Final answer:
A convergent squint in a 3-year-old child is initially managed by a comprehensive eye examination to check for visual acuity and farsightedness, and to establish the near point for spectacle correction. Converging spectacle lenses are used to correct farsightedness by increasing the eye's optical power, which helps in proper convergence.
Step-by-step explanation:
The first step in managing a convergent squint in a 3-year-old child is to conduct a thorough eye examination to assess the extent of the squint and determine the underlying cause. This may include testing for visual acuity, refraction, and alignment to check for conditions such as farsightedness. The converging spectacle lens is used for correcting farsightedness by increasing the optical power of an eye that is too weak, thus assisting in proper convergence of light rays. The near point, or the closest distance at which a person can see clearly, should be determined to decide on the spectacle power needed for correction. In cases of presbyopia, a similar approach is used where a converging lens adds power for close vision. However, this is typically in older adults, as presbyopia is the loss of the ability to accommodate with age. For young children, the accommodation-convergence reflex, which includes changing the lens shape for accommodation and coordinating eye muscle movements for convergence, is also assessed as part of the management strategy.