Amblyopia in children with severe unilateral congenital ptosis primarily occurs from either an uncorrected refractive error such as the astigmatism, or form deprivation because of the droopy eyelid interfering with vision [9]. Corneal astigmatism is a major problem in congenital ptotic eyes, and cycloplegic refraction examination is a useful method to determine the astigmatism degree and type [10]. Our data supported the existing data by presenting a higher degree of astigmatism in the ptotic eye than that in the fellow eye before surgery. Meanwhile, the against-the-rule and oblique astigmatism ratio was also higher in the ptotic eye, which could lead to amblyopia in younger children. Our results were consistent with those reported by Paik, who also reported that the ptotic eyes had more severe astigmatism and a greater percentage of OA than the fellow eyes [11]. Both findings indicated that severe unilateral congenital ptosis could threaten children’s vision and possibly developed amblyopia. However, some parents and ophthalmologist only focused on the child’s appearance due to the drooping eyelids, and often ignored the visual damage caused by ptosis. Most children with unilateral ptosis could see with their normal eyes, due to which abnormal behaviors, including raising their eyebrow or the head-up position, were not often exhibited by them. Surgery should be considered to improve their appearance with age. However, the damage to vision or even amblyopia caused by ptotic eyelid could not be treated satisfactorily due to the reduced cortical plasticity in the older children. Additionally, it may irreversibly damage the visual function in children with ptosis. Based on the aforementioned results, pediatric ophthalmologists need to further reflect on the timing of surgery for children with severe unilateral congenital ptosis [12].

We aimed to avoid traditional approach suggesting that the ideal patient age to surgically treat congenital ptosis was minimum 3 years. We performed the frontalis suspension surgery withPTFE in patients (age < 2 years) to correct severe unilateral congenital ptosis. Here, we used a frontalis suspension technique as described previously [8], with a different suspension material. Frontalis suspension surgery is considered suitable to treat particularly young patients [13]. There were several different suspensory materials used in surgery [14]. Although the autogenous fascia lata is considered the best material for frontalis suspension, it has several associated surgical complications from the harvest site and possibility of permanent scar. Considering this, most surgeons believe that it should not be harvested in children under the age of 4 years due to the immaturity of the leg [15, 16]. Some alternative materials [17, 18] including banked fascia lata, Mersilene mesh and silicone rods are not commonly used in our hospital, Hunan province of China. Therefore, frontalis suspension using PTFE method was an appropriate corrective option for our patients. This surgical technique is considered easy to master, is minimally invasive, with inexpensive suspensory material, is available, an generates reproducible and excellent cosmetic and functional results during the short-term follow up.

According to the result of Kaplan-Meier survival analysis, 33 children demonstrated good surgical results at 12 months after surgery, with their binocular eyelid cleft symmetry and upper eyelids in an acceptable position and contour. During the follow-up, the parents were satisfied with their child’s appearance and improvements in psychological inferiority. However, only 10 children maintained their good results when followed-up at the 30-month time point postoperatively. In brief, most patients showed disease recurrence at the end of follow-up. Our surgical success rate was slightly lower than of Ho [19], which could be possible due to the following reasons: the suture was not fixed on the frontal muscle and tarsus firmly during the surgery; absence of scar adhesion between tissues postoperatively, thus the tarsus was cut by the suture and shifted due to the effect of eyelid gravity; and ametropia of the ptotic eye was not corrected in time after surgery. Since the patient only used his/her normal eye, ptosis recurred due to the poor fixation and vision of ptotic eye. In addition, the younger age and severity of the ptotic eye were also important reasons for recurrence. Additionally, we summarized the postoperative complications. At the early stage after surgery, only eight children developed mild complications including suture reaction, epithelial keratopathy, infection and granuloma formation. We treated them promptly to avoid any adverse effects on the cornea and visual function of the patients. Similar to other types of ptosis correction surgery, including the superior palpebral levator muscle resection, almost all patients developed lid lag during the early stage of surgery. This was the common problem of all ptosis correction surgeries. The severity of eyelid ptosis was proportional to the degree of lid lag. However, the eyelid lag could improve eventually, which reduced the risk of exposure keratitis. The results of our clinical study were consistent with that reported before [19, 20]. In summary, frontalis suspension surgery withPTFE was safe for treating severe unilateral congenital ptosis patients under 2 years of age. The subsequent effects were stable and satisfactory for at least 1 year postoperatively, which could help the patients’ smooth transition to the reoperation after the age of 3 years.

Whether the correction of ptotic eyelid by the surgery could reduce the damage of vision and incidence rate of amblyopia caused by severe ptosis remains unclear. Therefore, we comparatively analyzed the astigmatism degrees and types in the ptotic eye before and after surgery. According to our study, because of the removal of pressure and occlusion on the eyeball caused by the drooping eyelid, the astigmatism degree slightly improved 1-month postoperatively, and then decreased significantly since 6-month after surgery. Meanwhile, the type of astigmatism in the ptotic eye changed from AR and OA, which significantly damaged the vision in than WR, which had a considerably lower effect on vision since 1 month after the procedure. After 1-year follow up, the astigmatism degree of the ptotic eyes was significantly lower than that before surgery, similar to the proportion of AR and OA astigmatism of ptotic eye. The results of refraction follow-up suggested that, to a certain extent, the surgery could reduce visual damage and amblyopia incidence rate caused by severe ptosis during the critical period of visual development. Our clinical observations revealed that frontalis suspension surgery withPTFE was invaluable in treating severe unilateral congenital ptosis patients (age < 2 years). It should be noted that the astigmatism degree of ptotic eye improved slightly 1-month after surgery, which may have been related to edema of the upper eyelid and surrounding tissues at the very early stage after surgery [21, 22]. Furthermore, average patient age in our study was considerably small, thus they could not accurately follow instructions of the doctors, nurses, or even their parents to keep their eyelids bandaged, or remain still after surgery. All of these would aggravate the eyelid edema or even hematoma, which may compress the cornea and increase astigmatism preoperatively. Therefore, we should instruct the parents to take the patients for routine reexaminations including the refractive examination at the 1-month point postoperatively. Changes in refraction should be immediately addressed by replacing the glasses in time to ensure clear vision and reduce chances of amblyopia.

In conclusion, considering the relatively stable eyelid position, prophylaxis against severe amblyopia, inexpensive surgical procedure, and considerable improvements in the young patients after more than 1 year postoperatively, we recommend the frontalis suspension surgery withPTFE to treat unilateral severe congenital ptosis. Although the present study was prospective, there might be biases regarding the loss of follow-up data in several patients. The relatively short follow-up period was also another limitation. Since the patients were too young, they were not cooperative with a number of tests, therefore there were no data of their corneal topography, along with the fact that several refraction results are absent. A prospective, long-term and multicenter-based study is being planned. The finding of the present study suggested that more attention should be paid to early surgical correction of unilateral severe congenital ptosis to avoid the development of severe astigmatism and amblyopia.