High-resolution adaptive optics findings in talc retinopathy
© Soliman et al. 2015
Received: 11 June 2015
Accepted: 30 June 2015
Published: 24 July 2015
Talc retinopathy is a recognized ocular condition characterized by the presence of small, yellow, glistening crystals found inside small retinal vessels and within different retinal layers. These crystals can be associated with retinal vascular occlusion and ischemia. Different diagnostic modalities have been used previously to characterize the retinal lesions in talc retinopathy. Adaptive optics, a high resolution imaging technique, is used to evaluate the location, appearance and distribution of talc crystals in a case of talc retinopathy.
KeywordsAdaptive optics Talc retinopathy Crystalline retinopathy
Talc retinopathy is a recognized ocular condition characterized by the presence of small, yellow, glistening crystals found inside small retinal vessels and within different retinal layers . The crystals are thought to be secondary to emboli derived from talc which is an insoluble inert particulate filler material (excipient) used in preparation of certain oral (methylphenidate hydrochloride, methadone, pentazocine and amphetamine), inhalational (crack cocaine), and intravenous (cocaine and heroin) drugs [2, 3]. When these oral tablets are crushed and injected intravenously, most of the talc particles get trapped in the pulmonary vasculature except for very small particles (<7 μm) that escape from pulmonary capillary bed and reach the eye through systemic circulation [3, 4]. Ocular findings usually develop after chronic intravenous drug abuse and range from asymptomatic crystalline retinopathy to ischemic manifestations of capillary non perfusion and neovascularization . Adaptive optics (AO) retinal imaging has been used to study retinal vessels in various retinal vascular diseases such as diabetic retinopathy and age-related macular degeneration. In this report, we used AO camera (rtx1; Imagine Eyes) and spectral domain optical coherence tomography to evaluate the location, appearance and distribution of talc crystals in a case of talc retinopathy.
Different diagnostic modalities have been used previously to characterize the retinal lesions in talc retinopathy. Fundus examination usually reveals a characteristic appearance of these crystals, which are found inside the small retinal vessels and throughout the fundus. Talc crystals should be differentiated from other conditions causing crystalline retinopathy and from other causes of retinal embolism. Classification of the detected materials was based on clinical diagnosis. Careful examination of these crystals have shown that they most commonly represent an accumulation or clumps of multiple talc particles rather than a single embolus of talc . Absence of retinal granuloma as may be seen in the lungs of IV drug users might be due to the blood retinal barrier. A vascular filling defect is seen on fluorescein angiography when the embolus block the small retinal blood vessels causing capillary non perfusion and retinal ischemia . With the introduction of SD-OCT, the locations of these crystals with respect to retinal layers have been demonstrated. They were found distributed among the inner retinal layers where retinal blood vessels reside .
In this report, SD-OCT has highlighted the structural damage of the retina as demonstrated by thinning of inner retinal layers most probably due to vascular occlusion as well as revealed the location of these crystals which were seen in all layers of the inner retina. AO allowed better elucidation of the clumps of the particles that form the talc microembolus with crystals clearly seen impacted inside the retinal arterioles and venules of the posterior pole as well as within the surface of the retina (Fig. 1) . In addition, AO imaging enabled establishment of the extent of tissue involvement through detecting numerous tiny talc particles that were neither evident on clinical examination nor by OCT. Talc particles smaller than 5 μm in size are generally not discerned clinically and are beyond the resolution limits of conventional OCT. However, they were made visible using the high resolution AO imaging technique. Detection of these tiny particles revealed retinal involvement in this case to be far more severe than apparent clinically. Therefore, AO imaging can be used as a valuable tool for screening of current or past drug abuse prior to the development of retinopathy and appearance of talc crystals. Moreover, this finding may add new insights into the extent of retinal involvement in different retinal diseases, which may be more extensive than what we think it really is. This may lead to modification of diseases classifications and might contribute to changing treatment paradigm with earlier intervention.
Written informed consent was obtained from the patient.
spectral domain optical coherence tomography
MK: Conception and design, AO imaging, analysis and interpretation of data and drafting the manuscript. SS: SD-OCT imaging, interpretation of data and participation in manuscript draft. MH: Participation in the abstract, interpretation of data. AS: Figures editing and interpretation. AA: Color photograph acquisition and interpretation. YJS: Revision. VG: Acquisition of data and revision. QDN: Revision and final approval of the version to be published. All authors read and approved the final manuscript.
The Truhlsen Eye Institute at the University of Nebraska Medical Center has received an unrestricted Grant from Research to Prevent Blindness. Dr. Vikas Gulati has also received a grant from the National Eye Institute (K23 EY023266).
Compliance with ethical guidelines
Competing interests The authors declare that they have no competing interests.
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