Pediatric cataracts: overview (2023)

Introduction and Epidemiology

In children, cataracts cause more visual impairment than any other form of treatable blindness. Children with untreated, visually significant cataracts are blind for life, with tremendous quality of life and socioeconomic costs to the child, family, and society. More than 200,000 children are blind due to unoperated cataracts, complications from cataract surgery, or eye abnormalities associated with cataracts.¹Many other children have partial cataracts, which can slowly progress over time and worsen the vision problems as the child grows. The cumulative cataract risk during the growing years is up to 1 in 1000.²

Treatment for childhood cataracts is long and often difficult, requiring many visits over many years. Success requires dedicated teamwork that often involves parents, pediatricians, surgeons, anesthesiologists, technicians, orthoptists, specialists in the rehabilitation of the visually impaired and community health workers.

Classification (categorization)

Cataracts in children can be classified using a number of methods, including age of onset, etiology, and morphology.

age of onset

Congenital/infantile

While the presence of cataracts at birth suggests congenital onset, diagnosis and detection of cataracts at a later age does not rule out congenital onset. It is important to provide a detailed description of the type of lens opacification prior to cataract extraction and in the surgical note so that the type can be determined and subsequent studies correlating genetic etiology or associated systemic disease can be more accurately conducted. Some morphologic categories of cataracts such as anterior pole, central fetal nucleus, and posterior pole clearly indicate congenital onset, while others such as cortical or lamellar cataracts may be associated with either later onset or be congenital.

Acquired/Juvenile

This category can be confusing. Strictly speaking, an acquired cataract is an external cause, as opposed to one where the cause is genetic, such as B. A mutation in one of the crystalline genes. However, some would use acquired to indicate onset after childhood, which does not necessarily indicate a non-genetic cause. Juvenile cataracts are defined as those of childhood onset, post-infancy, regardless of the underlying etiology.

etiology

Genetic

About 50% of childhood cataracts are caused by mutations in genes that code for proteins involved in lens structure or clarity.Table 1lists genes in which mutations can cause cataracts.³While many of these genes are inherited in a dominant manner, others are inherited in an autosomal recessive or X-linked manner. Drawing a pedigree and recognizing some cataract and ocular phenotypes associated with specific mutations will help determine the likely mode of inheritance and the underlying syndrome that may be involved. Recent advances in genetic testing, including next-generation sequencing, allow the exact genetic cause of isolated congenital cataracts to be determined in 75% of individual families and 63% of families with syndromic congenital cataracts.⁴Mutations in crystallines account for 50% of isolated cataracts (with no associated systemic abnormalities), while mutations in the gap-junction protein connexins account for 25% of cases, and mutations in genes for heat shock transcription factor-4, aquaporin-0, and beaded filament structural protein- 2 make up the remaining 25%.

Metabolic disorders can cause cataracts, which may exhibit specific morphologies that indicate the underlying cause. Next-generation sequencing of genes associated with syndromic or metabolic cataracts can provide an accurate diagnosis when the systemic findings fail to identify the metabolic or systemic disease.Table 1summarizes evidence on some of the major diseases associated with acquired syndromic cataracts.

Trauma remains a leading cause of acquired cataracts in children. Traumatic cataracts are more common in boys and can result from penetrating or blunt injuries to the eye. One must be cautious in excluding or ruling out the presence of an intraocular or intraorbital foreign body, hence the importance of a detailed physical examination and imaging studies such as ultrasonography and computed tomography. Magnetic resonance imaging (MRI) scans are contraindicated if the foreign body is suspected to be metallic.

Xu LT, Traboulsi EI. Genetics of congenital cataracts. In: Wilson ME, Trivedi RH, editors. Pediatric cataract surgery: Lippincott, Walters Kluwer 2014. p. 1-8

Secondary

Uveitis- Cataracts develop in patients with uveitis as a result of chronic ocular inflammation or as a result of chronic steroid use. Surgery of such cataracts can be complicated by severe postoperative inflammation, reflecting the lack of preoperative anterior segment inflammation and the pre-, intra-, and post-operative use of various combinations of topical, subconjunctival, intracameral, and sometimes systemic steroids. Many patients have a pupillary membrane covering the lens and attached to the iris, making surgery difficult. Such membranes can be peeled away from the anterior lens capsule at the time of surgery to facilitate lens removal. The use of an intraocular lens (IOL) is at the discretion of the individual surgeon.

