Showing papers by "Byron L. Lam published in 2015"

Diabetes Eye Screening in Urban Settings Serving Minority Populations: Detection of Diabetic Retinopathy and Other Ocular Findings Using Telemedicine

Abstract: Importance The use of a nonmydriatic camera for retinal imaging combined with the remote evaluation of images at a telemedicine reading center has been advanced as a strategy for diabetic retinopathy (DR) screening, particularly among patients with diabetes mellitus from ethnic/racial minority populations with low utilization of eye care. Objective To examine the rate and types of DR identified through a telemedicine screening program using a nonmydriatic camera, as well as the rate of other ocular findings. Design, Setting, and Participants A cross-sectional study (Innovative Network for Sight [INSIGHT]) was conducted at 4 urban clinic or pharmacy settings in the United States serving predominantly ethnic/racial minority and uninsured persons with diabetes. Participants included persons aged 18 years or older who had type 1 or 2 diabetes mellitus and presented to the community-based settings. Main Outcomes and Measures The percentage of DR detection, including type of DR, and the percentage of detection of other ocular findings. Results A total of 1894 persons participated in the INSIGHT screening program across sites, with 21.7% having DR in at least 1 eye. The most common type of DR was background DR, which was present in 94.1% of all participants with DR. Almost half (44.2%) of the sample screened had ocular findings other than DR; 30.7% of the other ocular findings were cataract. Conclusions and Relevance In a DR telemedicine screening program in urban clinic or pharmacy settings in the United States serving predominantly ethnic/racial minority populations, DR was identified on screening in approximately 1 in 5 persons with diabetes. The vast majority of DR was background, indicating high public health potential for intervention in the earliest phases of DR when treatment can prevent vision loss. Other ocular conditions were detected at a high rate, a collateral benefit of DR screening programs that may be underappreciated.

Risk factors for poor visual outcome in patients with idiopathic intracranial hypertension

Abstract: Objectives: Determine potential risk factors for progressive visual field loss in the Idiopathic Intracranial Hypertension Treatment Trial, a randomized placebo-controlled trial of acetazolamide in patients with idiopathic intracranial hypertension and mild visual loss concurrently receiving a low sodium, weight reduction diet. Methods: Logistic regression and classification tree analyses were used to evaluate potential risk factors for protocol-defined treatment failure (>2 dB perimetric mean deviation [PMD] change in patients with baseline PMD −2 to −3.5 dB or >3 dB PMD change with baseline PMD −3.5 to −7 dB). Results: Seven participants (6 on diet plus placebo) met criteria for treatment failure. The odds ratio for patients with grades III to V papilledema vs those with grades I and II was 8.66 (95% confidence interval [CI] 1.65–∞, p = 0.025). A 1-unit decrease in the number of letters correct on the ETDRS (Early Treatment Diabetic Retinopathy Study) chart at baseline was associated with an increase in the odds of treatment failure by a factor of 1.16 (95% CI 1.04–1.30, p = 0.005). Compared with female participants, the odds ratio for male participants was 26.21 (95% CI 1.61–433.00, p = 0.02). The odds of treatment failure were 10.59 times higher (95% CI 1.63–116.83, p = 0.010) for patients with >30 transient visual obscurations per month vs those with ≤30 per month. Conclusions: Male patients, those with high-grade papilledema, and those with decreased visual acuity at baseline were more likely to experience treatment failure. All but one of these patients were treated with diet alone. These patients should be monitored closely and be considered for aggressive treatment of their idiopathic intracranial hypertension.

Retrograde degeneration of retinal ganglion cells in homonymous hemianopsia.

Abstract: Background The aim of this study was to demonstrate the relationship between topographic reduction in macular ganglion cell complex (GCC) thickness as detected with spectral-domain optical coherence tomography and visual field defects caused by ischemic occipital cortical injury. Methods This study was a retrospective review of all patients who presented to our eye institution between January 2012 and July 2014 with visual field defects secondary to ischemic cortical injury. The visual field defect pattern and mean deviation were analyzed. Retinal nerve fiber layer (RNFL) and macular GCC were both assessed with spectral-domain optical coherence tomography. Patients with any ocular pathology that could affect these measurements were excluded. The topographic relationship of visual field defect to reduction in GCC was specifically analyzed. Results Nine patients met the inclusion criteria. Their average age was 65 (57-73) years; eight were men and six had right hemianopsias. The laterality of the visual field defect was used to assign an affected and unaffected side of analysis for RNFL and GCC layer thickness. A right hemianopsia meant that the nasal fibers of the right eye and temporal fibers of the left eye were assigned as the "affected side", and the temporal fibers of the right eye and nasal fibers of the left eye were assigned as "unaffected". There was no statistically significant difference between affected and unaffected RNFL. However, there was a significant difference in GCC layer reduction between the affected and unaffected sides (P=0.029). Conclusion There is evidence of retrograde trans-synaptic retinal ganglion cell loss in patients with homonymous hemianopsias from cortical visual impairment. This relationship is reflected in thinning of the GCC and maintains the topographic relationship of the visual field defect.

