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Corneal hysteresis in mucopolysaccharidosis I and VI
Kristina Teär Fahnehjelm1, Enping Chen, Jacek Winiarski
1Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. kristina.tear-fahnehjelm@sankterik.se
Insights
Children with mucopolysaccharidosis (MPS) often have falsely high intraocular pressure (IOP) readings due to increased corneal hysteresis. Correctly measured IOP is crucial to avoid unnecessary glaucoma treatments.
Area of Science:
- Ophthalmology
- Genetics
- Pediatrics
Background:
- Mucopolysaccharidosis (MPS) can affect the eyes, leading to concerns about high intraocular pressure (IOP) and glaucoma.
- Corneal changes are common in MPS, potentially affecting IOP measurements.
Purpose of the Study:
- To assess corneal hysteresis (CH) and IOP in children diagnosed with mucopolysaccharidosis I-Hurler (MPS I-H) and MPS VI.
- To investigate the relationship between corneal properties and IOP measurements in these pediatric patients.
Main Methods:
- Utilized the Ocular Response Analyzer (ORA) for clinical measurements.
- Evaluated seven patients: five with MPS I-H and two with MPS VI, some of whom had undergone stem cell transplantation (SCT) or enzyme therapy.
Main Results:
- All 14 eyes examined showed increased CH and falsely elevated IOP readings.
- Recalculated IOPs were normal in all patients.
- Mild to severe corneal opacities were present in all eyes, correlating with increased corneal resistance.
- Optic disc evaluation was normal in most eyes where possible, and no glaucoma was diagnosed.
Conclusions:
- Falsely high IOP readings in MPS patients are attributed to increased corneal resistance, linked to corneal clouding.
- Accurate IOP measurement is essential to prevent misdiagnosis and unnecessary hypotensive treatments for glaucoma.
- Further longitudinal studies are suggested to confirm the direct correlation between corneal deposits and resistance as corneas clear with treatment.
Purpose:
High intraocular pressure (IOP) and glaucoma are often suspected in patients with mucopolysaccharidosis (MPS). To determine corneal hysteresis (CH) and IOP in children with mucopolysaccharidosis I-Hurler (MPS I-H) and MPS VI.
Methods:
Clinical measurements with ocular response analyzer (ORA).
Results:
In seven patients, five with MPS I-H treated with stem cell transplantation (SCT), and two with MPS VI, one treated with SCT and the other with enzyme therapy, the IOP was examined with ORA. Ocular response analyzer measurements were made at a median age of 8.7 years in the patients with MPS I-H and at a median age of 9.3 years in the patients with MPS VI. Earlier measurements had raised suspicion of high IOP in one patient. The ORA showed an increased CH and a falsely high IOP values in all 14 eyes. The recalculated IOPs were normal in all 14 eyes. Mild to severe corneal opacities were present in all 14 eyes. Optic disc areas, borders and cupping were clinically normal in the 12 of 14 eyes that were possible to examine. Severe corneal opacities hampered optic disc evaluation in the older patient with MPS VI. Three eyes in two patients had normal thickness of the retinal nerve fibre layer measured with scanning laser polarimetry with corneal compensation (GDx VCC). No patient was diagnosed or treated for glaucoma.
Conclusion:
The IOPs are often falsely high because of an increased resistance of the cornea and correlate to the extent of corneal clouding. In this small, cross-sectional study, it appears that corneal resistance is directly correlated with corneal clouding, although a longitudinal study that evaluates resistance as the cornea clears with treatment would provide more direct evidence that corneal deposits are directly related to resistance. A correct measured IOP can avoid unnecessary medical or surgical hypotensive treatment.
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