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IPoster: Dilation or No Dilation for Threshold Visual Field Testing: Optometric Practice PatternsContains 2 Component(s)
Differences in philosophy for visual field (VF) testing have been noted. The purpose was to assess whether optometrists dilate their patients prior to threshold VF.
Purpose: Differences in philosophy for visual field (VF) testing have been noted. The purpose was to assess whether optometrists dilate their patients prior to threshold VF.
Methods: An electronic survey was sent to: Deans of the Schools/Colleges of Optometry, American Academy of Optometry Comprehensive Care Section members, Illinois College of Optometry faculty, as well as posted on ‘ODs on Facebook’. Those who received the survey link were asked to share it.
Results: There were 632 who completed the survey. They reported graduating from 22 different Optometry schools/universities (highest ICO 14%) and practicing in 47 states (highest California 12%), DC, Puerto Rico, Canada and 12 other countries . The highest % reported being in practice for 20 yrs. and 22.2% 10-20 yrs. Modes of practice included: private practice (34.7%), education (30.7%), governmental (17.9%), OD/MD (8.6%), commercial (3.2%), other (3.1%) and HMO (1.7%). The highest proportion (49.7%) reported they dilate some time for VF testing while 42.4% reported they do not dilate and 7.9% reported they dilate all patients. For those who dilate patients some or all of the time, reasons included: so dilated fundus evaluation could be performed (69.2%), pupil size (53%), consistent previous VF (42.6%), ocular diagnosis (27.2%), age (12.6%), and consistent with education (9.3%). For those who do not dilate patients, reasons included: unnecessary (65.7%), consistent with education (54.1%), inconvenient to patient (21.3%), and time consuming (13.8%). Most reported their philosophy has not changed (70.1%). However of those whose philosophy has changed, most (65.6%) reported less dilation. The majority (84.8%) reported managing glaucoma. Most (67.4%) order 20.
Conclusion(s): Practice patterns for VF and reasoning varied among the wide variety of respondents. Further research is needed to provide guidance in this area.
IPoster: Management of Corneo-Scleral Irregularities with Virtually Designed Custom Multi-Meridian Scleral LensesContains 2 Component(s)
Toric haptic scleral lens designs are prescribed more often than in previous years. Recent interest in mapping the sclera and conjunctiva is proving that scleral shape is highly variable, and may explain the difficulty in fitting some patients with scleral lenses. A corneo-scleral topographical system was utilized to evaluate ocular shape of two patients. Custom multi-meridian back surface toric haptic scleral lenses were empirically designed to address the unusual scleral shape, which significantly deviated from a sin2 bitoric curve with a periodicity of 180°.
Introduction: Toric haptic scleral lens designs are prescribed more often than in previous years. Recent interest in mapping the sclera and conjunctiva is proving that scleral shape is highly variable, and may explain the difficulty in fitting some patients with scleral lenses. A corneo-scleral topographical system was utilized to evaluate ocular shape of two patients. Custom multi-meridian back surface toric haptic scleral lenses were empirically designed to address the unusual scleral shape, which significantly deviated from a sin2 bitoric curve with a periodicity of 180°.
Case Reports: Case 1 had central corneal scarring due to recurrent herpes zoster and poor fitting scleral lenses, resulting in inferior decentration. Scleral topography showed a largely flat sclera with the exception of a 120° wide area of depression (~500µ deep) centered at 320°. A custom lens was designed to conform to this inferior depression which was well centered, comfortable, and provided better vision than previously obtained.
Case 2 had advanced keratoconus with corneal ring implants and poor fitting scleral lenses, resulting in a recurrent corneal ulcer overlying bulging edge of the right ring implant, and lens intolerance. Scleral topography showed high scleral/conjunctival toricity, but with the steep axis inferiorly (270°) having a SAG 500µ greater than the steep axis superiorly (70°). A custom lens was designed to conform to this irregular scleral shape which had an optimal fit per OCT and slit lamp evaluation, was comfortable, and provided excellent acuity.
Conclusion/Discussion: The novel topography device and innovative software technology accurately mapped both corneal and scleral irregularities, empirically designed the scleral lenses, and accurately predicted the fit and fluorescein patterns. These virtually fit scleral lenses provided both patients with good comfort and vision they did not experience with previous lens designs.