Smoking causes blindness: time for eye care professionals to join the fight against tobacco.

Abstract: Sight is an important indicator of health and quality of life. Approximately, 3.4 million Americans 40 years of age and older are visually impaired or blind. Evidence suggests that smoking increases the risk of the most common sight-threatening conditions of eye disease. Half a century after the release of the 1964 landmark Surgeon General's report on smoking and health, tobacco smoking continues to be the leading public health problem in the United States, and nearly half a million adults annually die prematurely from smoking-related diseases. On the historic occasion of the 50(th) anniversary of the 1964 report, the 2014 Surgeon General's report is devoted to smoking and health. This report provides new evidence about the link between cigarette smoking and eye disease, which signifies a new role for eye-care professionals in tobacco control on two levels. First, on a clinical level, eye care professionals should integrate smoking cessation treatment in the standard care of patients' management in eye-care settings in order to motivate and help smoking patients in quitting smoking. Second, on a political level, eye care providers can serve as powerful public advocates against tobacco use, thereby significantly enhancing public awareness about the link between smoking and eye disease.

Choroidal Thickness in Eyes With Central Geographic Atrophy Secondary to Stargardt Disease and Age-Related Macular Degeneration

Abstract: Choroidal thickness (CT) measurements from eyes with similar areas of macular geographic atrophy (GA) secondary to age-related macular degeneration (AMD) and Stargardt disease (STGD) were compared to determine whether GA from different diseases had a similar or different effect on the underlying subfoveal choroid.Eyes with the diagnosis of central GA secondary to STGD and AMD were matched, with subfoveal CT measurements obtained from the central B-scan using an enhanced depth imaging protocol. The area of GA was measured using fundus autofluorescence (FAF) imaging. AMD eyes were divided into those with and without reticular pseudodrusen.A total of 22 eyes of 22 patients were included in the STGD and AMD groups and were matched with respect to the area of GA. The mean age of the STGD patients was 48.9 years (standard deviation [SD]=17.1), and the mean age was 81.8 years (SD=6.2) for the AMD patients. Mean area measurements of GA for the STGD and AMD groups were 5.4 mm2 (SD=4.1) and 5.1 mm2 (SD=4.0), respectively (P=.83). After adjusting for age and axial length, eyes with STGD had a mean CT measurement greater than the AMD eyes (336.1 µm vs. 198.1 µm, respectively; P=.039). However, this difference was driven by AMD eyes with reticular pseudodrusen (RPD) and by a single Stargardt case with a very thick choroid. Eyes with RPD had statistically thinner subfoveal CT measurements when compared with all other groups.A small but statistically significant increase in the CT of STGD eyes was observed when compared with normal controls and AMD eyes without RPD. However, this small increase in CT was driven by a single case with a markedly thicker choroid within the STGD group, so it is unlikely that a clinically significant difference exists. However, AMD eyes with GA and RPD had significantly thinner subfoveal CT measurements.

Relationship Between Optic Nerve Protrusion Measured by OCT and MRI and Papilledema Severity.

