OVERVIEW: What every practitioner needs to know
An infant who may be visually impaired causes an extremely anxiety-provoking and stressful situation for parents and family, especially if impairment is unsuspected. When challenged by a chief complaint of “Can my baby see?” the practitioner must assess the situation and triage it with alacrity while trying to offer the family peace of mind. It can be extremely difficult for the caregiver inexperienced in dealing with a blind infant to convey to the family the needed sense of confidence to reduce their anxiety.
Knowledge about the infant’s developing visual system and causes of visual impairment and their treatment will help organize the approach and care of the infant who is blind or has a significant visual impairment.
Normal Visual Development
Vision is both genetically and environmentally determined. We are preprogrammed to form neuroanatomic pathways and structures, but require normal visual experiences with the environment during the first decade of life in order for this to happen. If the developing visual system does not get these opportunities at the appropriate time, then normal vision will not develop and amblyopia (decreased vision due to visual deprivation, a defocused retinal image, or an image focused away from the macula that occurs during the sensitive period of visual development) will be the consequence.
Unlike visually mature adults, children are at risk for poor vision from both their primary ocular disease and also secondarily from amblyopia as a consequence of visual deprivation from the organic ocular disease. Amblyopia causes changes in the visual cortex.
Anatomically, the newborn eye is small, approximately 16-17 mm in length compared to an adult eye of 23-24 mm. The photoreceptors of the retina are not yet tightly packed. The area of central vision, the macula (also called the fovea), is not fully formed. The optic nerve is not fully myelinized. The occipital (visual) cortex will require normal visual input to remodel and form ocular dominance columns. Vision in the normal newborn is in the range of 20/200 to 20/400, but quickly improves over the first several months of life.
In order to direct and maintain visual fixation, both the saccadic and vergence movement systems are needed to direct the target’s image onto the fovea. The vestibular system maintains a stationary stimulus on the fovea. The smooth pursuit system keeps a moving target locked on the fovea. The fusional convergence and divergence systems keep the images in each eye on corresponding retinal elements. These motor systems are not fully developed at birth, resulting in limited ocular motility, but they mature quickly over several months.
Visual landmarks that are normally seen include a blink reflex to bright light, which occurs even in the sleeping infant by several days of age. A pupillary reflex is present after 31 weeks gestation, but can be difficult to assess because of the naturally small (miotic) pupil of an infant. By 4-6 weeks of age, the baby can make eye-to-eye contact, and demonstrate both slow pursuit movements and purposeful eye movements. At age 2-3 months, interest in bright objects is noted. At 3-4 months, eye movements should be conjugate (coordinated). There should be only minimal periods of strabismus (misalignment) or none at all. If an intermittent strabismus is present, it should be occurring less and less frequently. Sunsetting, which can occur with hydrocephalus or be seen on occasion in normal infants, should be abolished.
Normal visual experiences are especially critical throughout the first 2-3 months of life in order to acquire normal vision and avoid amblyopia secondary to visual deprivation. Simply stated, abnormal retinal images or lack of normal retinal stimulation during the critical period, as occurs with congenital cataracts for example, result in damage to visual centers in the brain and, consequently, amblyopia.
This sensitive period of visual development occurs during a period of neuroplasticity of the sensory visual system. It is a period of refinement for synaptic connections. Normal visual inputs result in changes that are physiologic, resulting in normal visual development, while abnormal visual inputs (from abnormal retinal images) cause changes that are pathologic and result in amblyopia.
Amblyopia occurs during the critical or sensitive period of visual development, and results in abnormal neuroanatomic and neurophysiologic function of the visual cortex. Amblyopia can develop in as quickly as several days in a visually deprived infant.
The sensitive period for central vision lasts for much of the first decade of life. In regard to amblyopia, it is during this time that the visual cortex demonstrates neuroplasticity and can be injured or repaired. Unlike adults who have mature visual systems and are not at risk to develop amblyopia, visual loss or lack of visual development can be the result of a primary ocular disease, such as a cataract, and secondarily to the development of amblyopia.
Within 4-6 weeks, a full-term baby whose vision is developing normally shows conjugate (coordinated) eye movements and seems able to look at objects and faces. The child with poor vision is not as attentive. In children with very poor vision, in the range of light perception, extraneous eye movements described as wandering or roving may be present. In comparison, the child with poor vision in the 20/400 or better range develops nystagmus (a rhythmic to and fro movement quicker than roving eye movements).