• Juvenile idiopathic arthritis: One of the most common causes of anterior uveitis in children. The use of systemic antimetabolites in recent years has resulted in better control of uveitis in these patients and a reduction in the incidence of cataracts.
• Other types of uveitis can also cause cataracts, either due to inflammation or as a complication of steroid use.

Intraocular tumors– It is very rare for cataracts to develop as a result of intraocular tumors. The lens is characteristically clear in patients with untreated retinoblastoma. Treatments of the tumor such as radiation therapy can lead to the development of cataracts, in which case the timing of cataract removal must be considered very carefully and surgery only performed once all of the tumor in the eye has been eradicated. Patients with radiation cataracts may have significant ocular surface dryness and are intolerant of contact lenses, thus requiring intraocular lens (IOL) implantation.

Chronic retinal detachment– These cataracts occur as a result of injuries or in connection with Stickler syndrome. If the lens is completely opaque, sonography should be performed preoperatively to rule out chronic retinal detachment. The presence of an afferent pupillary defect is a poor prognostic sign.

Maternal infection (rubella)– This type of cataract has not been observed in countries where rubella has been eradicated, but it continues to occur in some parts of the world.

Iatrogen

• radiation– External radiation is avoided in patients with retinoblastoma. The eye is usually shielded when the brain or other parts of the head and neck are being irradiated.
• Systemic steroidsare very rare causes of cataracts in children. Inhaled steroids in asthma do not cause cataracts. The typical steroid-induced cataract is posteriorly subcapsular.
• Vitrektomie- A large percentage of children who undergo vitrectomy develop cataracts. These are mostly posterior subcapsular.
• Laser for retinopathy of prematurity– Cataracts may develop from thermal injury to the lens when a prominent tunica vasculosa lentis is present.

Morphology

As mentioned above, it is important to use the appropriate terminology to describe pediatric cataracts. The morphology may provide an indication of the underlying etiology (isolated or associated with systemic disease) and possibly the visual prognosis after surgery.

diffuse/total

This is not an uncommon form of congenital cataract. There are no specific causes of diffuse or total cataracts.

Anterior

front pole– The opacity is in the capsule itself and can protrude into the anterior chamber as a small nipple. There may be an underlying circular layer of cortical opacity that is slightly larger than the white polar opacity. While the majority are stable and do not affect vision, some can progress and require surgical removal. They can be inherited in a dominant manner, particularly in bilateral cases. Unilateral cases may present with anisometropia (astigmatism or hyperopia) which, if left untreated, can lead to amblyopia, even if the cataract itself is not visually significant.

Illustration 1.Anterior polar cataract.

Pyramidal– These are usually larger than polar cataracts and are more likely to develop into visual importance. They are difficult to remove with a vitrectomy instrument and may require excision and removal with forceps before the rest of the lens is aspirated.

Figure 2.Pyramidenkatarakt.

Front Lenticonus– This refers to a thinned central anterior capsule with or without anterior cortical opacities. Anterior lenticonus is said to be characteristic of Alport syndrome. Spontaneous rupture of the lens can occur, resulting in a hydrated total cataract.

Figure 3.Anterior Lenticonus (Courtesy of K. David Epley).

Kortical Lamellae

In this type of cataract, the opacification is a lamella (an egg-shaped layer of cortex) that can be visualized between adjacent clear lamellae. These are often associated with radial "rider" opacities. Familial lamellar cataracts are mostly autosomal dominant and are generally associated with a good visual prognosis after removal. They may be stable or associated with progressive opacification of the intervening cortex, necessitating removal.

