Open Access Short communication

Open Access Minireview Article

Overcoming Barriers: Controlled-Release Systems as Vectors, the Posterior Segment of the Eye Approach as a Model

Javier Rodríguez Villanueva, Laura J. Rodríguez Villanueva

Ophthalmology Research: An International Journal, Page 1-10
DOI: 10.9734/OR/2018/38862

Background: A successful therapy requires drug access to the target site. This is particularly complicated if the target is located in a well-protected location. Furthermore, if a chronic disease must be treated, the desirable system should be able to control drug release, maintain therapeutic concentrations during the necessary period and prolong administration needs.

Objective: To serve such purposes, the use of controlled-release systems as vectors has been suggested. This might be relevant, among other regions, in the posterior segment of the eye, a place where access is difficult due to different barriers.

Results: To achieve access, multiple strategies have been attempted. Dendrimers, microparticles and liposomes have been designed with varying success. The lack of clinical trials is an issue that must still be addressed.

Conclusion: These approaches are only the tip of the iceberg in terms of what pharmaceutical technology will develop over the next decades.

Open Access Original Research Article

Computer Vision Syndrome Survey among the Medical Students in Sohag University Hospital, Egypt

Mohammed Iqbal, Ahmed El-Massry, Mohammed Elagouz, Hosam Elzembely

Ophthalmology Research: An International Journal, Page 1-8
DOI: 10.9734/OR/2018/38436

Purpose: To analyze and describe the quantitative data of a specially designed well-structured questionnaire to survey the Computer Vision Syndrome (CVS) among the medical students in Sohag University, Egypt.

Design: A prospective descriptive non-comparative cross-sectional study.

Methods: 100 medical students included in this study (50 males and 50 females). After explanation of the nature of the CVS to the medical students, they fulfilled a specially designed form for CVS survey which included 20 questions of high validity and reliability. 

Results: The most remarkable result in this study was recording that 86% of the medical students sample was used to spend 3 hours or more on a daily basis thus were complaining of one or more of CVS manifestations. Dry eye, headache, blurred vision, eye strain, neck and shoulder pain, fatigue and eye redness were recorded in 28%, 26%, 31%, 16%, 24%, 21% and 15% respectively.

Conclusion: This study proved that CVS was a common syndrome that was simply misdiagnosed. Based on the survey performed in this study, 86% of the medical students were complaining of one or more of the CVS manifestations. This study recorded that dry eye, blurred vision, eye strain and headache were the most common CVS symptoms. This study recommended performing larger studies including many universities in Egypt, provided that the future studies should include both objective and subjective examination tools.


Open Access Original Research Article

Efficacy S-formula and Kinetics of Non-oxygen-mediated (Type-I) and Oxygen-mediated (Type-II) Corneal Cross-linking

Jui-Teng Lin

Ophthalmology Research: An International Journal, Page 1-11
DOI: 10.9734/OR/2018/39089

Aims: To derive analytic formulas for the overall efficacy of corneal collagen crosslinking (CXL) based on coupled kinetic equations including both non-oxygen-mediated (NOM) and oxygen-mediated (OM) type-II mechanisms.

Study Design:  modeling the kinetics of CXL.

Place and Duration of Study: Taipei, Taiwan, between June, 2017 and January 2018.

Methodology: Coupled kinetic equations are derived under the quasi-steady state condition for the 3-pathway mechanisms of CXL. For type-I CXL, the riboflavin triplet state [T3] may interact directly with the stroma collagen substrate [A] under NOM, or with the ground-state oxygen [O2] to form reactive oxygen species [O-] under OM. For type-II process, [T3] interacts with [O2] to form a singlet oxygen [1O2]. Both reactive oxygen species (ROS), [O-] and [1O2], can relax to [O2], or interact with the extracellular matrix (or the stroma substrate [A]) for crosslinking.

Results: In the first 3 to 20 seconds, CXL efficacy is governed by both type-I and –II mechanisms, and after that period type-I, NOM is the predominant contribution, while oxygen for OM only plays a limited and transient role, in contrary to the conventionally believed OM-dominant mechanism. The riboflavin profile has a much slower depletion rate than that of oxygen profile. The ratio between NOM-type-I and OM depends on the relative initial concentration of [A] and [1O2] and their diffusion depths in the stroma. The overall CXL efficacy is proportional to the UV light dose (or fluence), the riboflavin, C (z, t), and oxygen, [O2], initial concentration, where efficacy is limited by the depletion of either C (z, t) or [O2].

Conclusion: Resupply of riboflavin and/or oxygen concentration under a controlled-concentration-method (CCM) during the UV exposure may improve the overall efficacy, specially for the accelerated CXL which has lower efficacy than the standard Dresden low-power (under non-controlled concentration).


Open Access Review Article

Transcription Factor 7 Like 2 (TCF7L2) Expression Level Variation Contributes to VEGF Alteration in Diabetic Retinopathy

Mahmood Hassan Dalhat, Maimuna Musa

Ophthalmology Research: An International Journal, Page 1-7
DOI: 10.9734/OR/2018/38734

Diabetic retinopathy (DR) is a multifactorial disease which causes blindness among people with Diabetes worldwide. It has complex pathophysiology linked to various genetic variations. TCF7L2 (Transcription factor 7 like 2) is among the most important candidate genes which play a major role in hyperglycemia and neovascularization. Neovascularization is a clinical symptom of DR associated with upregulation of vascular endothelial growth factor (VEGF) as established by numerous published articles. The purpose of this review is to highlight the role of TCF7L2 polymorphism in the development of DR via alteration in VEGF expression level. We used available published data to explain the association of TCF7L2 polymorphism with DR. We concluded that genetic studies reports revealed TCF7L2 polymorphism might be associated with DR development.