Domains and learning outcomes (C109306)
• One distance learning CPD point for optometrists and dispensing opticians.
Clinical practice
Upon completion of this CPD, ECPs will be able
to describe various signs and symptoms of conditions that are linked to syndromic myopia (s5)
Upon completion of this CPD, ECPs will be able to better identify individuals who may/may not be suitable for myopia management (s7).

What should we do with cases of high myopia that are continuing to progress? Should we attempt myopia control to slow or halt the progression, or should we refer for investigation into the cause of the high myopia?  

According to the International Myopia Institute paper on high myopia, children up to the age of 10, with myopia equal to or greater than six dioptres should be investigated, or if a child has more myopia in dioptres than years of age then this would also warrant investigation.1  

But what of the high myopes who are over the age of 10 and progressing? Do all children with high myopia have a syndrome? Should myopia control be attempted on a child with a syndrome? 

A retrospective review of children with high myopia under the age of 10 presenting to Birmingham hospitals between 1995 and 1998 was published in 2001.2 High myopia was defined as greater than or equal to six dioptres of spherical equivalent myopia. One hundred and twelve children were identified as meeting the criteria and the researchers found that only nine children (8%) had simple high myopia with no associated ocular or systemic diseases. Fifty four percent of the children had an associated systemic disease and 38% had an associated ocular disease.  

The researchers recommended that children with high myopia should be referred for investigation of possible associated diseases or syndromes, if this has not previously been carried out. The figure of 8% of children with simple high myopia is often quoted, as this 26-year-old research remains the most current study in this area.  

New syndromes or variants of existing syndromes are continuously being discovered, through advances in genetic testing and it is possible that if this study was to be repeated in a centre with advanced genetic testing capabilities, the figure might be found to be lower. 

High myopia may indicate an underlying syndrome and early diagnosis and management of the side effects of some syndromes may help to improve vision and extend life, eg Marfan syndrome and homocystinuria. Other syndromes may not have any available treatment, but early diagnosis allows educational plans to be put in place, keeps medical staff informed and can allow for genetic counselling during reproductive years.  

Case study 

A six-year-old girl presented with an ophthalmologist’s prescription, which she needed dispensed. The prescription was as follows: 

R:-22.00/-3.00x20,  

L:-18.00/-0.75x160  

Binocular BSCVA 6/60 


The child already had spectacles, was using low vision aids and was registered with a low vision charity. She had previously been diagnosed with Knobloch syndrome. This is a very rare autosomal recessive disorder characterised by high myopia, cataract and retinal detachment. This patient’s older sibling had a similarly high myopic prescription. Patients with this syndrome may also have an occipital encephalocele, which is a sac-like protrusion of the brain through a defect in the bone at the base of the skull.  

Fortunately, neither this patient nor her sibling had an encephalocele, but their mother had previously miscarried a baby with this defect. Her parents had undergone genetic testing and were found to both be carriers of the defective gene responsible for the syndrome. 

High myopia is often associated with connective tissue disorders and while these disorders usually have systemic abnormalities, the disorder may be very mild in a child or indeed in the child’s whole family. This can mean that the systemic abnormalities may also be mild or absent, which can result in a child being overlooked for investigation. It is for this reason that sometimes myopia may be the presenting feature of a disorder and it falls to eye care professionals to refer these children for investigation. There have been cases where investigation of a child has led to diagnosis not only in the child, but subsequently in several other family members. 

There are over 200 hereditary connective tissue disorders. Connective tissue is the most common primary tissue in the body and disorders of connective tissue primarily affect the eye, skin, musculoskeletal and cardiovascular systems.  

In some disorders, the connective tissue of the sclera may be defective which means the sclera is unable to prevent axial elongation resulting in a myopic refractive error. Defective genes may show different expression during embryological development, postnatal growth and maintenance of tissue. 

 For this reason, some babies may be born with a considerable myopic refractive error that may increase during childhood, but which may stabilise at a young age and ultimately be non-progressive.  


Case study 

A 19-year-old girl came in for an eye exam as she felt her vision through her spectacles had deteriorated. There was only a small change in her prescription which was now:  

R:-13.50/-1.00x10,  

L:-13.00/-1.25x150.  


It was felt her perception of poor vision may be due to severe dry eye. On questioning she stated she had worn spectacles since a very young age and had originally been under the care of an ophthalmologist but had never been investigated for the cause of her myopia. Her mother had high myopia and her siblings had moderate myopia. She was a little taller than average for her age and gender and her arms were a little longer than average. She had problems with her joints and she reported that this was a problem for most of her family and that her family were all tall. It was suspected that she may have a connective tissue disorder and she was referred for testing, the results of which she is currently waiting for. 


Marfan syndrome 

Marfan syndrome is a connective tissue disorder, which is inherited in an autosomal dominant pattern. This means that a parent with the syndrome has a 50% chance of passing it on to their child. Marfan syndrome can also arise as a result of spontaneous genetic variant, so patients with no family history may inherit it. The signs of Marfan syndrome are: tall stature, long limbs and digits, high myopia, cataracts, lens subluxation, joint hyperflexibility, dental abnormalities, curvature of the spine and aortic abnormalities which can be life-threatening.  

Unfortunately, patients with very mild expressions of the disorder can remain undiagnosed and may die prematurely from heart complications. Eye care professionals are well-placed to refer patients with possible signs of Marfan syndrome for testing. Iridodonesis can preface lens subluxation. This is a wobble or tremor in the iris on eye movements and it may indicate some rupture of lens zonules. 