Of interest, nystagmus associated with poor vision usually does not become apparent until approximately 2-3 months of age. Additionally, the nystagmus is seen with bilateral ocular or anterior visual pathway disease (encompassing structures located in the eyes and extending to the optic chiasm), as opposed to occipital lobe disease where the visual cortex is located. An exception to this is damage to the optic radiations of the posterior pathway that may be associated with nystagmus.
Are you sure your patient is visually impaired? What are the typical findings for this disease?
Signs and symptoms of poor visual development include lack of recognition of familiar faces or objects, nystagmus or wandering eye movements, staring at lights, oculo-digital reflex (rubbing or poking eyes) or “blindisms” (such as the baby waving a hand in front of his/her face; see Figure 1), and strabismus. In addition, the infant may be photophobic, appear to have an empty stare, and have developmental delays. Worrisome signs include:
Lack of eye contact with mother/caregiver. A baby should be able to establish fixation on a mother’s face by 6 weeks of age. At that time or slightly later, babies will respond to mother’s face with a social smile.
Roving eye movements or nystagmus. While there may be short periods of extraneous eye movements in the newborn to 2-3 months of age, over time these movements should disappear and be replaced by purposeful, coordinated eye movements.
Poor visual tracking.At birth, the motor systems for eye movements are immature, allowing only slow pursuit movements of limited amount. This changes quickly in the first 2-3 months of life, resulting in more accurate tracking.
Staring at bright lights. This may be done for visual stimulation.
Waving hands up and down in front of the face. This may be self-stimulating by creating movement of shadows.
Eye rubbing and poking. This may be done to stimulate the retina and produce flashes of light that the baby finds interesting.
Poor tracking can be often be confused with poor vision, especially in the first two months of life. Another situation causing confusion is in a child who cannot make voluntary eye movements, known as ocular motor apraxia. Parents will often suspect that poor tracking means the baby cannot see. Still another situation in which poor tracking can occur is when large visual field defects are present. For example, in a child with a right hemianopia, objects on the right side will not be seen and the child will not turn in that direction.
What other diseases/conditions shares some of these symptoms?
Diseases/conditions that can mimic poor vision and blindness include:
1. Autism and severe developmental delay. It may be very difficult to establish normal eye contact or obtain an expected response when a child is autistic or has severe developmental delay. A lack of expected response could be behavioral or due to organic ocular disease or cortical visual impairment. Any of these could be contributing to a blunted visual response.
2. Delay in visual maturation is another reason that the question “Can my baby see?” gets raised. Delayed visual maturation may occur in otherwise healthy infants or infants with associated systemic disease, or it could be superimposed on ocular / neuro-ophthalmologic disease. When delayed visual maturation is an isolated phenomenon, marked improvement is seen by 6 months of age. Delayed maturation associated with central nervous system disease shows less improvement. When associated with ocular disease, the degree of improvement is better than the latter but less than the isolated type. (Paediatric Ophthalmology, 2nd ed. D. Taylor ed.)
3. Ocular motor apraxia. An inability to generate voluntary saccadic eye movements, usually in the horizontal plane. (See poor tracking above.)
4. Nystagmus. Back and forth eye movements associated with poor vision due to anterior pathway and ocular pathology. It should be noted that nystagmus can occur without ocular pathway disease, in which case vision can be good.
5. Visual autism. This term has been used for children who have high refractive disorders but refuse to wear glasses or contact lenses. It can be seen in children with autism, Down syndrome and severe developmental delay. These children are withdrawn and have poor functional vision because they do not wear their glasses. (Tyschen, L.)
6. Other central nervous system disease, including severe developmental delay, seizures, cerebral palsy, and neurodegenerative disease.
What caused this disease to develop at this time?
The causes for poor vision and blindness in an infant can be placed in several diagnostic categories (see last paragraph, this section). The clinician may be able to conclude that the impairment is ocular in nature or that pathology lies in the visual pathways behind the globes or in higher visual processing centers. The etiology of decreased vision in an infant can be multifactorial as well. While it is a given that blindness and poor vision are due to bilateral disease, one eye or visual pathway may be more severely affected than the other, resulting in one eye or area of the visual field having more function. Residual vision is often referred to as low vision.
