Fig. 12.1
(a) Clinical photograph of three siblings anterior with bilateral familial cataract. (b) Clinical picture of a child with bilateral rubella cataracts (note presence of dirty looking capsule with multiple posterior synechiae)
12.4 Clinical Features and Associations Noted in Pediatric Cataracts in India
Nuclear, zonular, membranous and total cataracts are the most commonly observed morphologies. In a study from Nepal, Adhikari and coworkers [15] the reported mean age at presentation was 5.63 ± 3.59 years for non-traumatic cataracts and 7.39 ± 3.94 years for traumatic cataracts. Only about 10 % of patients with non-traumatic cataract were brought for consultation below the age of 1 year. The situation is very similar on the Indian subcontinent. A child’s cataract may be noticed by parents, community health care workers, friends, or other family members early in life, but more often than not parents wait until their child is older before seeking treatment. As a result, many children with infantile cataracts have strabismus and nystagmus when they finally seek medical attention.
12.5 Laboratory Test Findings in Children with Pediatric Cataracts in India
Little is known regarding the laboratory findings in these children for two reasons: firstly, pediatric cataract care is often provided by anterior segment surgeons who do not perform extensive laboratory studies; and secondly, many patients cannot afford laboratory investigations. Hence, patients are usually classified simply as having familial or non-familial cataracts. In familial cases, further investigations are rarely performed. For non-familial cataracts, TORCH titers, serum calcium, and urine for reducing sugars may be performed. In patients with delayed development, failure-to-thrive, and seizures, further systemic work-up is recommended to rule out underlying metabolic conditions.
12.6 IOL Power Calculation
Axial lengths are usually measured in older and cooperative children using partial coherence interferometry because of its greater repeatability and reliability [16, 17]. However, in younger or uncooperative children, contact or immersion A scan biometry is preferred. Ben Zion et al. [18], reported that biometry done using immersion A scan has better test-retest reliability than applanation biometry. However, the difference between the two techniques is clinically and statistically significant only in children less than 2 years of age. In India most pediatric ophthalmologists’ tend to use contact A scan biometry in younger or uncooperative patients due to its ease of use and availability. We recommend the following when performing biometry and keratometry for IOL calculations:
Keratometry mires should be round, circular, complete and centered over the cornea,
When performing applanation biometry, careful attention should be paid to the retinal, scleral and choroidal echoes. They should have a gain of over 90 % without notches.
Multiple readings should be taken and the standard deviation for measurements should be <0.10 mm.
12.7 IOL Implantation
12.7.1 Decision to Implant or Not to Implant
Most pediatric ophthalmologists in India prefer primary intraocular lens (IOL) implantation in children 12–18 months of age. For children <1 year, most pediatric ophthalmologists prefer primary IOL implantation only if there are no contraindications, such as axial length <17.0 mm, horizontal corneal diameter <10.0 mm, or co-existing glaucoma or anterior segment dysgenesis.
IOL Types
Most pediatric ophthalmologists in India prefer a hydrophobic acrylic IOL rather than a PMMA IOL because they are associated with a reduced incidence and density of visual axis opacification (VAO, Fig. 12.2a, b), postoperative inflammation, and glaucoma. Aasuri and colleagues reported that, the incidence of clinically significant VAO was only 12 % after hydrophobic acrylic IOL implantation in children vs. 75 % after PMMA implantation with a median onset at 2.9 ± 0.7 months [19].
Fig. 12.2
Slit lamp photograph of children showing the pattern of the visual axis opacification after polymethylmethacrylate (PMMA) IOL implantation: (a) Dense fibrotic plaques; (b) Elschnig’s pearls. Children with PMMA IOLs tend to have denser and thicker PCO
In addition, both the incidence of postoperative inflammation (26 %) and presumed non-infectious postoperative endophthalmitis (8 %) were increased in children after PMMA IOL implantation. Pehere et al. [20] reported an increased incidence of calcium and phosphate deposits on hydrophilic single piece IOLs (Fig. 12.3). Hence, we recommend the use of hydrophobic acrylic lenses wherever possible; however, if the parents cannot afford them, PMMA IOLs may be used in children older than 1 year. In infancy, we recommend a hydrophobic acrylic IOL or leaving the child aphakic.
Fig. 12.3
Clinical photograph of a child with multiple pigmentary deposits on a hydrophilic acrylic IOLs in situ (a) and an explanted IOL (b). (c, d) Show the typical appearance of these deposits after staining with alizarin (Courtesy: Dr. Niranjan Pehere, Consultant, David Brown Children’s Eye Care Centre, LV Prasad Eye Institute, Vijayawada)
IOL Power Undercorrection
Most pediatric ophthalmologists in India target an undercorrection in children when an IOL is implanted in anticipation of a later myopic shift. The undercorrection is calculated using either Dahan’s formula [21] or Enyedi’s rule of seven. We have found Enyedi’s rule of seven to be a simple way of calculating the desired undercorrection.
