PHOTO ESSAY: Unilateral Christmas Tree Cataract
Save as PDFABSTRACT
A Christmas tree cataract is a rare, unique form of lens opacity. It typically appears as a group of several highly refractile colorful opacities that resemble ornaments decorating a Christmas tree, giving rise to its descriptive name. They are usually asymptomatic and discovered on routine examination. This case describes a patient with a Christmas tree cataract in the right eye.
KEYWORDS: Christmas tree cataract; myotonic dystrophy; polychromatic cataract; lens
CASE REPORT
A 66-year-old white male presented to the clinic for a routine diabetic exam with no visual complaints. Uncorrected distance visual acuity was 20/20 in both eyes. The systemic history was significant for well-controlled hypertension, hyperlipidemia, and Type 2 diabetes. A dilated fundus exam found no retinopathy, while the slit lamp showed multi-colored opacities in the superior temporal cortex of the right lens (Figure 1). There was no limitation of ocular motility, no ptosis, and the patient denied any symptoms of neuromuscular weakness, pain, or stiffness. A Christmas tree cataract was diagnosed, and routine monitoring was recommended. The patient has been followed routinely for 13 years with some progression of nuclear cataracts in both eyes, but the Christmas tree cataract has remained stable.
FIGURE 1: Christmas tree cataract in the cortex of the right lens.
DISCUSSION
Some morphologic presentations of cataracts can be quite distinctive, with remarkable shapes and colors that create a memorable picture. A Christmas tree cataract is a rare type of lenticular opacity, usually noted as an incidental finding on routine slit lamp examination. It appears as multiple clusters of polychromatic, highly reflective needle-like crystals in the cortex. These cataracts are most often unilateral and asymptomatic, although it is possible for them to progress to visual significance.1-3
The pathophysiology of this cataract has been debated. Hayes and Fisher proposed that the characteristic colors are diffractive due to parallel-sided stacks of fused cell membranes called membrane plates.4 Anders and Wollensak theorized that the crystals were cholesterol-based and were the result of local lens metabolism.5 Shun-Shin et al. conducted an analysis of twelve Christmas tree cataracts with scanning and transmission electron microscopy. They concluded that high levels of calcium accelerate the breakdown of membrane-associated proteins in the lens. Extracellular concentrations of the amino acid cystine in the cortex of the lens may then crystallize into the resultant colorful geometric forms.6
While these media opacities are generally idiopathic, in a subset of patients they have been associated systemically with autosomal-dominant myotonic dystrophy (dystrophia myotonica, DM). Myotonic dystrophy is a rare multisystem neuromuscular disease that is characterized by progressive muscle loss and weakness. It is estimated to occur in European populations at a frequency from 1 in 8,300 to 1 in 10,700, although recent genetic studies indicate that the prevalence may be higher. Two different genotypes, myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2), have been identified, with a diverse heterogeneity of clinical presentations ranging from mild myotonia and pain to cardiac dysrhythmia and respiratory arrest. It can manifest at any age, but 75% of classic myotonic dystrophy type 1 cases are diagnosed in adults between the second and fourth decades, with symptoms for type 2 usually starting in the second to sixth decade.7
Christmas tree cataracts are a common finding in myotonic dystrophy type 1 patients. One retrospective study of 23 subjects diagnosed with myotonic dystrophy type 1 found them in 13 people (56%).8 They were unilateral in 10 out of the 13 patients, and the mean age at diagnosis of the cataract was 47 years. Interestingly the cataract was reported to be the first sign of the type 1 disease in 11 of these 23 individuals; they were discovered during routine eye examinations, with the myotonic dystrophy diagnosis being made on average ten years afterward. Conversely, in another series of 18 patients with known Christmas tree cataracts, only 3 (16.7%) showed clinical signs of myotonic dystrophy type 1. In other words, while they are common in type 1 patients, most Christmas tree cataracts are probably idiopathic.9 Regardless, persons with these cataracts should be questioned for symptoms and considered for neuromuscular evaluation as indicated. In consultation with the primary care provider, it was not felt that additional testing was warranted for the patient presented in this case study.
REFERENCES
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- Hayes BP, Fisher RF. Ultrastructural appearances of a lens with marked polychromatic lustre: Evidence for diffraction as a cause. Br J Ophthalmol 1984;68:50-58.
- Anders N, Wollensak J. Christmas tree ornament cataract – an indication for disordered lipid metabolism? Klin Monbl Augenhelkd 1992;201:30-33.
- Shun-Shin GA, Vrensen G, Brown NP, et al. Invest Ophthalmol Vis Sci 1993;34(13): 3489-96.
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- Pagoulatos D, Kapsala Z, Makri O, Georgakopoulos CD. Christmas tree cataract and myotonic dystrophy type 1. Eye 2018;32:1794-95.
- Reiter C, Gramer E. Anticipation in patients with iridescent multicoloured posterior capsular lens opacities (“Christmas tree cataract”): The role in the diagnosis of myotonic dystrophy. Ophthalmologe 2009;106(12)1116-20.
Dr. Bennett graduated from The Ohio State University College of Optometry in 1988 and completed his ocular disease residency with the VA in Columbus and Chillicothe Ohio in 1989. He received his fellowship in the American Academy of Optometry in 1994. He has been with the James H. Quillen Veterans Affairs Medical Center since 1990, and is currently the optometric residency program director.
Dr. Nguyen received his Doctorate of Optometry from Southern College of Optometry in Memphis, Tennessee. He completed post-doctoral residency in ocular disease, primary care, and low vision at James H. Quillen VAMC. Dr. Nguyen also completed Optometric Medical Retina Fellowship at Bennett & Bloom Eye Centers, Advanced Competence in Medical Optometry, and anterior segment laser certification. He is a co-founder of Retina Rocks and a Fellow of the American Academy of Optometry. He is currently a senior optometrist at the Lawton North VA Outpatient Clinic in Fort Sill, OK.