In the developed countries of the world, causes of infant blindness include entities such as cataract (Figure 2 and Figure 3), glaucoma (Figure 4), retinal diseases, optic nerve diseases, congenital ocular malformations, and certain neurological diseases (see last paragraph, this section). Cortical blindness (also known as cerebral visual impairment) is a leading cause of visual impairment.
Delay in visual development is another cause of concern that an infant may not see as well as expected.
Beside these causes, in underdeveloped nations, other important causes of blinding disease include infection, toxic causes, and malnutrition.
Loss of vision in children with previously good vision can be caused by neurodegenerative diseases, hereditary retinal and optic nerve disease, intracranial tumors, hydrocephalus as well as occipital injury, accidental, and nonaccidental trauma.
Ischemic and hypoxic events such as cardiac or respiratory arrest or prolonged seizure activity may cause loss of vision due to cortical blindness.
Causes of visual impairment and blindness in children include the following diseases and pathological entities:
The fetal eye can be subjected to prenatal insults such as infections, radiation, drugs, and trauma that cause congenital malformations of the globe or selected structures of the eye like the lens
Non-accidental trauma should always be considered if the history of a traumatic event is vague and associated with intraocular hemorrhage and fractures of the long bones.
Failure of normal development of ocular structures can be due to genetic disease, either on an inherited basis or a new mutation. Retinoblastoma is an example of this. Others are cryptophthalmos, microphthalmia, and aniridia.
TORCHS diseases (toxoplasmosis, rubella, cytomegalovirus, herpes simplex and syphilis) can cause both retinal infection (chorioretinitis) and infect the brain and also cause congenital cataracts.
Corneal disease (ophthalmia neonatorum, vitamin A deficiency, microcornea, central corneal developmental abnormalities).
Cataracts (opacities of the lens) may be genetic, metabolic, or associated with infection. They may be associated with numerous syndromes and disorders or be an isolated finding.
Retinal diseases: retinopathy of prematurity, retinoblastoma, retinal dysplasia. Retinal dystrophies (Leber’s congenital amaurosis, achromatopsia, congenital stationary night blindness). Aicardi syndrome, foveal hypoplasia. Macular dystrophies (Stargardt’s, Best’s disease). Retinopathy of prematurity is the consequence of abnormal vessel growth due to retinal hypoxia in the premature infant. In severe cases, retinal detachment develops. Retinal dystrophies are diseases of the rods and cones, the retinal receptors.
Optic nerve disease and abnormalities: optic atrophy, optic nerve hypoplasia, optic nerve aplasia, colobomatous defects, optic neuritis, papilledema. Optic atrophy may be due to multiple causes including ischemia, increased intracranial pressure, toxicity, or be inherited. Infants of a diabetic mother are at risk of developing optic nerve hypoplasia (also the ingestion of certain drugs such as quinine predisposes to optic nerve hypoplasia), a failure in development of the optic nerves.
Central nervous system: Cortical blindness (also known as cerebral visual impairment), intracranial: tumors, periventricular leukomalacia,intracranial malformations, increased intracranial pressure,hypoxic/anoxic events. Damage to the optic radiations posterior to the chiasm, visual cortex, and higher processing centers such as the dorsal and ventral processing streams often is due to ischemic-hypoxic injury. Ischemic and hypoxic episodes may occur pre- or post-natally and affect the brain, causing cerebral visual impairment (cortical blindness). Prolonged seizure activity, hydrocephalus, maldevelopment of the brain, and meningitis are other examples that cause blindness and visual impairment.
Hereditary vitreoretinopathies (juvenile retinoschisis, Stickler syndrome, familial exudative vitreoretinopathy, Goldmann Favre syndrome, Norrie disease)
Other causes of visual impairment include nystagmus and albinism.
What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?
Many of the specific causes of blindness are made clinically by history and examination. Besides the initial examination done by the primary care specialist, the child will require a complete dilated examination by an ophthalmologist well versed in pediatric ophthalmology examination and the differential diagnosis of the blind or visually impaired child. An assessment of vision must be made, as well as an evaluation of ocular alignment and motility, and the presence or absence of nystagmus and roving eye movements. Corneal size and clarity are assessed, as is clarity of the lens and vitreous. Refraction should be noted. Fundus exam evaluates the health of each optic nerve, development of the macular reflex and health of the retina. At times, this information is collected with an exam under anesthesia with the possibility of concurrent treatment of the process causing visual loss.