Abstract: PURPOSE To develop measures of optic nerve protrusion length (NPL) from optical coherence tomography (OCT) and magnetic resonance imagining (MRI) and compare these measures with papilledema severity in idiopathic intracranial hypertension (IIH). METHODS Optical coherence tomography and MRI scans were obtained from 11 newly diagnosed untreated IIH patients (30 ± 10 years; body mass index [BMI] 36 ± 4 kg/m2). Optic nerve protrusion length was measured for each eye using OCT and MRI independently. The relationship between the NPL measures and their association with the Frisen scale for papilledema severity were assessed. Two different OCT-based measures of NPL were derived to assess the influence of the retinal thickness on the association with papilledema severity. Additional OCT scans from 11 healthy subjects (38 ± 7 years) were analyzed to establish reliability of the NPL measurement. RESULTS Optical coherence tomography and MRI measurements of NPL were significantly linearly correlated (R = 0.79, P < 0.0001). Measurements of NPL from OCT and MRI were significantly associated with Frisen papilledema grade (P < 0.0001). Mean OCT measurement of NPL in the papilledema cohort was significantly larger than in the healthy cohort (0.62 ± 0.24 vs. 0.09 ± 0.03 mm, P < 0.0001). CONCLUSIONS Significant linear correlation between OCT and MRI measurements of NPL supports the reliability of the OCT-based measurements of NPL in papilledema. Significant association between the papilledema grade and OCT- and MRI-based measurements of NPL highlights the potential of NPL as an objective and more sensitive marker of papilledema severity than the Frisen scale.

Depth-resolved rhodopsin molecular contrast imaging for functional assessment of photoreceptors.

Abstract: Rhodopsin, the light-sensing molecule in the outer segments of rod photoreceptors, is responsible for converting light into neuronal signals in a process known as phototransduction. Rhodopsin is thus a functional biomarker for rod photoreceptors. Here we report a novel technology based on visible-light optical coherence tomography (VIS-OCT) for in vivo molecular imaging of rhodopsin. The depth resolution of OCT allows the visualization of the location where the change of optical absorption occurs and provides a potentially accurate assessment of rhodopsin content by segmentation of the image at the location. Rhodopsin OCT can be used to quantitatively image rhodopsin distribution and thus assess the distribution of functional rod photoreceptors in the retina. Rhodopsin OCT can bring significant impact into ophthalmic clinics by providing a tool for the diagnosis and severity assessment of a variety of retinal conditions.

Influence of socio-demographic characteristics on eye care expenditure: data from the Medical Expenditure Panel Survey 2007.

Abstract: Objective: To evaluate the association between sociodemographic factors and eye care expenditure and to assess the burden of ocular expenditure compared to total health care expenditure.Methods: A retrospective analysis of ocular expenditure in participants of the 2007 Medical Expenditure Panel Survey. Data from 20,620 unique participants aged ≥18 years were evaluated for eye care expenditure by demographic characteristics.Results: A total of 22% of the studied population had eye care expenditures in 2007. Demographic factors significantly associated with higher probability of having eye care expenditures included older age (65+ years 35%, 45–64 years 23%, <45 years 17%), female sex (female 26%, male 19%), higher educational attainment (greater than high school education 25%, less than high school education 17%), having insurance (private 24%, uninsured 13%), and visual impairment (mild 31%, none 22%). Older age, female sex, higher educational attainment, having insurance, and presence of visual i...

In vivo imaging rhodopsin distribution in the photoreceptors with nano-second pulsed scanning laser ophthalmoscopy

Abstract: Background: Rhodopsin is a biomarker for the function of rod photoreceptors, the dysfunction of which is related to many blinding diseases like retinitis pigmentosa and age-related macular degeneration. Imaging rhodopsin quantitatively may provide a powerful clinical tool for diagnosis of these diseases. To map rhodopsin distribution accurately in the retina, absorption by rhodopsin intermediates need to be minimized. Methods and materials: We developed nano-second pulsed scanning laser ophthalmoscopy (SLO) to image rhodopsin distribution in the retina. The system takes advantage of the light-induced shift of rhodopsin absorption spectra, which in turn affects the fundus spectral reflection before and after photobleaching. By imaging the retina twice, one in the dark-adapted state and the other one in the light-adapted state, the rhodopsin absorption change can be calculated from the differential image, which is a function of the rhodopsin concentration in the rod photoreceptors. Results: The system was successfully applied to in vivo imaging of rat retina in different bleaching conditions to verify its feasibility. Our studies showed that the differential image between the dark- and light-adapted states represents rhodopsin distribution in the retina. We also conducted a dynamic bleaching experiment to prove the importance of reducing light absorption of rhodopsin intermediates. Conclusions: The preliminary results showed that our nano-second pulsed-light SLO is promising in imaging the functional biomarker of the rod photoreceptors. By using nanosecond pulsed laser, in which one laser pulse generates one pixel of the image, the absorption of rhodopsin intermediates can be reduced.

Retinal ganglion cell thickness to assess the optic nerve.

