Introduction
Macular toxicity secondary to pentosan polysulfate sodium (PPS) (Elmiron; Janssen Pharmaceuticals, Beerse, Belgium) was first reported in 2018.1 PPS is the only U.S. Food and Drug Administration (FDA)-approved oral treatment for interstitial cystitis (IC), a painful urological condition2 affecting approximately 45 in 100,000 women and eight in 100,000 men globally.3 Pearce et al. initially described six patients with PPS exposure (approximately 400 mg/day, average of 15 years) presenting with pigmentary maculopathies characterized by paracentral hyperpigmentation and nodular excrescences on optical coherence tomography (OCT) at the level of the retinal pigment epithelium (RPE) with negative genetic testing.1
Subsequent articles investigated the strength of the association,4 described the phenotypic range of presentation,5,6 and generated screening recommendations.7 Diagnostic criteria described include: 1) bilateral pathology centered on the fovea, 2) paracentral macular hyperpigmented spots, 3) dense array of hyper- and hypoautofluorescent spots and reticular fundus autofluorescence (FAF) abnormalities, and 4) foci of nodular RPE enlargement on OCT corresponding to hyperreflectance on near-infrared reflectance imaging. Humphrey visual fields (HVF) ranged from normal to dense paracentral to central scotomas correlating with the degree of atrophy5 and analysis of electroretinography (ERG) revealed normal to diffusely dampened amplitudes.1,4–6
One study described findings on OCT angiography (OCTA) in a case with a choroidal neovascular membrane,8 and none commented on the foveal avascular zone (FAZ) or choriocapillaris layers. No studies have described electro-oculography (EOG) or quantified dark adaptometry (DA). The novel features described here may contribute to a better understanding of the pathophysiology of PPS maculopathy.
Patients and Methods
A chart review at two academic institutions was performed. Potential cases of PPS toxicity were identified if they did not exhibit classical findings or test results of their initial diagnosis and met criteria listed by Hanif et al.4,5 Table 1 lists patient demographics, referral diagnosis, and PPS exposure.
All patients underwent ocular examination (dilated fundus examinations, multimodal imaging, and genetic testing). Multimodal imaging included OCT and FAF using Spectralis (Heidelberg Engineering, Heidelberg, Germany). OCTA was performed for Patients 1 and 2 using the Plex Elite 9000 (Zeiss Meditec, Jena, Germany) and for Patients 3 and 4 using the Spectralis. OCTA morphometric analyses were performed with AngioTool open-source software ( http://angiotool.nci.nih.gov; NIH, Bethesda, MD), with analysis of the choriocapillaris following methodology reported by Sugano et al.9 Color thickness maps of the difference between RPE and Bruch's membrane evaluated RPE excrescence changes over time. Two authors (RM and AD) performed quality control and corrected segmentation errors manually from the automated segmentation performed on the Spectralis software (Heidelberg Eye Explorer V.1.10.0.0). The same software was utilized for total retina color thickness maps.
With appropriate genetic counseling, retinal dystrophy panels were performed: Patients 1 to 3 with a “My Retina Tracker” panel with next-generation sequencing of 266 genes (Blueprint Genetics, San Francisco, CA) and Patient 4 with inherited retinal dystrophy panel of 248 genes (Invitae, San Francisco, CA). Electrophysiology was performed following International Society for Clinical Electrophysiology of Vision protocols. The ERGs and EOGs for Patients 1 and 2 were performed using Espion E3 (Diagnosys LLC, Lowell, MA) and for Patient 4 with LKC Utas Sunburst (LKC, Gaithersburg, MD). DA was obtained in patients 1 and 2 (MonCV, Metrovision, Paris, France).
This research was performed in concordance with the tenets of the declaration of Helsinki and using Institutional Review Board approved protocols.