Figure 4. lamellar cataracts (Top: Courtesy of K. David Epley, MD.bottom: Courtesy of Faruk H. Orge, MD).

fetal nucleus

These opacities occupy the most central part of the lens. They can be punctiform or quite dense. They generally measure 2-3.5mm and can be associated with microphthalmia. They are said to be associated with a higher incidence of postoperative glaucoma due to the associated microphthalmia and the need for surgery in early infancy.

Figure 5. Congenital nuclear cataract.

rear pole

In this type of cataract, the opacification lies in the capsule itself. It is necessary to distinguish posterior polar from posterior subcapsular cataracts. Posterior polar cataracts are genetic and some have been linked to mutationsPLOT3.

Figure 6. Posterior polar cataract.

Posterior lentiglobulus (Lenticonus)

In this group of disorders, the central and sometimes paracentral posterior capsule is thin and posteriorly bulging. This usually occurs where the hyaloid system attaches to the eye. The distortion can cause a localized area of ​​extreme myopic refraction. Subcapsular cortical opacities may or may not be present. Vision problems can be the result of optical distortion or capsule opacification. Most cases are unilateral, although bilateral and familial cases have been reported. Surgery is associated with good visual results in most cases. In rare cases, spontaneous lens rupture can occur, leading to abrupt progression to total cataracts.

Figure 7. Cataract of the posterior lentiglobe (Lenticonus). (A)Early clear defect in the central posterior capsule and(B)early opacification of the central defect.(C)Ultrasound biomicroscopy of the advanced posterior lenticonus.

posterior subcapsular

These can be congenital but are more commonly acquired as a result of injury or steroid use. The opacities are cortical and do not involve the actual capsule.

Figure 8. Posterior subcapsular cataract.

Persistent fetal vasculature (PFV) (severe variants are still referred to as persistent hyperplastic primary vitreous)

The lens opacities in patients with PFV are generally capsular and may be associated with capsule shrinkage, thickening, and vascularization. There may be a posterior plaque outside or on the lens capsule with a clear lens that still needs to be treated as a cataract.

Figure 9. Persistent fetal vessels.

Traumatic disruption of the lens

In children, a traumatic rupture of the anterior lens capsule quickly leads to a hydrated white cataract. However, in children, the lens cortex in the anterior chamber can be well tolerated without an increase in intraocular pressure (IOP). Cataract surgery can often be delayed for a few days or as long as 3 or 4 weeks to allow traumatic iritis to subside prior to cataract and IOL surgery.

Figure 10. Traumatic lens disruption (courtesy of K. David Epley).

evaluation and processing

role of vision screening

An eye test is mandatory to detect cataracts as soon as possible. Late detection can lead to poor visual results. All newborns must have red reflex screening, ideally followed by another red reflex screening at the 6-8 week neonatal visit. The red reflex test is performed using a direct ophthalmoscope from a distance of 1-2 feet in a darkened room. Preschool (ages 3 and 5) vision screening is often performed in the community. Photo screeners are used with preverbal and verbal children. These can help the pediatrician save time during screening. They work with a computer that analyzes the red reflex for disparities in colour, intensity or clarity. New screeners that use polarized laser light are more accurate in detecting impaired vision. The presence of opacities, an absence of red reflex, or leukocoria should prompt urgent referral to a pediatric ophthalmologist.

Assessment by the ophthalmologist

A detailed anamnesis is taken, which is asked about the milestones in the child's development and about health problems of the siblings and parents. The visual assessment is based on age-appropriate tests. When the infant is two months old, visual assessment can be performed using forced preferential gaze techniques (eg, Teller visual acuity maps, Cardiff maps), fixation, and then scoring and assessing objections to occlusion of each eye. The presence or absence of nystagmus is noted. Subjective visual tests (HOTV matching, LEA symbols, or tumbling It) are performed once the child is able to play a matching game or identify the symbols and letters. These tests can usually be performed from the age of 3 years.

Biomicroscopy (standard or portable slit lamp examination) is complete. Cataract severity and morphology and any associated corneal or anterior segment abnormalities are documented. Examination of siblings and parents can indicate inherited cataracts. If possible, the intraocular pressure is checked.

