The authors describe four children with progressive keratoconus treated by corneal crosslinking (CXL). The current CXL guidelines recommend treatment of patients 18 years and older. Nevertheless, keratoconus can rapidly progress in young teenagers. CXL could be a safe procedure to prevent a keratoplasty at a young age.
From the Utrecht Cornea Research Group, Department of Ophthalmology, University Medical Center Utrecht, Utrecht, The Netherlands.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Nineke Soeters, BOptom, Department of Ophthalmology, HP E03.136, University Medical Center Utrecht, Heidelberglaan 100, 3508 GX Utrecht, The Netherlands. E-mail: N.Soeters@umcutrecht.nl
Received: February 21, 2011
Accepted: April 26, 2011
Posted Online: June 21, 2011
Keratoconus is generally diagnosed in teenagers, can be progressive in nature, and its severity is inversely correlated with age.1 Clinically, it presents with subjective visual loss, irregular corneal shape, and astigmatism. The exact cause of keratoconus is unknown, although multifactorial causes and associations have been described.2
Corneal crosslinking (CXL) is a minimally invasive medical treatment that can halt progressive keratoconus by increasing corneal biomechanics.3 CXL has the potential to reduce the need for a keratoplasty procedure in (young) individuals with keratoconus. This rather new medical treatment involves the application of ultraviolet-A light to corneas pretreated with riboflavin (vitamin B) eye drops, which subsequently leads to a molecular crosslinking and strengthening of collagen tissue in the corneal stroma.
The standard inclusion criteria for CXL currently are a minimum patient age of 18 years, a significant increase in maximal keratometry (Kmax) values over 6 to 12 months’ time, and a minimum corneal thickness of 400 μm.4 To our knowledge, specific pediatric CXL criteria have not been described. Progression at the pediatric age, including corneal thinning and weakening, can be rapid and requires closer observation and probably earlier intervention with CXL.
We report four pediatric cases of rapidly progressive keratoconus in which a one-time treatment of CXL was applied between January and June 2010.
An 11-year-old girl was diagnosed as having a severe keratoconus. Her medical history was otherwise normal. Corrected distance visual acuity (CDVA) was 20/60 in the right eye with −6.50 −4.50 × 5 and 20/30 in the left eye with −4.00 −1.50 × 75. Thinnest pachymetry (Pentacam; Oculus Instruments, Wetzlar, Germany) was 404 μm in the right eye and 482 μm in the left eye. Central keratometry (K) values were 67.8 × 58.5 diopters (D) in the right eye and 55.2 × 51.5 D in the left eye. Kmax was 73.1 D in the right eye. Slit-lamp examination showed Vogt striae in both eyes and a superficial haze in the right eye. Considering her young age and the only alternative of a keratoplasty, we referred her for CXL in the right eye (our clinic had not started CXL procedures at that time). She was also fitted with scleral lenses, leading to CDVA of 20/30 in both eyes.
One month after CXL (VEGA CBM X-linker; SOOFT Italia SpA, Pisa, Italy), uncorrected distance visual acuity (UDVA) was 20/4000 in the right eye. Central K values were 68.4 × 56.7 D and Kmax was 76.1 D. Slit-lamp examination showed a stromal scar (Fig. 1). Three months after CXL, UDVA was 20/4000 in the right eye and Kmax was 74.2 D. The stromal scar was unchanged. Nine months after CXL, UDVA remained 20/4000 and Kmax was 66.8 D with a thinnest pachymetry of 374 μm in the right eye. We planned a keratoplasty procedure in the right eye because the scar caused visual disturbance and a CXL in the left eye because the left eye developed a progression of 1 D in Kmax.
Figure 1. Stromal scar after corneal crosslinking (case 1).
A 16-year-old boy was referred for a keratoconus in the left eye. His medical history was otherwise normal.
UDVA was 20/15 in the right eye and CDVA 20/40 in the left eye with +4.00 −4.00 × 107. Slit-lamp examination showed a minimal Fleischer ring in the left eye. Pentacam imaging showed a normal corneal pattern in the right eye and an irregular central bowtie pattern in the left eye with Kmax of 61.4 D. Thinnest pachymetry was 593 μm in the right eye and 499 μm in the left eye.
Compared to previous Pentacam evaluations, the right eye was stable and the left eye showed a keratometric progression of 4.3 D over 1.5 years. We performed standard CXL (UV-X; Peschke Meditrade, Huenenberg, Switzerland) in the left eye.
One month after CXL in the left eye, CDVA was 20/40 with +4.50 −5.75 × 105 and Kmax was 62.6 D. Three months after CXL, CDVA was 20/70 with −3.0 −1.0 × 110 and Kmax was 62.7 D. He was referred for a contact lens fitting. Six months after CXL, CDVA was 20/70 with −1 −3.50 × 100, Kmax was 62.7 D, and the thinnest pachymetry was 490 μm. One year after CXL, CDVA was 20/40 with +0.75 −4.00 × 100. Compared to before CXL, Kmax remained stable at 61.7 D. Thinnest pachymetry was 502 μm in the right eye. The patient remained stable and will be evaluated closely.
