Clinical Study of Focus NIGHT &DAY® contact lenses

Objectives: To investigate the visual and ocular implications of continuous wearing a silicon hydrogel contact lens for up to 3 weeks , in a dry semi-arid climate environment. Methods: Clinical examination of eye conditions (visual acuity, Schirmer test, corneal thickness and endothelial cells counts) for 9 healthy voluntary students was carried out between September and November of 2004 in Riyadh\'s King Saud University clinical facilities, using Ciba Vision\'s ocus Day & Night® lotrafilcon lenses. Which is measured weekly for 3 weeks. Results: Visual acuity testing revealed no significant changes after three weeks of continuous wear of the Focus lens. An average minimum angle of resolution (MAR) of 1.045 min arc was maintained throughout the 3 weeks. No significant drop had been recorded (p>0.05). The Schirmer test for eye lubrication showed an overall decrease in the wetting of the strip from about 36 mm to around 27 mm. Corneal thickness for the 9 subjects perior to CL wearing was 0.529 ± 0.050 mm, slightly increased to 0.533 ± 0.044 mm at the end of the study. The mean cell area value was 359 ± 67 Um2 at first visit, becoming only marginally higher at 361 ± 71 Um2 after three weeks of contact lens wear. Conclusion: The Focus NIGHT & DAY® lenses can be worn safely as extended-wear contact lenses for up to 3 weeks without ocular complications. Visual acuity, tear functions or corneal structure are not altered. Keywords: optometry, silicone hydrogel materials, resolution, ocular.Sudan Journal of Medical Sciences Vol. 3 (2) 2008: pp. 115-12

Informed consent in refractive surgery: in-person vs telemedicine approach.

Purpose:The aim of this study was to compare the quality of consent process in refractive surgery between patients who had a preoperative consent discussion with the surgeon using a telemedicine approach and those who had a face-to-face discussion. Methods:Patients treated between January and December 2017 (8,184 laser vision correction [LVC] and 3,754 refractive lens exchange [RLE] patients) that attended day 1 and 1-month postoperative visit were retrospectively reviewed. Preoperative consent preparation included a consultation with an optometrist, observation of an educational video, and written information. Patients then selected either a face-to-face appointment with their surgeon (in-clinic group) or a telemedicine appointment (remote group) for their consent discussion, according to their preference. Patient experience questionnaire and clinical data were included in a multivariate model to explore factors associated with consent quality. Results:Prior to surgery, 80.1% of LVC and 47.9% of RLE patients selected remote consent. Of all LVC patients, 97.5% of in-clinic and 98.3% of remote patients responded that they were adequately consented for surgery (P=0.04). Similar percentages in the RLE group were 97.6% for in-clinic and 97.9% for remote patients (P=0.47). In a multivariate model, the major predictor of patient's satisfaction with the consent process was postoperative satisfaction with visual acuity, responsible for 80.4% of variance explained by the model. Other significant contributors were postoperative visual phenomena and dry eyes, difficulty with night driving, close-up and distance vision, postoperative uncorrected distance visual acuity, change in corrected distance visual acuity, and satisfaction with the surgeon's approach. The type of consent (remote or in-clinic) had no impact on patient's perception of consent quality in the regression model. Conclusion:The majority of patients opted for telemedicine-assisted consent. Those who chose it were equally satisfied as those who had a face-to-face meeting with their surgeon. Dissatisfaction with surgical outcome was the major factor affecting patient's perception of consent quality, regardless of the method of their consent

The effects of night wear orthokeratology lenses on central cornela thickness

Purpose: This study was performed to determine the effectiveness and safety of Night Move™ orthokeratology lenses and to examine their effects on central corneal thickness. Methods: Ten subjects (20 eyes) with myopia less than 5D and with the rule astigmatism less than 1.50D were fitted with the Night Move™ orthokeratology lenses. The lenses were worn at night for a period of 30 days. Subjects were examined prior to the study, at 1 day, 7 days and 30 days. Unaided visual acuity, refractive error, keratometric readings, intraocular pressure and central pachymetry measurements were determined at each visit. Results: All eyes reached unaided visual acuities of at least 20/40 with 90% reaching 20/20 or better. Mean refractive error demonstrated a decrease in myopia from -2.26D to -0.04D at 30 days. The mean steep K was reduced 1.46D at 30 days. The mean decrease in central corneal thickness was 0.022mm after 30 nights of lens wear. Mild cases of epithelial staining were seen in 2 eyes at 1 day and 7 days. No staining was seen after 7 days. All other ocular health was unremarkable throughout the study. Conclusions: Changes in mean keratometric readings and mean refractive error do not explain the acuities achieved by the subjects in the study. A decrease in central corneal thickness provides the additional power to allow subjects to achieve optimum visual acuity. The change in corneal thickness is small compared to photorefractive surgeries and provides a safer alternative maintaining greater corneal integrity

Vision and Foraging in Cormorants: More like Herons than Hawks?

