An introduction to nutrition for an optometrist

http://www.optometryinpractice.org

Measurement of Scleral Thickness in Humans Using Anterior Segment Optical Coherent Tomography

Anterior segment optical coherent tomography (AS-OCT, Visante; Zeiss) is used to examine meridional variation in anterior scleral thickness (AST) and its association with refractive error, ethnicity and gender. Scleral cross-sections of 74 individuals (28 males; 46 females; aged between 18-40 years (27.7±5.3)) were sampled twice in random order in 8 meridians: [superior (S), inferior (I), nasal (N), temporal (T), superior-temporal (ST), superior-nasal (SN), inferior-temporal (IT) and inferior-nasal (IN)]. AST was measured in 1mm anterior-toposterior increments (designated the A-P distance) from the scleral spur (SS) over a 6mm distance. Axial length and refractive error were measured with a Zeiss IOLMaster biometer and an open-view binocular Shin-Nippon autorefractor. Intra- And inter-observer variability of AST was assessed for each of the 8 meridians. Mixed repeated measures ANOVAs tested meridional and A-P distance differences in AST with refractive error, gender and ethnicity. Only right eye data were analysed. AST (mean±SD) across all meridians and A-P distances was 725±46μm. Meridian SN was the thinnest (662±57μm) and I the thickest (806 ±60μm). Significant differences were found between all meridians (p<0.001), except S:ST, IT:IN, IT:N and IN:N. Significant differences between A-P distances were found except between SS and 6 mm and between 2 and 4mm. AST measurements at 1mm (682±48 μm) were the thinnest and at 6mm (818±49 μm) the thickest (p<0.001); a significant interaction occurred between meridians and A-P distances (p<0.001). AST was significantly greater (p<0.001) in male subjects but no significant differences were found between refractive error or ethnicity. Significant variations in AST occur with regard to meridian and distance from the SS and may have utility in selecting optimum sites for pharmaceutical or surgical intervention

Presbyopic LASIK using hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments.

PURPOSE: To evaluate distance and near image quality after hybrid bi-aspheric multifocal central presbyLASIK treatments. DESIGN: Consecutive case series. METHODS: Sixty-four eyes of 32 patients consecutively treated with central presbyLASIK were assessed. The mean age of the patients was 51 ± 3 years with a mean spherical equivalent refraction of -1.08 ± 2.62 diopters (D) and mean astigmatism of 0.52 ± 0.42 D. Monocular corrected distance visual acuity (CDVA), corrected near visual acuity (CNVA), and distance corrected near visual acuity (DCNVA) of nondominant eyes; binocular uncorrected distance visual acuity (UDVA); uncorrected intermediate visual acuity (UIVA); distance corrected intermediate visual acuity (DCIVA); and uncorrected near visual acuity (UNVA) were assessed pre- and postoperatively. Subjective quality of vision and near vision was assessed using the 10-item Rasch-scaled Quality of Vision and Near Activity Visual Questionnaire, respectively. RESULTS: At 1 year postoperatively, 93% of patients achieved 20/20 or better binocular UDVA; 90% and 97% of patients had J2 or better UNVA and UIVA, respectively; 7% lost 2 Snellen lines of CDVA; Strehl ratio reduced by ∼-4% ± 14%. Defocus curves revealed a loss of half a Snellen line at best focus, with no change for intermediate vergence (-1.25 D) and a mean gain of 2 lines for near vergence (-3 D). CONCLUSIONS: Presbyopic treatment using a hybrid bi-aspheric micro-monovision ablation profile is safe and efficacious. The postoperative outcomes indicate improvements in binocular vision at far, intermediate, and near distances with improved contrast sensitivity. A 19% retreatment rate should be considered to increase satisfaction levels, besides a 3% reversal rate

Ledger and account book Buckhurst Plantation, 1855-1871

This item has been aggregated as part of the Association of Southeastern Research Libraries (ASERL)\u27s Deeply Rooted: The Agricultural & Rural History of the American South project. [This item is currently being re-scanned.]https://egrove.olemiss.edu/deeplyrooted/1127/thumbnail.jp

