Intraretinal crystalline deposits in neovascular age-related macular degeneration

DESCRIBING THE LOCATION AND MORPHOLOGY OF THE DOTS IN WHITE DOT FOVEA USING ADAPTIVE OPTICS

PURPOSE

To characterize the white dots in white dot fovea, an entity chiefly described in Japan, using adaptive optics imaging and propose a hypothesis regarding their origin.

METHOD

The patient underwent comprehensive ophthalmic examination, including color and green monochromatic fundus photography, fluorescein angiography, spectral-domain optical coherence tomography, and adaptive optics imaging.

RESULTS

An asymptomatic 66-year-old Korean woman presented with bilateral white, glistening deposits in a ring pattern around the fovea of both eyes. The dots were highly reflective on green monochromatic images, were not visible on fluorescein angiography, and appeared hyperreflective in the inner retina using spectral-domain optical coherence tomography. Adaptive optics showed polygonal granules ranging from 1 to 10 μ m in size. The patient denied any systemic disorder or the use of any medications related to crystalline retinopathy. The patient had lived in Japan for 35 years before just moving to the United States.

CONCLUSION

The location, small size, and polygonal shape of the dots in white dot fovea are suggestive of intraretinal deposition of crystals, and not cells on the surface of the fovea as has been previously proposed. Carotenoid deposition related to dietary habits is a plausible cause because of the similarity to other retinopathies associated to these compounds.

Characterization of West African Crystalline Macular Dystrophy in the Ghanaian Population

OBJECTIVE/PURPOSE

West African Crystalline Maculopathy (WACM) is characterized by the presence of macular hyper-refractile crystal-like deposits. Although the underlying pathophysiology has not been elucidated, a few biological drivers have been proposed. We analysed a large WACM case series to gain a more robust understanding of its features and etiology.

DESIGN

Prospective, Cross-sectional cohort study.

SUBJECTS/PARTICIPANTS

Participants with WACM were selected from the large cohort recruited into the Ghana Age-Related Macular Degeneration Study (Ghana AMD Study).

METHODS

Demographic and detailed medical histories, full ophthalmic examinations, digital colour fundus photographs and optical coherence tomography (OCT) images were obtained. All WACM cases were evaluated by three retina experts. Crystal numbers, location, and distribution were determined. Associations between WACM and Caucasian AMD risk variants were assessed using Firth's bias-reduced logistic regression, including age and gender as covariates.

MAIN OUTCOME MEASURES

Phenotypic features of, and genetic associations with, WACM.

RESULTS

WACM was identified in 106 eyes of 53 participants: 22 were bilateral and 24 unilateral. Grading for AMD was not possible in one eye of seven WACM participants; therefore, laterality was not assessed in these subjects. Thirty-eight participants were female, and 14 male; gender was unrecorded for one participant. Mean age was 68.4 years (range 45-101). OCT demonstrated typical WACM crystals, which were more easily identified at high contrast and predominantly located at the inner limiting membrane (ILM). In eyes with co-pathology, crystals localised deeper in the inner retina with wider retinal distribution over co-pathology lesions. There was no age or gender association. A significant association was observed between the complement factor H (CFH) 402H risk variant and WACM.

CONCLUSION

This study confirms localization of crystals adjacent to the ILM, and distribution over lesions in eyes with co-pathology. Evaluation of OCT images under high contrast allows improved identification. WACM may be associated with the CFH-CFHR5 AMD-risk locus identified amongst Caucasians; however, it is also possible that combination of crystals and the CFH 402H allele increases the risk for developing late AMD. Further analyses using larger sample sizes are warranted to identify causalities between genotype and WACM phenotype.

A case of proliferative diabetic retinopathy in which scintillating particles appeared in the intravitreal cavity after laser photocoagulation

BACKGROUND

To report a case of proliferative diabetic retinopathy (PDR) exhibiting the appearance of scintillating particles presumed to be crystallin inside the intravitreal cavity after laser photocoagulation.

