| Background:Congenital cataract is the most important cause of treatable blindness, accounting for 1.2-15/10000 blind children worldwide. The incidence of congenital cataract in developing countries is 5-fold higher than that in developed countries. China is the largest developing country in the world. Infantile cataract is the second major cause of blindness in China.Treatment of congenital cataract is important for the prevention and treatment of blindness, which is still lagging behind in China. In this field, there is a big gap between China and India, another developing country. Our study investigated the status quo of congenital cataract treatment in Chongqing, one of the biggest city in west China, so as to provide references for the research of our counterparts and the policy-making of government.Compared with adult cataract surgery, pediatric cataract surgery is more complex and has more complications. In recent years, the technique of pediatric cataract surgery has been improved. However, some issues on optimal timing of surgery, timing of intraocular lens implantation, prevention of complications and influence of surgery on the structure and development of children eyes still need further research.Purpose:This study is to investigate the surgical outcomes and complication of congenital cataracts and to determine the relationship between visual prognosis and surgical complications according to age at operation and adopted surgical procedure and the general clinical features. Furthermore, the effect of surgery on the cornea and anterior chamber angle structures was evaluated.Methods:1. From May 1994 to February 2009, some children with congenital cataract who underwent surgery at the several medical centers in Chongqing were followed up. Eyes with traumatic cataracts, complicated cataract, congenital glaucoma, retinopathy of prematurity, systemic diseases, or neurological disorders were excluded.2. Study parameters included preoperative clinical characteristics (microcornea, unilateral or bilateral cataract, nystagmus, etc.), age at operation, time period of follow-up, operation (aphakia, primary IOL or secondary IOL). The postoperative best corrected visual acuity, intraocular pressure, central corneal thickness, postoperative complications and structural change of anterior chamber, optic nerve changes (if possible) were recorded and analyzed.3. Statistical data were obtained using SPSS10.0 software. Qualitative data (complication rates between the different age groups and between the three different groups associated with surgical procedures) were compared using the chi-square test. Visual outcomes were compared using the K-independent samples test. Quantitative data(CCT, AOD500, TIA)was compared with student T test.Results:1. Totally 112 children (165 eyes), 69 males and 43 females, were included in this study, including 59 cases of unilateral cataract. Before operation, 28 eyes were associated with nystagmus, 17 eyes microcornea. Mean age at operation was 4.47 years and mean time period of follow-up was5.24 years.the incidence of primary IOL implantation in children who was younger than 2 years old at congenital cataract surgery was 21.2% in Chongqing.2. The best corrected visual acuity (BCVA) were checked in 165 eyes with a Snellen chart. There were 127 eyes(76.9%)with BCVA≥0.1, 82 eyes (49.7%)≥0.3 and 42 eyes (25.5%)≥0.6. BCVA in patients with nystagmus or unilateral cataract were worse than their controls (P <0.01). Totally, 53.1% eyes in primary IOL group had BCVA>0.3, 26.2% eyes in aphakia group, 37.5% eyes in secondary IOL group. The difference was statistically significant (P <0.01). The prognosis had no significant difference at different age groups.3. The most common complication was posterior capsular opacity (PCO) in 41.8% of affected eyes. The incidence of PCO in the four age groups (<2 years, 2-6 years, 6-12 years and≥12 years) was 51.9%, 42.4%, 39.2% and 15.8%, respectively. There was significant difference . Secondary glaucoma occurred in 20 eyes (12.1%). The prevalence of secondary glaucoma was 29.4% in patients with microcornea, 10.1% in control group. The difference was significant. The occurrence of glaucoma were 30.5% in patients≤2 years and 41.6% in patients≤1 years, which had significant difference compared with control group (P values were 0.016 and 0.031, respectively).4. Central corneal thickness (CCT) was measured in 141 eyes (85 undergoing congenital cataract surgery, 28 non-operative eyes with congenital cataract and 28 eyes of healthy controls). The mean CCT of postoperative eyes was higher than that of non-operative eyes with congenital cataract and healthy controls. The CCT of non-operative eyes was similar to the healthy controls (P>0.05). The regression analysis suggested that the postoperative increase of CCT was negatively correlated with age at operation.5. Ultrasound biomicroscopy and gonioscopy were performed on 45 eyes undergoing congenital cataract surgery, 8 non-operative eyes with congenital cataract and 10 healthy eyes as control. The angle-opening distance at 500 um (AOD500) and trabecular-iris angle (TIA) were measured. Change of anterior chamber pigments was observed. AOD500 in congenital cataract surgery group was smaller than that in non-operative group and control group, and the difference was significant (P<0.01), but there was no statistical difference between non-operative group and control group. The angel opening distance of patients with secondary glaucoma record was significantly smaller than that in normal intraocular pressure group. It was suggested that the younger age at operation, the smaller AOD500. Trabecular iris angle in all groups showed no statistically significant difference (P >0.05). The pigment of anterior chamber angle over 3 degree in three age groups (<2 years,2-6 years and≥6 years) were 80%, 45.5% and 25% respectively. The difference was significant (P <0.05).Conclusions:1. Primary intraocular lens implantation for children with congenital cataract is effective for visual rehabilitation. Unilateral congenital cataract and infantile cataract with strabismus indicate worse postoperative visual acuity.2. The younger age at surgery, the higher occurrence of PCO and secondary glaucoma. Microcornea is an important risk factor for secondary glaucoma. Primary intraocular lens implantation does not increase the risk of postoperative complications.3. CCT in children with congenital cataract is normal. The postoperative change of CCT is due to the surgical procedure. Children's age at operation could influence corneal thickness. 4. Surgery causes the antelocation of iris root and the increased degree of anterior chamber angle pigmentation, which is correlated with pathogenesis about secondary glaucoma. The young age at surgery is a risk factor for surgery... |
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