Evaluation of modern intraocular lenses

Accommodating Intraocular Lenses (IOLs), multifocal IOLs (MIOLs) and toric IOLs are designed to provide a greater level of spectacle independency post cataract surgery. All of these IOLs are reliant on the accurate calculation of intraocular lens power determined through reliable ocular biometry. A standardised defocus area metric and reading performance index metric were devised for the evaluation of the range of focus and the reading ability of subjects implanted with presbyopic correcting IOLs. The range of clear vision after implantation of an MIOL is extended by a second focal point; however, this results in the prevalence of dysphotopsia. A bespoke halometer was designed and validated to assess this photopic phenomenon. There is a lack of standardisation in the methods used for determining IOL orientation and thus rotation. A repeatable, objective method was developed to allow the accurate assessment of IOL rotation, which was used to determine the rotational and positional stability of a closed loop haptic IOL. A new commercially available biometry device was validated for use with subjects prior to cataract surgery. The optical low coherence reflectometry instrument proved to be a valid method for assessing ocular biometry and covered a wider range of ocular parameters in comparison with previous instruments. The advantages of MIOLs were shown to include an extended range of clear vision translating into greater reading ability. However, an increased prevalence of dysphotopsia was shown with a bespoke halometer, which was dependent on the MIOL optic design. Implantation of a single optic accommodating IOL did not improve reading ability but achieved high subjective ratings of near vision. The closed-loop haptic IOL displayed excellent rotational stability in the late period but relatively poor rotational stability in the early period post implantation. The orientation error was compounded by the high frequency of positional misalignment leading to an extensive overall misalignment of the IOL. This thesis demonstrates the functionality of new IOL lens designs and the importance of standardised testing methods, thus providing a greater understanding of the consequences of implanting these IOLs. Consequently, the findings of the thesis will influence future designs of IOLs and testing methods

Safety and effectiveness of a new toric presbyopia-correcting posterior chamber silicone intraocular lens.

PURPOSE: To evaluate the safety and effectiveness of the Trulign toric intraocular lens (IOL) in adults with cataract. SETTING: Eight private practices in the United States and 1 in Canada. DESIGN: Prospective randomized single-masked multicenter study. METHODS: A toric IOL (1.25 D, 2.00 D, or 2.75 D, determined by a toric calculator) was implanted in eligible patients with age-related cataract requiring a 16.00 to 27.00 diopter (D) spherical IOL power and with a predicted postoperative astigmatism of 0.83 to 2.50 D. Eyes within the lowest cylinder range (predicted postoperative astigmatism 0.83 to 1.32 D) were randomized in a 1:1 ratio between the 1.25 D toric IOL group and the nontoric accommodating IOL (Crystalens) control group. RESULTS: The toric 1.25 D group had a statistically significantly greater percentage reduction in absolute cylinder (P < .001) and uncorrected distance visual acuity (P = .002) than the control group at the 120- to 180-day visit. The mean monocular uncorrected vision at distance, intermediate, and near was 20/25, 20/22, and 20/39, respectively, with the 1.25 D, 2.00 D, and 2.75 D toric IOLs in aggregate (toric group). In addition, 96.1% of patients (123/128) had 5.0 degrees or less absolute IOL rotation postoperatively. Regarding safety, the endpoints for preservation of corrected visual acuity and the incidence of complications and adverse events were met. CONCLUSION: The toric IOL was safe and effective in reducing the effects of preoperative corneal astigmatism and provided excellent uncorrected distance and intermediate vision and functional near vision. FINANCIAL DISCLOSURES: Dr. Pepose is a consultant to Bausch & Lomb and was medical monitor of this study. Drs. Buckhurst, Whitman, Feinerman, Hovanesian, Davies, Labor, and Carter are consultants to Bausch & Lomb. At the time of the study, Drs. Hayashida, and Khodai were employees of Bausch & Lomb. Drs. Colvard and Mittleman have financial or proprietary interest in any material or method mentioned

Experimental Assessment of the Spatial and Temporal Distribution of Non-Contact Tonometer Airflows