A 12-year-old boy was referred for a keratoconus in both eyes. His medical history consisted of attention-deficit hyperactivity disorder, allergies, and extensive eye rubbing.
CDVA was 20/25 in both eyes with 0.0 −0.75 × 180 in the right eye and −0.25 −1.25 × 5 in the left eye. Slit-lamp examination showed Fleischer rings in both eyes. Pentacam imaging showed an irregular central bowtie pattern in both eyes, with Kmax 62.2 D in the right eye and 60.9 D in the left eye. Thinnest pachymetry was 488 μm in the right eye and 493 μm in the left eye. Topography examinations showed a significant keratometric progression of 2 D in the right eye and 5 D in the left eye over 1 year. Standard CXL was performed in both eyes.
One month after CXL in the left eye, CDVA was 20/30 and Kmax was 59.3 D. Three months after CXL, CDVA was 20/25 and Kmax was 55.9 D. Six months after CXL, CDVA was 20/25. Compared to before CXL, Kmax had decreased by 3.1 D (Fig. 2). Thinnest pachymetry was 491 μm.
Figure 2. Pentacam (Oculus Instruments, Wetzlar, Germany) images demonstrating keratometric values before corneal crosslinking (A and C) and 6 months after corneal crosslinking (B and D) in both eyes (case 3).
One month after CXL in the right eye, CDVA was 20/30 and Kmax was 61.0 D. Three months after CXL, CDVA was 20/25 and Kmax was 58.0 D. Six months after CXL, CDVA was 20/25. Compared to before CXL, Kmax had decreased by 4.6 D (Fig. 2). Thinnest pachymetry was 485 μm.
A 10-year-old boy was referred for a keratoconus in both eyes. His medical history consisted of asthma and eczema. We initially referred him for a scleral lens fitting. One year later, CDVA was 20/25 in the right eye and 20/3000 in the left eye due to a hydrops in the left eye. Seven weeks later, CDVA in the right eye was 20/30 with −9.50 −2.25 × 170. Kmax in the right eye had increased from 54.9 to 57.6 D and the thinnest pachymetry was 419 μm. We planned standard CXL in the right eye and a penetrating keratoplasty procedure in the left eye.
One month after CXL in the right eye, CDVA was 20/30 with −9.50 −1.50 × 168 and Kmax was 54.5 D. Three months after CXL, CDVA was 20/30 with −8.25 −1.50 × 180 and Kmax was 55.0 D. Six months after CXL, CDVA was 20/30 with −7.00 −1.50 × 170. Compared to before CXL, Kmax had decreased by 1.1 D (Fig. 3). Thinnest pachymetry was 394 μm.
Figure 3. Pentacam (Oculus Instruments, Wetzlar, Germany) images demonstrating keratometric values before (A) and 6 months after (B) corneal crosslinking (case 4). OD = right eye.
Among the treatment criteria for standard CXL in keratoconus is a keratometric increase of 1 D or greater over 1 year.5 Exclusion criteria such as significant central corneal haze and stable keratoconus apply to both adults and children. However, because pediatric keratoconus cases can progress rapidly, this age group probably requires more specific treatment criteria than young adults. To our knowledge, these specific criteria have not yet been described for children.
In this case report, the children demonstrated a rapid progression ranging from 2.6 D in 7 weeks to 5.0 D over 1 year. Considering the fast progressive nature of their disease, a keratoplasty procedure at a young age was imminent, so CXL at this point was proposed as an alternative. Regression was found in 3 of 5 eyes, ranging from 1.1 to 4.6 D after 6 months, whereas 1 eye remained stable (Figs. 4 and 5; Table). One eye was treated despite a superficial haze, which resulted in a stromal scar after CXL.
Figure 4. Maximal keratometry before and after corneal crosslinking. OS = left eye; OD = right eye; D = diopters.
Figure 5. Thinnest pachymetry before and after corneal crosslinking. OS = left eye. OD = right eye.
Table: Visual Acuity, Pachymetry, and Maximal Keratometry In 4 Children Before and After Corneal Crosslinking
This case report aims to demonstrate the importance of close evaluation of pediatric keratoconus. CXL in young children should be considered when there is any sign of clinical progression, because CXL can potentially prevent the need for a keratoplasty at a young age. The timing, durability, and re-treatment options of CXL in progressive keratoconus cases in children need further evaluation.
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Visual Acuity, Pachymetry, and Maximal Keratometry In 4 Children Before and After Corneal Crosslinking
|Pt||Eye||Age (Y)||Sex||Thinnest Pachymetry (μm)||Kmax Value (D)||CDVA (Snellen)||Resulted in PKP|
|Preop||6 Mo||12 Mo||Preop||1 Mo||3 Mo||6 Mo||12 Mo||Preop||1 Mo||6 Mo||12 Mo|