CASE PRESENTATION

A 56-year-old male patient presented at our outpatient clinic after becoming aware of decreased vision in his right eye. Ocular examination performed at the patient's initial visit revealed a massive preretinal macular hemorrhage due to PDR in his right eye. Fundus fluorescein angiography revealed extensive retinal non-perfusion areas and neovascularization in both eyes. However, no opacity was observed in the intravitreal cavity of his left eye. Vitreous surgery was performed on the patient's right eye after ultrasonic phacoemulsification aspiration and intraocular lens implantation. Post surgery, the corrected VA in that eye improved from 0.1 to 1.0. In correlation with the treatment performed on the patient's right eye, we began panretinal photocoagulation on his left eye. Examination performed prior to the patient's third session of panretinal photocoagulation revealed a large number of scintillating particles in the posterior vitreous gel in front of the retina. Examination via slit-lamp microscopy revealed that the particles were of varied hues, and closely resembled a 'Christmas tree' cataract. No posterior vitreous detachment was observed, and since these particles were situated as if captured in the posterior vitreous gel, no eye-movement-associated mobility of the particles was observed. Since the cloudiness was not severe enough to interfere with photocoagulation, additional photocoagulation was performed, and the patient is currently under observation. Six months have now passed since the fourth photocoagulation procedure was performed, and there has been no change in the state of the particles. Optical coherence tomography imaging revealed no change before and after the panretinal photocoagulation. The corrected VA in his left eye has remained at 1.0 during the postoperative follow-up period.

CONCLUSIONS

We speculate that the production of crystallin in the retina in this case was triggered by the photocoagulation procedure performed for diabetic retinopathy.

The Onion Sign in Neovascular Age-Related Macular Degeneration Represents Cholesterol Crystals

PURPOSE

To investigate the frequency, natural evolution, and histologic correlates of layered, hyperreflective, subretinal pigment epithelium (sub-RPE) lines, known as the onion sign, in neovascular age-related macular degeneration (AMD).

DESIGN

Retrospective observational cohort study and experimental laboratory study.

PARTICIPANTS

Two hundred thirty eyes of 150 consecutive patients with neovascular AMD and 40 human donor eyes with histopathologic diagnosis of neovascular AMD.

METHODS

Spectral-domain optical coherence tomography (SD OCT), near-infrared reflectance (NIR), color fundus images, and medical charts were reviewed. Donor eyes underwent multimodal ex vivo imaging, including SD OCT, before processing for high-resolution histologic analysis.

MAIN OUTCOME MEASURES

Presence of layered, hyperreflective sub-RPE lines, qualitative analysis of their change in appearance over time with SD OCT, histologic correlates of these lines, and associated findings within surrounding tissues.

RESULTS

Sixteen of 230 eyes of patients (7.0%) and 2 of 40 donor eyes (5.0%) with neovascular AMD had layered, hyperreflective sub-RPE lines on SD OCT imaging. These appeared as refractile, yellow-gray exudates on color imaging and as hyperreflective lesions on NIR. In all 16 patient eyes, the onion sign persisted in follow-up for up to 5 years, with fluctuations in the abundance of lines and association with intraretinal hyperreflective foci. Patients with the onion sign disproportionately were taking cholesterol-lowering medications (P=0.025). Histologic analysis of 2 donor eyes revealed that the hyperreflective lines correlated with clefts created by extraction of cholesterol crystals during tissue processing. The fluid surrounding the crystals contained lipid, yet was distinct from oily drusen. Intraretinal hyperreflective foci correlated with intraretinal RPE and lipid-filled cells of probable monocytic origin.

CONCLUSIONS

Persistent and dynamic, the onion sign represents sub-RPE cholesterol crystal precipitation in an aqueous environment. The frequency of the onion sign in neovascular AMD in a referral practice and a pathology archive is 5% to 7%. Associations include use of cholesterol-lowering medication and intraretinal hyperreflective foci attributable to RPE cells and lipid-filled cells of monocyte origin.

