Aims: The main aim of present study is to investigate the effect of luminance on identifying the Ishihara colour vision plates in normal trichromats.
Place and Duration of Study: Dr. Rishi Bhardwaj Visual Psychophysics laboratory, School of Medical sciences, University of Hyderabad-INDIA, 1-year (07/2015 to 07/07/2016).
Methodology: This experimental quantitative study design conducted with n=60 participants of age group 18 to 21 years both male & female genders and inclusion criteria was trichromats, emmetropes with no history of ocular pathology and randomized sampling was done to study the experiment in lab setting with three different illuminations (Compact fluorescent light- CFL), fluorescent light, LED light) with constant 400-lux is maintained for the experiment followed by colour vision assessment with Ishihara colour vision plates 38th edition (printed) version. Followed by satisfactory and feedback of comfort was received by participants.
Results: The relation between lighting and isochromatic colour vision plates response was not statistically significance (P=0.007) males & females (P=0.056). But the isochromatic plate identifying speed is faster (1 - 3 sec) under fluorescent lighting compare to CFL and LED, similarly the distribution of symptoms related to colour vision was very less in fluorescent lighting (10-30%) followed by CFL (10-55%) and maximum (30 – 75%) under LED lighting, shown more symptomatic. Satisfactory feedback from sixty participants showed that 36 participants recommended (Fluorescent=63%) lighting was good while identifying ishihara colour vision plates followed by CFL and LED similarly, 12 recommended (CFL=20%) and 10 participants recommended (LED=17%).
Conclusion: This experiment concludes that ishihara colour vision plates are a tool for red and green deficiency screening. But the luminance intensity and types of lighting play a vital role for discriminating the numerals that imbedded in isochromatic plates, fluorescent lighting showed better results and faster speed to recognize the isochromatic plates compare to CFL and LED luminance in trichromats.
Purpose: The objective of this study was to undertake an analysis of the eye care services situation in Yemen and to assess ophthalmic human resources, eye units’ ownership and ophthalmic equipments.
Methods: Eye care providers were surveyed by a standardized questionnaire which was sent to the 184 eye units in governmental, university, military, private and charity clinics and hospitals in Yemen and covered the period between 01 January to 31 December 2012. The questionnaire determined location, human resources and eye units’ ownership and ophthalmic equipments.
Results: The response rate to the questionnaire was 80.7%. During 2012, 184 eye units involved in providing eye care services in Yemen. 25% of eye units represent public sector, 72.3% represent private sector and 2.7% belong to non-governmental charity organizations. 682 people worked in eye care services of which 268 are ophthalmic doctors that is equivalent to 1.06 per 100,000 populations. Human resources and eye care equipments were below vision 2020 targets. There is significant unequal distribution of eye care services provision between urban and rural areas in Yemen.
Conclusion: Deficiency, maldistribution and inadequate training of ophthalmic doctors in addition to poor financial resources to establish and provide eye care units with good infrastructure. All these factors are regarded as major factors that cause underperformance in the Yemeni eye health system. We recommend equal distribution of trained ophthalmic doctors and personnel with good financial support for eye care services in rural areas of Yemen.
Aims: To determine the level of agreement between the visual Fields easy application (VFE) for iPad and a standard clinical test for assessing peripheral vision in stroke survivors.
Study Design: This was a prospective cross-sectional study comparing the VFE application to the Humphrey Field Analyser (HFA) SITA Fast c30-2 program in identifying and diagnosing visual field defects post-stroke.
Place and Duration of Study: The ophthalmic department at Imperial College Healthcare NHS Trust. Data collection was undertaken between January 2016 and August 2016.
Methodology: A total of 50 participants with a diagnosis of stroke and a suspected visual problem were recruited to the study. Normative data was collected from 50 participants with no history of stroke or visual loss. Analysis comprised of comparing the extent of the visual field loss detected by both the VFE and HFA, and clinically assessing the results for normality.
Results: Bland-Altman analysis demonstrated that with more severe visual field loss, the agreement between both modalities was found to decrease. There was a higher proportion of false negatives with the VFE compared to the HVF. The bias towards detecting more missed test locations with the VFE application compared to the HFA was 6% for the normal participants and 2% for the stroke participants. The limits of agreement between the two modalities were large; 20% and 40% for the normal and stroke participants respectively. The sensitivity of the VFE application to determine an abnormal visual field in comparison to HFA was 88% and specificity was 76% in the stroke cohort based upon a clinical impression of its findings. The majority of stroke participants (88%) found the VFE test more comfortable to perform.
Conclusion: As a screening tool, the VFE application is quick and easy to administer, preferred by patients and has good sensitivity and specificity for detecting the presence of an abnormal visual field when compared to HFA. In patients with extensive visual field loss, the VFE may overestimate visual field reduction.
Aims: To derive analytic formulas for the efficacy of type-II corneal collagen crosslinking (CXL) based on coupled macroscopic kinetic equations with an emphasis on the role of oxygen.
Study Design: modeling and analysis of type-II CXL
Place and Duration of Study: Taipei, Taiwan, between Feb. and June 2017.
Methodology: Coupled macroscopic kinetic equations are derived under the quasi-steady state condition. For type-I CXL, the riboflavin triplet state [RF3] interacts directly with the stroma collagen substrate for crosslinking. For type-II process, [RF3] interacts with the ground-state oxygen [O2] to form a reactive oxygen singlet (ROS) which can relax to [O2], or interact with the extracellular matrix for crosslinking.
Results: Both type-I and type-II efficacy are nonlinear increasing function of the UV light dose (or fluence). Oxygen is required for type-II CXL, but not absolutely needed in type-I CXL. With the presence of oxygen external source, the steady-state type-II efficacy is a decreasing function of the UV intensity (for the same dose), same as that of type-I. Sufficient external oxygen supply, either pre-CXL or during CXL, will enhance the CXL overall efficacy. UV light in pulsing-mode may also improve the efficacy, but only when UV-off period is long enough for oxygen replenishment. Thin cornea (under the safety thickness criteria), low UV intensity (3 to 18 mW/cm2), and epi-off CXL will achieve higher overall efficacy than that of thick corneas, or epi-on CXL under high intensity (>18 mW/cm2).
Conclusion: We have derived analytic formulas for the efficacy of type-I and type-II CXL. The overall CXL efficacy is proportional to the UV light dose (or fluence), the riboflavin and oxygen initial concentration and their diffusion depths in the stroma.
Traumatic cataract is more common in younger individuals. Traumatic cataract is an important cause of uniocular visual loss and is often sudden in onset. Traumatic lens damage may be caused by mechanical or non-mechanical injury. Traumatic cataract is an indication of intraocular lens (IOL) implantation in children. In trauma visual outcome depends on the interval from injury to the surgery. Early intervention provides better visual outcome and less chance of developing amblyopia and strabismus. Intraocular lens implantation for unilateral cataract in children has a definite role in correcting aphakia, resulting in good visual outcome and thus helping to maintain binocularity.
This article explains the basic pathology involving traumatic cataract, pathogenesis and management.