Farzin Forooghian

Central Serous Chorioretinopathy: Update on Pathophysiology and Treatment

Recent technological advances--new pathophysiological insights, new imaging techniques for diagnosis and management, and new treatments--have led to an improved understanding of central serous chorioretinopathy (CSC). The primary role of the choroid has become more widely accepted with widespread use of indocyanine green angiography. Optical coherence tomography (OCT), and particularly enhanced depth imaging OCT, demonstrate a thickened and engorged choroid. Adaptive optics, fundus autofluorescence, multifocal electroretinography, microperimetry, and contrast sensitivity testing reveal that patients with even a mild course suffer previously undetected anatomic and functional loss. Although focal laser and photodynamic therapy are the current standard of care for persistent subretinal fluid in CSC, they are not appropriate in all cases, and the optimal timing of intervention remains unclear.

Evaluation of time domain and spectral domain optical coherence tomography in the measurement of diabetic macular edema

PURPOSE To evaluate macular thickness and volume measurements and their intrasession repeatability in two optical coherence tomography (OCT) systems: the Stratus OCT, a time domain system, and the Cirrus HD-OCT, a spectral domain system (both by Carl Zeiss Meditec, Inc., Dublin, CA), in the context of diabetic macular edema (DME). METHODS Thirty-three eyes of 33 diabetic patients with clinically significant macular edema (CSME) were scanned in a single session by a single operator on both OCT systems. Macular thickness measurements of nine standard macular subfields and total macular volume were obtained and analyzed. Bland-Altman plots were constructed to assess agreement in macular measurements. Intraclass correlation coefficients (ICCs), coefficients of repeatability (CR(W)), and coefficients of variation (CV(W)) were used to assess intrasession repeatability. RESULTS Macular thickness in nine retinal subfields and macular volume were significantly higher in the Cirrus HD-OCT system compared with the Stratus OCT system. Subfield thickness and total volume measurements, respectively, were 30 to 55 microm and 3.2 mm(3) greater for the Cirrus HD-OCT system compared with the Stratus OCT system. Both Stratus OCT and Cirrus HD-OCT systems demonstrated high intrasession repeatability, with overlapping ranges for CR(W), CV(W), and ICC. Repeatability measures (CR(W) and CV(W)) differed significantly between systems in only one of nine subfields (outer temporal subfield). CONCLUSIONS Absolute measures of macular thickness and volume in patients with DME differed significantly in magnitude between the Stratus OCT and Cirrus HD-OCT systems. However, both OCT systems demonstrated high intrasessional repeatability. Although the two systems may not be used interchangeably, they appear equally reliable in generating macular measurements for clinical practice and research.

Tachyphylaxis after intravitreal bevacizumab for exudative age-related macular degeneration.

Purpose: To describe tachyphylaxis to intravitreal bevacizumab (IVB) in patients with exudative age-related macular degeneration (AMD). Methods: We retrospectively reviewed the records of 59 consecutive patients treated with IVB at the National Eye Institute over a 14-month period and identified cases demonstrating loss of treatment efficacy as revealed by spectral domain optical coherence tomography. We defined tachyphylaxis as a loss of therapeutic response to IVB 28 ± 7 days after administration in an eye that had previously demonstrated a therapeutic response in the same time interval. Results: Five patients (six eyes) were identified as developing tachyphylaxis after repeated treatment with IVB. High-dose IVB (2.50 mg) did not restore therapeutic response in these patients. Bilateral tachyphylaxis to IVB was seen after an episode of unilateral postinjection anterior uveitis. After the first treatment of IVB, the median time taken to develop tachyphylaxis was 100 weeks (range: 31–128 weeks), and the median number of IVB treatments to the development of tachyphylaxis was 8 treatments (range: 5–10 treatments). Conclusion: Tachyphylaxis can occur after long-term intravitreal use of bevacizumab in patients with AMD. The precise mechanism of tachyphylaxis is unclear, but both local and/or systemic factors may be involved.

