Question 1: Which is an example of Simple Myopic Astigmatism?
- A. +2.00 sphere
- B. +1.00 -3.00 × 90°
- C. -2.00 sphere
- D. plano -2.00 × 90° (Correct Answer)
Explanation: ***plano -2.00 × 90°***
- This prescription indicates a **spherical equivalent of zero (plano)** in one meridian and **-2.00 diopters of myopia** in the meridian 90 degrees away.
- This perfectly fits the definition of **simple myopic astigmatism**, where one principal meridian is emmetropic and the other is myopic.
*+2.00 sphere*
- This prescription represents **simple hyperopia**, meaning the eye is **farsighted** but without any astigmatism.
- All light rays focus behind the retina, and there is no difference in refractive power between the principal meridians.
*-2.00 sphere*
- This represents **simple myopia**, where the eye is **nearsighted** but without any astigmatism.
- All light rays focus in front of the retina, and there is no difference in refractive power between the principal meridians.
*+1.00 -3.00 × 90°*
- This prescription is an example of **mixed astigmatism**, where one principal meridian is hyperopic (+1.00 D) and the other is myopic (-2.00 D, calculated as +1.00 + [-3.00]).
- This differs from simple myopic astigmatism where one meridian is emmetropic.
Question 2: Patient with eye surgery done 2 days ago presents with pain and dimness of vision. Which of the following is not useful for management?
- A. Intravenous antibiotics
- B. Intravitreal antibiotics
- C. Pars plana vitrectomy
- D. Topical antibiotics (Correct Answer)
Explanation: ***Topical antibiotics***
- This patient presents with symptoms suggestive of **post-surgical endophthalmitis** (pain and dimness of vision after eye surgery), which is a severe infection of the intraocular fluids (vitreous and/or aqueous humor).
- Topical antibiotics typically do not achieve sufficient intraocular concentrations to effectively treat a deep-seated infection like endophthalmitis.
*Intravenous antibiotics*
- **Intravenous antibiotics** can provide systemic coverage and may reach the posterior segment of the eye, although their penetration into the vitreous can be limited.
- They are often used as an adjunct to more direct routes of administration in severe endophthalmitis.
*Intravitreal antibiotics*
- **Intravitreal antibiotics** are injected directly into the vitreous cavity, providing high local concentrations of medication directly at the site of infection.
- This is considered a cornerstone of endophthalmitis management due to its immediate and potent antimicrobial effect.
*Pars plana vitrectomy*
- **Pars plana vitrectomy** involves surgical removal of the infected vitreous, which reduces the bacterial load and inflammatory mediators, and allows for direct sampling for microbiology.
- It is particularly indicated in cases of severe endophthalmitis or when there is poor response to antibiotics, often improving visual outcomes.