If the retina is visible, a complete retinal examination is performed with documentation of the optic nerve, retina and fovea. If there is no vision, an ultrasound examination (B-scan) is performed. If trauma is present, child abuse must be ruled out. Laboratory tests are not required for unilateral cataracts.

With bilateral cataracts, if there is a family history of childhood cataracts, the child has no other medical problems, and the parents have lens opacities, systemic and laboratory tests are not required. If there is no family history of cataracts, a pediatric systemic evaluation is required because these cataracts may be associated with systemic or metabolic disease. Laboratory tests may also be required. The ophthalmologist often works with a pediatrician and/or a clinical geneticist when conducting the laboratory evaluation. A urine test to reduce sugars, a TORCH (toxoplasmosis, rubella, cytomegalovirus, chickenpox) screening, a Venereal Disease Research Laboratory (VDRL) test for syphilis, and a blood test for calcium, phosphorus, glucose, and galactokinase levels may do be checked.

Most inherited cataracts are autosomal dominant. Recessive and X-linked cataracts are less common. Genetic testing is a rapidly developing field. Mutations that cause congenital cataracts have been discovered in over 100 genes. With the latest sequencing tests, it will be possible to check all genes involved in congenital cataracts from a blood sample. This could lead to faster and cheaper personalized treatment and advice from the geneticist.

If cataracts are less than 3mm in diameter or partially dense, they can be observed or treated with dilating drops. Any dense central opacity in the lens of three or more mm in a young child is significant and requires surgery. In addition to the size of the cataract, the blackening of the retinoscopy reflex is the most important factor in the need for surgery.⁵In an older child, any opacification that impairs quality of life should be considered for surgery. At the same time, the loss of accommodation that occurs when removing a child's lens should be taken into account when deciding on an operation. As children grow older, their visual demands increase and the assessment of whether a partial cataract is visually significant needs to be reassessed.

Biometry is performed to obtain keratometry measurements, preferably without a speculum. Axis length in children is often measured by A-scan ultrasound, with the immersion method being more accurate than the contact method.^6,7These measurements are often not possible in the clinic and an examination under anesthesia is required. If the child is older and cooperative, and the cataract is not very dense, optical biometry is performed.

Third generation theoretical formulas (e.g. SRK/T, Holladay I & II, Hoffer Q I & II and Haigis) can be used to calculate the IOL. Target refraction can be aimed for initial hypermetropia (high or low) or emmetropia. Recommended target refractions for age are givenTable 2.⁵Other factors such as amblyopia, other eye diseases or refraction, assumed compliance, and parental refractive errors should also be considered when interpreting the table: A choice of IOL power for every age does not work for every situation.

Operation

Who should perform the operation?

Cataract surgery in adults is a focus of specialist training in ophthalmology. The skills required to perform cataract surgery in adults are also important to perform cataract surgery in children, but additional skills are required for pediatric surgery. Cataract surgery in children should only be performed by eye surgeons who perform it weekly or bi-weekly so that they can perform it with a high level of competency.⁸Because of this, most large group practices only assign one surgeon in their office to perform these surgeries. If possible, children should be referred to regional centers where many pediatric cataract surgeries are performed. After the post-operative phase, these children can in most cases be looked after by a local doctor and only be referred back to the regional center if problems arise. Pediatric ophthalmologists interested in performing pediatric cataract surgery should undertake fellowship training at a facility where they will be trained to perform pediatric cataract surgery. Upon completion of their scholarship, they should take instructional courses as needed to incorporate new techniques as they arise. While adult cataract surgeons are typically proficient in performing intraocular surgeries, they have often not been taught the specific techniques required to successfully perform pediatric cataract surgery. If they are interested in performing pediatric cataract surgery, they should look for opportunities to learn the best practices either through observation or by attending training courses.