Abstract: A ssessment of the retinal ganglion cell layer (GCL) using automated quantitation of retinal ganglion cell–inner plexiform layer (IPL) thickness has become increasingly available with spectral domain optical coherence tomography (SD-OCT). Given the clinical benefits of using GCL thickness as an objective anatomic measure, there are now many reasons to incorporate GCL thickness into clinical practice. This is exemplified by 3 articles in this issue of Journal of Neuro-Ophthalmology (1–3). Available SD-OCT algorithms provide GCL thickness measures in the macular region where the retinal ganglion cells are most numerous. Retinal ganglion cells are absent in the center of the fovea and increase dramatically to a peak of .10,000 cells per square degree at 0.6° eccentrically, followed by a decrease to ,100 cells per square degree at 10° eccentricity (4). Meaningful measures of GCL thickness beyond the macular region are not available due to the resolution of the SD-OCT. Nevertheless, when permanent anatomic damage occurs as the result of optic neuropathy, reduction in GCL thickness is expected in the macula where the most of retinal ganglion cells reside. There are several advantages of using SD-OCT macular GCL thickness as an objective measure of optic nerve injury compared with SD-OCT peripapillary retinal nerve fiber layer (RNFL) thickness. First, optic disc edema as a result of swollen axons increases RNFL thickness and may obscure retinal nerve fiber loss. GCL thickness detects optic nerve injury when optic disc edema is present and is helpful to predict prognosis and monitor treatment. However, when optic disc edema produces substantial peripapillary retinal edema, the SD-OCT GCL–IPL thickness algorithm may fail to provide proper segmentation resulting in falsely low values. Second, the RNFL thickness sector distribution for an anomalous optic nerve head may be altered and difficult to interpret, whereas macular GCL layer thickness is less likely to be affected. Third, macular GCL thickness may provide more precise topographical correlation with central visual field defects than peripapillary RNFL thickness. For instance, the corresponding optic nerve damage from homonymous hemianopia related to cerebral stroke is more apparent and correlates far better topographically with GCL thickness than RNFL thickness (5). Macular GCL–IPL thickness is an additional clinical tool rather than a replacement for peripapillary RNFL thickness. The dynamic ranges of the 2 parameters in detecting an optic nerve abnormality are different in various clinical scenarios. The peripapillary RNFL thickness is sensitive in detecting optic disc edema. When optic disc edema is not present, RNFL thickness correlates reasonably well with visual field defects, particularly with sectoral or 2-dimensional en face analysis. Although macular GCL thickness may be sensitive in detecting early optic nerve damage, peripapillary RNFL thickness may be a better measure in more advanced optic neuropathies when macular GCL thickness has “bottomed out.” Because visual field defects may not occur until a considerable loss of axons has occurred, both GCL and RNFL thickness measures are especially helpful in scenarios where the visual field may be near normal (e.g., recovered optic neuritis, early compressive optic neuropathy). The GCL and RNFL measures also are useful when the patient cannot provide reliable visual fields. However, in advanced optic neuropathies, when both GCL and RNFL thickness have been maximally reduced, visual field testing remains the test of choice in following disease progression (e.g., severe optic nerve atrophy from idiopathic intracranial hypertension or from compressive optic neuropathy). Macular GCL–IPL thickness analysis is obtained from typical macular SD-OCT without additional scanning time. Concurrent review of the retinal OCT is important because altered macular anatomy

Clinical and Electrophysiologic Characteristics of a Large Kindred with X-Linked Retinitis Pigmentosa Associated with the RPGR Locus.

Abstract: Purpose: To phenotypically and genotypically characterize a large Puerto Rican kindred with X-linked retinitis pigmentosa associated with a novel RP GTPase regulator (RPGR) genotype.Methods: A total of 100 family members of a single kindred with X-linked RP were evaluated with ophthalmic examinations and blood DNA analysis. Visual fields, OCT, and full-field ERG were obtained on all affected males and carriers.Results: Of the 100 family members examined, 13 were affected males and 18 were carriers. A deletion of 2 base pair of the RPGR gene in the ORF15 region at position c.2267-2268 (Lys756del2aaAG hemi) was identified with the affected and carriers. Best eye visual acuity was correlated with age (Spearman coefficient = 0.95) with hand-motion acuity by age 35 and light perception to no light perception by age 50–60. Visual fields were minimally plottable by age 40, and ERG responses reached non-detectable levels by late teens. Carriers had no or mild visual symptoms. All carriers had visual acuit...

