Keratoconus in children management.
Optometrists [COMMUNICATION] [OCULAR DISEASE]
Dispensing opticians [COMMUNICATION] [OCULAR ABNORMALITIES]
1 CET POINT
Optometrists are perfectly placed to detect keratoconus (KC) in children during routine examination through retinoscopy, ophthalmoscopy and careful observation of refractive changes. It is important for practitioners to understand the appropriate management of these cases following referral to secondary care.
Management of keratoconus in children
It is well known that in a keratoconic patient there is rapid change in refraction, and for optimal visual development full refractive correction should be prescribed. To address KC, the child should be referred to a specialist centre where correct diagnosis can be made and other differentials ruled out. Once a diagnosis of KC is confirmed, there is now established and effective treatment, corneal crosslinking (CXL), which is approved by NICE in adults and addresses weakening of the cornea by increasing and strengthening collagen bonds in the stroma. (1) There is growing evidence that CXL is beneficial to young children with KC as it can be aggressive if present at an early age. (2)
Early detection is essential in children when factors such as amblyopia, schooling, reaching developmental milestones, and behavioural issues are at stake. A child must have the best possible opportunity to thrive during what is a crucial part of life. Having the best possible visual acuity and minimising time away from school would be the best outcome in KC. Delaying or even obviating the need for keratoplasty would be an ideal goal at this stage in the child's life.
Concerns regarding corneal crosslinking treatment in children
In adult studies, there have been reports of complications following CXL such as corneal haze, sterile infiltrates and infectious keratitis. (3-6) In the majority of studies looking at CXL in children, there are very few safety concerns and documented complications following CXL are scarce. (7) The key point to consider is that appropriate patients are selected for CXL as UVA can be cytotoxic and could result in endothelial damage and corneal melt if used on thin corneas. NICE guidelines indicate minimum corneal thickness of 450[micro]m for CXL. There should be adequate provision for postoperative care to prevent or detect infection and inflammation. With a lack of in vivo studies looking at the effect of UVA and riboflavin on limbal stem cells it is advisable to use some protecting shield around the limbus for children, especially those known to have ocular surface disease, limbal stem cell deficiency or peripheral corneal ectasia. CXL may also reactivate herpes simplex virus (HSV) in the cornea, and any signs of HSV scarring should be investigated before subjecting a child to CXL as reactivation could lead to corneal scarring and/or melting. Prophylactic antiviral treatment might be advisable in these cases.
Defining progression in children
The standard definition of KC progression is over a minimum period of six months there is at least 1.00-1.50D increase in the steepest keratometry (Kmax) measurement (depending on the study), 1.00D increase in manifest cylinder/astigmatism, 0.50D increase in spherical equivalent manifest refraction, loss of two lines of BCVA, and/or a subjective reduced overall VA. (8) In the authors' experience, to detect progression in paediatric cases one needs to consider changes in cycloplegic refraction, visual performance and function before topographical assessment. Getting accurate topography in children may be challenging due to poor fixation and positioning on the machine. While changes in topographic parameters in children is still being investigated, changes in Kmax and thinning | of the cornea, especially in the affected area, are helpful and can indicate progression, although one cannot rely entirely on these data. So in a child it is collective evidence that can indicate progression. While performing retinoscopy the practitioner should always look out for scissoring of the reflex. New appearance of scissoring in a child who is normally followed up for astigmatic myopia could mean that the cornea has started to take an irregular shape and become unstable. The importance of doing retinoscopy in a child rather than relying on autorefraction cannot be over emphasised as looking at the quality of the reflex is very informative. It is also important to look out for overall deterioration in vision or visual function, which may be corroborated by the parents and changes in refraction.
The management algorithm for KC in children is remarkably similar to that for adults. The main difference is the importance of early visual rehabilitation. Use of early spectacle correction, timely diagnosis and recognition of progression along with prompt treatment when needed is a must. The option of leaving a child without any treatment should always be made with very careful consideration, as poor and worsening vision will affect the child during vital developmental years. CXL, if successful, could prevent development of amblyopia, allow for better tolerance of contact lenses to allow for optimal vision during what is a crucial time to allow for effective schooling, and may push back the need for corneal surgery. It is prudent to have monitoring programmes in place for suspect cases with vigilant three-monthly visits to a specialist for repeated refraction, corneal topography and retinoscopy.
