Igor Kozak

The Role of Abnormal Vitreomacular Adhesion in Age-related Macular Degeneration: Spectral Optical Coherence Tomography and Surgical Results

PURPOSE To assess the incidence of vitreomacular adhesion and traction in age-related macular degeneration (AMD), and to evaluate surgical treatment in a subset of patients with choroidal neovascularization (CNV) nonresponsive to anti-neovascular growth factor (anti-VEGF) treatment. DESIGN Retrospective observational case-control and interventional case series. METHODS Spectral optical coherence tomography, combined with simultaneous scanning laser ophthalmoscope (Spectral OCT/SLO), was performed in 170 eyes of 94 elderly patients, 61 with exudative AMD, 59 with nonexudative AMD, and 50 control eyes. The presence of hyaloid adhesion to the posterior pole, and vitreomacular traction (VMT) were determined. Five patients with VMT underwent surgical hyaloid removal. Best-corrected visual acuity (BCVA) and retinal thickness were evaluated as outcomes. RESULTS Hyaloid adhesion was present in 17 eyes with exudative AMD (27.8%), 15 eyes with nonexudative AMD (25.4%), and eight control eyes (16%). Significant difference was found among the groups (P = .002). Among the eyes with hyaloid adhesion, VMT was shown in 10 eyes (59%) with exudative AMD, two eyes (13%) with nonexudative AMD, and one control eye (12%). VMT was associated with the severity of AMD (P = .0082). The area of hyaloid adhesion was significantly smaller than and concentric to the area of CNV complex in eyes with exudative AMD. Eyes with VMT that underwent surgery experienced a modest improvement of BCVA and decrease of retinal thickness. CONCLUSIONS Hyaloid adhesion to the macula is associated with AMD, and frequently causes VMT in eyes with CNV. Tractional forces may antagonize the effect of anti-VEGF treatment, and cause pharmacological resistance in a subpopulation of patients. Future studies are needed to define the role of vitreoretinal surgery in such cases. Spectral OCT/SLO allows careful diagnosis and follow-up.

Choroidal Volume Variations with Age, Axial Length, and Sex in Healthy Subjects: A Three-Dimensional Analysis

PURPOSE To demonstrate the 3-dimensional choroidal volume distribution in healthy subjects using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT) and to evaluate its association with age, sex, and axial length. DESIGN Retrospective case series. PARTICIPANTS A total of 176 eyes from 114 subjects with no retinal or choroidal disease. METHODS The EDI SD-OCT imaging studies of healthy patients who had undergone a 31-raster scanning protocol on a commercial SD-OCT device were reviewed. Manual segmentation of the choroid was performed by 2 retinal specialists. A macular choroidal volume map and 3-dimensional topography were automatically created by the built-in software of the device. Mean choroidal volume was calculated for each Early Treatment Diabetic Retinopathy Study (ETDRS) subfield. Regression analyses were used to evaluate the correlation between macular choroidal volume and age, sex, and axial length. MAIN OUTCOME MEASURES Three-dimensional topography and ETDRS-style volume map of the choroid. RESULTS Three-dimensional topography of the choroid and volume map was obtained in all cases. The mean choroidal volume was 0.228 ± 0.077 mm(3) for the center ring and 7.374 ± 2.181 mm(3) for the total ETDRS grid. The nasal quadrant showed the lowest choroidal volume, and the superior quadrant showed the highest choroidal volume. The temporal and inferior quadrants did not show different choroidal volume values. Choroidal volume in all the EDTRS rings was significantly correlated with axial length after adjustment for age (P < 0.0001), age after adjustment for axial length (P < 0.0001), and sex after adjustment for axial length (P < 0.05). Choroidal volume decreases by 0.54 mm(3) (7.32%) for every decade and by 0.56 mm(3) (7.59%) for every millimeter of axial length. Male subjects have a 7.37% greater choroidal volume compared with that of female subjects. CONCLUSIONS Enhanced depth imaging SD-OCT is a noninvasive and well-tolerated procedure with an excellent ability to visualize 3-dimensional topography of the choroid and to measure choroidal volume at the posterior pole using manual segmentation. Age and axial length are inversely correlated with choroidal volume, most likely leading to changes in retinal metabolic support in elderly, highly myopic patients. Sexual differences should be considered when interpreting an EDI SD-OCT scan of the choroid. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Lanosterol reverses protein aggregation in cataracts

The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.

