Hi there,
Taking your questions one by one.
1. Regarding the refractive error., at his age it needs power verification with dilating drops (mostly cyclopentolate). So get his dilated power and retina checkup done.
2. Regarding dengue and refractive error, not related directly.
3. Regarding spectacles, will be able to tell you further after seeing the powers. Plus powers tend to decrease with age, minus powers tend to increase with age and cylindrical powers may remain constant. Accordingly we can start glasses and take a call on refractive correction surgery after 18-19yr of age. Nothing concerning now.
4. Dengue and developmental delay can sometimes be related especially if there had been any hypoxic brain injury. Get a pediatric opinion as well.
5. Those drops are safe given under medical guidance, but moxcip-d contains a strong steroid, usually not prescribed for small kids. But can be used under proper guidance. Do review properly with your eye doctor.
6. Adults and kids can use many similar drops not all, when given under medical guidance.
Regards.
Next Steps
Get dilated retinal exam and power verification. Continue drops only under advice. Get a consult here for any further queries that you may have.