Dendritic cataract – A case series of an unusual cataract morphology in nine patients with diffuse retinal pigmentary changes

We describe a new morphology of cataract in subjects with retinal pigmentary changes. The study involved a review of case records (cross-sectional study of incoming clinic patients over 4 months) at a tertiary eye care centre in northern India. Nine subjects sharing this morphology of cataract (three bilateral, six unilateral) had some form of retinal pigmentary changes because of retinal dystrophies, laser sequelae, or self-settled retinal detachments. Subjects with asymmetrical retinal pigmentation in either eye had asymmetrical cataracts as well. During the study period, we failed to detect this form of cataract in the absence of primary or secondary retinal pigmentary changes. In conclusion, “dendritic” cataract being an unusual lenticular opacification very specific to patents with generalized retinal pigmentary changes may be considered as a biomarker for the latter. Efforts are necessary to understand its etiopathogenesis. Cataract is any opacity in the lens causing either visual obscuration or change in refractive index of the lens. The disorder can occur congenitally, developmentally, post trauma, or post ocular inflammation or can be age-related. The morphology of cataracts can be sometimes specific for the underlying cause; for example, blue dots or sutural opacities are congenital, zonular cataracts are developmental, rosettes are specific to trauma sequelae, and feathery cataracts follow vitrectomy. We incidentally detected this heretofore never described dendritiform (as it resembles the cyton of a neuron) pattern of posterior sub-capsular cataract[1] (PSC) in a patient with retinitis pigmentosa. Over the subsequent months, we came across eight more patients with the same morphology of cataract, and common to all these patients was some form of retinal pigmentary changes. Case Series Case 1 This was a 29-year-old male with complaints of diminished vision and night vision problem since childhood with “dendritic cataract” in either eye as shown [Figure 1a and b]. Bilateral fundus showed changes of retinitis punctata albiscens [Figure 1c and d].Figure 1: (a) Right eye and (b) left eye showing the dendritic cataract; (c) right and (d) left fundus showing retinitis punctata albicansCase 2 This was a 28-year-old male with intense photophobia and diminished vision in either eye since childhood. He had bilateral cataract, right “dendritic” and left evolving “dendritic” [Figure 2a and b], and rod-cone dystrophy as shown [Figure 2c and d].Figure 2: (a) Right eye showing typical and (b) left eye showing evolving dendritic cataract; (c) right and (d) left fundus showing changes of rod-cone dystrophyCase 3 This was a 40-year-old female with visual diminution and field defects with photophobia. She had bilateral dendritic cataract [Figure 3a and b] and rod-cone dystrophy as shown [Figure 3c and d].Figure 3: (a) Right and (b) left eye showing dendritic cataract; (c) right and (d) left fundus showing rod-cone dystrophyCase 4 This was a 25-year-old female with diminished vision in her left eye since childhood. The right eye lens was clear; the left eye had cataract as shown [Figure 4a and b]. She had sectoral retinitis pigmentosa in the right eye and complete retinitis pigmentosa in the left eye [Figure 4c and d].Figure 4: (a) Right eye showing minimal PSC; (b) left eye showing typical dendritic cataract; (c) right eye showing sectoral retinitis pigmentosa; (d) left eye showing complete retinitis pigmentosaCase 5 This 25-year-old male had similar cataract [Figure 5a]. He was operated for vitreoretinal surgery 7 years back with peripheral laser and cryo-scars [Figure 5b]. The other eye was normal.Figure 5: (a) Eye showing dendritic cataract; (b) fundus showing laser and cryotherapy scarsCase 6 This was a 40-year-old male with similar cataract in his left eye [Figure 6a]. Left eye fundus had pigmentary changes corresponding to self-settled retinal detachment [Figure 6b]. The right eye had inferior rhegmatogneous retinal detachment, but the lens was normal.Figure 6: (a) Eye showing dendritic cataract; (b) fundus showing changes of self-settled retinal detachmentCase 7 This was a 40-year-old male with vascular occlusion secondary to vasculitis which had been lasered in both eyes. The right eye had a small PSC, while the left eye had the typical dendritic cataract [Figure 7a and b]. The right eye had inferior 90 degrees of laser scars; the left eye had 300 degrees laser scars with more anterior extensions [Figure 7c and d].Figure 7: (a) Right eye showing minimal PSC; (b) left eye showing dendritic cataract; (c) right fundus showing 1 quadrant