Oral Fluoroquinolones and the Risk of Retinal Detachment

CONTEXT Fluoroquinolones are commonly prescribed classes of antibiotics. Despite numerous case reports of ocular toxicity, a pharmacoepidemiological study of their ocular safety, particularly retinal detachment, has not been performed. OBJECTIVE To examine the association between use of oral fluoroquinolones and the risk of developing a retinal detachment. DESIGN, SETTING, AND PATIENTS Nested case-control study of a cohort of patients in British Columbia, Canada, who had visited an ophthalmologist between January 2000 and December 2007. Retinal detachment cases were defined as a procedure code for retinal repair surgery within 14 days of a physician service code. Ten controls were selected for each case using risk-set sampling, matching on age and the month and year of cohort entry. MAIN OUTCOME MEASURE The association between retinal detachment and current, recent, or past use of an oral fluoroquinolone. RESULTS From a cohort of 989,591 patients, 4384 cases of retinal detachment and 43,840 controls were identified. Current use of fluoroquinolones was associated with a higher risk of developing a retinal detachment (3.3% of cases vs 0.6% of controls; adjusted rate ratio [ARR], 4.50 [95% CI, 3.56-5.70]). Neither recent use (0.3% of cases vs 0.2% of controls; ARR, 0.92 [95% CI, 0.45-1.87]) nor past use (6.6% of cases vs 6.1% of controls; ARR, 1.03 [95% CI, 0.89-1.19]) was associated with a retinal detachment. The absolute increase in the risk of a retinal detachment was 4 per 10,000 person-years (number needed to harm = 2500 computed for any use of fluoroquinolones). There was no evidence of an association between development of a retinal detachment and β-lactam antibiotics (ARR, 0.74 [95% CI, 0.35-1.57]) or short-acting β-agonists (ARR, 0.95 [95% CI, 0.68-1.33]). CONCLUSION Patients taking oral fluoroquinolones were at a higher risk of developing a retinal detachment compared with nonusers, although the absolute risk for this condition was small.

Relationship between Photoreceptor Outer Segment Length and Visual Acuity in Diabetic Macular Edema

Purpose: The purpose of this study was to quantify photoreceptor outer segment (PROS) length in 27 consecutive patients (30 eyes) with diabetic macular edema using spectral domain optical coherence tomography and to describe the correlation between PROS length and visual acuity. Methods: Three spectral domain–optical coherence tomography scans were performed on all eyes during each session using Cirrus HD-OCT. A prototype algorithm was developed for quantitative assessment of PROS length. Retinal thicknesses and PROS lengths were calculated for 3 parameters: macular grid (6 × 6 mm), central subfield (1 mm), and center foveal point (0.33 mm). Intrasession repeatability was assessed using coefficient of variation and intraclass correlation coefficient. The association between retinal thickness and PROS length with visual acuity was assessed using linear regression and Pearson correlation analyses. The main outcome measures include intrasession repeatability of macular parameters and correlation of these parameters with visual acuity. Results: Mean retinal thickness and PROS length were 298 μm to 381 μm and 30 μm to 32 μm, respectively, for macular parameters assessed in this study. Coefficient of variation values were 0.75% to 4.13% for retinal thickness and 1.97% to 14.01% for PROS length. Intraclass correlation coefficient values were 0.96 to 0.99 and 0.73 to 0.98 for retinal thickness and PROS length, respectively. Slopes from linear regression analyses assessing the association of retinal thickness and visual acuity were not significantly different from 0 (P > 0.20), whereas the slopes of PROS length and visual acuity were significantly different from 0 (P < 0.0005). Correlation coefficients for macular thickness and visual acuity ranged from 0.13 to 0.22, whereas coefficients for PROS length and visual acuity ranged from −0.61 to −0.81. Conclusion: Photoreceptor outer segment length can be quantitatively assessed using Cirrus HD-OCT. Although the intrasession repeatability of PROS measurements was less than that of macular thickness measurements, the stronger correlation of PROS length with visual acuity suggests that the PROS measures may be more directly related to visual function. Photoreceptor outer segment length may be a useful physiologic outcome measure, both clinically and as a direct assessment of treatment effects.