Results
Four patients were evaluated. Median age was 58 years, and three of the four patients were female. Difficulty reading was the most common symptom. All carried other initial diagnoses and presenting acuities ranged from 20/20 to count fingers (CF), with seven of eight eyes having acuity better than 20/50. Genetic testing was negative for definitive mutations, although Patient 4 had three variants of unknown significance (VUS) that did not explain the phenotype (Table 2).
Patient 1 had a diagnosis of Stargardt's, but after negative genetic testing and given her exposure history, her diagnosis was subsequently changed because, although she had discontinued the PPS 4 years previously, she had a 20-year cumulative exposure and characteristic FAF. Patient 2 had both an 18-year exposure to PPS and a 10-year exposure to hydroxychloroquine (HCQ) (Plaquenil; Sanofi, Paris, France) 400 mg daily, which was discontinued 6 years before for nonspecific macular changes. Lacking the typical bull's-eye pattern of HCQ toxicity, her clinical picture was more consistent with PPS, which she was still on. Patient 3 presented with supposedly idiopathic cystoid macular edema (CME) visible on fluorescein angiography (Figure A, available at www.healio.com/OSLIRetina) and had previously received intravitreal triamcinolone in the left eye. Her CME responded moderately to carbonic anhydrase inhibitors (CAIs) but with a 17-year PPS exposure and FAF findings, her diagnosis was changed to PPS toxicity. Patient 4 presented with worsening vision, a family history of age-related macular degeneration (ARMD) in his father and brother, and significant urological pathology with consequent 10-year PPS exposure. FAF findings and presentation were consistent with PPS toxicity, potentially with overlapping ARMD component.
OCTA imaging in Patients 1 and 2 demonstrated abnormal configurations of the foveal avascular zone (FAZ), including lack of circularity and one patient with an abnormally small FAZ. The vessel density was preserved at the superficial and deep plexus compared to controls (Figure 1). Choriocapillaris imaging of all patients revealed significant flow voids (average of 54.38%, standard deviation of 2.76), and choriocapillaris atrophy with visualization of large choroidal vessels (Figure 2). For reference, in normative data average flow void percentage has been reported as 14.44% (SD 4.35) in healthy patients after thresholding, consistent with our internal comparison with a normal OCTA (flow void percentage of 13.2%) (Figure 2). Sample size was inadequate to perform statistical analysis.
All patients demonstrated varying degrees of macular pigmentary changes on fundus photography (Figure B, available at www.healio.com/OSLI-Retina). FAF demonstrated a striking speckled pattern of hypo and hyperautofluorescence in Patients 1 to 3 and extensive hypoautofluorescence centered on the posterior pole and nerve in Patient 4 (Figure 3). Comparison to FAF images obtained 4 to 5 years prior demonstrated progression for Patient 1 with increased hyperautofluoresence, and for Patient 2 with increased hyperautofluoresence area.
OCT in all patients demonstrated nodular RPE abnormalities and excrescences, which in Patient 1 collapsed over time leaving ellipsoid band discontinuities without RPE atrophy (Figure 4). Patients 1 and 3 demonstrated CME, which responded to CAIs, and Patient 4 exhibited significant geographic papillomacular atrophy. Patients 1 and 2 demonstrated progressive global retinal thinning over 4 to 5 years (Figure 5), even after Patient 1 discontinued PPS 4 years prior.
Electrophysiology showed normal photopic and scotopic responses on ERG and normal Arden ratios on EOG in Patients 1 to 3 (Table 2). DA was prolonged in Patients 1 and 2 with rod-intercept time during a 30-minute period (Figure C, available at www.healio.com/OSLIRetina). Patients 1, 2, and 4 had recurrence of their bladder spasms on cessation of PPS, so significant in Patient 4 that he chose to resume the PPS and sought out other providers to dispense it.
Discussion
This study provides novel information about the phenotype of PPS maculopathy. We demonstrate progression of FAF changes over 4 to 5 years (despite PPS discontinuation in one patient), collapse of nodular RPE excrescences over time, and quantification of drastic total retinal thinning in two patients during a 4- to 5-year follow-up period. We further showed FAZ abnormalities and choriocapillaris dropout on OCTA, and functional quantification of the previously reported subjective DA symptoms.