of retinal laser; (d) left eye showing more than 3 quadrants of retina laseredCase 8 This was a 50-year-old male patient who had the right eye with the typical dendritic cataract and a normal left eye lens [Figure 8a and b]. The right eye had 360 degree laser scars in the retina (cause unknown); the left eye had occasional pigmentary changes [Figure 8c and d].Figure 8: (a) Right eye showing evolving dendritic cataract; (b) left eye lens clear; (c) right eye having 360 degree pan retinal laser scars; (d) left eye having occasional retinal scarCase 9 This 24-year-old female had right eye dendritic cataract; the left eye lens was normal [Figure 9a and b]. Right eye fundus had corresponding unilateral retinal dystrophic changes; the other eye was normal [Figure 9c and d].Figure 9: (a) Right eye showing dendritic cataract; (b) left eye normal; (c) right eye fundus showing dystrophic changes; (d) left eye normalDiscussion This cataract had no gender predilection, evident predisposing factors, or systemic disorders. The morphology of the cataract was common to all affected patients and had characteristic features – a central irregular posterior sub-capsular plaque of a varying size from which slender extensions in the same plane were found to be emanating. These features resembled the dendritic cyton of a neuron. The retina in all these patients had some for pigmentary disorders, be it dystrophy, self-settled detachment, or laser scars. As we failed to detect this form of cataract in patients without retinal pigmentary changes, we feel that there is a strong association between the two. Further, cases 4–8 describe unilateral dendritiform cataractous changes only in the eye with the more severe pigmentary change. The word “amoeboid” has been described earlier for PSC in retinitis pigmentosa patients with a similar picture by Vasavada et al.[1] They found this typical cataract in seven out of eight eyes of retinitis pigmentosa which they studied. No pathomechanism has been described by the authors. They did not elucidate this type of PSC in any other ocular anomaly. Our observations further strengthen their findings and in addition highlight that these cataracts are not specific to retinitis pigmentosa but may be a concurrent change related to retinal pigmentary changes occurring from any cause – self-settled retinal detachment, laser sequelae, and so on. It could be possible that the proliferating/dysplastic retinal pigment epithelial cells might be producing some molecular factors with selective action on some lens fibers more than others. A similar shape of cataract is also seen in the left eye photograph of case 1 (retinal dystrophy) documented by Khan et al.,[2] but authors did not describe it as a separate entity and also did not provide any detailed description. In the literature, types of cataracts described in retinitis pigmentosa are PSC (most common), anterior polar, nuclear, and other non-specific types.[3,4] However, no characteristic type/pathognomic shape of PSC has been described so far. Cataract formation has been documented post argon retinal photo-coagulation,[5,6] but these were reported to be secondary to direct laser insult to the crystalline lens, were seen in the lenticular stroma, and were seen immediately after laser procedure. In addition to post-laser sequelae, we also found this characteristic cataract morphology in patients with retinitis puctata albiscens and self-settled retinal detachments with pigmentary changes. Development of PSC in retinitis pigmentosa has been linked to pro-inflammatory cytokines with similarity to uveitic cataracts. First of all, the cataract we have described is very different from uveitic cataracts as dendritic extensions are rarely seen in the latter. Moreover, we have two patients of vasculitis, who had the disease in both eyes, but the cataract was asymmetric, being more characteristic and advanced in the eye having a greater area of pigmentary change. Although an asymmetric magnitude of inflammation could have led to asymmetric cataract, our hypothesis that factors driving the pigmentary change are also inducing the cataract in a linear fashion also seems plausible. Conclusion Herein, we describe the characteristic features of a unique cataract morphology, “Dendritic cataract”, which was very specifically associated with significant primary or secondary retinal pigmentary changes. The paper is handicapped by the less sample size because of rarity of this cataract. We hypothesize that the hyperplastic/dysplastic retinal pigment epithelium might be responsible for release of some molecular factors that could target some lens fibers and not the others. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.