Clinical Assistant Professor, Ophthalmology
Professional Education: UC Berkeley School of Optometry Registrar (1994) CA
O.D., University of California, Optometry (1994)
Comparison of Automated Self-Refraction Using NETRA with Table-Mounted Autorefractor and Subjective Refraction in an Academic Optometry Clinic
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2018
View details for Web of Science ID 000442932800275
Slower saccadic reading in Parkinson's disease
2018; 13 (1): e0191005
Idiopathic Parkinson's Disease (PD) is characterized by degeneration of dopaminergic and other neurons, leading to motor and non-motor deficits. Abnormal eye movements in PD, including fixations, saccades, and convergence, are well described. However, saccadic reading, which requires serial and alternating saccades and fixations, is not well studied, despite its obvious impact on the quality of life. In this study, we assessed saccadic reading using variations of the King-Devick (KD) test, a rapid single digit number naming test, as a way to assess the ability to make serial left-to-right ocular motor movements necessary for reading. We recruited 42 treated PD patients and 80 age-matched controls and compared their reading times with a variety of measures, including age, duration of disease, Unified Parkinson's Disease Rating Scale (UPDRS), the National Eye Institute 25-Item Visual Functioning Questionnaire 25 (VFQ-25), and Montreal Cognitive assessment (MoCA) test. The subjects performed 4 trials of reading 120 single digit numbers aloud as fast as possible without making errors. In each trial, they read 3 pages (KD1, KD2, and KD3), and each page contained 40 numbers per page in 8 lines with 5 numbers/line. We found that PD patients read about 20% slower than controls on all tests (KD1, 2, and 3 tests) (p < 0.02), and both groups read irregularly spaced numbers slower than regularly spaced numbers. Having lines between numbers to guide reading (KD1 tests) did not impact reading time in both PD and controls, but increased visual crowding as a result of decreased spacing between numbers (KD3 tests) was associated with significantly slower reading times in both PD and control groups. Our study revealed that saccadic reading is slower in PD, but controls and PD patients are both impacted by visuospatial planning challenges posed by increased visual crowding and irregularity of number spacing. Reading time did not correlate with UPDRS or MoCA scores in PD patients but significantly correlated with age, duration of disease, and VFQ-25 scores. The presence of convergence insufficiency did not significantly correlate with reading time in PD patients, although on average there was slower reading time in those with convergence insufficiency by 8 s (p = 0.2613). We propose that a simple reading task using 120 single-digit numbers can be used as a screening tool in the clinical setting to assess functional ocular motor difficulties in Parkinson's disease that can have a profound impact on quality of life.
View details for PubMedID 29364897
- Longterm cultures of the aged human RPE do not maintain epithelial morphology and high transepithelial resistance GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY 2012; 250 (2): 313-315
Reduction of iatrogenic RPE lesions in AMD patients: evidence for wound healing?
GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY
2008; 246 (3): 345-352
Our purpose was to study retinal pigment epithelium (RPE) wound healing in patients with age-related macular degeneration (AMD).Abrasive debridement of nasal RPE was performed with a metal cannula during pars plana vitrectomy for foveal choroidal neovascularization (CNV) membrane excision combined with simultaneous autologous RPE transplantation. Fundus autofluorescence, fluorescein angiography images, and red-free pictures were taken initially within 1-2 weeks postoperatively, subsequently in 2-week intervals until 3 months, monthly until 6 months, and every 3 months thereafter. The borders of these lesions were measured; areas were calculated and compared using ArchiCad Software. Fourteen eyes of 14 patients suffering from AMD were included (nine women and four men, mean age 75.6 years +/-6.6 years).Six of 14 (42.9 %) patients showed a reduction of the RPE debrided area. The size of these lesions reduced 5.6-20% within 2 postoperative months compared with their size at first examination (from a mean of 13.7 mm2 +/- 7.2 at baseline to a mean of 12.8 mm2 +/- 6.7 at 2 months postoperatively). No further reduction of the lesions was seen after the 2 months. In eight cases, borders of the RPE debrided areas stayed stable during observation time.Wound healing of abrasively debrided RPE monolayer defects in patients with AMD occurs to a certain extent in nearly half of the cases. This process seems to stop after 2 months.
View details for DOI 10.1007/s00417-007-0658-6
View details for Web of Science ID 000252992000004
View details for PubMedID 17704936
- Perspective: Tissue engineering for RPE transplantation in AMD SPEKTRUM DER AUGENHEILKUNDE 2007; 21 (4): 212-217
Transplantation of the RPE in AMD
PROGRESS IN RETINAL AND EYE RESEARCH
2007; 26 (5): 516-554
The retinal pigment epithelium (RPE) maintains retinal function as the metabolic gatekeeper between photoreceptors (PRs) and the choriocapillaries. The RPE and Bruch's membrane (BM) suffer cumulative damage over lifetime, which is thought to induce age-related macular degeneration (AMD) in susceptible individuals. Unlike palliative pharmacologic treatments, replacement of the RPE has a curative potential for AMD. This article reviews mechanisms leading to RPE dysfunction in aging and AMD, laboratory studies on RPE transplantation, and surgical techniques used in AMD patients. Future strategies using ex vivo steps prior to transplantation, BM prosthetics, and stem cell applications are discussed. The functional peculiarity of the macular region, epigenetic phenomena leading to an age-related shift in protein expression, along with the accumulation of lipofuscin may affect the metabolism in the central RPE. Thickening of BM with age decreases its hydraulic conductivity. Drusen are deposits of extracellular material and formed in part by activation of the alternative complement pathway in individuals carrying a mutant allele of complement factor H. AMD likely represents an umbrella term for a disease entity with multifactorial etiology and manifestations. Presently, a slow progressing (dry) non-neovascular atrophic form and a rapidly blinding neovascular (wet) form are discerned. No therapy is currently available for the former, while RPE transplantation and promising (albeit non-causal) anti-angiogenic therapies are available for the latter. The potential of RPE transplantation was demonstrated in animal models. Rejection of allogeneic homologous transplants in patients focused further studies on autologous sources. In vitro studies elucidated cell adhesion and wound healing mechanisms on aged human BM. Currently, autologous RPE, harvested from the midperiphery, is being transplanted as a cell suspension or a patch of RPE and choroid in AMD patients. These techniques have been evaluated from several groups. Autologous RPE transplants may have the disadvantage of carrying the same genetic information that may have led to AMD manifestation. An intermittent culturing step would allow for in vitro therapy of the RPE, its rejuvenation and prosthesis of BM to improve the success RPE transplants. Recent advances in stem cell biology when combined with lessons learned from studies of RPE transplantation are intriguing future therapeutic modalities for AMD patients.
View details for DOI 10.1016/j.preteyeres.2007.02.002
View details for Web of Science ID 000250095700004
View details for PubMedID 17532250