If a diagnosis of ophthalmia neonatorum is suspected, then bacterial cultures must be obtained (and the possibility of HIV considered), especially with the knowledge that N. gonorrhoeaecan quickly destroy a cornea and cause blindness. Chlamydia and other bacterial infections also need to be ruled out or treated if present. The parents require examination if the cause of the conjunctivitis is due to a sexually transmitted disease.
If chorioretinitis (retinal infection and/or inflammation) occurs in an infant with or without systemic or central nervous system involvement, it may be necessary to obtain TORCHS titers and titer for lymphocytic choriomeningitis virus.
The work-up for bilateral congenital cataracts may include blood glucose, calcium and phosphorus checking for hypoparathyroidism, galactose-1-phosphate uridyltransferase and galactokinase and serum ferritin. Urine positive for amino acids helps make a diagnosis of Lowe syndrome in infants with cataracts and glaucoma. A karyotype delineates various chromosomal disorders, including trisomies such as Down syndrome, which is associated with cataracts.
Karyotypes may also be of value in other visually impairing ocular diseases that are seen with systemic pathology or failure in the normal development of ocular structures secondary to genetic diseases that occur on an inherited basis or as a new mutation. Wilms tumor-aniridia is associated with a deletion on the 11p chromosome. The PAX 6 gene linked to aniridia is situated on this part of the chromosome. With retinoblastoma, a deletion on chromosome 13 p- may be found. Many more genes have been linked to serious ophthalmic diseases. The National Library of Medicine’s OMIM (Online Mendelian Inheritance in Man) website (http://www.omim.org) is an excellent resource to explore the genetics of human diseases.
Inborn errors of metabolism with enzyme deficiencies may require testing of the enzyme or metabolic product. Visual involvement may be present from birth or later in childhood. The eye may be involved as an isolated organ or with multisystem disease. Visual impairment may be from corneal clouding, retinal changes, or optic atrophy. Amniocentesis may be indicated with a positive family history of metabolic disease.
Would imaging studies be helpful? If so, which ones?
Imaging studies can be an important adjunct in the evaluation of the child with visual impairment. History and examination as well as clinical suspicion will help the practitioner decide whether studies are needed. Generally, it is brain imaging that will be required. Orbital views may be required. MRI offers excellent detail without X-irradiation. Sedation is generally required for infants and children. If nonaccidental trauma is suspected, long bone studies are required.
MRI may demonstrate intraocular pathology, but it is not the preferred modality to show intraocular calcification associated with retinoblastoma. It may not be the preferred modality to study boney lesions. While CT scanning is generally better to study boney lesions and to search for intraocular calcifications, there is concern about the radiation that the lens and other tissues receive. When the ocular media is opaque or the posterior segment of the eye cannot be visualized, B scan ultrasonography may be the preferred imaging study. Retinal and vitreal disease can be studied, and calcification that can be present with retinoblastoma can be observed.
MRI is an excellent modality to study optic nerve disease. Changes in the brain that can be associated with optic nerve hypoplasia include absence of the septum pellucidum, agenesis of the corpus callosum, an aberrant pituitary bright spot, and schizencephaly. Colobomatous defects of the optic nerves can occur with encephaloceles. Optic atrophy has many causes that include tumors and hydrocephalus. The ex-premature infant may have damage to the optic radiations from periventricular leukomalacia that damaged white matter.
Confirming the diagnosis
If a child is brought to the office with the question “can my child/baby see?”, the following history and examination will be useful in determining the etiology of the impairment .
History.To help diagnose what caused the visual impairment and assist in determining prognosis, a careful history is important along with examination. Laboratory testing and imaging is done on a selective basis. While the chief complaint is often “can my baby see?”, it is important to note whether or not the child previously could see or whether the impairment goes back to birth.
A perinatal history that also includes the pregnancy should include questions about maternal infection, drug use, trauma, radiation, living with animals, and eating undercooked meat. Perinatal history should ask about Apgar scores, prematurity, being small for gestational age, intrauterine growth retardation, fetal distress, meconium staining, hypoxia, apnea and bradycardia, intraventricular hemorrhage, periventricular leukomalacia, seizures, and hydrocephalus.
Review of systems should investigate for any systemic abnormalities and for delays in reaching developmental landmarks.