Background Great cormorants (Phalacrocorax carbo L.) show the highest known foraging yield for a marine predator and they are often perceived to be in conflict with human economic interests. They are generally regarded as visually-guided, pursuit-dive foragers, so it would be expected that cormorants have excellent vision much like aerial predators, such as hawks which detect and pursue prey from a distance. Indeed cormorant eyes appear to show some specific adaptations to the amphibious life style. They are reported to have a highly pliable lens and powerful intraocular muscles which are thought to accommodate for the loss of corneal refractive power that accompanies immersion and ensures a well focussed image on the retina. However, nothing is known of the visual performance of these birds and how this might influence their prey capture technique. Methodology/Principal Findings We measured the aquatic visual acuity of great cormorants under a range of viewing conditions (illuminance, target contrast, viewing distance) and found it to be unexpectedly poor. Cormorant visual acuity under a range of viewing conditions is in fact comparable to unaided humans under water, and very inferior to that of aerial predators. We present a prey detectability model based upon the known acuity of cormorants at different illuminances, target contrasts and viewing distances. This shows that cormorants are able to detect individual prey only at close range (less than 1 m). Conclusions/Significance We conclude that cormorants are not the aquatic equivalent of hawks. Their efficient hunting involves the use of specialised foraging techniques which employ brief short-distance pursuit and/or rapid neck extension to capture prey that is visually detected or flushed only at short range. This technique appears to be driven proximately by the cormorant's limited visual capacities, and is analogous to the foraging techniques employed by herons

Self-awareness of driving impairment in patients with cataract or glaucoma

This study compared the driving performance of individuals with the eye diseases cataracts or glaucoma with age-matched controls, as well as the individual’s own perceptions of driving. Participants included drivers over the age of 50 years who had been diagnosed with glaucoma (n=29) or cataracts (n=33) and a control group with no ocular pathology (n=13). Driving performance was measured on a closed road circuit using a range of standardised measures of vehicle control and hazard recognition and avoidance, while visual performance was measured with a battery of tests including visual acuity, contrast sensitivity and visual fields. Perceptions of vision and driving were assessed using the Activities of Daily Vision Scale, Driver Behaviour Questionnaire and a driving exposure questionnaire. Driving performance was significantly poorer (p<0.05) for each of the ocular disease groups compared to the control group. Impaired contrast sensitivity and the higher disease severity scores (for the glaucoma group only) correlated most strongly with poorer driving performance. While participants with cataracts rated their vision significantly more poorly than those in the glaucoma and control groups, there were no significant differences between the participant groups rating of their own driving performance. These findings suggest that there is no direct relationship between self-rated driving ability and actual vision and driving performance. This has serious road safety implications

Visual characteristics of elderly night drivers in the Salisbury Eye Evaluation Driving Study

PURPOSE. To characterize visual factors among those who continue to drive and those who restrict night driving in the elderly population. METHODS. The Salisbury Eye Evaluation Driving Study (SEEDS) is a study of vision, cognition, and driving behaviors of older drivers living in the greater Salisbury, Maryland, metropolitan area. Patients were recruited from listings in the Department of Motor Vehicle Administration. Data are reported from two visits conducted 2 years apart. Night driving was assessed using a real-time driving assessment tool, the Driving Monitor System. Night driving was defined by the presence of at least one episode of driving at night during a 5-day time period (seasonally adjusted). Participants also underwent a battery of cognitive and visual function testing including distance acuity, contrast sensitivity, and visual fields. Logistic regression was used to model factors associated with night driving. RESULTS. Complete data were available for 990 of the 1080 participants (92%) attending both visits; 41% of participants were driving at night in each visit. Those who were younger (P < 0.001), male (P < 0.001), and had better measures of cognitive (P 1/4 0.007) and visual function were observed driving at night, whereas those who were older, female, and had poorer measures of cognitive and visual function restricted their night driving behavior. An association was observed between depressive symptoms and less night driving in females (P 1/4 0.003). In multivariate analysis, better contrast sensitivity (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.02-1.36, P 1/4 0.02) and visual field detection (OR 1.21, 95% CI 1.00-1.47, P 1/4 0.05) were associated with driving at night. Visual acuity was not found to be significantly related to night driving (OR 1.08, 95% CI 0.95-1.18, P 1/4 0.12). CONCLUSIONS. Restricting driving at night is a multifactorial behavior that has a vision component, notably poor contrast sensitivity, and some loss of visual fields

Clinical disorders affecting mesopic vision

Vision in the mesopic range is affected by a number of inherited and acquired clinical disorders. We review these conditions and summarize the historical background, describing the clinical characteristics alongside the genetic basis and molecular biological mechanisms giving rise to rod and cone dysfunction relevant to twilight vision. The current diagnostic gold standards for each disease are discussed and curative and symptomatic treatment strategies are summarized

Prevalence of Ocular Morbidity Among School Adolescents of Gandhinagar District, Gujarat

Objective: To study the prevalence of ocular morbidity (abnormal condition) and various factors affecting it among school attending adolescents. Methods: A cross-sectional study was conducted to study abnormal ocular conditions like refractive errors, vitamin A deficiency, conjunctivitis, trachoma, ocular trauma, blephritis, stye, color blindness and pterygium among school adolescents of 10-19 years age in rural and urban areas of Gandhinagar district from January to July, 2009. Systematic sampling was done to select 20 schools having 6th to 12th standard education including 12 schools from rural and 8 from urban areas. Six adolescents from each age year (10-19) were selected randomly to achieve sample size of 60 from each school. In total, 1206 adolescents including 691 boys and 515 girls were selected. Information was collected from selected adolescents by using proforma. Visual acuity was assessed using a Snellen’s chart and all participants underwent an ophthalmic examination carried out by a trained doctor. Results: Prevalence of ocular morbidity among school adolescents was reported 13% (7.8% in boys, 5.6% in girls); with 5.2% have moderate visual impairment. Refractive error was most common ocular morbidity (40%) both among boys and girls. Almost 30% of boys and girls reported vitamin A deficiency in various forms of xerophthalmia. Prevalence of night blindness was 0.91% and of Bitot`s spot 1.74%. Various factors like, illiterate or lower parents’ education, lower socio-economic class and malnutrition were significantly associated with ocular morbidity. Conclusion: Ocular morbidity in adolescents is mainly due to refractive error, moderate visual impairment and xerophthalmia