Impairment of the Retinal Nerve Fiber Integrity and Blood Flow Velocity in Multiple Sclerosis (P5.224)

Abstract: OBJECTIVE: To quantify the retardation of the retinal nerve fiber layer and blood flow velocity in relapsing and remitting multiple sclerosis (RRMS) BACKGROUND: The diffuse cerebral hypoperfusion in MS is reported, but whether it contributes to neurodegeneration or is the result of decreased metabolic demand due to the neurodegeneration remains unclear The retina has been used to study the pathophysiology of MS The thinning of the retinal nerve fiber layer (RNFL) has been established as an ocular biomarker of neurodegeneration in MS The vasculature in the eye and brain are similar anatomically and physiologically Polarization-sensitive OCT (PS-OCT) is able to detect retardation changes of RNFL which represents the microtubal alteration DESIGN/METHODS: The right eye of 6 RRMS patients and 16 healthy subjects were imaged using a custom-built PS-OCT The thickness and retardation of the RNFL were measured Additionally, those MS patients and 16 healthy subjects were imaged using Retinal Functional Imager (RFI, Optical Imaging, Rehovot, Israel), and the blood flow velocities in the arterioles and venules were measured RESULTS: Measured by PS-OCT, the thickness and retardation of the RNFL in MS patients were significantly reduced (P < 005) compared to the healthy group Measured by the RFI device, the velocities were 333 ± 072 mm/s (artery) and 273 ± 062 mm/s (vein), which were significantly lower than the healthy group 403 ± 092 mm/s (artery) and 324 ± 070 mm/s (vein) (P < 005) CONCLUSIONS: This study demonstrates that retinal hypoperfusion and the impairment of microtubal function in the retinal nerve fiber layers in MS compared to controls, indicating retinal vascular dysfunction coexists with the retinal microstructural changes in RRMS Further studies with a larger sample and different stages of MS patients are needed to further elucidate the findings Study Supported by: NMSS pilot grant, R01EY020607, NIH R01EY020607S Disclosure: Dr Jiang has nothing to disclose Dr Delgado has nothing to disclose Dr Yuan has nothing to disclose Dr Yan has nothing to disclose Dr Cabrera DeBuc has nothing to disclose Dr Lam has nothing to disclose Dr Wang has nothing to disclose

Risk factors for Poor Visual Outcome in Idiopathic Intracranial Hypertension Patients with Mild Visual Loss (S26.004)

Abstract: OBJECTIVE: To study risk factors related to progressive visual field loss in the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) BACKGROUND: The IIHTT is a multicenter randomized, double-masked, placebo-controlled clinical trial (NCT01003639) Analysis from the IIHTT has shown the use of acetazolamide (maximally tolerated up to 4 g/day) with a low-sodium weight-reduction diet compared with diet alone resulted in modest improvement in visual field function in IIH patients with mild visual loss DESIGN/METHODS: Participants (n=165) were enrolled from 2010 to 2012 and followed for 6 months All participants met the modified Dandy criteria and had a perimetric mean deviation between -2 to -7 dB The mean age was 29 years and all but four participants were women 151 subjects were followed for more than one month and were used for analysis Seven patients (5 women, 2 men; 6 placebo, 1 acetazolamide) had progressive visual field loss that met IIHTT criteria for treatment failure RESULTS: Patients with higher grade papilledema but lower ETDRS visual acuity in the study eye were more likely to have progressive field loss The odds ratio (OR) for patients with grades III-V grade papilledema vs those of grades I-II was 86 (95[percnt]CI:17,infinite;p-value=0025) A one unit increase in the number of ETDRS letters correct at baseline was associated with a decrease in the odds of progressive field loss by a factor of 086 (CI:077,096:p=0005) Compared to female patients, the OR for male patients was 263 (CI:16,5000;p-value=00054) Subjects with progressive field loss had over 2½ times as many transient visual obscurations monthly; the difference was not significance (p=013) CONCLUSIONS: Male patients, those with high grade papilledema and those with decreased visual acuity at baseline were more likely to experience progressive field loss These patients should be monitored closely and provided with appropriate treatment of their IIH Study Supported by: NEI-1U10EY017281-01A1 Disclosure: Dr Lam has nothing to disclose Dr Falardeau has nothing to disclose Dr Fletcher has nothing to disclose Dr Granadier has nothing to disclose Dr Longmuir has nothing to disclose Dr Patel has nothing to disclose Dr He has nothing to disclose Dr McDermott has nothing to disclose Dr Wall has received personal compensation for activities with Boeringer Ingelheim as a consultant