A family history is important. Find out if any maternal or paternal family member had impaired vision as a child or had any childhood ocular problem such as cataracts, glaucoma, retinoblastoma, albinism, nystagmus, retinal or optic nerve problems, or whether other structural eye problems have been present.
Key questions that may be pertinent follow:
For how long has vision been a concern? Was vision ever present and normal?
Functionally, how well does the child see? Is there eye-to-eye contact, ability to follow your face, see across the room, note objects and colors, or distinguish between moving and stationary objects? Can your child maneuver safely?
Does the child stare at bright lights or appear light sensitive?
Are there random or roving eye movements? Do the eyes jiggle (nystagmus)?
Obtain a perinatal and developmental history. Were the pregnancy, labor, and delivery normal? Was the child premature? (How many weeks? What was birth weight? Were there any associated problems? Was there retinopathy of prematurity (ROP)? Did it require treatment?) Was the labor and delivery stressful? What were the Apgar scores? Is the child developing well or are there delays?
Review of systems and general health: Are there problems, known diseases, or syndromes present?
Explore the family ocular history. Is there any childhood blindness, visual impairment or childhood eye diseases? Any strabismus, nystagmus, or tumors? This history should include siblings, parents, grandparents (great grandparents and other ancestors, if known), maternal and paternal aunts, uncles and cousins.
Examination. If the underlying cause of the infant’s poor vision is a media opacity, the primary care giver has an opportunity to discover this. An excellent instrument commonly found in the office of the primary care practitioner is the direct ophthalmoscope. It may be used in one of two ways to evaluate for media opacities. The first is to observe the brightness (quality) of the red reflex when the instrument’s light is shined through the pupil to illuminate the retina. If the media are clear, without cataract (lens opacity) or opacity of the vitreous gel, the light reflex (reflection) should be bright. In children of color, the reflex may appear darker than in Caucasian children. It is useful to compare the light reflex in each eye.
Testing each eye individually is preferred in the newborn. The light reflex from each eye can also be compared simultaneously using the direct ophthalmoscope. This is known as the Bruckner test. With both of the child’s eyes open, the examiner, who is at a distance of approximately 18-24 inches, shines the instrument’s light into both pupils, observing the light reflexes and comparing both pupils for brightness and for the presence of a dark spot in the pupil, indicating a media opacity. This test requires the baby to have both eyes open. Examining an infant with the ophthalmoscope can be difficult to perform or interpret if the baby’s pupils are small (miotic). Dimming the room lights may be helpful.
While lens opacities (cataracts) are the most common cause of media opacity and are potentially blinding, the clinician should examine each eye for malformations, corneal opacity, and taking note as to whether the eye appears to be of expected size.
Although an infant sleeps much of the time, shining a bright light on the closed lids of each eye should elicit a blepharospastic response if the visual pathways are intact. This reflex is present in virtually all newborns from 31 weeks of gestation onward. A nonresponse is worrisome in regard to sight. It is also worthwhile to check pupillary responses to bright light. Pupils that do not react to light or react sluggishly may indicate the presence of optic nerve or retinal disease.
At 6 weeks, an infant should make eye-to-eye contact and slowly follow a face at a distance of arm’s length.
The following are helpful findings:
Does each eye appear normal in structure and size?
In a sleeping infant: do the pupils react to light? Is there a strong blink (blepharospastic) response to bright light?
Can the awake infant fix on and follow a face? What about a toy or bright light?
If testable, does peripheral vision appear intact to confrontation with a toy or finger puppet?
Are eye movements intact horizontally?
Are extraneous eye movements, such as nystagmus, or roving movements present?
Is strabismus present?
Pupils: do they react to bright light? Is the red reflex present and normal-appearing when tested with the ophthalmoscope? Is the Bruckner reflex present and is it normal? (see above “What every practitioner needs to know”)
Can you see the fundus? Does it appear normal?
If the child is not seeing normally or it is uncertain that the child sees normally, a referral to a pediatric ophthalmologist is needed.
If you are able to confirm that the patient has visual impairment, what treatment should be initiated?
Early diagnosis and early treatment is critical for vision-threatening disorders. To prevent severe amblyopia from visual deprivation, immediate treatment is necessary. This includes disorders of anterior visual pathways that include cataracts, glaucoma, leukocoria, retinal diseases such as retinopathy of prematurity, retinoblastoma, and some causes of optic nerve disease as well. Other causes of low vision may be intracranial or systemic diseases. Appropriate treatment may likely require a team approach.
