Frequently Asked Questions

Strabismus 

What is strabismus and how common is it?

Strabismus is any misalignment of the eyes. Affects approximately 4 out of every 100 children .

Are there different types of strabismus and if so, how are they named?

There are many different types of strabismus. Strabismus is most commonly described by the direction of the eye misalignment; common types of strabismus are esotropia, exotropia, hypotropia, and hypertropia.

Strabismus can also be described by its cause. The 3 cranial nerves (III, IV, VI) responsible for eye movement can be weak or palsied and cause strabismus. Some examples of paralytic strabismus include third nerve palsy and superior oblique palsy.

Special patterns of strabismus can have unique names such as Brown syndrome, and Duane syndrome.

What causes strabismus?

Most strabismus is the result of an abnormality of the poorly understood neuromuscular (including brain) control of eye movement. Less commonly, a problem with the actual eye muscle causes strabismus.

How is strabismus related to poor vision?

Eye misalignment can cause amblyopia in children. When the eyes are oriented in different directions, the brain receives 2 different visual images. The brain may ignore the image from the misaligned eye to avoid double vision, resulting in poor vision development of that eye. Also, an eye that sees poorly tends to be misaligned.

Who develops strabismus as a child?

Strabismus often occurs in children who are otherwise completely normal. However, disorders that affect the brain such as cerebral palsy, Down syndrome, hydrocephalus and brain tumour are more likely to develop strabismus.

What adult disorders cause strabismus?

Stroke is the leading cause of strabismus in adults. Trauma, neurological problems, and Graves disease (thyroid eye disorders) are other common causes of strabismus.

How does trauma cause strabismus?

Trauma can cause strabismus by 1) brain damage that impairs control of eye movement, 2) damage of the nerves that control eye movement and/or 3) damage of the eye muscles either directly or secondarily from trauma to the eye socket.

How is strabismus treated?

The goal of strabismus treatment is to improve eye alignment which allows for better work together (binocular vision). Treatment may involve eye glasses, eye exercises, prism, and/ or eye muscle surgery. Problems associated with strabismus (including amblyopia, ptosis, and cataract) are usually treated prior to eye muscle surgery

Q: I had an operation for a squint as a child. My eyes seemed straight for a few years but now one eye is drifting out. As I have already had surgery, is there anything that can be done about it?
A: It is not uncommon for a squint that has been corrected in childhood to re-appear in adulthood. Yes, further surgery is often possible and it would be worth having an assessment by a specialist squint surgeon. Your GP or optometrist should be able to refer you to a local specialist. 

Q: I had a “lazy eye” as a child and it has now come back. I would like to know who to turn to. Can you help?
A: “lazy eye” to most people means a squint; one eye or the other turning in or out. The best place to start is your optometrist. They will be able to assess the situation and refer you to the appropriate specialist. 

Q: I have a “lazy eye” and was wondering about treatment, if it could be helped or cured in any way. I am 54 years old. Would that be a problem?
A: Age is not, itself, a restriction to correcting a squint with surgery. Most squint surgery is performed under general anaesthetic (you are put to sleep for it) which requires that your general health is reasonable. 

Q: I have poor vision in my lazy eye since I was a child. The eyes seem to work together and I do not have a visible squint like most of your patients. Is it possible to make the vision better?
A: I am afraid the answer is probably not. If one eye is longer sighted or short sighted in childhood or there is a very small squint which is not noticeable, sometimes the brain decides to ignore that eye. If the vision is corrected early enough, the brain can be taught to start using the eye again (which may require patching treatment). However, this treatment needs to be done as early as possible and certainly before the age of 10. There are a very few cases reported where the vision has been improved in early teenagers but this is not common. Once you get to 10 or so, the vision is mature and there is no treatment that is likely to improve the vision. 

Q: My 10 year old daughter has just been diagnosed with a lazy eye. I have been told that it is too late for anything to be done, is this correct?
A: It is probably too late to improve the sight in the lazy eye, but it is usually possible to correct the cosmetic appearance of her eyes. You need to seek a second opinion

Q: I have a severe phobia of needles, is it possible to have treatment without having to see a needle?
A: Yes. The anaesthetic can be administered by using gas induction without you seeing or feeling a needle and all surgery is carried out while you are asleep under a General Anaesthetic.

What are the common eye problems seen in paediatric age group?

