork, slit like radial transillumination defects in the iris. The iris is inserted posteriorly and shows a concave configuration in the mid periphery. This feature is best demonstrated by ultrasound biomicroscopy (UBM) or anterior segment OCT(3)

 Early PDS diagnosis is crucial to detect patients with pigment-related ocular hypertension that can eventually lead to pigmentary glaucoma (PG).  Treatment of PG includes medical management, lasers and surgical management. Miotic treatment produces a convex iris configuration, and may help in  inhibiting pigment liberation. All anti-glaucoma medication used in POAG can be used in PG. Laser iridotomy equalizes the pressure between the AC and the PC, relieving reverse-pupillary block, flattening the iris and reversing posterior iris bowing to prevent further pigment release and hence it can be used in early PG. Trabeculectomy has been reported as the most effective treatment for PG, with fewer eyes deteriorating compared with eyes on medical therary(1).

Our patient presented with advanced pigmentary glaucoma with significantly raised IOP and RNFL loss in BE. We could not demonstrate iris transillumination in her. This may be because Indian eyes are highly pigmented and the iris is thicker. The degree of pigmentary loss and dispersion may not be sufficient to induce iris transillumination defects unlike in caucasian subjects where the iris is light coloured and thin and may have less pigment, thereby leading to the development of iris transillumination defects. Gonioscopy showed highly pigmented trabecular meshwork. Laser PI helps to equalize AC and PC pressure, therefore a laser PI was done for her. However it failed to control IOP. This may have been anticipated, since there was at presentation a significant elevation of IOP and therefore the Laser PI may not be significantly beneficial in influencing the elevated IOP at this stage when a permanent  decrease in outflow has set in.  Since the patient had significant visual field loss and significant RNFL damage, she was advised trabeculectomy with MMC. Patient underwent the surgical procedure in the RE and has responded well with significant reduction in the IOP.  She has been advised to undergo glaucoma surgery in the left eye also following the inability to reduce IOP  with laser PI. 

ReadWise

  1. 1.Andres Bustamante-Arias, Raul E. Ruiz-Lozano, J. Carlos Alvarez-Guzman, Sara Gonzalez-Godinez, Alejandro Rodriguez-Garcia, Pigment dispersion syndrome and its implications for glaucoma,Survey of Ophthalmology, 2021, doi: https://doi.org/10.1016/j.survophthal.2021.01.002
  2. 2.Niyadurupola N, Broadway DC. Pigment dispersion syndrome and pigmentary glaucoma–a major review. Clin Exp Ophthalmol. 2008 Dec;36(9):868-82. doi: 10.1111/j.1442-9071.2009.01920.x.
  3. 3.Reistad CE, Shields MB, Campbell DG, Ritch R, Wang JC, Wand M; American Glaucoma Society Pigmentary Glaucoma Iridotomy Study Group. The influence of peripheral iridotomy on the intraocular pressure course in patients with pigmentary glaucoma. J Glaucoma. 2005 Aug;14(4):255-9. doi: 10.1097/01.ijg.0000169383.05605.4b.
  4. 4.Harasymowycz PJ, Papamatheakis DG, Latina M, De Leon M, Lesk MR, Damji KF. Selective laser trabeculoplasty (SLT) complicated by intraocular pressure elevation in eyes with heavily pigmented trabecular meshworks. Am J Ophthalmol. 2005 Jun;139(6):1110-3. doi: 10.1016/j.ajo.2004.11.038.

Correspondence 

Dr Vinay Nangia
MS, FRCS, FRCOphth
Director 
Suraj Eye Institute
Nagpur
Email –education@surajeye.org

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