What about longer term treatment? Many of the potentially blinding diseases of childhood require long-term treatment for several reasons. Ocular disease, such as cataracts, is associated with deprivational amblyopia which often requires ongoing treatment throughout the first decade of life. Strabismus supervenes not uncommonly. Glaucoma is also associated with infantile cataracts and can occur at any time. Since the eye undergoes growth, its refraction changes and new spectacles or contact lenses must be prescribed. Eyes that have been treated for glaucoma (elevated intraocular pressure) must be periodically monitored. Eyes treated for retinoblastoma must be monitored and retreated if necessary, and the affected child needs to be under the care of an oncologist. Children with JIA (juvenile idiopathic arthritis) must have periodic eye exams since they are at risk for iritis (intraocular inflammation), cataract, and macular edema.
Remember, too, that blind and visually impaired children will require rehabilitation and accommodations in schooling. If there is multi-system disease or multi-handicaps, rehabilitation becomes more difficult.
Circadian rhythms may be aberrant in children with severe visual loss.
What are the adverse effects associated with each treatment option?
Visually significant infantile cataracts and glaucoma are primarily surgical diseases. While good outcomes are expected, complications include loss of an eye or vision, development of glaucoma after cataract surgery, and continued elevated pressure after glaucoma surgery, causing damage to ocular structures, membrane formation and infection.
Significant corneal opacities may require corneal transplantation, which carries a greater risk of failure than when done in adults.
Repair of retinal detachment may fail to reattach the retina or may fail to provide function after anatomic reattachment.
Initial treatment of retinoblastoma may not cause tumor regression or spread of the disease.
Any of the ocular diseases that cause amblyopia may lead to a poor visual outcome if compliance with the treatment for the amblyopia is poor.
What are the possible outcomes of visual impairment?
What are the possible visual outcomes from the many different causes?
The family should be apprised of the degree of visual impairment and the cause when determined. Especially on the first visit, the clinician should be sensitive to psychological needs and try not to devastate the family. Conveying a feeling of optimism may be called for if the suspected cause of poor vision is delayed visual maturation, especially in an otherwise healthy child. Genetic counseling often is recommended.
Prognosis for the many causes of visual impairment varies based on multiple factors, such as age of the child at the onset of disease, time of discovery, and time of initiation of treatment. For those diseases where treatment is available, compliance with treatment will make a difference. For example, the child with glaucoma may need eye drops, optical correction, patching therapy for amblyopia, and regular follow-up examinations. Timely treatment may minimize the development of amblyopia. Good compliance with treatment should improve the likelihood of obtaining the best visual potential for that child.
In general, definitive treatment when available is required urgently to prevent or minimize permanent structural damage, reattach structures anatomically, prevent spread of tumor (retinoblastoma), and minimize amblyopia. Recommended treatment depends on the surgeon’s assessment of the situation.
What causes this disease and how frequent is it?
As noted above, there are many causes of infantile and acquired childhood blindness and low vision. In infants, either ocular disease, possibly on a genetic basis or cerebral visual impairment (often associated with other neurological findings) will account for many of the cases of impairment. In previously sighted children, neurodegenerative disorders need to be considered.
Infectious causes of impaired vision may be due to the TORCHS group of infections (toxoplasmosis, rubella, cytomegalovirus, herpes simplex and syphilis) occurring in utero. Chorioretinitis may result, as well as damage to optic tracts located more posteriorly. Herpetic infection in a newborn may cause severe corneal disease and or cataract. Fetal exposure via transplacental transmission of the TORCHS organisms is known to occur. For example, eating undercooked meat during pregnancy places the fetus at risk for infection with toxoplasmosis.
In third world countries where there is poor sanitation and public health, risk of infection increases. Vitamin A deficiency also increases the risk of corneal disease and blindness. Treatment with tribal medicines may also cause corneal scarring and blindness.
What’s known about the genetics? Knowledge about the genetics of the various diseases that can cause blindness is increasing rapidly. The National Library of Medicine’s OMIM (Online Mendelian Inheritance in Man) website (http://www.omim.org) is an excellent resource to explore the genetics of human diseases. It is often recommended that a child with congenital ocular disease be seen by a geneticist.
How do these pathogens/genes/exposures cause the disease?