Fundus Autofluorescence Imaging of the White Dot Syndromes

OBJECTIVE To characterize the fundus autofluorescence (FAF) findings in patients with white dot syndromes (WDSs). METHODS Patients with WDSs underwent ophthalmic examination, fundus photography, fluorescein angiography, and FAF imaging. Patients were categorized as having no, minimal, or predominant foveal hypoautofluorescence. The severity of visual impairment was then correlated with the degree of foveal hypoautofluorescence. RESULTS Fifty-five eyes of 28 patients with WDSs were evaluated. Visual acuities ranged from 20/12.5 to hand motions. Diagnoses included serpiginous choroidopathy (5 patients), birdshot retinochoroidopathy (10), multifocal choroiditis (8), relentless placoid chorioretinitis (1), presumed tuberculosis-associated serpiginouslike choroidopathy (1), acute posterior multifocal placoid pigment epitheliopathy (1), and acute zonal occult outer retinopathy (2). In active serpiginous choroidopathy, notable hyperautofluorescence in active disease distinguished it from the variegated FAF features of tuberculosis-associated serpiginouslike choroidopathy. The percentage of patients with visual acuity impairment of less than 20/40 differed among eyes with no, minimal, and predominant foveal hypoautofluorescence (P < .001). Patients with predominant foveal hypoautofluorescence demonstrated worse visual acuity than those with minimal or no foveal hypoautofluorescence (both P < .001). CONCLUSIONS Fundus autofluorescence imaging is useful in the evaluation of the WDS. Visual acuity impairment is correlated with foveal hypoautofluorescence. Further studies are needed to evaluate the precise role of FAF imaging in the WDSs.

Hypoxia-inducible factor expression in human RPE cells

Background: Hypoxia-inducible factor (HIF) is a common transcription factor for many angiogenic proteins. Retinal pigment epithelial (RPE) cells are an important source of angiogenic factors in the retina. The expression of HIF, its regulation by proline hydroxylase (PHD) enzymes, and its downstream regulation of angiogenic factors like vascular endothelial growth factor (VEGF) and erythropoietin (EPO) was studied in RPE cells in order to determine some of the molecular mechanisms underlying ischaemic retinal disease. Methods: ARPE-19 cells were cultured for various times under hypoxic conditions. Cellular HIF and PHD isoforms were analysed and quantified using western blot and densitometry. VEGF and EPO secreted into the media were assayed using enzyme-linked immunosorbent assay (ELISA). Messenger RNA (mRNA) was quantified using real-time quantitative reverse transcriptase polymerase chain reaction (qPCR). RNA interference was achieved using siRNA techniques. Results: HIF-1&agr; was readily produced by ARPE-19 cells under hypoxia, but HIF-2&agr; and HIF-3&agr; could not be detected even after HIF-1&agr; silencing. HIF-1&agr; protein levels showed an increasing trend for the first 24 h while HIF-1&agr; mRNA levels fluctuated during this time. After 36 h HIF-1&agr; protein levels declined to baseline levels, a change that was coincident with a rise in both PHD2 and PHD3. Silencing HIF-1&agr; significantly decreased VEGF secretion. Significant production of EPO could not be detected at the protein or mRNA level. Conclusions: HIF-1&agr; appears to be the main isoform of HIF functioning in ARPE-19 cells. Under hypoxia, HIF-1&agr; levels are likely self-regulated by a feedback loop that involves both transcriptional and post-translational mechanisms. VEGF production by human RPE cells is regulated by HIF-1&agr;. EPO was not produced in significant amounts by RPE cells under hypoxic conditions, suggesting that other cells and/or transcription factors in the retina are responsible for its production.

Fundus Autofluorescence in Type 2 Idiopathic Macular Telangiectasia: Correlation with Optical Coherence Tomography and Microperimetry