IPoster: OCT Angiography in Central Retinal Vein OcclusionContains 2 Component(s)
OCT Angiography (OCTA) provides an in-vivo, non-invasive visualization of both the retinal and choroidal vasculature including segmentation of all major vascular layers. OCTA allows for valuable insight into the microvascular circulation of various retinal and choroidal disorders allowing for an in-depth analysis of pathological alterations in specific disease states including retinal vascular occlusion (RVO).
Introduction: OCT Angiography (OCTA) provides an in-vivo, non-invasive visualization of both the retinal and choroidal vasculature including segmentation of all major vascular layers. OCTA allows for valuable insight into the microvascular circulation of various retinal and choroidal disorders allowing for an in-depth analysis of pathological alterations in specific disease states including retinal vascular occlusion (RVO).
Case Report: A 58 y/o diabetic, hypertensive male presented with complaints of decreased vision OS x 2months with light sensitivity and pain. He reported a BS of 225 but was unsure of his HBA1C. BCVA OD was 20/20 and 20/200 OS. Anterior segment exam was unremarkable. Fundoscopy revealed widespread hemorrhaging in the posterior pole, vascular tortuosity and macular edema consistent with CRVO OS. OCTA was performed and identified significant vascular changes to the DCP including widespread ischemia and capillary non-perfusion. A disturbance in macular microcirculation can be visualized on OCTA as an enlarged, asymmetric FAZ with irregularity of the surrounding vascular arcades. These findings provide insight into the causative factor behind the visual impairment associated with CRVO.
Discussion: Fluorescein Angiography (FA) has historically been used in the evaluation of RVO as it has identified abnormalities at the level of the superficial capillary plexus including enlargement of the foveal avascular zone (FAZ). However, FA does not provide segmentation into the individual vascular layers and thus is unable to visualize the deep capillary blood supply. OCTA has allowed for precise visualization of abnormalities at the deep capillary plexus (DCP) in RVO.
Conclusion(s): Depth encoded mapping via OCTA of CRVO patients has allowed for enhanced visualization of the microvascular changes occurring at the level of the DCP. These changes are directly correlated with the level of visual impairment suggesting that these changes are functionally relevant.
IPoster: Ocular Microbial Flora in Contact Lens and Non-Contact Lens Wearers – Are They Symptomatic?Contains 2 Component(s)
To evaluate the microbial profile in Contact Lens (CL) wearers and non- Contact Lens wearers and to compare with symptomatic and asymptomatic contact lens wearers.
Purpose: To evaluate the microbial profile in Contact Lens (CL) wearers and non- Contact Lens wearers and to compare with symptomatic and asymptomatic contact lens wearers.
Methods: Contact lens wearers with minimum of one year of soft CL wear and controls with no history of any CL wear were included. Subjects went through preliminary examination followed by a comprehensive battery of clinical tests. At the end of all these test comfort rating using visual analogue scale of vision, comfort, dryness and redness were documented. Conjunctival swab, contact lens sample and lens case sample were collected for microbial assessment.
Results: A total of 24 contact lens wearers and 24 non contact lens wearers were included in the study. There was no growth of organism in conjunctival swab between CL and non-CL wearers, except for 2 subjects in each category with increased number of non pathogenic organism (Staphylococcus epidermidis). A positive growth of non-pathogenic organisms was observed in contact lens of 9 subjects. Pathogenic organisms were predominantly isolated from lens case (11/24 samples) than in CL (8/24 samples). The subjective comfort rating of dryness and the clinical findings of papillary roughness and meibomitis were higher in symptomatic than asymptomatic CL wearers which was found to be statistically significant (p < 0.05). Surprisingly only 5 samples from symptomatic and 9 samples from asymptomatic CL wearers were identified with pathogenic organisms. Pathogenic organisms namely Pseudomonas species and non pathogenic organism Staphylococcus epidermidis were identified in both symptomatic and asymptomatic group. Significant positive correlation (r=0.61, p=0.001) was found between years of lens wear and comfort with lenses and between hours of contact lens wear and with a positive growth of organisms in CL(r=0.44, p=0.02).
Conclusion(s): Both pathogenic and non pathogenic microorganisms were isolated in contact lens and lens case samples of a daily wear soft contact lens users. Both symptomatic and asymptomatic subjects showed presence of pathogenic organisms though only few subjects presented with positive clinical signs.
Rajeswari Mahadevan, PhD, FAAO
Dr. Rajeswari Mahadevan is the head of contact lens clinic at the Medical Research Foundation, Sankara Nethralaya, India. She is also an associate Professor at the Elite school of optometry and SN academy. She has been recently elected as the Asia pacific regional president for IACLE executive board.