Thus, if a child is 3 years old and an IOL power of + 30 D is calculated for emmetropia, we would reduce the IOL power by 4 D to +26 D. Although there is no published data reporting long-term outcomes with this technique, in unpublished data from our institute, we have noted a mean refractive error ranging from −1.38 to +1.4 D when these patients are 7 years of age. We have also noted that the results are more unpredictable in children younger than 2 years of age.
Although most surgeons’ target an undercorrection, some believe a large undercorrection may itself be amblyogenic and therefore prefer to target a smaller undercorrection.
We take into account the likelihood of a patient returning for follow-up and wearing contact lenses when choosing the magnitude of the undercorrection. If we deem it unlikely that parents will bring their child back for follow-up and if it is not likely that they can afford contact lenses, we target emmetropia or a small undercorrection.
12.8 Surgical Technique
12.8.1 Lens Aspiration + Primary Posterior Capsulotomy + Anterior Vitrectomy + PCIOL Implantation (LA + PPC + AV + PCIOL)
We perform cataract surgery as soon as a child is healthy enough to undergo general anesthesia. We wait 1 week before performing surgery on the second eye for children with bilateral cataracts. Cataract surgery is performed using either a scleral or clear corneal incision. A scleral tunnel incision with two side port incisions is preferred while implanting a PMMA IOL. Since, many children in India have total or membranous cataract; most pediatric ophthalmologists stain the anterior capsule with 0.5 % trypan blue. Many surgeons use a high molecular weight viscoelastic agent such as hyaluronic acid (Healon or Healon GV, Pharmacia). However, 2 % Methylcellulose is used for patients who cannot afford Healon or Healon GV. Muralidhar et al. [22] reported an anterior and posterior capsulorrhexis completion rate of 81.8 % and 90.9 % respectively in children <6 years undergoing pediatric cataract surgery using 2 % methylcellulose.
After injecting a viscoelastic into the anterior chamber, a continuous curvilinear capsulorhexis is initiated with a cystitome and completed with pediatric capsulorrhexis forceps (23 G, Model no. IG- 3984, Pediatric Capsulorhexis forceps; Indo-German, Mumbai, India) (Video 12.1). Lens aspiration is performed through two corneal incisions using an automated bimanual irrigation and aspiration cannula or an anterior chamber maintainer and an aspiration cannula. The targeted size of the anterior capsulorhexis is 5.0–5.5 mm and 4.0–4.5 mm for the posterior capsulotomy (Fig. 12.4).
Fig. 12.4
Intra-operative photograph of an adequate sized anterior capsulorhexis (white arrowhead) and posterior capsulorhexis (black arrowhead)
Another commonly used surgical technique is using a vitrector to perform the anterior capsulorhexis, lens aspiration, and primary posterior capsulotomy prior to lens implantation (Video 12.2). This approach is particularly useful in children less than 1 year of age, in whom it can be difficult to control a manual capsulorhexis, as well as in older children with thick fibrosed anterior capsules.
As mentioned previously, our preferred implants are hydrophobic acrylic IOLs (Acrysof SA60 AT, MA60AC, or SN60WF; Alcon Laboratories) with an optic diameter of 6 mm and overall diameter of 13 mm or a rigid PMMA IOL (Ocular Vision SF 102; Eye Care, Vadodara, India) with an optic diameter of 5.5 mm and overall diameter of 12 mm.
Primary Posterior Capsulotomy (PPC)
In accordance with the surgeon’s preference, primary posterior capsulotomy (PPC) is performed before or after IOL implantation. In cases, where the primary capsulotomy is performed after IOL implantation, a vitrector is passed under the edge of the IOL edge to create a PPC. Some surgeons prefer to nick the posterior capsule using a 26G cystitome or a MVR knife, and then enlarge the posterior capsular opening using a vitrector with a cut rate of 150 cuts per minute and vacuum of 80–100 mmHg. This is typically followed by an anterior vitrectomy. Although most pediatric ophthalmologists perform a manual posterior capsulorhexis using microrhexis or utrata forceps, less experienced surgeons often prefer a posterior vitrectorhexis. In a study of 50 eyes, Kochgaway et al. [23] reported that a posterior vitrectorhexis is easier, has a shorter learning curve, and is more associated with in-the-bag IOL implantation compared to manual capsulorhexis.
Anterior Vitrectomy
An anterior vitrectomy is performed in all pediatric cases. After completing the PPC, an anterior vitrectomy is performed with settings of 800 cuts per minute and aspiration of 80–100 mmHg. The end point of the vitrectomy is when the remnants of the posterior capsule fall backwards with a smooth margin. Some pediatric ophthalmologists use adjuncts such as intravitreal triamicinolone acteonide [24, 25] or an external endoilluminator [26] to visualise remnants of the vitreous.
Wound Closure
Most pediatric ophthalmologists suture all wounds closed in children <7 years of age. For children >7 years, surgeons typically assess the integrity of the wound/scleral tunnel and then decide whether sutures are needed. Non-absorbable 10-0 nylon sutures are most commonly used. These are removed 7–10 days postoperatively either in the office or during an examination-under-anesthesia in young children.
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