Complement factor H genotypes impact risk of age-related macular degeneration by interaction with oxidized phospholipids

The rs1061170T/C variant encoding the Y402H change in complement factor H (CFH) has been identified by genome-wide association studies as being significantly associated with age-related macular degeneration (AMD). However, the precise mechanism by which this CFH variant impacts the risk of AMD remains largely unknown. Oxidative stress plays an important role in many aging diseases, including cardiovascular disease and AMD. A large amount of oxidized phospholipids (oxPLs) are generated in the eye because of sunlight exposure and high oxygen content. OxPLs bind to the retinal pigment epithelium and macrophages and strongly activate downstream inflammatory cascades. We hypothesize that CFH may impact the risk of AMD by modulating oxidative stress. Here we demonstrate that CFH binds to oxPLs. The CFH 402Y variant of the protective rs1061170 genotype binds oxPLs with a higher affinity and exhibits a stronger inhibitory effect on the binding of oxPLs to retinal pigment epithelium and macrophages. In addition, plasma from non-AMD subjects with the protective genotype has a lower level of systemic oxidative stress measured by oxPLs per apolipoprotein B (oxPLs/apoB). We also show that oxPL stimulation increases expression of genes involved in macrophage infiltration, inflammation, and neovascularization in the eye. OxPLs colocalize with CFH in drusen in the human AMD eye. Subretinal injection of oxPLs induces choroidal neovascularization in mice. In addition, we show that the CFH risk allele confers higher complement activation and cell lysis activity. Together, these findings suggest that CFH influences AMD risk by modulating oxidative stress, inflammation, and abnormal angiogenesis.

Repeatability and Reproducibility of Manual Choroidal Volume Measurements Using Enhanced Depth Imaging Optical Coherence Tomography

PURPOSE To evaluate the repeatability and reproducibility of manual choroidal volume (CV) measurements by spectral domain- optical coherence tomography (SD-OCT) using enhanced depth imaging (EDI). METHODS Sixty eyes of 32 patients with or without any ocular chorioretinal diseases were enrolled prospectively. Thirty-one choroidal scans were performed on each eye, centered at the fovea, using a raster protocol. Two masked observers demarcated choroidal boundaries by using built-in automated retinal segmentation software on two separate sessions. Observers were masked to each others and their own previous readings. A standardized grid centered on the fovea was positioned automatically by OCT software, and values for average CVs and total CVs in three concentric rings were noted. The agreement between the intraobserver measurements or interobserver measurements was assessed using the concordance correlation coefficient (CCC). Bland-Altman plots were used to assess the clinically relevant magnitude of differences between inter- and intraobserver measurements. RESULTS The interobserver CCC for the overall average CV was very high, 0.9956 (95% confidence interval [CI], 0.991-0.9968). CCCs for all three Early Treatment Diabetic Retinopathy Study concentric rings between two graders was 0.98 to 0.99 (95% CI, 0.97-0.98). Similarly intraobserver repeatability of two graders also ranged from 0.98 to 0.99. The interobserver coefficient of reproducibility was approximately 0.42 (95% CI, 0.34-0.5 mm(3)) for the average CV. CONCLUSIONS CV measurement by manual segmentation using built-in automated retinal segmentation software on EDI-SD-OCT is highly reproducible and repeatable and has a very small range of variability.

Correlation between Spectral-Domain Optical Coherence Tomography and Fundus Autofluorescence at the Margins of Geographic Atrophy

PURPOSE To study the appearance of margins of geographic atrophy in high-resolution optical coherence tomography (OCT) images and to correlate those changes with fundus autofluorescence (FAF) imaging. DESIGN Retrospective, observational case study. METHODS Patients with geographic atrophy secondary to dry age-related macular degeneration were assessed by means of spectral-domain OCT (Spectralis Heidelberg Retinal Angiograph/OCT; Heidelberg Engineering, Heidelberg, Germany; or OTI Inc, Toronto, Canada) as well as autofluorescence imaging (Heidelberg Retinal Angiograph or Spectralis; Heidelberg Engineering). The outer retinal layer alterations were analyzed in the junctional zone between normal retina and atrophic retina and were correlated with corresponding FAF. RESULTS Twenty-three eyes of 16 patients between 62 and 96 years of age were examined. There was a significant association between OCT findings and the FAF findings (r = 0.67; P < .0001). Severe alterations of the outer retinal layers at margins on spectral-domain OCT correspond significantly to increased autofluorescence; smooth margins on OCT correspond significantly to normal FAF (kappa, 0.7348; P < .0001). CONCLUSIONS Spectral-domain OCT provides in vivo insight into the pathogenesis of geographic atrophy and its progression. Visualization of reactive changes in the retinal pigment epithelial cells at the junctional zone and correlation with increased FAF; secondary to increased lipofuscin, together these methods may serve as determinants of progression of geographic atrophy.