She obtained her B.S.Optometry degree, the M.Phil degree in optometry specializing in the subject of contact lens and completed PhD from Elite School Of Optometry, Birla Institute of Technology and Science.
She has presented several scientific presentations in international and national conferences and has 20 peer reviewed publications. She has mentored 10 post graduate students since the year 1999. She is a mentor for 7 post graduate students currently. She has recently authored a book on “Trouble shooting and problem solving in contact lens practice.” She has authored a chapter on “Role of contact lens in different environment” in a book published on occupational optometry. She is the principal investigator for different clinical trials on contact lens at the Vision and Medical Research Foundation.
IPoster: Ocular Surface Imaging to Assess Tear Film Dynamics Associated with Contact Lens WearContains 2 Component(s)
To evaluate the use of ocular surface imaging on pre-corneal tear film (PCTF) and pre-lens tear film (PLTF) dynamics associated with contact lens wear. To quantify changes in the PLTF on contact lens surfaces differing in material composition. To assess possible visual effects of PLTF changes during the course of a 6 hour period using high and low contrast visual acuity.
Purpose: To evaluate the use of ocular surface imaging on pre-corneal tear film (PCTF) and pre-lens tear film (PLTF) dynamics associated with contact lens wear. To quantify changes in the PLTF on contact lens surfaces differing in material composition. To assess possible visual effects of PLTF changes during the course of a 6 hour period using high and low contrast visual acuity.
Methods: 5 clinically normal subjects were fit into 2 contact lens designs, delefilcon A and etafilcon A. Lipid layer thickness measurements of the PCTF were acquired using the Stroboscopic Video Color Microscope prior to lens insertion. The PLTF was assessed 15 minutes after lens insertion, and after 6 hours of lens wear. High and low contrast logMAR acuities were measured at each time interval. Average lipid layer thickness and logMAR acuity were averaged between the right and left eye and compared using paired t-tests.
Results: A trend towards decreased lipid layer thickness was found after 6 hours of contact lens wear when compared to the baseline PCTF, -6.2 ± 7.7 nm (p = 0.14) in delefilcon A and -9.6 ± 13.8 nm (p = 0.19) in etafilcon A. From 15 minutes to 6 hours of contact lens wear, there was an average decrease in lipid layer thickness of -3.0 ± 7.9 nm (p = 0.44) in delefilcon A and -9.2 ± 14.8 nm (p = 0.24) in etafilcon A. After 6 hours in delefilcon A, there was no significant change in high (p = 0.24) or low contrast (p = 0.11) logMAR acuity. After 6 hours in etafilcon A, there was no difference in high contrast acuity (p=0.41), but a significant decrease in low contrast acuity, 0.10 ± 0.6 logMAR (p = 0.02).
Conclusion(s): Ocular surface imaging is useful in assessing tear film dynamics associated with contact lens wear, where quantifiable changes in lipid layer thickness can be identified over the course of a wearing cycle. Low contrast acuity may be a more sensitive marker than high contrast acuity for vision changes associated with PLTF dynamics.
IPoster: Predicting End-of-Day Clearance and Effect of Solution Viscosity in Scleral Lens Wear Over TimeContains 2 Component(s)
This study aims to evaluate the settling of a scleral lens and if this process is influenced by the nature of the fluid layer.
Purpose: This study aims to evaluate the settling of a scleral lens and if this process is influenced by the nature of the fluid layer.
Methods: A prospective, non-randomized control study was performed using an 18 mm scleral lens. They were fitted with a central clearance of 400 um at insertion. One eye was randomly assigned to be fitted with a non-preserved gel solution of carboxymethylcellulose, while the other was inserted with non-preserved saline. Measurements of clearance in 3 locations were taken (OCT) at baseline, every 30 min up to 1h30 post insertion and every 2 h thereafter up to 6h00 of wear. A two-way repeated measure analysis of variance (liquids × times) was used to test central, nasal and temporal fluid thickness.
Results: Following 6 h of wear, the 18 mm lens had a mean central settling of 70.0 ± 9.8 μm, 36.7 ± 9.8 μm of which occurred within the first 30 min of wear. There was no significant difference between lenses filled with non-preserved saline to those with non-preserved gel. However, a paired comparison concluded to a significant difference between mean nasal settling (41.4 μm) and temporal settling (20.4 μm).