Imaging of Sub-retinal Pigment Epithelial Linear Structures in Patients with Age-Related Macular Degeneration

Purpose

To evaluate hyperreflective linear structures (HLS), as assessed using spectral-domain optical coherence tomography (SD-OCT), identified under the retinal pigment epithelium (RPE) in patients with age-related macular degeneration (AMD).

Methods

This retrospective observational case study was conducted on 427 eyes of 408 consecutive patients who were scheduled to undergo anti-vascular endothelial growth factor (anti-VEGF) therapy for AMD. Patients with HLS under the RPE were investigated based on the SD-OCT findings at baseline or during the follow-up period. The associations between HLS and the lesion subtypes, localization in SD-OCT, clinical findings, and structural change after anti-VEGF treatment were also investigated.

Results

HLS were identified in 18 eyes of 16 patients. From the eyes with HLS, 12 eyes (66.7%) were diagnosed with retinal angiomatous proliferation (RAP), 4 eyes (22.2%) were diagnosed with occult choroidal neovascularization, and the remaining 2 eyes (11.1%) were diagnosed with polypoidal choroidal vasculopathy. HLS were multifocal and exhibited multilocalization under the RPE in all the eyes. Although it was difficult to identify these structures in the clinical findings at baseline, crystalline deposits correlated with the linear bands were observed during the follow-up period in 16 eyes (88.9%). After the anti-VEGF treatments, the HLS remained between the Bruch membrane and RPE or combined with the fibrovascular component.

Conclusions

HLS are rare SD-OCT findings found in patients with AMD, found in only 4.2% of the patients examined in this study. HLS were found especially in RAP lesions.

Retinal crystals in type 2 idiopathic macular telangiectasia

PURPOSE

To characterize the phenotype and investigate the associations of intraretinal crystalline deposits in a large cohort with type 2 idiopathic macular telangiectasia (MacTel).

DESIGN

Case-control study.

PARTICIPANTS

Patients with and without retinal crystals from the Macular Telangiectasia Project, an international multicenter prospective study of type 2 MacTel.

METHODS

Grading of stereoscopic 30-degree color fundus (CF), confocal blue light reflectance (CBR), red-free (RF), and infrared (IR) images was performed according to the MacTel Natural History Study protocol and staged using the classification system devised by Gass and Blodi. Spectral domain-optical coherence tomography (SD-OCT) and adaptive optics imaging were used for a finer analysis of the phenotype. Associations between crystals and other characteristics of the disease, as well as potential risk factors, were investigated.

MAIN OUTCOME MEASURES

Presence of crystals, fundus signs of MacTel, clinical characteristics, and presence of potential risk factors of MacTel.

RESULTS

Of 443 probands enrolled in the MacTel study, 203 (46%) had crystalline deposits present; 60% of the cases were bilateral at baseline. Eyes with crystals had a mean letter score of 70.7 (standard deviation [SD] = 15.9), whereas those without crystals had a mean letter score of 66.5 (SD = 15.5, P < 0.001). Crystals were present at all stages of the disease and showed high reflectivity within a wide wavelength range. They were located at the anterior surface of the nerve fiber layer, arranged along the nerve fibers, within an annular area centered on the fovea. Significant associations of crystalline deposits were found with a loss of retinal transparency, macular pigment optical density (MPOD) loss, fluorescein leakage, retinal thickness, and a break in the inner segment/outer segment junction line. Associations with environmental risk factors were not found.

CONCLUSIONS

Intraretinal crystals are a frequent phenomenon associated with type 2 MacTel. They may appear at all stages and aid in the early diagnosis of the disease. Their morphology further implicates Müller cells in the pathogenesis of the disease. Insight into their physical and chemical properties may provide clues to the metabolic pathways involved in the pathogenesis of the disease.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.