Maternally acquired causes like rubella, toxoplasma, cytomegalovirus, herpes simplex and varicella (TORCH) may be the causes of congenital cataracts.^5,6 Of these, rubella is the commonest infection affecting the pregnant mother in the first trimester. This has been dramatically reduced due to intense anti-rubella vaccination and health education. The visual outcome of children following the surgical management of congenital cataract is determined by the presence of visual axis opacification postoperatively in the form of membrane, posterior capsular opacification and anterior hyaloid vitreous opacification. Hence, the importance of performing a perfect posterior continuous curvilinear capsulorhexis (PCCC) with or without vitrectomy as a primary procedure is emphasised. Unlike adults, visual axis opacification not only reduces vision but is a major cause for amblyopia. Posterior capsule opacification is almost inevitable ^7,8,9,10 and almost close to 100 percent.¹¹ Age of IOL implantation is always debatable. Less than one year of age and associated co-morbid ocular conditions like microphthalmos, will be a contraindication for IOL implantation. IOL implantation is always a single-piece acrylic foldable intraocular lens in the bag.

MATERIALS AND METHODS

This is a retrospective analysis performed in 50 children from birth to 17 years of age involving both sexes in the Department of Paediatric Ophthalmology, Mahathma Eye Hospital, Trichy, India. Only children with congenital cataract were included in the study. Children less than 15 years of age undergoing cataract surgery due to traumatic cataract and steroid induced cataracts or any other form of cataract were excluded. All types of congenital cataracts with different morphology were included in the study. Some children underwent cataract surgery for unilateral congenital cataract whereas others were operated for bilateral congenital cataract. Eyes with corneal diameter of 10 mm and above were selected for IOL implantation. Others who had microphthalmos, corneal opacity, coloboma iris had lens aspiration alone. All the cases underwent single piece hydrophobic spherical design AcrySof IOL in the bag. All the children had either unilateral or bilateral congenital cataract of different morphology for which they underwent cataract surgery with or without IOL implantation. Parents were evaluated for consanguineous marriages, genetic abnormalities, anti-natal history in the form of first trimester fever and rashes (rubella) etc. Preoperatively, vision assessment was performed by fixation pattern and presence of nystagmus and strabismus. Specialised Vision charts like Keeler cards, Cardiff cards, Sheridan – Gardiner charts and Snellen’s chart wherever appropriate were used. Examination under anaesthesia (EUA) was performed for children below 8 years of age. During EUA, corneal diameter, corneal clarity, iris and pupillary status, morphology of congenital cataract, IOP measurement, indirect ophthalmoscopic evaluation to rule out retinal and optic nerve pathologies were investigated and documented. In cases of dense total cataract, ultrasound imaging of retina was performed.

Keratometry and immersion biometry was performed to calculate the right IOL power. Even 0.1 mm difference in axial length may result in 0.75 difference in IOL calculation. Since the children’s eyes are shorter, axial length error can be magnified to 14 D/mm¹². In all children subjected to congenital cataracts surgery, we used SRK-T formula and under correction of IOLs was performed according to the age¹³. In our study IOL power ranging from +13 D to +30 D was used. These children underwent TORCH TITRE evaluation and evaluation for any metabolic disorders. Postoperative targeted refraction in our series, we always aimed for under correction resulting in mild to moderate hypermetropia in the immediate postoperative period. Wherever significant, these children were given appropriate unifocal lenses for less than 5 years of age and bifocal above 5 years of age. Surgical technique used was anterior limbal approach lensectomy and vitrectomy for aphakic cases. 2.2 mm clear corneal incision with two numbers of 1 mm side port incision was made in children who were subjected to cataract extraction with IOL implantation. Whenever PCCC was performed, it was made 2 mm smaller than anterior rhexis. Hydrophobic spherical design single piece AcrySof IOL was implanted in the bag. All three corneal incisions were sutured using 10 – 0 nylon suture. In cases of 50 children who underwent IOL implantation, 36 children underwent PCCC with vitrectomy and 14 children did not have posterior capsule procedures. Postoperatively these children were closely monitored for immediate postoperative inflammation and late postoperative visual axis opacification. Children who underwent lens aspiration without IOL implantation, were periodically assessed for glaucoma and retinal complications.

Refraction was performed in all cases in all visits because of the growing nature of paediatric eye. Refraction plays a major role in visual rehabilitation to provide appropriate glasses and for better management of amblyopia management also. All children with aphakia were managed with high plus spectacles. Children with IOL implantation in the school going age group needed either bifocals or progressive lenses. Children with posterior capsule opacification needed either anterior limbal approach or pars plica membranectomy to avoid amblyopia. Grown up children who were cooperative enough underwent YAG capsulotomy.

