BLOG: Corneal haze after pediatric cross-linking has no long-term effect
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In adults, corneal haze following cross-linking is uncommon and resolves quickly.
However, in teens and children — especially those with more advanced keratoconus — it is my experience that significant haze occurs more frequently. In fact, among children with thinner corneas, I have seen haze occur in most cases.
It is not clear why these young eyes are particularly disposed to haze. It is possible that pediatric patients generally have more reactive keratocytes. Early presentation of keratoconus also indicates more severe disease, so the phenomenon may be related to disease severity. While epithelial removal is likely a contributing factor, haze also has been reported in epi-on or transepithelial cross-linking (Lai et al; Badawi).
In our tertiary care setting at Children’s Mercy Hospital in Kansas City, Missouri, we evaluate and treat pediatric keratoconus patients every day. But for comanaging optometrists who see fewer cross-linking cases overall, a case of corneal haze after cross-linking may be alarming or confusing, so it is important to know that it can happen. The good news is that the haze will eventually resolve, and we can help patients see well in specialty lenses prior to its resolution.
Identifying, managing corneal haze
Corneal haze that appears after cross-linking is sterile and noninfectious. It typically occurs during the immediate postoperative period, within days or weeks of the procedure, and resolves within 1 year. Researchers reported that haze plateaued between 1 and 3 months, and that corneal clarity returned to baseline between 3 and 12 months (Lai et al). Most importantly, there is no correlation between haze and postoperative visual or topographic outcomes (Lai et al).
Scheimpflug densitometry analysis with the Oculus Pentacam device is an objective, reproducible way of measuring corneal haze. This analysis provides a unit that corresponds to the amount of light scatter, with 0 representing minimum light scatter (maximum transparency), and 100 representing maximum light scatter (minimum transparency). See the accompanying images for corneal densitometry results for three patients.
![[Fig 1] This normal cornea has a Kmax of 45 D and corneal thickness of 536 µm. Images: Christina Twardowski, OD, FAAO](/~/media/temporary/pcon0223kcnblog_twardowski_fig1.png?h=516&w=564)
Images: Christina Twardowski, OD, FAAO
Patients with this type of sterile haze typically won’t have any symptoms, such as redness, pain or discharge, but they may have a significant transient decrease in vision. If vision was poor to start with, the patient may not even notice a subjective change.
But in cases in which the patient had good vision in glasses at baseline, a decrease in vision after cross-linking can be very upsetting. The family may be worried that the treatment didn’t work or even worsened their child’s condition. As clinicians, we need to explain that cross-linking is absolutely the best choice for halting progression of keratoconus and maximizing the child’s long-term ocular health, even while we manage this short-term complication.
Ideally, patients and families should be educated before cross-linking that it could temporarily make their vision worse. Some practitioners actually make it part of their routine conversation that pediatric patients undergoing cross-linking will likely have to wear contact lenses after surgery, even if they have no prior contact lens wear.
![[Fig 2] This pediatric patient with keratoconus has a Kmax of 60.4 D, with a corneal thickness of 460 µm.](/~/media/temporary/pcon0223kcnblog_twardowski_fig2.png)
Treating disease, rehabilitating vision
It is critical that ophthalmologists and optometrists work as a team to both treat the disease and rehabilitate the vision when needed. In all the cases I’ve seen, I’ve been able to successfully fit the child or teen in gas-permeable or scleral lenses and get them to 20/30 or better visual acuity.
![[Fig 3] This pediatric patient with keratoconus has a Kmax of 64.9 D and central corneal thickness of 356 µm. Central scarring from the corneal ectasia process is present.](/~/media/temporary/pcon0223kcnblog_twardowski_fig3.png?h=558&w=618)
In a cornea already distorted by keratoconus, haze may contribute additional light diffraction and scattering, reducing the retinal image quality. A GP or scleral lens can help focus the light more clearly, providing better vision than can be achieved in spectacles. In some cases, a longer steroid taper may be prescribed, but more often there is no change in management except to monitor closely, as we would in a progressing pediatric case.
More research on the phenomenon of post-treatment corneal haze in young patients is needed, but colleagues should know that this problem can be managed and that it does not affect long-term outcomes of cross-linking.
References:
- Badawi AE. J Curr Ophthalmol. 2022;doi:10.4103/joco.joco_145_21.
- Lai MJ, et al. Cornea. 2020;doi:10.1097/ICO.0000000000002334.
For more information:
Christina Twardowski, OD, FAAO, is a pediatric optometrist and director of the pediatric optometry residency program at Children’s Mercy Hospital in Kansas City, Missouri. She can be reached at ctwardowski@cmh.edu.
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