Reflex convergence

FAT-P

 

1. Proximal convergence: Psychological awareness of a near object initiates this type of convergence.
2. Tonic: It means that when the patient is awake there is an inherent tone in the extraocular muscles.
3. Fusional: It is initiated by a bi-temporal retinal image disparity and is not associated with change in refractive status of eyeball. It ensures that image of an object falls on corresponding retinal points in the two eyes.
4. Accommodative: It is initiated by act of accommodation. It means that when we accommodate; we converge. It is a part of near reflex. One dioptre of accommodation is accompanied by 4-5 prism diopters of accommodative convergence and it remains fairly constant. Abnormalities of accommodative convergence are associated with squint.