Conclusion(s): With respect to the lens studied, current results suggest that practitioners can evaluate the lens 30 min post insertion and can estimate the amount of fluid that will remain after lens stabilization by doubling the value obtained initially. The use of non-preserved saline or non-preserved more viscous solution to fill the lens does not influence its settling.
Claudine Courey, OD, MSc, FAAO
IPoster: Scleral Lenses in Current Ophthalmic Practice Evaluation: Patient Demographics, Indications and Lens DesignsContains 2 Component(s)
This multi-center study reports demographics of scleral lens wearers and scleral lens prescription patterns as reported in an online survey.
Purpose: This multi-center study reports demographics of scleral lens wearers and scleral lens prescription patterns as reported in an online survey.
Methods: An online survey was conducted from December 13, 2016 to March 31, 2017. Scleral Lens Education Society members were invited to participate via e-mail, links to the survey were posted on the Scleral Lens Fitters Facebook page and were included in two monthly online newsletters. Fitters were asked to provide information about their most recently evaluated established scleral lens patient (history of ≥ 6 months of lens wear). We describe demographics of scleral lens wearers, indications for wear, and lens designs prescribed.
Results: We received 376 responses. Mean patient age (n=339) was 44 ± 14 years (range 9-86 years). Male gender was reported in 62% of patients (n=352). Primary indications for scleral lens wear (n=312) were corneal irregularity (84%), ocular surface disease (7%) and correction of refractive error (5%). Median lens diameter was 16 mm (range 10-23 mm) for both right (n=207) and left (n=212) eyes. Single vision lenses were prescribed for 97% of right eyes (n=207) and 98% of left eyes (n=211). Right lenses (n=201) incorporated spherical (69%), toric (28%) and wavefront-corrected (3%) optics. Left lenses (n=207) incorporated spherical (70%), toric (28%) or wavefront-corrected (2%) optics. Right lenses (n=201) featured spherical (61%), toric (28%), quadrant-specific (8%) or impression-based (3%) haptics. Left lenses (n=207) featured spherical (63%), toric (27%), quadrant-specific (7%) or impression-based (2%) haptics.
Conclusion(s): Scleral lenses are most commonly prescribed for management of corneal irregularity. Median lens diameter prescribed is 16 mm. Most scleral lenses feature single vision optical correction, and a majority of lenses prescribed feature spherical optical power and haptic designs.
IPoster: SD-OCT May Help Differentiate Adult-Onset Fovealmacular Vitelliform Dystrophy from Age-Related Macular DegenerationContains 2 Component(s)
Adult-onset fovealmacular vitelliform dystrophy (AOFVD) is a retinal dystrophy, characterized by bilateral foveal, yellow, round elevated subretinal lesions. These lesions mimic drusen and are often misdiagnosed as age-related macular degeneration (AMD). SD-OCT may be a useful technique to assist in distinguishing these two conditions.
Introduction: Adult-onset fovealmacular vitelliform dystrophy (AOFVD) is a retinal dystrophy, characterized by bilateral foveal, yellow, round elevated subretinal lesions. These lesions mimic drusen and are often misdiagnosed as age-related macular degeneration (AMD). SD-OCT may be a useful technique to assist in distinguishing these two conditions.
Case Report: Patient 1, an 85yo WM, complained of blurry vision OU. BCVA were 20/30 OD and 20/40 OS. Dilated eye exam revealed mild RPE changes OD, and a large elevated yellow lesion OS. SD-OCT revealed a small lesion between the inner/outer segment (IS/OS) interface and the RPE band OD, and a large vitelliform-like lesion OS consistent with AOFVD. Patient 2, a 72yo WM, reported blurry vision OS at distance. BCVA were 20/30 OD and 20/60 OS. Dilated eye exam revealed several small drusen OS>OD, and a large elevated lesion OS. SD-OCT confirmed small drusen OU, and a large pigment epithelial detachment (PED) with mild sub-retinal fluid OS, consistent with wet AMD.
Conclusion(s): AOFVD and AMD have similar clinical features making differentiation challenging. SD-OCT may distinguish subtle differences between these conditions. The early yellow subretinal deposits in AOFVD on OCT have been localized between the IS/OS interface and the RPE band. In contrast, AMD drusen have been described as irregularities generally within the level of the RPE on OCT. AOFVD progression presents as a large vitelliform lesion, similar to PED in AMD. It has been suggested that vitelliform lesions in AOFVD may maintain photoreceptor integrity and visual function longer than AMD, because the contact between the apical RPE and IS/OS is preserved. PED lesions in AMD exhibit RPE elevation and gradual IS/OS loss. Since both conditions may develop choroidal neovascularization leading to significant vision loss, SD-OCT is useful in differentiating between AOFVD and AMD, and identifying the need for further treatment.