The strength of this analysis is the length of follow-up with incidental multimodal imaging over 4 years. FAF findings demonstrate increasing intensity and area of characteristic changes, and OCT data show progressive macular thinning. The choroidal thickness during the same period remained stable, whether that implies a degree of direct retinal toxicity remains to be elucidated. OCT data for Patient 2 (Figure 4) demonstrated that the RPE conglomerations and excrescences are not necessarily static and can collapse over time, leaving an interrupted ez-band configuration without RPE atrophy. Hanif et al also reported this instability, noting that the RPE nodule and shape in one patient changed over a year, and another had resolution of the spots with onset of atrophy.5 The pathophysiological implications are still unclear.
The clinical findings were consistent with the largest case series of 35 patients from Hanif et al.5 in terms of PPS exposures, gender, RPE changes and FAF findings, possibility of CME, and negative genetic testing with normal ERGs. Another finding consistent with literature is the demonstrated progression in Patient 1 over 4 years despite cessation of PPS, also noted by Huckfeldt et al.10 Parallel to current understanding regarding HCQ toxicity,11,12 the progression may be reflective of progressive destabilization of damaged cells rather than the continued toxicity through a retained reservoir of PPS, but this theory is unproven.
We demonstrated significant choriocapillaris flow voids (average of 54.38% compared with literature normative data of approximately 14%).9 Varying degrees of choriocapillaris atrophy, as demonstrated by visualization of large choroidal vessels, may be secondary to RPE toxicity. One could also argue the reverse, given the significant degree and diffuse nature of choriocapillaris dropout compared to the relative amount of RPE atrophy. However, relative sparing of visual acuity except in cases of atrophy has been reported previously5,6 and could support the idea that the mechanism is primary damage to the choriocapillaris, which potentially causes the RPE changes. This hypothesis is supported by the relative sparing of the inner retina and photoreceptors on OCT except in cases of advanced atrophy or edema, as all patients had significant flow voids regardless of phenotype. Two patients had abnormal FAZ configurations, which is of uncertain significance given the small sample. We hypothesize the pan-retinal thinning and decreased retinal volume may affect FAZ configuration.
The previously postulated mechanism of PPS toxicity by Greenlee et al.13 was of RPE toxicity secondary to blockage of fibroblast growth factor (FGF) either from direct damage or the prevention of repair of damage to the RPE. The exact cellular mechanism requires further study, but the theory was based on previously noted associations of FGF with retinal organization in zebrafish14,15 and with maintaining photoreceptor health and regeneration in response to injury.16,17 The choroidal involvement we observed suggests either a more direct mechanism of damage to the RPE through damage to the choriocapillaris or perhaps potentiation of the proposed mechanism of FGF antagonism through additional damage to the blood-RPE barrier. Further analysis of more patients with OCTA and potentially other vascular imaging modalities is required to ascertain whether these choriocapillaris findings are as reproducible as the OCT and FAF findings. Longitudinal imaging of patients with intermediate exposures may demonstrate which changes manifest earliest and help elucidate the precise pathophysiological mechanism.
The study limitations include small sample size, and the potential for confounding factors- especially in Patient 2 with concomitant HCQ use and Patient 4 with the unknown degree of macular degeneration and the presence of genetic VUS on the RP1 gene, resulting in a replacement of glycine with serine at codon 796. This variant has not been reported previously in patients with retinitis pigmentosa (RP), is present in population databases, in-silico tools show the resulting change to be tolerated or benign (SIFT and Polyphen, respectively) and the demonstrated phenotype was inconsistent with RP. Patient 4 also had the confounding factor of a potential ARMD component. However, compared to his similarly aged brother, the clinical picture was drastically different and the striking pattern of RPE changes implicates PPS. One might hypothesize that baseline ARMD resulted in a lower toxic threshold given that he presented with worst phenotype and atrophy with the smallest exposure (10 years). Further research is required to ascertain causation and factors associated with poorer prognoses.
