BLOG: Clinical appearance of keratoconus differs in children, adults
Pediatric keratoconus is often placed in the same category as adult keratoconus, but it is important to understand these are two separate populations, as each group presents with unique clinical findings and management strategies.
With this brief review, I want to emphasize some of the key differentials between the adult and pediatric populations, as these dissimilarities are what will assist with diagnosis in children but are also the challenges that can lead to poor visual outcomes if not detected early.
Epidemiology
Pediatric keratoconus is defined by corneal ectasia found in patients younger than 18 years, with most of the literature supporting onset around puberty. Keratoconus is often an isolated disease, but more studies are finding a connection with certain conditions such as vernal keratoconjunctivitis, atopy, Down syndrome and connective tissue disorders (Mukhtar et al.). Although I have seen an array of children with keratoconus in my office, research has shown that the most common characteristics for children include: most likely male, diagnosed with allergies, a history of frequent eye rubbing and a family history of keratoconus (Léoni-Mesplié et al).
Clinical appearance
There is a distinct difference in the morphology of the cornea in pediatric patients, with the ectasia presenting centrally vs. the classic inferior-temporal location for adults. This unique location lends to the late prognosis of many pediatric patients, as the typical irregular astigmatism is masked or often less pronounced.
Further, the progression of this condition in children is frequently asymmetric between the eyes, allowing the pediatric patient to function normally until the dominant or less effected eye becomes involved. As a result, vision screeners or the patient’s family may not pick up on the need for an eye exam until the visual function has drastically deteriorated.
Diagnosis, disease progression
The clinical characteristics described above contribute to the late diagnosis for many of these patients. A study by Léoni-Mesplié and colleagues found that 27.8% of the patients 15 years old or younger had stage 4 keratoconus vs. the 7.8% found in patients 27 years or older. Another study by El-Khoury and colleagues found that 30% of the pediatric patients at initial presentation were diagnosed with stage 4 keratoconus. The severity of diagnosis is not only secondary to unique cone location but is also associated with the rapid progression found in the pediatric population.
A study by Chatzis and Hafezi noted an increase in Kmax of greater than 2 D in 1 year among patients ranging from 9 to 19 years, which equates to 88% of the study population progressing from initial visit. This younger cohort tends to have debilitating progression of their condition that will lead to a higher risk for corneal transplantation and a lifelong road of visual rehabilitation if treatment is not initiated.
Treatment
Once a pediatric patient has been diagnosed as having keratoconus it is imperative that a referral for cross-linking be made, as this is the only treatment for this condition that has been successful in children. There tends to be a common misconception that documented progression of corneal ectasia is required or we need to wait until the patient is an unsuccessful contact lens wearer due to their keratoconus progression. It is important to know that both scenarios are false. Once the diagnosis of keratoconus has been made, cross-linking will truly be the patient’s best option. Remember, time is everything for these pediatric patients, as they progress rapidly, which will lead to poor visual prognosis if treatment is not initiated in a timely manner.
References:
- Chatzis N, Hafezi F. J Refract Surg. 2012;doi:10.3928/1081597X-20121011-01.
- El-Khoury S, et al. J Refract Surg. 2016;doi:10.3928/1081597X-20160513-01.
- Léoni-Mesplié S, et al. Fr J Ophthalmol. 2012;doi:10.1016/j.jfo.2011.12.012.
- Léoni-Mesplié S, et al. Am J Ophthalmol. 2012;doi:10.1016/j.ajo.2012.01.025.
- Mukhtar S, et al.. Int Ophthalmol. 2018;doi:10.1007/s10792-017-0699-8.
- Olivo-Payne A, et al. Clin Ophthalmol. 2019;doi.org/10.2147/OPTH.S183347.
- Soeters N, et al. J Refract Surg. 2014;doi:10.3928/1081597X-20140527-03.
For more information:
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.
Collapse