Open Access Short Research Article

Optometric Screening of Elementary Students in Greece

Melinta Bollano-Lazaridis, Aristeidis Chandrinos

Ophthalmology Research: An International Journal, Page 42-49
DOI: 10.9734/or/2021/v14i430201

Background: The aim of this study is to provide a wide screening test in elementary school students in Greece in order to trace undiagnosed visual deficiencies, which can affect the visual performance and efficiency.

Methods: Examination procedures were approved by the Ministry of Education for the optometric team to enter the school premises and perform the assessments. The researchers performed optometric testing according to standard protocols to evaluate visual acuity (VA), near point of convergence (NPC), accommodative amplitude and facility, vergence facility, stereopsis, and pursuit and saccade oculomotor function.

Results: The 835 students that were examined came from a total number of 14 schools so as to enable social stratification of high, medium, and low living standards. Fewer than 17% of the children managed to pass all visual tests at published goal levels. Testing identified a significant number of students who had undiagnosed visual deficiencies (83%).

Conclusion: Visual Function in elementary students needs to be evaluated on a regular basis following a comprehensive Optometric screening so that a wide range of visual dysfunctions can be detected. Our ultimate goal is to ensure adequate conditions for every student to develop vision skills needed to meet academic demands.

Open Access Original Research Article

Association between Diabetic Macular Edema and Capillary Non Perfusion; An Optical Coherence Tomography Angiography Study

Mostafa A. Waly, Hammouda Hamdi Ghoraba, Mohamed Hosni El-Bradey, Mostafa Abd El Latif Abo El Einen

Ophthalmology Research: An International Journal, Page 1-7
DOI: 10.9734/or/2021/v14i430197

Aims: The aim is to use of OCTA to describe the retinal structural damages observed in DME and the relationship between the edema and the capillary non perfusion and to quantify VD and the FAZ area.

Study Design: prospective, cross sectional, observational study

Place and Duration of Study: University Hospitals in the period between March 2018 to March 2020.

Methodology: OCTA images were obtained using the AngioVue (Optovue Inc., CA, USA). For quantitative analysis of the VD and the FAZ area with the help of the manufacturer’s automated software.

Results: The study included included 160 eyes of 135 diabetic patients, 61 (45%) females and 74 (55%) males and 20 eyes from 20 age-matched healthy individuals (12 males and 8 females). A significantly worse visual acuity was found in diabetic eyes with CME (mean (x̅) ± SD LogMAR 0.61 ± 0.33), than NPDR eyes without macular edema (0.25 ± 0.19), and controls (Mean ± SD LogMAR 0.02 ± 0.05),the values of VD of the SCP were significantly affected more than the DCP very early in the diabetic course (No DR stage) (P=0.040). Moving one stage more in the disease (mild to moderate NPDR with no edema stage) the deep layer got significantly more affected than the superficial layer (P=0.038). In the more advanced stages of the disease and as the macular edema develop and progress (spongy edema and CME) the two plexuses showed decreased VD values nearly to the same degree with the deep plexus affected slightly more (low VD values) than the superficial plexus

Conclusion: Using the OCTA machine with AngioAnalytics parameters (vessel density and non-flow area) aided in the objective quantification of macular perfusion and accurate measurement of the FAZ area in diabetic eyes with and without macular edema. Both parameters were significantly correlated with visual function in treatment-naive diabetic eyes with macular edema.

Open Access Original Research Article

Perception and Acceptance of COVID-19 Vaccination among Patients in a Tertiary Hospital in South-East Nigeria

A. I. Apakama, C. C. Uzozie, M. C. Amobi, M. C. Okosa, A. A. Onwuegbuna

Ophthalmology Research: An International Journal, Page 8-16
DOI: 10.9734/or/2021/v14i430198

Aims: To determine the perception and acceptance of COVID-19 vaccination among patients in a tertiary eye hospital.

Study Design: A cross-sectional hospital-based study.

Place and Duration of Study: Guinness Eye Centre Onitsha, South-East Nigeria between 1st to 29th June 2021

Methodology: An interviewer-administered semi-structured pretested questionnaire on sociodemographic, knowledge, perception and acceptance on coronavirus disease and its vaccine was used to collect data on eligible patients. Data obtained was analyzed with SPSS version 23 (IBM Corporation, Armonk, NY, USA). Descriptive statistics including frequency tables, mean and standard deviation was used to present categorical variables.

Results: A total of 386 patients were interviewed comprising 157 (40.7%) males and 229(59.3%) females, and aged 18 to 93 years (mean age of 44.73±18.49 years). Two hundred and fifty-eight (66.8%) patients knew of COVID-19 vaccine availability in Nigeria, with 90 (34.9%) not knowing where they could obtain the vaccine. Only 34 (8.8%) had taken the vaccine. Uptake of COVID-19 vaccine is strongly associated with patient’s perception of COVID-19 being real (P=0.006), patients trust in the information head about the vaccine (P=0.001), and their trust on the efficacy and safety of the COVID-19 vaccine (P˂0.001). Acceptance of COVID-19 vaccine is not significantly associated with their faith in the previous human vaccinations(P=0.076).