(1) The aim of the study was to investigate the spatial and temporal characteristics of the airflow created by two commercially available non-contact tonometers: the CorvisST and the Ocular Response Analyser (ORA). (2) The airflow pressure was measured using a microelectromechanical system (MEMS) pressure sensor to investigate the spatial and temporal distribution. The airflow from the CorvisST and Ocular Response Analyser were mapped to a 600 µm and a 1 mm resolution grid, respectively. (3) Central airflow pressure of the CorvisST (96.4 ± 1.4 mmHg) was higher than that of the Ocular Response Analyser (91.7 ± 0.7 mmHg). The duration of the air-puffs also differed, with the CorvisST showing a shorter duration (21.483 ± 0.2881 ms) than that of the ORA (23.061 ± 0.1872 ms). The rising edge of the CorvisST airflow pressure profile demonstrated a lower gradient (+8.94 mmHg/ms) compared to that of the Ocular Response Analyser (+11.00 mmHg/ms). Both had similar decay response edges: CorvisST −11.18 mmHg/ms, Ocular Response Analyser −11.65 mmHg/ms. (4) The study presents a valid method to investigate the physical dimensions of the airflow pressure of non-contact tonometers. Novel findings relating to the magnitude, duration and spatial characteristics of the respective airflow pressures are reported. It is anticipated that this information will better inform clinical studies and theoretical models relating to ocular biomechanics

Experimental Assessment of the Spatial and Temporal Distribution of Non-Contact Tonometer Airflows

(1) The aim of the study was to investigate the spatial and temporal characteristics of the airflow created by two commercially available non-contact tonometers: the CorvisST and the Ocular Response Analyser (ORA). (2) The airflow pressure was measured using a microelectromechanical system (MEMS) pressure sensor to investigate the spatial and temporal distribution. The airflow from the CorvisST and Ocular Response Analyser were mapped to a 600 µm and a 1 mm resolution grid, respectively. (3) Central airflow pressure of the CorvisST (96.4 ± 1.4 mmHg) was higher than that of the Ocular Response Analyser (91.7 ± 0.7 mmHg). The duration of the air-puffs also differed, with the CorvisST showing a shorter duration (21.483 ± 0.2881 ms) than that of the ORA (23.061 ± 0.1872 ms). The rising edge of the CorvisST airflow pressure profile demonstrated a lower gradient (+8.94 mmHg/ms) compared to that of the Ocular Response Analyser (+11.00 mmHg/ms). Both had similar decay response edges: CorvisST −11.18 mmHg/ms, Ocular Response Analyser −11.65 mmHg/ms. (4) The study presents a valid method to investigate the physical dimensions of the airflow pressure of non-contact tonometers. Novel findings relating to the magnitude, duration and spatial characteristics of the respective airflow pressures are reported. It is anticipated that this information will better inform clinical studies and theoretical models relating to ocular biomechanics.</jats:p

Tablet App halometer for the assessment of dysphotopsia

Purpose To assess the validity and repeatability of the Aston Halometer. Setting University clinic, United Kingdom. Design Prospective, repeated-measures experimental study. Methods The halometer comprises a bright light-emitting-diode (LED) glare source in the center of an iPad4. Letters subtending 0.21° (∼0.3 logMAR) were moved centrifugally from the LED in 0.05 degree steps in 8 orientations separated by 45 degrees for each of 4 contrast levels (1000, 500, 100, and 25 Weber contrast units [Cw]) in random order. Bangerter occlusion foils were inserted in front of the right eye to simulate monocular glare conditions in 20 subjects (mean age 27.7 ± 3.1 years). Subjects were positioned 2 meters from the screen in a dark room with the iPad controlled from an iPhone via Bluetooth operated by the researcher. The C-Quant straylight meter was also used with each of the foils to measure the level of straylight over the retina. Halometry and straylight repeatability was assessed at a second visit. Results Halo size increased with the different occlusion foils and target contrasts (F = 29.564, P <.001) as expected and in a pattern similar to straylight measures (F = 80.655, P <0.001). Lower contrast letters showed better sensitivity but larger glare-obscured areas, resulting in ceiling effects caused by the screen's field-of-view, with 500 Cw being the best compromise. Intraobserver and interobserver repeatability of the Aston Halometer was good (500Cw: 0.84 to 0.93 and 0.53 to 0.73) and similar to the straylight meter. Conclusion The halometer provides a sensitive, repeatable way of quantifying a patient-recognized form of disability glare in multiple orientations to add objectivity to subjectively reported discomfort glare