These cases highlight the importance of considering alternate diagnoses when confronted with pigmentary maculopathies carrying diagnoses without proven genetic mutations or with atypical presentations. When considering medication toxicities, in patients (such as Patient 2) with multiple prolonged high-risk exposures, attention to the clinical presentations and FAF is key. Although hydroxychloroquine and PPS toxicity take years to develop and can progress despite cessation, full-blown hydroxychloroquine toxicity presents typically with a “bull'seye” parafoveal pattern of photoreceptor loss in most Caucasian patients,12 whereas PPS toxicity appears to manifest most apparently at the RPE with focal reticular excrescences. The potential for overlapping toxicities has not yet been explored. Both hydroxychloroquine and PPS are individually very effective in treating their respective associated conditions, and all four patients had recurrence of their IC symptoms on cessation of PPS. A detailed discussion with the patient is crucial in deciding at what level of findings to recommend cessation versus dose reduction of one or both medications.
The preponderance of evidence suggests a need for further inquiry into the association and potential screening of all patients on PPS, and the ideal timing of screening. Data are lacking in patients with intermediate exposures (between 1 and 10 years). The onset of symptoms in Patient 1 correlating with the onset of medication use, and the progressive nature over time may imply a relatively quick potential onset time with an additive effect, but further study is required especially given recent population studies without robust associations at low levels of exposure.18
Although the most striking findings with PPS toxicity are found with FAF, multifaceted testing may contribute to diagnosis. Potential OCTA findings are discussed above. Screening and evaluation may include questions about and measuring DA, as subjective difficulty has been reported as a significant initial finding5 and two of two patients in this series had times greater than 30 minutes. More rapid tests validated in evaluating DA in AMD patients19 may be feasible for these patients. Because prolonged DA times are also found in AMD and other macular disorders, this may not be diagnostic but could prove helpful in supporting the diagnosis. Similarly, electrophysiological analysis such as ERG and EOG are critical to evaluating unknown maculopathies, even in the setting of PPS exposure.
Conclusions
Patients with long-term exposure to PPS may present with various pre-existing diagnoses but most PPS toxicity cases manifest with a specific constellation of OCT, FAF, and OCTA findings. Established maculopathy patients should be questioned regarding exposure to PPS, especially with negative genetic testing or atypical presentations. For patients with CME, CAIs can be effective and may need to be continued long after the PPS has been withdrawn. Patients can have progressive RPE changes even after medication discontinuation, and vascular changes may imply mechanisms of toxicity involving both the choriocapillaris and RPE. The finding of significant choriocapillaris dropout may inform understanding of the pathophysiology.
References
- Pearce WA, Chen R, Jain N. Pigmentary Maculopathy Associated with Chronic Exposure to Pentosan Polysulfate Sodium. Ophthalmology. 2018;125(11):1793–1802. doi:10.1016/j.ophtha.2018.04.026 [CrossRef] PMID:29801663