Timing and critical period

Hubel and Wiesel in the 1960s⁹introduced the concept of a "latency period" and a "critical period" for visual development. During the latency period, vision deprivation has no lasting effect on the vision of the deprived eye. After the latency period, there is a critical period during which vision deprivation leads to irreversible vision loss in the deprived eye. The critical period for a child with cataracts extends to 9-10 years of age.

one-sided

The optimal age for performing cataract surgery on a child with unilateral congenital cataract is generally considered to be 6 weeks of age. Birch and Stager¹⁰investigated the relationship between age at cataract surgery and visual outcome in neonates with dense unilateral congenital cataracts. The model that best fitted their data was bilinear, with no differences in visual outcomes when surgery was performed between birth and 6 weeks of age. However, after 6 weeks of age, there was a linear decrease in visual outcomes related to age at cataract surgery. Their model would suggest that there is a 6-week latency period for dense unilateral cataracts in humans. Recently, Hartmann et al¹¹found that age at cataract surgery was only weakly associated with visual acuity. While mean visual acuity was better in patients who underwent cataract surgery between the ages of 4 and 6 weeks, the association between age at cataract surgery and visual outcome was less robust than the data reported by Birch and Stager.

Bilateral

It is generally accepted that bilateral congenital cataracts should be removed by 8 weeks of age to achieve the best visual results. Lambert and associates¹²found that delaying cataract surgery to 10 weeks of age or later increases the likelihood of a visual outcome of 20/100 or worse. Birch and staff¹³reported a bilinear relationship between age at surgery and visual outcome in infants with dense bilateral congenital cataracts. Between birth and 14 weeks of age, they found progressively worse visual outcomes the older a child was at the time of cataract surgery. After weeks 14 to 31, however, the visual outcome was independent of the age of the child at the time of cataract surgery. Because it is unclear whether there is a latency period in children with dense bilateral congenital cataracts, the timing of cataract surgery in these children is often dictated by other comorbidities and the increased risk of glaucoma associated with very early cataract surgery.

Threshold/indication for surgery

Determining the need for surgery in preverbal children

Dense cataracts that block the red reflex before the pupils dilate and are associated with abnormal vision should be removed in infancy. Other signs that suggest visually significant cataracts are strabismus in a child with unilateral cataracts or nystagmus in a child with bilateral cataracts. Incomplete cataracts do not always require cataract surgery. If the child has an incomplete cataract and normal vision, and the fundi is clearly visible with an ophthalmoscope, cataract surgery should be postponed. In general, posterior lens opacities are more visually significant than anterior lens opacities. If the incomplete cataract(s) is/are unilateral or asymmetric, part-time patch therapy of the normal/better eye may be beneficial to improve or maintain vision in the most affected eye.

Visual acuity table threshold for surgery

In general, cataract surgery should not be performed on children with bilateral cataracts who have a best-corrected visual acuity of 20/40 or better. However, the visual threshold for performing cataract surgery should be tailored to the needs of the child. For example, if a child has less than 20/40 visual acuity but does well in school and has no vision problems, cataract surgery may be postponed until later. Visual behavior is less helpful in assessing the need for cataract surgery in children with unilateral cataracts. In general, if best-corrected visual acuity cannot be improved to 20/50 or better with amblyopia therapy, cataract surgery should be considered.

Visual dysfunction weighed against postoperative loss of accommodation

The improvement in visual acuity associated with cataract surgery must be balanced against the loss of accommodation associated with removal of the lens of the eye. While multifocal or accommodative IOLs are available for adults and may somewhat mitigate the loss of accommodation associated with cataract surgery, they are rarely implanted in growing children because of the refractive changes that occur as an immature eye grows. Parents should be informed that while their child may see more clearly after cataract surgery, the child must wear bifocals to optimize distance and near vision.

Declaration of consent/parental advice

The risks and benefits of cataract surgery should be clearly outlined to parents. It is often helpful to show them eye models or illustrations so they understand what cataracts are and how cataract surgery is performed. The importance of amblyopia therapy and optical correction after cataract surgery should be discussed in detail. The advantages and disadvantages of IOL implantation or posterior capsulotomy should be discussed with parents. It should also be explained that the US Food and Drug Administration (FDA) has not approved the implantation of IOLs in children and their use in children is off-label.