Stickler syndrome 

Stickler syndromes are a group of connective tissue disorders that can be autosomal dominant, autosomal recessive or as a result of spontaneous genetic variants. The ocular signs of the syndromes can be; high myopia, retinal detachment, cataracts, vitreous abnormalities, strabismus and glaucoma. The systemic signs can be; hearing problems, cleft palate, joint problems including osteoarthritis and scoliosis. Again, the expression of the syndrome may be very mild and so patients can remain undiagnosed.  

However, Stickler syndromes are rarely life-threatening. The myopia associated with the syndromes may be mild to severe and it normally manifests at a young age and is non-progressive, but it can develop later in adolescence or adulthood.3  

In 15% of cases, patients with Stickler syndrome may be emmetropic. This is because their eyes can have anterior megalophthalmos (large anterior chamber) in combination with a relatively flat cornea. These patients should have their axial lengths measured as they may be at risk of retinal problems, in spite of their emmetropia.1 Even with normal axial lengths, patients with these syndromes can develop retinal detachments secondary to vitreous abnormalities.  

Myopia control strategies in patients with connective tissue disorders, such as Marfan’s, Stickler’s etc, are unlikely to be successful as the underlying axial length progression is probably due to deficiencies in connective tissue.4 


Premature delivery 

There are two types of myopia associated with premature birth. In cases where the baby has retinopathy of prematurity the eyes normally develop myopia sometimes with a reduced best corrected visual acuity.  

However, even in premature babies without retinopathy of prematurity, myopia can develop. The cause of the myopia associated with premature birth appears to be primarily related to the eye’s lens. Studies have found that premature babies’ myopia is mostly due to a thicker and more powerful lens, whereas in full-term babies the myopia tends to be axial.5, 6  

This means that myopia control strategies may not be very useful in addressing this lenticular myopia, as most strategies are designed to address the progression of axial myopia. Myopia of prematurity also appears to stabilise by the age of three.7 It is of course possible that a child could start with myopia of prematurity, which stabilises and may then later develop progressive axial myopia. Measurement of axial length is important here to determine if increases in the myopia are definitely due to axial elongation and if they are at this point, it may be sensible to consider myopia control strategies. 


Developmental Delay 

In the Birmingham hospital review of children with high myopia, the most common systemic condition found was severe developmental delay.2 In a 2021 study of children with developmental delay in South India, researchers found that 70% of the children had refractive errors but that only 9% of children were purely myopic.8 In a 2023 study also from India, out of a group of 94 children with developmental delay 83 (88%) were found to have ocular problems including 70 with refractive errors.9  

The authors do not specify the type of refractive error apart from stating that astigmatism was the most common error. There is also a high prevalence of low vision and strabismus in children with developmental delay.8, 9 These children may not be the best candidates for myopia control if they have co-existing ocular morbidities. If they have intellectual issues, it may be difficult to ensure that they are adhering correctly to any myopia control strategy. 


Simple high myopia 

If a child with high myopia has been investigated and found to have simple high myopia, ie myopia without any other systemic or ocular conditions, then myopia control may be considered. However, parents should be made aware that there is limited evidence on the effectiveness of myopia control strategies on high myopia as most myopia control studies recruit subjects with up to a maximum of -5D of myopia.  

Studies on the effect of partial correction with orthokeratology on the progression of high myopia have shown some success, but sample sizes were small and the patients recruited for these studies did not have more than -8.50D of myopia.10-12  

Although myopia control contact lenses are now available in prescriptions up to -15D and myopia control spectacles are available up to at least -10D, caution should be advised when prescribing for high myopia due to the lack of evidence of efficacy for these higher prescriptions. 


Myopia and exotropia 

Many syndromes that are associated with myopia may also be associated with strabismus. Intermittent exotropia has been found to be strongly associated with myopia. A Chinese study into the refractive error of 2,250 patients attending for exotropia surgery found that more than half (51.2%) of patients had myopia, which is a larger percentage than that found in the general population in Southern China.13 A 2010 study from the USA found that 90% of patients with intermittent exotropia were myopic by the age of twenty.14 There does not appear to be a difference in myopia progression between children with and without exotropia.15  

Children whose exotropia was managed by using overminused spectacles were found to have more myopia progression than those who were not overminused.16 Children who have their myopia corrected by contact lenses rather than spectacles may find a worsening of their exodeviation due to the loss of base in prism at near that they would normally get from their spectacles.  

If considering myopia control in a child with an exodeviation then myopia control spectacles or atropine would be preferable to myopia control contact lenses, but there have not been any clinical trials for myopia control on children with any kind of exotropia. 


Summary 

Children with high myopia should be referred for investigation if they have not already been. If the child does have a syndrome that might explain their high myopia, it does not preclude them from also developing ‘normal’ progressive axial myopia (in addition to their syndromic myopia). Axial length measurements should be taken over time, in order to establish if axial elongation is occurring before considering myopia control.  

Parents should be advised that the highest myopic refractive error of subjects recruited for myopia control trials has been -8.50D. The parent can then make an informed decision as to whether they would like to try myopia control for their own child or not, in cases where their child may have myopia greater than -8.50D. Patients with axial lengths greater than 26mm or with syndromes known to be associated with retinal problems should be reviewed regularly in order to facilitate the early diagnosis and possible treatment of any retinal changes.  

  • Claire McDonnell is an optometrist and lecturer at Technological University Dublin. She is also a member of BUCCLE (British and Irish University and College Contact Lens Educators). Her research area is specialist contact lenses. She has presented in the UK, Ireland and Europe on contact lenses and optometric education. 

References 

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