Correlation between morphologic features on spectral-domain optical coherence tomography and angiographic leakage patterns in macular edema.

Purpose: The purpose of this study was to determine the morphologic patterns of angiographic macular edema using simultaneous colocalization of fluorescein angiography and spectral-domain optical coherence tomography (SD-OCT) images in diabetes, epiretinal membrane, uveitic and pseudophakic cystoid macular edema, and vein occlusion. Methods: Eighty-seven consecutive patients (107 eyes) with macular edema from 5 different etiologies were imaged by simultaneous scanning laser ophthalmoscopy/OCT to study the morphologic patterns of edema on SD-OCT and then correlated/colocalized with the fluorescein angiographic patterns of leakage. Statistical analysis was done to analyze the differences in the morphologic OCT pattern by different diseases. Results: Spectral-domain OCT characteristics of macular edema showed a significant difference across different diseases (P = 0.037). Cystic fluid pockets were found to be more commonly seen in patients with diabetic macular edema and retinal vein occlusions, whereas those cases with macular edema secondary to epiretinal membrane showed noncystic changes on OCT. Seventy of the 107 eyes had diffuse angiographic leakage, and the remaining 37 eyes had cystoid leakage on angiography. Of the 70 eyes with diffuse leakage, 24.28% showed microcysts on SD-OCT in the area of edema, and 70% eyes had diffuse thickening or distorted architecture without cyst. All 37 eyes with cystoid leakage showed cysts in the area of edema by SD-OCT. A total of 3.73% of eyes with fluorescein angiographic leakage had no abnormalities on SD-OCT. Conclusion: Eyes with diabetic macular edema and retinal vein occlusions have a significantly higher incidence of cyst formation on SD-OCT. There was no correlation between visual acuity and cyst formation. Diffuse noncystoid angiographic macular edema may show microcysts on SD-OCT, but diffuse edema is more commonly associated with thickening or distortion of the retinal layers without cyst formation. Cystoid leakage on fluorescein angiography is always associated with cystic changes on SD-OCT.

Clinical Evaluation and Treatment Accuracy in Diabetic Macular Edema Using Navigated Laser Photocoagulator NAVILAS

PURPOSE To evaluate the clinical use and accuracy of a new retinal navigating laser technology that integrates a scanning slit fundus camera system with fluorescein angiography (FA), color, red-free, and infrared imaging capabilities with a computer steerable therapeutic 532-nm laser. DESIGN Interventional case series. PARTICIPANTS Eighty-six eyes of 61 patients with diabetic retinopathy and macular edema treated by NAVILAS. METHODS The imaging included digital color fundus photographs and FA. The planning included graphically marking future treatment sites (microaneurysms for single-spot focal treatment and areas of diffuse leakage for grid pattern photocoagulation) on the acquired images. The preplanned treatment was visible and overlaid on the live fundus image during the actual photocoagulation. The NAVILAS automatically advances the aiming beam location from one planned treatment site to the next after each photocoagulation spot until all sites are treated. Aiming beam stabilization compensated for patients eye movements. The pretreatment FA with the treatment plan was overlaid on top of the posttreatment color fundus images with the actual laser burns. This allowed treatment accuracy to be calculated. Independent observers evaluated the images to determine if the retinal opacification after treatment overlapped the targeted microaneurysm. MAIN OUTCOME MEASURES Safety and accuracy of laser photocoagulation. RESULTS The images were of very good quality compared with standard fundus cameras, allowing careful delineation of target areas on FA. Toggling from infrared, to monochromatic, to color view allowed evaluation and adjustment of burn intensity during treatment. There were no complications during or after photocoagulation treatment. An analysis of accuracy of 400 random focal targeted spots found that the NAVILAS achieved a microaneurysm hit rate of 92% when the placement of the treatment circle was centered by the operating surgeon on the microaneurysm. The accuracy for the control group analyzing 100 focal spots was significantly lower at 72% (P<0.01). CONCLUSIONS Laser photocoagulation using the NAVILAS system is safe and achieves a higher rate of accuracy in photocoagulation treatments of diabetic retinopathy lesions than standard manual-technique laser treatment. Precise manual preplanning and positioning of the treatment sites by the surgeon is possible, allowing accurate and predictable photocoagulation of these lesions. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.