Conclusion: The uptake of COVID-19 vaccine in the study group is low. Therefore, there is an urgent need for re-strategizing on various ways to enlighten the public and widen the scope of information dissemination.

Open Access Original Research Article

Critical Analysis of Corneal Cross-linking (Part-I): Formulas for Efficacy, Safety Dose, Minimum Thickness, Demarcation Line Depth and the Role of Oxygen

Sheng-Fu Cheng, Jui-Teng Lin

Ophthalmology Research: An International Journal, Page 29-41
DOI: 10.9734/or/2021/v14i430200

Purpose: To update and derive formulas for the efficacy and kinetics of corneal collagen crosslinking (CXL) including both type-I and oxygen-mediated type-II mechanisms, the role of oxygen, the initiator regeneration, safety dose, minimum corneal thickness and demarcation line depth.

Study Design: Modeling the kinetics of CXL in UV light and using riboflavin as the photosensitizer.

Place and Duration of Study: Taipei, Taiwan, between June, 2021 and July, 2021.

Methodology: Coupled kinetic equations are derived under the quasi-steady state condition for the 2-pathway mechanisms of CXL. For type-I CXL, the riboflavin (RF) triplet state [T] may interact directly with the stroma collagen substrate [A] to form radical (R) and regenerate initiator. For type-II process, [T] interacts with oxygen to form a singlet oxygen [1O2]. Both reactive radical (R) and [1O2], can interact with the substrate [A]) for crosslinking. Based on a safety dose and a threshold dose, formulas for the minimum corneal thickness and demarcation line depth (DLD) are derived.

Results: Our updated theory/modeling showed that oxygen plays a limited and transient role in the process, in consistent with that of Kamave. In contrary, Kling et al believed that type-II is the predominant mechanism, which however conflicting with the epi-on CXL results. For both type-I and type-II, a transient state conversion (crosslink) efficacy in an increasing function of light intensity (or dose), whereas, its steady state efficacy is a deceasing function of light intensity. RF depletion in type-I is compensated by the RF regeneration term (RGE) which is a decreasing function of oxygen. For the case of perfect regeneration case (or when oxygen=0), RF is a constant due to the catalytic cycle. Unlike the conventional Dresden rule of 400 um thickness, thin cornea CXL is still safe as far as the dose is under a threshold dose (E*), based on our minimum thickness formula (Z*). Our formula for thin cornea is also clinically shown by Hafez et al for ultra thin (214 nm) CXL.

Conclusion: For both type-I and type-II, the transient state conversion (crosslink) efficacy in an increasing function of light intensity (or dose), whereas, its steady state efficacy is a deceasing function of light intensity. CXL for ultra thin corneas are still safe, as far as it is under a threshold dose (E*), based on our minimum thickness (Z*) formula, which has a similar tend as that of demarcation line depth (Z').

Open Access Review Article

Principles of Accommodation and Technology Update of Presbyopia Corrections using IR and UV Lasers

Jui-Teng Lin

Ophthalmology Research: An International Journal, Page 17-28
DOI: 10.9734/or/2021/v14i430199

Purpose: To update and review the technology and principles of laser presbyopia reversal (LAPR) via sclera ablation and thermal shrinkage using infrared and UV lasers. Recent clinical data and new methods are also summarized.

Study Design: LAPR using laser sclera ablation for increased accommodation of presbyopic eyes.

Place and Duration of Study: New Taipei City, Taiwan, between June, 2021 and July, 2021.

Methodology: Accommodation gain was obtained by laser scleral ablation of an eye using Er:YAG laser (at 2.94 um) using either line-pattern or dots-pattern outside the limbus in the oblique quadrants of an eye. The principles of accommodation and the key factors influencing the outcomes are discussed. The accommodation gain (AG) after the surgery is mainly due the change in anterior curvature and anterior shift of the lens. The effectiveness of ciliary body contraction for lens relaxation (or accommodation) may be influenced by the combined aging factors, including lens property changes (index, size, thickness and curvature), tissue elastic changes (in sclera and ciliary) and the zonular tension change. Classical theories of accommodation include Helmholtz and Schachar hypothesis. The key issues and new directions to overcome the drawbacks of the existing LAPR procedure (based on scleral ablation) are proposed. Clinical outcomes from two major groups, SurgiLight and Ace Vision, with two years follow are summarized.

Results: Clinical outcomes during 2000 to 2020 are summarized showing an average Accommodation gain about 2.0 D, and postoperative egression about 0.25 D (after two years).

Conclusion: Laser presbyopia reversal (LAPR) via sclera ablation using infrared laser is safe and effective, but suffers drawbacks of being invasive and procedures are too slow. New directions are required for improved outcomes.