IPoster: Variability in Retinal Vessel Density Using Manufacturer Software and Publicly Available Image Processing Software in Optical Coherence Tomography AngiographyContains 2 Component(s)
Many optical coherence tomography angiography (OCTA) devices are available, but not all of them provide quantitative measurements of retinal vasculature. Practitioners usually use publicly available image processing software to analyze OCTA images. This study compared vessel density results obtained using ImageJ with those obtained using a software recently launched by a manufacturer.
Purpose: Many optical coherence tomography angiography (OCTA) devices are available, but not all of them provide quantitative measurements of retinal vasculature. Practitioners usually use publicly available image processing software to analyze OCTA images. This study compared vessel density results obtained using ImageJ with those obtained using a software recently launched by a manufacturer.
Methods: A Zeiss Cirrus HD-OCT 5000 (Carl Zeiss Meditec, Dublin, CA) was used to measure the retinal vasculature of 21 eyes from 21 healthy young subjects. A 3x3mm OCTA image was acquired and analyzed using AngioPlex software. The retinal vessel perfusion density in the superficial plexus was provided according to a ETDRS grid. OCTA images were exported using three different settings of brightness (120 from a 255 gray scale, 140/255 and 180/255), followed by a manual calculation of the vessel density by using ImageJ (National Institutes of Health). Images were first converted into a binary format and were then analyzed using an automated thresholding method. Two OCTA images were acquired to study the repeatability for evaluating the vessel density.
Results: Using AngioPlex software, the median perfusion density at a 3mm ETDRS circle was 0.373 (IQR 0.034). No significant difference was observed between the two measurements, 0.376 (0.013) (Wilcoxon signed rank test: p = 0.60). The vessel density obtained using ImageJ depended on the brightness setting applied when exporting the images. The densities were 0.380 (0.042), 0.346 (0.030) and 0.299 +/- 0.040 at brightness settings of 120/255, 140/255, and 180/255, respectively. Only images obtained in the 120/255 setting had vessel density similar to those obtained using AngioPlex (Wilcoxon signed rank test: p = 0.06). The vessel density was significantly lower at other brightness settings. AngioPlex software also provided repeatable results for the perimeter and circularity of the foveal avascular zone (FAZ). Significant variation was observed between the two measurements for the FAZ area (mean difference 0.006mm², 95% CI 0.001 to 0.011mm²; paired t-test, t = 2.65, p = 0.015).
Conclusion(s): When built-in software is not provided, practitioners may use publicly available image processing software to analyze the vessel density obtained from OCTA. For repeatability or follow-up studies, the same setting should be used when exporting OCTA images. Practitioners should be cautious when comparing the results obtained using publicly available image processing software.
Andrew KC Lam, PhD, FAAO
Dr. Andrew Lam graduated from the then Hong Kong Polytechnic with a Professional Diploma in Optometry. After working in a private optometric practice for two years, he returned to the then Hong Kong Polytechnic working as a Research Assistant and later obtained his Masters and PhD degrees from the Department of Optometry, University of Bradford, in the UK. He is now the Programme Leader of the Bachelor of Science in Optometry Programme at the School of Optometry, PolyU. He was a recipient of the Department's Teaching Excellence Award in 2002 and also 2008. Dr. Lam is a Fellow of the American Academy of Optometry. He is Chairperson of the Preliminary Investigation Committee and the Registration Committee of the Optometrists Board of Hong Kong. He has also served as Chairperson in various Committees of the Optometrists Board of Hong Kong, including Education Committee and Examination Committee. He was Treasurer of the Hong Kong Society of Professional Optometrists from 1993 to 1998. Dr. Lam’s research interests include the study of cornea, ocular blood flow and intraocular pressure. He has published in many scientific journals, including Ophthalmic and Physiological Optics, Optometry and Vision Science, and Clinical and Experimental Optometry. He teaches Ocular Pathology and Ocular Pharmacology for the BSc (Hons) in Optometry at PolyU. Away from the university and Optometry, Dr. Lam has had a long-standing interest in travelling and photography.