Several surgical techniques are available in the form of (a) lensectomy with anterior vitrectomy either through anterior limbal approach or posterior pars plicata / plana approach (b) lens aspiration with IOL implantation with or without PCCC and anterior vitrectomy. The anterior chamber was accessed by clear corneal incision the size of incision was 2.8 mm at 12 o’ clock position always. Two side ports of each 1 mm in size were made at 3 and 9 o’clock position. Trypan blue staining of anterior capsule was performed in total cataracts only. Zonular / lamellar cataract and cataracts with good red glow, trypan blue staining was not performed. Anterior continuous curvilinear capsulorhexis (CCC) of 5 mm diameter was performed under viscoelastics. The lens material was aspirated using bimanual irrigation aspiration hand pieces. Primary posterior CCC was performed in required cases at least 1.5 to 2 mm smaller than anterior CCC. Adequate anterior vitrectomy was also performed before implantation of IOL. AcrySof single piece non-aspheric IOL implantation in the bag performed. Corneal incision was sutured using 10-0 nylon and children less than 2 years of age both side ports were also sutured.

Statistical Analysis

Data was analysed using SPSS (Version 17.0) software. The frequency (No. of respondents) and percentage (%) of respondents selected for the study were analysed through the software.

RESULTS

The Analysis of Visual outcome after surgical management of congenital cataract with or without IOL implantation was carried out in 50 children of both sexes from birth to 17 years of age involving both sexes in the Department of Paediatric Ophthalmology, Mahathma Eye Hospital, Trichy, India. All the children diagnosed had either unilateral or bilateral congenital cataract of different morphology. Of these different age group tested, the highest number of 13 children with congenital cataract was observed in less than one year of age, followed by the age group 3 to 5, in which 12 children were affected. The children affected with congenital cataract between 8 to 12 years of age and above 12 years were found to be of equal number (7 children). The number of affected children was very less in the age group of 1 to 2 years. The results were tabulated in table -1. The gender analysis showed 32 male children and 18 female children (Figure – 2). The laterality study revealed 64% of the children were affected by bilateral congenital cataract and 36% of children was observed with unilateral congenital cataract, thus, posing postoperative challenges during rehabilitation. The results were predicted in figure – 2. From this study it was concluded that, the children less than one year of age reporting for congenital cataract treatment was the highest number because of absence of fixation or roving eye movement as noticed by the mother.

The Morphology of congenital cataract in children was recorded as total cataract, Lamellar cataract, zonular cataract, blue dot cataract, membranous cataract, infantile embryonic cataract, posterior polar cataract with or without posterior subcapsular component. Among the different types, the commonest encountered was lamellar cataract which is a bilateral cataract reported in 26 children. The lamellar cataract presented to us with high level of asymmetry. It followed by total and membranous cataracts, in which five children were affected in each. The membranous cataract is usually not identified in routine ophthalmological evaluation unless fully well dilated. The missed membranous cataracts were brought to us with nystagmus after two years of age. The Zonular, blue dot and PCC and PPC cataract were not predominant in our study (Table – 2). The total cataracts were due to intrauterine infections as proven by torch titre especially rubella.

The axial length of eye ball of children affected by congenital cataract was measured and presented in figure – 3. Higher axial length of 20 mm to 22 mm was noticed in 30 children. Twelve children were observed within the range of 22 mm to 24 mm. In four children the axial length in the range of 16 mm to 18 mm was recorded. Three children had above 24 mm. Higher axial length implies pre-existing axial myopia which may be mild or severe and may be associated with fundus pathology. The very low axial length denotes pre-existing hypermetropia. At birth the infant eyes physiologically hypermetropic. According to the axial length and keratometric values IOL power was calculated by immersion biometry and appropriate IOL was used in children with congenital cataract. Among the 50 children, 28 of them underwent cataract surgery with IOL implantation within the power range of 18 to 24D. This embraces normal standard IOL power. Myopic eyes were observed in three children, hence IOL power of lower dioptric values were implanted in those children. These children need to be closely followed up anticipating myopic manifestation, in order to avoid amblyopia. Hypermetropia was noticed in 17 children and these children underwent IOL implantation of higher dioptric values. Two children were diagnosed as posterior polar cataracts with pre-existing large posterior capsular dehiscence, hence they were left aphakic. The results were presented in table – 3.

Visual acuity assessment was started in the one-month post-operative period for all the children. Depending upon the patient’s age group, cooperation status and intensity of amblyopia, visual acuity assessment showed gross variability as shown in the table- 4. Children with severe visual loss of less than 6/60 were due to stimulus deprivation amblyopia in congenital cataracts like embryonal cataract, nuclear cataract and total cataract. Five children manifested nystagmus, as their embryonal cataract or total cataract was operated after the age of 2 yrs. Children with visual acuity of 6/6, 6/9, 6/12, suffered from congenital zonular cataract or lamellar cataract. These are the cataracts where they are not dense enough to cause dense amblyopia. The visual deprivation induced by them are only partial.