Even in confirmed cases of KC, monitoring is important so that appropriate management or treatment plans are in place. CXL treatment can be repeated in adults who show progression after the first treatment. A study by Chatzis and Hafezi shows that although CXL seems to be safe in children and adolescents, progression of keratoconus occurred in 88% within three years. (8)
The following three cases highlight the patient pathway of paediatric KC from identification, referral, diagnosis and management.
Case study 1
A child was referred by her GP as she had a strong family history of KC (maternal aunt and grandfather). The patient was subsequently reviewed in the clinic when she was almost six years in age. She had no ocular history and the parents did not have any concerns about her vision. Her medical history of note was epilepsy for which she was taking Lamotrigine 25mg, one tablet twice daily. Clinical findings were as follows:
* Unaided vision (Kay pictures): R3/3L3/3
* Orthoptic assessment: normal
* Anterior segment: both eyes white and quiet
* Fundi: both unremarkable
* Direct ophthalmoscopy: suspicious with small 'oildrop' seen
* Retinoscopy: mild irregularity in reflex noted
* Corrected cycloplegic refraction: R -0.25/-0.50 x 180 L -0.25/-0.50 x 180
* Topography: suspicious of KC (see Figure 1)
* Management: monitor (consultant noted that she was probably one of the youngest patients suspected of KC that they have seen).
* Topography was stable
* Unaided vision (Snellen): R 6 /12 improving to 6/9.5 with pinhole, L 6/15 improving to 6/7.5 with pinhole
* Corrected cycloplegic refraction: R -0.25/ -0.50 x 180 L -0.25/-0.50 x 180
* Again, mild scissoring was noted on retinoscopy and 'oil-drop' effect on direct ophthalmoscopy.
Almost two years after the original referral, the findings were as follows:
* R 6/19 -1.00/-1.00 x 180 VA6/6 LE 6/19 -1.25/-1.00 x 180 VA6/6
* Topography was stable
* Management: spectacles were prescribed and advice on monitoring. CXL was discussed with parents if there is sign of progression in future as it is difficult to predict when the condition will progress and become aggressive. Three monthly reviews for corneal topography were recommended to allow detection of early signs of disease progression. One could argue in this case that there is progression on the basis of 'oil-drop' or scissoring on retinoscopy and worsening of unaided vision and increase in myopia. However, as the child was compliant with corneal topography and although abnormal it was reliable and remained stable. Hence it was decided to monitor in this case.
Case study 2
A child was found to have reduced vision at their five -year school vision screening and was subsequently seen privately by a consultant ophthalmologist with the following outcome:
* Ocular history: intermittent convergent squint at one year old, which decreased with time
* General history: eczema as a baby but otherwise fit and healthy. No asthma or hay fever
* Family history: both parents wore contact lenses but no pathology
* Orthoptic assessment: full range of ocular motility. No deviation
* Anterior segment: anterior blepharitis. Prominent corneal nerves but no other signs
* Fundi: both eyes showed healthy discs and maculae
* Retinoscopy: marked scissoring in the left eye indicating irregularity in cornea
* Unaided vision: R 6/12 with no improvement with pinhole L 3/60 improving to 6/24 with pinhole
* Corrected cycloplegic refraction: R -1.00/-0.50 x 100 L -1.25/-6.50 x 163
* Topography: signs of early KC with posterior surface elevation in the left eye
* Management: spectacles were prescribed and occlusion treatment was discussed if after next visit vision reduced. Also CXL treatment was discussed and referral to NHS was made via the GP. Next review was a month later under NHS. Repeated topography, retinoscopy and ophthalmoscopy confirmed diagnosis of KC (see Figure 2). CXL treatment with risks, benefits and alternatives of the treatment were discussed. Parents were informed about the current knowledge on KC and CXL in children and an option to observe or to treat was offered. Parents were keen to proceed with treatment. The child had CXL with epithelium-off under general anaesthesia the following month. At six day review there was no epithelial defect. Anterior stromal haze was noted which is a common feature after CXL and can last up to three to four months. Next review one month later showed marked reduction in corneal haze. A three-month review was scheduled for topography, retinoscopy, refraction and ophthalmoscopy to be repeated.
