Currently, many parents of children with congenital ptosis believe that the earlier the ptosis surgery is performed, the better. This is not true, especially in severe ptosis, and the timing of surgery and the indications for surgery should be based on the specific circumstances of the child.
I. Examination and diagnosis.
1. Gradation of ptosis
(1) Normal, the upper lid margin is located at the level of the midpoint between the upper edge of the pupil and the upper edge of the cornea when gazing in situ with the eyes naturally open, i.e., the upper lid margin covers the upper cornea by 1.5 to 2.0 mm.
(2) In mild ptosis, the upper lid margin is located at the upper edge of the pupil, covering within 1/3 of the pupil, and the amount of ptosis is about 1 to 2 mm;
(3) In moderate ptosis, the upper lid margin covers the upper 1/3 to 1/2 of the pupil and the amount of ptosis is about 3 to 4 mm;
(4) In severe ptosis, the upper lid margin falls to the level of the central pupil or below, covering 1/2 to 2/3 of the pupil or all of it, and the amount of ptosis is approximately 4 mm or more.
(Measure the height of both lids in situ, and the difference between the two is the amount of ptosis.)
2. Grading of the strength of the levator muscle (for older children who are cooperative in the examination)
(1) How to measure the muscle strength of the levator palpebrae: Press the affected side of the entire eyebrow backwards with the thumb, trying to completely block the frontalis muscle from lifting the upper eyelid. The patient is instructed to gaze downward as far as possible, align the upper lid margin with the zero point of the meterstick, and then instruct the patient to look upward as far as possible; the magnitude (expressed in mm) of the raising of the lid margin from below to above is the levator muscle strength. Note that the fingers should not be pressed upward or downward to avoid obstructing the upper lid movement and affecting the correctness of the examination.
(2) Normal human levator muscle strength is 13-16 mm without frontalis muscle involvement, increasing to 16-19 mm with frontalis muscle involvement. muscle strength can be classified into three levels depending on the need for clinical surgical options.
Good (greater than 10 mm)
Moderate (4 to 9mm)
Weak (less than 4mm)
The timing of surgery for congenital ptosis
1. Congenital severe or complete ptosis (upper lid covering 2/3 or more of the pupil)
(1) In cases of unilateral complete ptosis, it is recommended that surgery be performed around the age of 1-2 years.
Rationale.
To avoid form deprivation amblyopia, the earlier the surgery is performed theoretically the better the improvement in visual function for the child.
Surgery under general anesthesia within 1 year of age is too risky due to the unstable general condition.
If the surgery is performed within 1 year of age, the frontalis and levator muscles are incompletely developed, thin and fragile, and the frontalis is easily damaged during surgery, causing fibrosis, so premature surgery is bound to affect the outcome.
We have operated on hundreds of cases of severe ptosis in children aged 1 to 2 years with good results. We have observed that the frontalis muscle in children is relatively thin, but it is well developed and is not easily damaged during separation. Moreover, the younger the child, the easier the separation of the frontalis muscle, the less bleeding, the faster the postoperative recovery, and the more natural the lid will look as it ages. Therefore, we also believe that children with severe ptosis can be operated on at the age of 1-2 years as long as they are in good general condition.
It is important to get the surgery done as soon as possible and without delay.
For children who cannot be operated on in time for various reasons, preoperative amblyopia prophylaxis is required.
Depending on the age of the child, the duration of coverage of the healthy eye may vary.
Cover the healthy eye once a day or once every other day.
Observe the ptosis eye gaze after masking.
(2) If the ptosis is complete bilaterally, surgery is recommended before the child is 3 years old – school age.
Rationale: The child mostly adopts head-up gaze, so there is no need for premature surgery as there is no occurrence of masked amblyopia. However, because the child’s long-term head-up vision can cause a backward curvature of the spine, the surgery should not be performed too late.
In congenital moderate ptosis (upper lid covering about 1/2 of the pupil), the timing of surgery depends on the determination of the refractive state of the dilated pupil.
If there are refractive abnormalities and amblyopia is judged, surgery should be performed around the age of 3 years and amblyopia training should be performed as early as possible after surgery.
In children without amblyopia, the poor appearance of the lid can cause psychological impairment of the child’s personality, and the drooping upper lid can cause corneal irregularity due to astigmatism, so surgery can be performed before school age if the parents request it.
3. For congenital mild ptosis (upper lid covering 1/3 of the pupil or less), local anesthesia is recommended after the age of 12 to 15.
Rationale: Most children with this condition do not have amblyopia, do not affect their appearance, and have less surgical risk if they can cooperate with local anesthesia. The muscle development is more mature and the surgical result is more stable.