PURPOSE To use multiple imaging methods to investigate patients with type 2 idiopathic macular telangiectasia (IMT) at different disease severity stages so as to characterize and categorize disease progression through the full spectrum of disease phenotypes. DESIGN Observational case series. METHODS Twelve patients with type 2 IMT (22 eyes) examined with fundus photography, angiography, optical coherence tomography imaging, fundus autofluorescence (FAF), and microperimetry testing in an institutional setting. RESULTS Eyes examined by multiple imaging methods were classified into 5 proposed categories (0 through 4): category 0 (fellow) eyes had normal results on all imaging methods. Category 1 eyes had increased foveal autofluorescence on FAF imaging as the only imaging abnormality. Category 2 eyes had increased foveal autofluorescence together with funduscopic and angiographic features typical of type 2 IMT. Category 3 eyes had additional evidence of foveal atrophy on optical coherence tomography, and category 4 eyes had all the above features plus clinically evident pigment clumping. FAF signal increased in intensity in the foveal region from category 0 through category 3, whereas category 4 eyes demonstrated a mixed pattern of increased and decreased FAF signal. CONCLUSIONS The findings here outline a sequence of progressive changes seen with multiple imaging methods in advancing stages of disease. Increase in foveal autofluorescence is an early anatomic change in type 2 IMT that may precede typical clinical and angiographic changes. Loss of macular pigment density in the fovea and a changing composition of fluorophores in the retinal pigment epithelium may underlie these changes on FAF in the fundus.

Alterations in the Intraocular Cytokine Milieu after Intravitreal Bevacizumab

PURPOSE Several complications after intravitreal bevacizumab (IVB) treatment have been described including tears of the retinal pigment epithelium and tractional retinal detachment. The etiology of these complications remains unclear. The purpose of this study was to characterize changes in the intraocular levels of inflammatory cytokines after IVB as a possible explanation for these complications. METHODS Twenty-nine patients with proliferative diabetic retinopathy (PDR) undergoing pars plana vitrectomy (PPV) for vitreous hemorrhage (VH) with IVB pretreatment were prospectively enrolled. Aqueous humor samples were taken at the time of IVB pretreatment and approximately 1 week later at the time of PPV. Multiplex cytokine arrays were used to assay 20 different cytokines. Multivariate general linear regression was performed to determine differences in cytokine levels between the two study visits. Proportional hazards regression was performed to determine the relationship between cytokine levels at PPV and postoperative outcomes. RESULTS After treatment with IVB, vascular endothelial growth factor (VEGF) concentrations in the aqueous humor decreased (P = 0.0003), whereas the concentrations of IL-8 and transforming growth factor (TGF)-beta(2) increased after IVB (P < 0.03). The level of IL-8 at the time of PPV was associated with the occurrence of recurrent VH after surgery (hazard ratio, 1.32; P = 0.02). CONCLUSIONS Alterations in the intraocular inflammatory cytokine milieu occur after IVB injection, possibly as a compensatory mechanism in response to VEGF inhibition. The increased concentrations of inflammatory cytokines after IVB may be clinically significant and may be responsible for some of the complications after IVB.

Visual Acuity Outcomes after Cataract Surgery in Patients with Age-Related Macular Degeneration: Age-Related Eye Disease Study Report No. 27

OBJECTIVE To evaluate visual acuity outcomes after cataract surgery in patients with varying degrees of age-related macular degeneration (AMD). DESIGN Cohort study. PARTICIPANTS A total of 4757 participants enrolled in the Age-Related Eye Disease Study (AREDS), a prospective, multicenter, epidemiological study of the clinical course of cataract and AMD and a randomized controlled trial of antioxidants and minerals. METHODS Standardized lens and fundus photographs, performed at baseline and annual visits, were graded by a centralized reading center using standardized protocols for severity of AMD and lens opacities. History of cataract surgery was obtained every 6 months. Analyses were conducted using multivariate logistic regression. MAIN OUTCOME MEASURE The change in best-corrected visual acuity (BCVA) after cataract surgery compared with preoperative BCVA. RESULTS Visual acuity results were analyzed for 1939 eyes that had cataract surgery during AREDS. The mean time from cataract surgery to measurement of postoperative BCVA was 6.9 months. After adjustment for age at surgery, gender, type, and severity of cataract, the mean change in visual acuity at the next study visit after the cataract surgery was as follows: Eyes without AMD gained 8.4 letters of acuity (P<0.0001), eyes with mild AMD gained 6.1 letters of visual acuity (P<0.0001), eyes with moderate AMD gained 3.9 letters (P<0.0001), and eyes with advanced AMD gained 1.9 letters (P = 0.04). The statistically significant gain in visual acuity after cataract surgery was maintained an average of 1.4 years after cataract surgery. CONCLUSIONS On average, participants with varying severity of AMD benefited from cataract surgery with an increase in visual acuity postoperatively. This average gain in visual acuity persisted for at least 18 months.