Immediate Sequential Bilateral Cataract Surgery for Children

The possibility of immediate sequential bilateral cataract surgery should be discussed with the parents of infants, especially if there are comorbidities that increase the risk of general anesthesia. They should be informed of the risks and benefits associated with immediate sequential bilateral cataract surgery, including the benefit of administering only general anesthesia but the increased risk of bilateral endophthalmitis.¹⁴It should also be explained that precautions are taken to reduce the risk of endophthalmitis, including using different instrument trays for each eye, disposable cannulas, re-covering between the eyes, and using different amounts of irrigating solution and medication for each eye.

Anesthesia management considerations

General anesthesia is required for pediatric cataract surgery. Anesthetic agents should only be administered under the direct supervision of an anesthetist with particular experience or training in pediatric anesthesia. Very young children, especially premature babies, often require overnight hospitalization after cataract surgery because they are at increased risk of apnea after general anesthesia. Cataract surgery can be performed on an outpatient basis in older children.

Operative Techniques

Preoperative preparation is typically done using povidone iodine. The use of intracameral antibiotics, either in the lavage solution or injected postoperatively, has been extensively tested in adults, and while not widely used among pediatric cataract surgeons, trends predict greater adoption in the years to come.

Surgical incisions are usually made anteriorly through a clear cornea or using a scleral tunnel. When no IOL is to be placed, a minority of surgeons opt for a posterior pars plana/plicata approach. Continuous curvilinear capsulorhexis, with or without capsular staining, is the gold standard of capsulotomy, but vitrectorhexis also works well and is often used in the early years of life when the capsule is very elastic. The anterior chamber is serviced with either a separate, non-constrained infusion needle (an anterior chamber holder) or with appropriate hand-held bimanual irrigation and aspiration handpieces. Pupillary dilation is enhanced by unpreserved epinephrine or phenylephrine/ketorolac (recently FDA approved for adults) added to the IV bottle.

The lens content is completely aspirated (Figure 11). Phacoemulsification ultrasonic energy is never needed in pediatric cataract. Hydrodissection is not required but can be performed at the surgeon's discretion. However, the large number of pediatric cataracts associated with posterior capsular pathology must be considered. Hydrodissection is contraindicated for posterior polar cataracts.

Figure 11.An irrigation/aspiration handpiece for removing a lamellar cataract (courtesy of Faruk H. Orge).

A posterior chamber IOL inserted into the capsular bag is always preferred, but placement of a foldable acrylic or one-piece rigid IOL in the ciliary sulcus can be done. In cases without capsule support, posterior chamber IOLs can be sewn in; However, placement of iris (claw) fixed lenses is becoming increasingly popular.

In children who are too young to tolerate in-office posterior YAG laser capsulotomy, primary posterior capsulotomy is recommended at the time of initial cataract surgery. This can be done either before or after the insertion of an IOL and can be done anteriorly through the corneal tunnel or posteriorly through the pars plana. All but the smallest watertight incisions in children should be closed, usually with a 10-0 synthetic absorbable suture.

Postoperative medication

Antibiotics

After pediatric cataract surgery, either moxifloxacin or tobramycin, the two most commonly used antibiotic eye drops, can be used. The eye drops are instilled four times a day for a week. There is no need to prescribe systemic antibiotics.

steroids

Prednisolone eye drops are the mainstay of treatment to control severe inflammation that is generally unavoidable. In some cases of very severe postoperative inflammation, steroid eye drops have to be instilled up to every hour. Otherwise, the routine dosage range is 4-8 times per day. Some surgeons advocate supplementing the topical steroid with oral prednisolone at a dosage of 1 mg/kg/day for the first week to reduce inflammation.

Cycloplegics and Mydriatics

Homatropine or atropine eye drops are sometimes used postoperatively as cycloplegics. The possible side effects of atropine must be discussed with the patient's parents.

Follow up

Pediatric cataract cases are usually evaluated on the first postoperative day. The next follow-up depends on the extent of the inflammation, but usually takes place 1 week after the operation. Once both eyes are operated, periodic examinations are required to determine refraction, intraocular pressure, and retinal evaluation. Glasses or contact lenses are prescribed as early as possible, preferably within the first week for aphakic correction and within 4 weeks for residual ametropia in pseudophakic children.

frequency

The typical frequency of follow-up is as follows: postoperative day 1, week 1, month 1, month 3, every 3 months for 2 years and every 6 months thereafter for 3 years.