A faulty gene may lead to a structural or metabolic defect. Accumulation of metabolic products may become toxic when there are enzyme deficiencies. Pathogens may foster inflammation and destruction. Retinal hypoxia/ischemia in ROP may lead to elaboration of vascular endothelial growth factor (VEGF) and neovascularization and then vitreoretinal traction and subsequent retinal detachment. Hypoxia/ischemia of the optic nerve results in atrophy. The optic radiations and visual cortex are also susceptible to this mechanism.
Other clinical manifestations that might help with diagnosis and management
What complications might you expect from the disease or treatment of the disease?
Blindness and visual impairment have significant implications for a child’s development. Mother-child bonding may be affected. Developmental delay may result or accompany visual impairment. Mobility may be affected. Accommodations may be necessary in the child’s educational plan. Future employment may be limited.
Are additional laboratory studies available; even some that are not widely available?
Gene testing is becoming increasingly available for some blinding ocular diseases.
How can blindness be prevented?
Prophylactic drugs and vaccines include vaccination for rubella.
Behavioral factors that promote premature births place the baby at risk for retinopathy of prematurity (ROP) and the potential for blindness, in addition to cortical blindness (cerebral visual impairment)
Since many of the ocular diseases causing blinding disease may be inherited, genetic counseling may be important in preventing subsequent blinding disease in future offspring. For example, if a disease is inherited as an autosomal recessive condition, after having an affected child, the family can be told of having a 25% risk of having another affected child.
Nutritional factors may be particularly important in those parts of the world where vitamin deficiencies exist. Ingestion of undercooked meat should be avoided during pregnancy.
What is the evidence?
Brodsky, MC. “Pediatric neuro-ophthalmology”. 2010.
Wright, KW, Spiegel, PH. “Pediatric ophthalmology and strabismus”. 1999.
Taylor, D. “Paediatric ophthalmology”. 1997.
Steinkuller, PG, Du, L, Gilbert, C. “Childhood blindness”. J AAPOS. vol. 3. 1999. pp. 26-32.
Steinkuller, PG. “Nutritional blindness in Africa”. Soc Sci Med. vol. 17. 1983. pp. 1715-21.
Titiyal, JS, Pal, N, Murthy, GV. “Causes and temporal trends of blindness and severe visual impairment in children in schools for the blind in North India”. Br J Ophthalmol. vol. 87. 2003. pp. 941–5.
Gilbert, C, Foster, A. “Childhood blindness in the context of VISION 2020–the right to sight.Bull World Health Organ”. vol. 79. 2001. pp. 227-32.
Goggin, M, O’Keefe, M. “Childhood blindness in the Republic of Ireland: a national survey”. Br J Ophthalmol. vol. 75. 1991. pp. 425-9.
Nallasamy, S, Anninger, WV, Quinn, GE. “Survey of childhood blindness and visual impairment in Botswana”. Br J Ophthalmol. vol. 95. 2011. pp. 1365-70.
Acland, GM, Aguorre, GD, Ray, J. “Gene therapy restores vision in a canine model of childhood blindness”. Nature Genet. vol. 28. 2001. pp. 92-5.
Acland, GM, Aguirre, GD, Bennett, J. “Long-term restoration of rod and cone vision by single dose rAAV-mediated gene transfer to the retina in a canine model of childhood blindess”. Mol Ther. vol. 12. 2005. pp. 1072-82.
Tyschen, L, Hoekel, J, Ghasia, F, Yoon-Huang, G. “Phakic intraocular lens correction of high ametropia in children with neurobehavioral disorders”. JAAPOS. vol. 12. 2008. pp. 282-9.
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- OVERVIEW: What every practitioner needs to know
- Are you sure your patient is visually impaired? What are the typical findings for this disease?
- What other diseases/conditions shares some of these symptoms?
- What caused this disease to develop at this time?
- What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?
- Would imaging studies be helpful? If so, which ones?
- Confirming the diagnosis
- If you are able to confirm that the patient has visual impairment, what treatment should be initiated?
- What are the adverse effects associated with each treatment option?
- What are the possible outcomes of visual impairment?
- What causes this disease and how frequent is it?
- How do these pathogens/genes/exposures cause the disease?
- Other clinical manifestations that might help with diagnosis and management
- What complications might you expect from the disease or treatment of the disease?
- Are additional laboratory studies available; even some that are not widely available?
- How can blindness be prevented?
- What is the evidence?