Assessing susceptibility to age-related macular degeneration with genetic markers and environmental factors

OBJECTIVES To evaluate the independent and joint effects of genetic factors and environmental variables on advanced forms of age-related macular degeneration (AMD), including geographic atrophy and choroidal neovascularization, and to develop a predictive model with genetic and environmental factors included. METHODS Demographic information, including age at onset, smoking status, and body mass index, was collected for 1844 participants. Genotypes were evaluated for 8 variants in 5 genes related to AMD. Unconditional logistic regression analyses were performed to generate a risk predictive model. RESULTS All genetic variants showed a strong association with AMD. Multivariate odds ratios were 3.52 (95% confidence interval, 2.08-5.94) for complement factor H, CFH rs1061170 CC, 4.21 (2.30-7.70) for CFH rs2274700 CC, 0.46 (0.27-0.80) for C2 rs9332739 CC/CG, 0.44 (0.30-0.66) for CFB rs641153 TT/CT, 10.99 (6.04-19.97) for HTRA1/LOC387715 rs10490924 TT, and 2.66 (1.43-4.96) for C3 rs2230199 GG. Smoking was independently associated with advanced AMD after controlling for age, sex, body mass index, and all genetic variants. CONCLUSION CFH confers more risk to the bilaterality of geographic atrophy, whereas HTRA1/LOC387715 contributes more to the bilaterality of choroidal neovascularization. C3 confers more risk for geographic atrophy than choroidal neovascularization. Risk models with combined genetic and environmental factors have notable discrimination power. CLINICAL RELEVANCE Early detection and risk prediction of AMD could help to improve the prognosis of AMD and to reduce the outcome of blindness. Targeting high-risk individuals for surveillance and clinical interventions may help reduce disease burden.

Optical coherence tomography-raster scanning and manual segmentation in determining drusen volume in age-related macular degeneration.

Purpose: Drusen are the hallmark of age-related macular degeneration (AMD), and substantial evidence exists that the amount of drusen and their effect on retinal pigment epithelium is a strong predictor of progression of AMD and vision loss. Until recently, it was not possible to quantitate the volume of the drusen. However, the use of image-stabilized scanning laser ophthalmoscope or spectral domain-optical coherence tomography (OCT) has enabled determination of drusen volume of this abnormal material. The purpose of this study was to assess the correlation of drusen volume with Age-Related Eye Disease Study (AREDS) grade and drusen area in dry AMD. Methods: Thirty-six eyes from 18 patients with nonexudative AMD with visual acuity between 20/16 and 20/160 were studied. Spectral domain-OCT or simultaneous OCT scans were taken as color fundus photographs (35°) of each eye. Early Treatment Diabetic Retinopathy Study visions were also recorded. The full AREDS score excluding late-stage AMD was determined by agreement between two trained observers. Drusen volume was determined by examination of a series of 96 spectral domain-OCT scans taken from arcade to arcade for a length of 6 mm. The volume was determined by calculating the drusen area in each scan and determining the drusen volume by calculating the effective volume of each cut using National Institutes of Health Image J. Drusen were identified and outlined manually, not using an automated algorithm. Results: There was a strong and significant correlation between drusen volume and AREDS-determined drusen area (P < 0.0001, r = 0.78). In addition, there was a correlation between AREDS classification and drusen volume (P = 0.023, r = 0.43) as determined by pairwise correlation. Conclusion: Drusen volume as determined by spectral domain-OCT correlates with AREDS-determined drusen area and AREDS grade in nonexudative AMD. The correlation is not perfect, however, because drusen area and volume average 40% and 82% of the variation, respectively. Drusen volume can provide additional information in grading the severity of eyes with dry AMD.