Evaluation

It is important to check visual acuity, eye alignment, intraocular pressure, refraction, and visual axis clarity at each visit. If complications are identified during any of the follow-up visits, they should be addressed promptly.

Optical rehabilitation after cataract surgery

Since uncorrected refractive error in the early years can lead to amblyopia, attention to proper refractive correction after cataract surgery is crucial to achieve good final visual acuity. In infants and young children, the refractive correction should lead to good near vision (myopic refraction of about -2 dioptres). From the 2nd or 3rd year of life or up to kindergarten age, however, a correction for distance and a bifocal correction for near should be offered. Children who wear contact lenses can still benefit from glasses overcorrection after the age of 2 or 3.

Glasses

In children with IOL implantation, some residual refractive error is typical and eyeglass correction may be required for distance and/or near vision. In addition, if IOL implantation occurs at an early age, the growing eye will experience myopic displacement, so changing refraction with residual hyperopia is expected in the early years, but some degree of myopia is expected later. In infants and young children in whom IOL implantation is not possible or is intentionally delayed, correction of aphakia with glasses may be preferred. Aphakic glasses are generally well tolerated, particularly by children who are bilaterally aphakic. Unilateral aphakia can also be corrected with glasses, although this is less desirable due to the pronounced disparity in image size (aniseikonia) and the possible interference with binocular vision, if present.

contact lenses

Contact lens correction for aphakia is often planned for very young infants after lensectomy, typically with either a silicone elastomer lens (prolonged wear) or a rigid, gas permeable lens (daily wear). One advantage of wearing contact lenses is the ease of adjusting the power for the rapidly changing refractions encountered in young children. A contact lens correction of the remaining ametropia is also possible after IOL implantation and is sometimes requested by young patients.

Postoperative complications and consequences

Postoperative complications after pediatric cataract surgery are inversely proportional to age at the time of surgery. Associated ocular abnormalities, surgical technique, and length of follow-up are some of the other important variables affecting the prevalence and severity of postoperative complications after cataract surgery in children.

visual axis opacity

If the posterior capsule remains intact at the time of cataract surgery in children, posterior capsule opacification (PCO) is inevitable. The younger the child, the more acute the opacification will be. Visual axis opacification (VAO) is rare in older children after primary posterior capsulectomy and vitrectomy; However, despite posterior capsulectomy and vitrectomy, VAO is commonly seen in infants. VAO in infants receiving posterior capstectomy and vitrectomy typically requires surgical removal 3 months to 1 year after the original surgery, while PCO in older children with an intact posterior capsule typically requires Nd:YAG laser or surgical removal of the PCO 2 years or more required after cataract surgery.¹⁵

Glaucoma

Secondary glaucoma is the most visually threatening complication of pediatric cataract surgery. Younger age at the time of surgery is the most commonly reported risk factor. Open-angle glaucoma can develop months to many years after surgery, and children need to be monitored regularly throughout their lives.

Inflammatory Complications

Due to the increased tissue reactivity, inflammatory complications (e.g. anterior chamber cell and flare, cell deposits on the IOL optic, posterior synechiae, etc.) are observed more frequently in children. Toxic anterior segment syndrome (TASS) is a rare inflammatory condition usually observed in the early postoperative period.

contact lenses related

Bacterial keratitis, corneal opacity due to tight contact lenses, and corneal vascularization are the most common contact lens-related complications.

IOL malposition

Excessive capsular contracture and asymmetric IOL fixation are the most common causes leading to misplacement of an IOL. It can also occur due to traumatic zonular loss and/or inadequate capsular support. The IOL may need to be repositioned or explanted in some cases if there is significant decentering/dislocation.

