American Board of Ophthalmology (ABO) Practice Exam

Which type of lens would be best for a patient with a high prescription requiring thinner edges?

1. High index lens

2. Standard plastic lens

3. Polycarbonate lens

4. Glass lens

The correct answer is: High index lens

High index lenses are designed specifically to address the challenges faced by patients with high prescriptions. The most significant advantage of these lenses is that they have a higher refractive index compared to standard plastic or glass lenses. This means that they can bend light more efficiently, allowing for the same optical power to be achieved with less material. For patients with high prescriptions, thicker lenses can lead to noticeable edge thickness, which may not only be cosmetically unappealing but can also create additional weight and discomfort. High index lenses help to mitigate these issues by being thinner and lighter, which is particularly beneficial for individuals who require significant correction. Additionally, high index lenses can reduce the 'magnification' effect that normally occurs with high prescriptions, providing a more natural appearance for those who wear them. This is particularly important for ensuring patient comfort and aesthetic satisfaction. In contrast, other lens materials, such as standard plastic, polycarbonate, and glass, do not offer the same level of thickness reduction for high prescriptions. Standard plastic lenses tend to be thicker and heavier in these situations, while polycarbonate lenses, while durable, also fall short in terms of thickness for high prescriptions. Glass lenses, although used traditionally, are not favored for high prescriptions due to their weight and potential for