Children can have variety of eye problems. Some of the relatively common disorders are refractive errors, redness of eyes (conjunctivitis – infective or allergic), watering of eyes, strabismus (deviation of eyes), amblyopia (lazy eyes), lid abnormalities (ptosis), congenital cataracts, congenital glaucoma, developmental abnormalities of the eyes (microphthalmos), vitreous haemorrhage, retinopathy of prematurity, persistent foetal vasculature syndrome (PHPV), chorioretinal coloboma, tumours (retinoblastoma) , foveal hypoplasia and optic disc abnormalities (coloboma, hypoplasia, optic atrophy, swollen optic discs). Shreya Eye Centre is fully equipped in managing these ocular disorders.

How early does my child need an eye check-up?

Some common indirect pointers to the presence of vision problems in children are repeated watering of eyes, squeezing of eyes, frequent rubbing of eyes, habit of keeping visual targets at close distance, headaches, adoption of abnormal head postures. In very young children, gross discrepancy of vision between the two eyes can be tested by covering one eye at a time, in a subtle manner. Observation of delayed visual milestones should prompt an early eye check-up. Presence of deviation of eyes, nystagmus (to and fro movements of the eyes), abnormal head postures, roving eye movements are often associated with amblyopia.

These conditions require an urgent consult. In the absence of any of the above problems, we still recommend that every child should have a routine eye check-up at around 3 years of age. Vision screening should be made mandatory at the time of school admission. It should be followed by annual routine check-ups.

What are the common causes of Red Eye in children?

Red eye,” or conjunctivitis, is a non-specific finding that simply indicates conjunctival inflammation. The vast majority of children who present with “pink eye” will have a simple conjunctivitis. Other causes of a “red, teary eye” in a newborn include congenital glaucoma and nasolacrimal duct obstruction. The most common causes for pediatric pink eye are allergic conjunctivitis, bacterial conjunctivitis, viral conjunctivitis, and blepharitis (inflammation of lid margins).

What is a chalazion?

Obstruction of the meibomian gland openings in the eyelids may result in an acute infection, but more commonly produces a chalazion. A chalazion appears as a lump near the eyelid margin, either on the upper or lower lid. Chalazia may resolve spontaneously over several weeks; however, applying hot fomentation over the closed lid helps the drainage of lipid material. Topical and systemic medication may be required to decrease the inflammation around the lump. If it does not resolve, incision and drainage may be necessary.

What is normal binocular vision?

Normally, both eyes are aligned on the same visual target and the images from each eye are merged in the brain to form a single three-dimensional image, or binocular vision. The brain’s process of merging or “fusing” images from each eye into one image is called binocular fusion. The perception of three-dimensional depth is called stereoscopic vision. Binocular vision develops during early infancy, and proper alignment during this time is necessary for normal binocular development to occur.

What is Pseudo-strabismus?

Pseudo-strabismus is a common condition that needs to be distinguished from deviation of eyes (true strabismus). With pseudo-esotropia, the infant usually has a wide nasal bridge and wide, prominent lid folds, giving the appearance of eyes crossing. But, in fact, the eyes are straight. When the child looks to either side, the eye hides behind the eyelid folds or wide bridge and looks like they are crossing. It is important to document proper eye alignment in these cases by an orthoptic examination.

Comprehensive ocular examination and follow-up is important in patients diagnosed with pseudo-strabismus, as a small percentage of these patients will develop a true esotropia

What is Amblyopia (Lazy Eyes) and what are its important causes?

Amblyopia or ‘Lazy Eyes’ is simply defined as binocular or uniocular decrease in best corrected vision (even after spectacle correction), for which no apparent organic cause is found on eye examination. It is commonly caused from conditions that produce blurred image on the retina (e.g. media opacities like congenital cataract, which obstruct the light from entering the eye; high refractive errors) or abnormal binocular coordination of the two eyes (deviation of eyes) or combination of both (unequal refractive errors between the two eyes, astigmatic refractive errors).Amblyopia occurs during the critical or sensitive period of development and maturation of the visual system, which is estimated to be 0-8 years in children. It has to be remembered that the patient has to undergo a complete ocular examination to rule out any organic cause of loss of vision before the diagnosis of lazy eyes is established

How Amblyopia is commonly diagnosed?

Subnormal best corrected vision (even after spectacle correction) points towards the possibility of amblyopia. Vision can be tested in children by many innovative picture/letter acuity/symbol charts. It can be done in a child as young as 2-3-year-old. In a very young child, the ability of an eye to take up and maintain fixation is an indirect sign of the presence or absence of amblyopia. In children with eye deviation, strong fixation preference of one eye indicates amblyopia.