Endophthalmitis

The incidence of postoperative endophthalmitis in children is similar to that seen in adults. Common organisms areStaphylococcus aureus, Staphylococcus epidermidis,AndStreptococcus viridans. Recent studies in adults have reported a marked reduction in endophthalmitis with intracameral antibiotic use. In the US, the lack of an ophthalmic preparation specific for intracameral injection use has slowed the adoption of intracameral antibiotics for fear of toxicity from dilution errors during drug preparation. Studies in adults have used cefuroxime, vancomycin, and undiluted moxifloxacin.^{16, 17, 18, 19, 20}

retinal detachment

The incidence of retinal detachment (RD) after pediatric cataract surgery appears to have decreased significantly with advanced surgical techniques. However, because RD can develop many years after surgery, a retinal exam is recommended at least annually after cataract surgery. This is especially important for eyes at higher risk of RD due to long axial length for age, persistent fetal vasculature, traumatic cataract, ectopia lentis, Stickler syndrome, recurrent surgeries, etc.

Myopic shift

A tendency to axial stretching and a myopic shift in refraction are known. This is more of a concern if the child is receiving an IOL. The younger the child is at the time of implantation, the greater the myopia shift. High myopia in pseudophakic eyes can be treated with glasses or contact lenses. Alternatively, IOL exchange, piggyback IOL implantation, or corneal refractive surgery may be required.

Other Complications

Corneal edema, corneal decompensation, iris prolapse, heterochromia iridis, suture-related complications, postoperative IOP increase, astigmatism, ptosis, or phthisis bulbi are other complications reported after pediatric cataract surgery.

Peeling

Strabismus may coincide with congenital cataracts and is seen more commonly in unilateral cases but not infrequently in bilateral cataract cases, particularly when nystagmus is present. Esotropia is the most common form of strabismus in congenital cataracts, although cyclovertical strabismus may also contribute to the clinical picture. In a minority of patients, exotropia of the affected eye is the first sign of congenital cataracts.

Management of co-existing amblyopia

Deprivation amblyopia is very common in children with unilateral cataracts, particularly when the opacification is congenital or infantile. In addition, children with bilateral cataracts may develop unilateral or bilateral deprivation amblyopia if the cataracts are asymmetric, if they are removed too late, or if the aphakia is not properly corrected. Sensory nystagmus further limits the visual outcome. Treatment of amblyopia should begin as soon as possible since compliance is better in young children than in 2- to 3-year-old children. Patching the healthy eye is the mainstay of treatment. However, atropine punishment may be an alternative if the amblyopic eye can provide fixation. This is rather rare, as the aphakic or pseudophakic eye has lost accommodation and is therefore always at a disadvantage compared to the healthy eye, which can take in up to 10 dioptres, depending on the age of the child. For bilateral aphakic eyes wearing contact lenses, the dominant eye's contact lens can be removed as a punishment strategy a few hours or several days per week. The younger the child, the better the effect of amblyopia treatment per hour of occlusion.

Measures for the rehabilitation of poor eyesight and quality of life

In cases where congenital cataract treatment is less successful, visual impairment rehabilitation plays an important role in how the patient copes with visual impairments in school and in everyday life. In most countries, visual rehabilitation and education for visually impaired and blind patients is organized either by the government, various non-governmental organizations, or private foundations. The motto should be: Use the remaining visual function with all other senses in order to achieve the optimal quality of life.

future directions

Early detection will allow more timely treatment of pediatric cataracts in the future. Eye screening programs and improved education of primary health care professionals and the public will help this development. Surgical techniques continue to improve, enabling cataract removal in children with fewer and fewer surgical traumas. Planning for IOL implantation will become easier as our knowledge of myopic displacements and axial growth of the globe advances. Ultimately, future technological advances in IOLs are aimed at restoring or maintaining youthful accommodation and the ability to easily compensate for the inevitable myopia shift. Intracameral medications specifically for ophthalmic use are being developed and these will improve outcomes for children by reducing the confidence we now have in parents' ability to administer topical medications after surgery.

references

1. Gilbert C. Global causes of blindness in children. In: Wilson ME, Saunders RA, Trivedi RH, eds.Pediatric Ophthalmology: Current Thoughts and a Practical Guide. Heidelberg, Deutschland: Springer; 2009: 47-60.
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