Case study 3
A six-year-old patient was referred from another hospital eye service for suspected KC. The referral letter referenced that the child had worn spectacles since age three years and demonstrated frequent changes in prescription. Clinical evaluation was as follows:
* Orthoptic assessment showed poor corrected vision: R +2.25/-3.00 x 44 VA6/12 L +2.75/-1.75 x 135 VA6/[9.sup.-2]
* Optometrist had noted split retinoscopy reflex and topography showed asymmetry with inferonasal steepening in both corneas
* Anterior segments: both were white and quiet
* Fundi: both unremarkable
* Topography: confirmed KC in both eyes (see Figure 3)
* Retinoscopy showed scissoring
* Ophthalmoscopy showed 'oil-drop' effect
* Management: similar discussion as in previous case and the parents chose to proceed with CXL. Bilateral CXL was carried out under general anaesthesia three months later
* The patient was reviewed at five days, one month, three months and six months following CXL treatment
* At six-month review, topography was stable. No corneal haze was noted and eyes were white and quiet. Unaided and corrected visual acuities were:
* R 6/24 improving to 6/9.5 with spectacles
* L 6 /15 improving to 6/9.5 with spectacles
Although the purpose of CXL is to strengthen the cornea and stop the progression of KC, some cases will show flattening of the steepest keratometry reading and improvement in corrected vision, (9) which this case showed.
For patients under the age of 12 years the cornea has different physiological properties and biomechanics compared to that of an adult and should be addressed accordingly. (10,11) There is growing evidence that KC can present as early as four-years-old. (12-14) If KC is diagnosed in the very young it is likely to be aggressive and progress rapidly and can be easily missed in the early stages. Pre-disposing factors include: family history, race, atopic diseases, eye rubbing and certain systemic associations, such as Down syndrome. (15) KC can be detected with simple tools such as an ophthalmoscope or retinoscope which give 'oil-drop' fundal reflex and 'scissoring'. A rapid change in refraction, particularly an increase in myopia and astigmatism, should also be treated with suspicion. The primary care optometrist is in ideal position to discover cases of suspect keratoconus and refer the child to a specialist paediatric cornea unit for diagnosis and management. A delay could result in amblyopia, schooling issues, failure to reach developmental and social milestones and behavioural issues in the child, alongside the socioeconomic consequences from delayed diagnosis and treatment.
Exam questions and references
Under the enhanced CET rules of the GOC, MCQs for this exam appear online at www.optometry.co.uk. Please complete online by midnight on 18 August 2017. You will be unable to submit exams after this date. Please note that when taking an exam, the MCQs may require practitioners to apply additional knowledge that has not been covered in the related CET article.
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Visit www.optometry.co.uk, and click on the 'Related CET article' title to view the article and accompanying 'references' in full.
Shruti Malde MCOptom, Dip Tp (AS), Dip Tp (SP) and Samer Hamada MD, MSc, DO (Hons), FRCSEd, FRCOphth
Shruti Malde is a specialist optometrist at Queen Victoria Hospital, East Grinstead and is responsible for reviewing cataract and glaucoma cases along with assisting in corneal clinics undertaking collagen cross-linking follow-up checks. She has a diploma in Therapeutics Additional Supply and Supplementary Prescribing.
Samer Hamada is consultant ophthalmic surgeon and cornea specialist at Queen Victoria Hospital, East Grinstead. His special interest includes management of complex corneal disease in both adults and children, modern corneal transplantation and anterior segment reconstructive surgery.
Course code: C-56002 Deadline: 18 August 2017
* Be able to explain the management of keratoconus to patients (Group 1.2.4)
* Understand the management of keratoconus (Group 6.1.3)
* Be able to explain the management of keratoconus to patients (Group 1.2.4)
* Understand the management of keratoconus (Group 8.1.3)
Caption: Figure 1 Corneal topography with suspicion of KC at six years in age
Caption: Figure 2 Confirmation of KC with corneal topography
Caption: Figure 3 Bilateral KC confirmed with corneal topography--plot of right eye
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|Author:||Malde, Shruti; Hamada, Samer|
|Date:||Jul 1, 2017|
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