That is a question that many parents may have. It is true that eye doctors use eye drops to dilate the pupils to enable them to access the health of the back of one’s eyes. It is also true that most eye disease (not all) tend to manifest in adults. Then, why would a doctor use the “dilating drops” on young kids?
Not all eye drops instilled in the eyes during an exam is for the purpose of dilating the pupils. Eye drops used during an eye examination serve many purposes: some are used to numb the front of the eye, some help evaluate signs of dry eyes, some dilate the pupils, and others temporarily paralyze the ciliary muscles in the eye . These are the muscles that auto focus and accommodate when we transition from looking at an object in the distance to a near object, and vice versa. These are the same muscles that tend to not work as well as we age. (see our article on multifocals).
Certain eye drops used to dilate the pupil have a minor disruptive effect on our ability to auto focus, hence, the blurry near vision commonly experienced by patients. The purpose of these drops is to enlarge the pupils, enabling the doctor to better examine the inside of the eyes (the retina, macula, optic nerve, and vitreous).
The ability to auto focus functions extremely well in young kids, especially those under the age of ten. In some cases, the auto-focusing is so engaged that it is unable to relax, in a sense, it is “locked” in that state and can cause discomfort or headaches. Young kids have the ability to auto focus to compensate a minor farsighted prescription. In some cases, kids with a significant farsighted prescription may develop amblyopia (see article on amblyopia) because one of their eye muscles cannot compensate for their prescription.
At the eye doctor, if a child’s eyes are unable to relax the auto focus, the doctor cannot come to an accurate endpoint for their glasses prescription. To obtain the most accurate prescription for young kids, sometimes it is necessary to relax the auto focusing muscles with specific eye drops. These eye drops’ primary goal is to relax those muscles, NOT to dilate the pupil. But, pupil dilation is a secondary effect of these drops. When the doctor relaxes the accommodating muscles to arrive at a glasses prescription, it is called a cycloplegic refraction.
The drops that relax accommodation is also used in adults who cannot relax their auto focus due to a variety of reasons. More commonly, prior to refractive surgery (LASIK, LESIK, etc…) a cycloplegic refraction is done to assure that the surgery is performed with the correct data. It is not uncommon to have poor and inaccurate outcomes when a cycloplegic refraction is not done prior to these surgeries.