- Nickel JC, Moldwin R. FDA BRUDAC 2018 Criteria for Interstitial Cystitis/Bladder Pain Syndrome Clinical Trials: Future Direction for Research. J Urol. 2018;200(1):39–42. doi:10.1016/j.juro.2018.02.011 [CrossRef] PMID:29452126
- Patnaik SS, Laganà AS, Vitale SG, et al. Etiology, pathophysiology and biomarkers of interstitial cystitis/painful bladder syndrome. Arch Gynecol Obstet. 2017;295(6):1341–1359. doi:10.1007/s00404-017-4364-2 [CrossRef] PMID:28391486
- Hanif AM, Shah R, Yan J, et al. Strength of Association between Pentosan Polysulfate and a Novel Maculopathy. Ophthalmology. 2019;126(10):1464–1466. doi:10.1016/j.ophtha.2019.04.024 [CrossRef] PMID:31004677
- Hanif AM, Armenti ST, Taylor SC, et al. Phenotypic Spectrum of Pentosan Polysulfate Sodium-Associated Maculopathy: A Multi-center Study. JAMA Ophthalmol. 2019;137(11):1275. doi:10.1001/jamaophthalmol.2019.3392 [CrossRef] PMID:31486843
- Hanif AM, Yan J, Jain N. Pattern Dystrophy: An Imprecise Diagnosis in the Age of Precision Medicine. Int Ophthalmol Clin. 2019;59(1):173–194. doi:10.1097/IIO.0000000000000262 [CrossRef] PMID:30585925
- Ferguson TJ, Geraets RL, Barker MA. Chronic use of pentosan polysulfate sodium associated with risk of vision-threatening disease. Int Urogynecol J Pelvic Floor Dysfunct. 2019;30(3):337–338. doi:10.1007/s00192-018-3850-9 [CrossRef] PMID:30612180
- Mishra K, Patel TP, Singh MS. Choroidal Neovascularization Associated with Pentosan Polysulfate Toxicity. Ophthalmol Retina. 2020;4(1):111–113. doi:10.1016/j.oret.2019.08.006 [CrossRef] PMID:31570285
- Sugano Y, Sekiryu T, Furuta M, et al. Morphometrical evaluation of the choriocapillaris imaged by swept-source optical coherence tomography angiography. Clin Ophthalmol. 2018;12:2267–2276. doi:10.2147/OPTH.S179634 [CrossRef] PMID:30464388
- Huckfeldt RM, Vavvas DG. Progressive Maculopathy After Discontinuation of Pentosan Polysulfate Sodium. Ophthalmic Surg Lasers Imaging Retina. 2019;50(10):656–659. doi:10.3928/23258160-20191009-10 [CrossRef] PMID:31671200
- Marmor MF, Kellner U, Lai TYY, Lyons JS, Mieler WFAmerican Academy of Ophthalmology. Revised recommendations on screening for chloroquine and hydroxychloroquine retinopathy. Ophthalmology. 2011;118(2):415–422. doi:10.1016/j.ophtha.2010.11.017 [CrossRef] PMID:21292109
- Marmor MF, Kellner U, Lai TYY, Melles RB, Mieler WFAmerican Academy of Ophthalmology. Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision). Ophthalmology. 2016;123(6):1386–1394. doi:10.1016/j.ophtha.2016.01.058 [CrossRef] PMID:26992838
- Greenlee T, Hom G, Conti T, Babiuch AS, Singh R. Re: Pearce et al.: Pigmentary maculopathy associated with chronic exposure to pentosan polysulfate sodium (Ophthalmology. 2018;125:1793–1802). Ophthalmology. 2019;126(7):e51. doi:10.1016/j.ophtha.2018.12.037 [CrossRef] PMID:31229012
- Vinothkumar S, Rastegar S, Takamiya M, Ertzer R, Strähle U. Sequential and cooperative action of Fgfs and Shh in the zebrafish retina. Dev Biol. 2008;314(1):200–214. doi:10.1016/j.ydbio.2007.11.034 [CrossRef] PMID:18177854
- Hernández-Bejarano M, Gestri G, Spawls L, et al. Opposing Shh and Fgf signals initiate nasotemporal patterning of the zebrafish retina. Development. 2015;142(22):3933–3942. doi:10.1242/dev.125120 [CrossRef] PMID:26428010
