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BLOG: Small eyes have big problems with pediatric keratoconus
by Christina Twardowski , OD, FAAO
Pediatric keratoconus exhibits several unique characteristics that can make an otherwise difficult situation even more complex.
Children who develop keratoconus tend to start the corneal ectasia process at an early age, with faster progression compared to adult patients. The frequent eye rubbing in children is exacerbated by inflammatory conditions such as vernal keratoconjunctivitis, leading to a higher rate of rubbing and progression. In addition, when children are confirmed as having keratoconus they tend to be in a more advanced stage of the disease, which may, in part, be due to the difficulty of initially diagnosing this patient population.
Source: Christina Twardowski, OD, FAAO
Difficulties in confirming the presence of childhood keratoconus are often due to the inability of obtaining subjective data. Cooperation in this age group can be challenging at times, but looking at the overall clinical picture is crucial. Although verbal vision can be helpful, it is only one piece of the puzzle.
Working in a children’s hospital, I have many patients who come to the clinic for second opinions. Whenever keratoconus is suspected the first tool I reach for is my retinoscope. Retinoscopy is easy to do, can be performed at a comfortable distance to alleviate potential patient anxiety and is quite reliable in its diagnostic capabilities.
A recent study in Cornea compared the results of retinoscopy and Pentacam (Oculus) examinations on patients referred for questionable keratoconus diagnosis (Al-Mahrouqi et al.). The authors concluded that the retinoscopy results showed great specificity and sensitivity in confirming the diagnosis of keratoconus when compared to positive keratoconus identification with Pentacam imaging.
A simple case example to show the importance of interpreting a patient’s global clinical findings is a 10-year-old boy who came to my clinic for a second opinion due to a failed vision screening. The three tests I attempt on all suspected keratoconus patients are retinoscopy, slit lamp examination and topography. For this patient the retinoscopy reflex was abnormal, and the slit lamp exam confirmed the presence of a Fleischer ring in both corneas.
With these two tests the patient was diagnosed as having keratoconus, so you can imagine my surprise when I took a first glance at the patient’s topography scans. Initially, the scans appeared to show normal, with-the-rule astigmatism, but upon further interpretation, the keratometry values were quite consistent with keratoconus. The unique topography scans were a result of the corneal ectasia being located centrally on the cornea vs. the typical inferior temporal location. These scans provided an unusual presentation of keratoconus, but they were only one piece of the exam.
There are times when more evidence may be needed to support a keratoconus diagnosis, and in those cases I would recommend a follow-up in 3 to 6 months to monitor for progression. Trusting your objective findings is crucial in pediatric patients and is often all you need to confirm a suspected diagnosis. It may not be possible to perform every test you would like in your pediatric patients, but looking at all the clinical results will help guide you.
The ultimate goal in this patient population is referral for cross-linking as soon as possible to maintain their current vision and allow for minimal visual rehabilitation.
References:
Al-Mahrouqi H, et al. Cornea. 2019;doi:10.1097/ICO.0000000000001843.
Kankariya VP, et al. Indian J Ophthalmol. 2013;doi:10.4103/0301-4738.116070.
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Christina Twardowski, OD, FAAO, practices in the ophthalmology department at Children’s Mercy Hospital and is the director of optometry services. She is also co-director of the pediatric optometric residency program and the director of the Illinois College of Optometry student externship program. Twardowski is on medical staff at the University of Missouri-Kansas City as an assistant professor.
Disclosure: Twardowski reports no relevant financial disclosures.