From our research, there are several factors and causes that may influence the visual acuity outcome which are ages, ethnicity, the number of injections, types of regimen injected and gender.
Initiating
injection at older ages was also associated with a marked risk toward poor
visual outcome.
According to our finding, increase in age number resulting in decreasing of visual acuity letter scored. This is due to a decrease in pupil size. The lens is composed of transparent and flexible tissue and is located directly behind the iris and the pupil. It is responsible for the change of focal distance of the eyes, allowing it to focus on objects at various distances by changing its shape, becomes heavier and thicker and loses its elasticity due to the anatomical changes, which is ageing. Increasing of injection, numbers will have resulted in the probability of achieving a negative outcome. This is because it will cause the patients to have a higher risk of developing Ischemic Optic Neuropathy (ION). The anti-VEGF may reduce the blood flow to the eye’s optic nerve, causing vision loss. In addition, the patients who receive greater numbers of anti-VEGF injections usually are older and have a significantly higher prevalence in hypertension or heart disease. These systemic factors may also lead to the development of ION.
The patient who received Ranibizumab were more likely to reach less letter score of 35( 20/200) compared to patients who received Aflibercept and the number of patients who received Aflibercept is more than the number of patients who received Ranibizumab.
There are two types of regimen injections that can be injected into the body to increase visual acuity which is Ranibizumab and Aflibercept. Aflibercept has a great binding affinity than Ranibizumab. Hence, more injection numbers of Ranibizumab in order to achieve the ideal letter score (>=70). Thus, Aflibercept is considered more efficient in treating Neovascular AMD and results in good visual acuity. This is maybe due to Aflibercept hinder VEGF more strongly compared to Ranibizumab whereas Aflibercept inhibits both VEGF-A and VEGF-B together with placental growth factor but Ranibizumab can only inhibit VEGF-A. Therefore, some patients with certain genetic variants of VEGF-A will have a poor response to Ranibizumab. Nevertheless, researchers are still unable to explore the dissimilarities between Aflibercept and Ranibizumab and adjust analyses completely.
Ethnicity or race will also influence visual acuity.
Referring to our finding, Caucasian is the race that displaced the highest in visual acuity among the other races. The causes of the factor are still unknown but it is possible is due to the poor behavioural health, risk-taking behaviour and chronic disease. Exposure to ultraviolet radiation (UV ray) from the sun especially UV-A and UV-B will cause eye-related problems for instance cataracts. Ultraviolet radiation will damage to the retinas of adults as well as children.
Lastly, females are more exposed to the age-related macular degeneration, rather than men.
Based
on our finding, females have higher visual acuity compared to males. However, there is almost no study on
gender differences in visual acuity. This is because the initiation of visual
acuity will also depend on age. Genetic factors are also one of the strong determinants of sharp visual acuity. Thus, visual acuity can be inherited from one generation to another.
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