- Hochmann S, Kaslin J, Hans S, et al. Fgf signaling is required for photoreceptor maintenance in the adult zebrafish retina. PLoS One. 2012;7(1):e30365. doi:10.1371/journal.pone.0030365 [CrossRef] PMID:22291943
- Qin Z, Kidd AR III, Thomas JL, et al. FGF signaling regulates rod photoreceptor cell maintenance and regeneration in zebrafish. Exp Eye Res. 2011;93(5):726–734. doi:10.1016/j.exer.2011.09.003 [CrossRef] PMID:21945172
- Ludwig CA, Vail D, Callaway NF, Pasricha MV, Moshfeghi DM. Pentosan polysulfate sodium exposure and drug-induced maculopathy in commercially insured patients in the United States. Ophthalmology. 2020;127(4):535–543. doi:10.1016/j.ophtha.2019.10.036 [CrossRef] PMID:31899034
- Jackson GR, Scott IU, Kim IK, Quillen DA, Iannaccone A, Edwards JG. Diagnostic sensitivity and specificity of dark adaptometry for detection of age-related macular degeneration. Invest Ophthalmol Vis Sci. 2014;55(3):1427–1431. doi:10.1167/iovs.13-13745 [CrossRef] PMID:24550363
Patient Demographics and Pentosan Polysulfate Exposures
Case No. | Gender | Ethnicity | Age (Years) | Urologic Diagnosis | Presenting BCVA (Snellen) | Presenting Ocular Symptoms | Diagnosis at Referral | PPS Daily Dose (mg) | Weight (kgs) | Dose by Body Weight (mg/kg) | Duration Exposure (Years) | Cumulative Dosage (g) |
---|
1 | Female | White | 59 | IC | 20/40 OD; 20/25 OS | Difficulty reading; Dark adaptation; photopsias | Stargardt disease | 300* | 77.11 | 3.9 | 20 | 2190 |
2 | Female | White | 57 | IC | 20/25 OU | Difficulty reading; dark adaptation; Blue photopsias | Hydroxychloroquine toxicity ** | 400 | 56.9 | 7.02 | 18 | 2628 |
3 | Female | White | 42 | IC | 20/20 OD 20/30-2 OS | Blurry vision | idiopathic CME | 300 | 61.6 | 4.87 | 17 | 1862 |
4 | Male | White | 77 | IC, CBPS, Kidney stones | 20/40 OD; CF OS | Difficulty reading; Worsening vision OU | ARMD | 300 | 86.1 | 3.48 | 10.3 | 1128 |
| Median | 58 | | Median | 300 | 14.29 | 4.38 | 17.5 | 2026 |
Standard Deviation | 14.34 | Standard Deviation: | 50 | 14.29 | 1.57 | 16.325 | 632.7 |
Genetic Testing, Multimodal Imaging, and Electrophysiology Findings
Case No. | OCT | FAF | OCTA Findings* | Choriocapillaris Flow Void % ** | ERG Findings | Genetic Testing*** | VUS | EOG Arden Ratio | DA RIT Time (min) |
---|
1 | Nodular excrescences at the level of the RPE, CME | Reticular mixed hyper- and hypofluorescence centered on posterior pole bilaterally | Abnormal FAZ configuration, Flow voids at the level of the choriocapillaris | 55.8 | Normal | Negative | None | 4.88 OD 3.11 OS | > 30 |
2 | Nodular excrescences at the level of the RPE | Reticular mixed hyper- and hypofluorescence centered on posterior pole bilaterally | Abnormal FAZ configuration Flow voids at the level of the choriocapillaris | 52.7 | Normal | Negative | CNGA1 (het) | 4.06 OD 4.00 OS | > 30 |
3 | Nodular excrescences at the level of the RPE, CME | Reticular mixed hyper- and hypofluorescence centered on posterior pole bilaterally | Flow voids at the level of the choriocapillaris | 51.5 | Normal | Negative | None | 1.67 OD 3.46 OS | N/A |
4 | Nodular excrescences at the level of the RPE, geographic papillomacular atrophy | Central hypo-autofluorescence geographically with reticular changes at the edges | Flow voids at the level of the choriocapillaris | 57.5 | N/A | Negative | MYO7A (het); (pAla1541Ser), TUBCP6(het); (Silent) RP1 (het) c.2386G>A (p.Gly796Ser) | N/A | N/A |
| Median | 54.25 | |
Standard Deviation | 2.76 |