What are the Management options for Amblyopia?

Amblyopia is treatable in appropriate cases. Early treatment of amblyopia is critical for best results. The first step is to clear the retinal image by giving appropriate glasses or by removal of media opacities like cataract or corneal opacities. The second step is to correct ocular dominance, if present, by forcing fixation to the weaker eye and thereby stimulating it. This is achieved either by covering (patching) the good eye or by blurring the image in the good eye (by some drugs or by altering the spectacle number). Once amblyopia is diagnosed, it has to be managed by strict vigilance and monitoring of therapy.

How is cataract managed in children and what is its visual prognosis?

Paediatric cataracts can occur in one eye (unilateral) or both eyes (bilateral). They can be complete or partial and can be present at birth or occur sometime after birth. Cataracts can be partial at birth and later progress to become visually significant. In contrast to adults, cataracts in children present a special challenge, since early visual rehabilitation is critical to prevent irreversible amblyopia (lazy eyes). The earlier the onset, and the longer the duration of the cataract, the worse the prognosis. With new techniques and material in the treatment of congenital cataracts and improved surgical and clinical management, visual prognosis has improved. Now ophthalmologists operate as early as the first week of life and visually rehabilitate the child with either glasses or contact lenses.

Children born with cataracts are also at risk for developing glaucoma, strabismus, nystagmus, and poor stereopsis, further complicating successful outcomes. In most cases, it is the willpower and resolve of the parents or caregivers to follow post-operative management that determines visual success for the child. Patients with acquired progressive cataracts have less amblyopia and a much better visual prognosis than patients with cataracts that cover the visual axis since birth.

Unilateral infantile cataracts are rarely caused by a systemic disease, except in some cases of intrauterine infections such as rubella. Generally, monocular congenital cataracts have a relatively good prognosis if surgery and optical correction is provided by two months of age. Beyond this age, there is a possibility of having dense amblyopia in the operated eye.

Bilateral cataracts are often inherited. The work-up for bilateral congenital or infantile cataracts should include a careful paediatric examination and special tests. Dense bilateral congenital cataracts require urgent surgery and visual rehabilitation. In general, bilateral cataracts operated prior to two months of age have a good visual prognosis with approximately 80% achieving vision of 20/50 or better.

Cataract surgery in children is done under general anaesthesia. It involves removal of the cataractous (opaque) crystalline lens. This is often accompanied by surgical measures (primary posterior capsulorrhexis /anterior vitrectomy) to ensure the clarity of the central visual axis in the postoperative period, which can otherwise get obscured by the ‘after cataract’ (collection of inflammatory cells and fibrous tissue) formation. We currently consider IOL implantation in patients who are one year or older, and IOL implantation is the procedure of choice in children 2 years and older. The use of aphakic glasses or contact lenses continues to be the treatment of choice for congenital cataracts in neonates, while an IOL is preferred for children over one year of age. Postoperatively, the child will still require glasses after the IOL implantation. The child may require occlusion therapy for the management of amblyopia.

What is the common cause of watering of eyes in infancy and how is it managed?

Infants with a nasolacrimal duct obstruction present with a watery eye and an increased tear lake, mattering of the eyelashes, and mucus in the nasal corner of the eyelids. This is due to improper canalization of the nasolacrimal duct pathway (which drains tears from the eyes to the nose). Congenital nasolacrimal duct obstruction is common and occurs in 1 to 5% of the population, with approximately 1/3 occurring in both eyes. Medical management during the observational period (initial six months of age) is a combination of nasolacrimal sac massage and intermittent topical antibiotics. In case the lacrimal massage fails to open the obstruction, syringing and probing is done. Under sedation or general anaesthesia, a small steel wire is passed through the punctum into the nasolacrimal system, and down out into the nasal cavity. This does not hurt, nor does it create any problem in the nose. The success rate for a single nasolacrimal duct probing is approximately 90%. It might need repeat sittings to relieve the nasolacrimal obstruction. In cases where nasolacrimal duct probing fails, intubation with silicone tubes is indicated to establish a working system. In case the above procedures don’t provide relief, the child may require a dacryocystorhinostomy (DCR) procedure at around 3.5 to 4 years of age. This involves making an alternate bypass between the tear drainage system and the nasal cavity