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Changes in Corneal Clouding Over Time in Patients With Mucopolysaccharidosis
Orlaith McGrath1,2, Krishanthy Sornalingam1,2, Tariq Aslam1,2
1Manchester Royal Eye Hospital, Manchester, United Kingdom; and.
Purpose:
Mucopolysaccharidoses (MPSs) are a rare group of lysosomal storage disorders characterized by the accumulation of incompletely degraded glycosaminoglycans (GAGs) in multiple organ systems, including the eye. Visual loss occurs in MPS predominantly due to corneal clouding. Despite the success of enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT) in improving many systemic manifestations of MPS, less is known about their effect on corneal clouding. This study prospectively analyses the effect of both ERT and HSCT on corneal clouding using objective measures over time.
Methods:
This is a prospective longitudinal observational study. Corneal clouding was assessed in each participant using slitlamp, digital slit-lamp photographs, and an iris camera (Corneal Opacification Measure [COM] and the Pentacam system).
Results:
Data were collected for 65 participants: 39 MPS I (Hurler), 5 MPS II (Hunter), 12 MPS IV (Morquio), and 9 MPS VI (Maroteaux-Lamy). Follow-up data are available for 45 participants (29 MPS I, 3 MPS II, 6 MPS IV, and 7 MPS VI).
Conclusions:
This study found corneal clouding to be stable in most participants with MPS I, II, IV, and VI over a follow-up period of 5 to 75 months (median of 30 months) when measured with clinical corneal grading systems, graded digital slit-lamp images, and iris camera COMs. For those with Pentacam densitometry measures, there was a progression of corneal clouding, on average, in those with MPS I and MPS VI. There was no apparent difference in progression of corneal clouding between patients who were on ERT, HSCT, or no treatment.
Insights
Corneal clouding in mucopolysaccharidoses (MPS) remained stable for most patients, regardless of enzyme replacement therapy (ERT) or stem cell transplant (HSCT). However, Pentacam measures indicated progression in some MPS I and MPS VI patients.
Area of Science:
- Ophthalmology
- Genetics
- Metabolic Disorders
Background:
- Mucopolysaccharidoses (MPS) are rare genetic disorders causing glycosaminoglycan buildup.
- Corneal clouding leading to vision loss is a common ocular manifestation in MPS.
- The impact of enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT) on MPS-related corneal clouding is not well-established.
Purpose of the Study:
- To prospectively evaluate the effect of ERT and HSCT on corneal clouding in MPS patients.
- To utilize objective measures to assess changes in corneal opacity over time.
Main Methods:
- Prospective longitudinal observational study design.
- Corneal clouding assessed via slit-lamp examination, digital slit-lamp photography, and iris camera (Corneal Opacification Measure [COM]).
- Pentacam system used for objective densitometry measurements.
Main Results:
- Data collected from 65 MPS patients (MPS I, II, IV, VI); follow-up available for 45.
- Clinical grading and COM showed stable corneal clouding in most patients over 5-75 months.
- Pentacam densitometry indicated average progression of corneal clouding in MPS I and MPS VI patients.
Conclusions:
- Corneal clouding in MPS I, II, IV, and VI is generally stable based on clinical assessments.
- Objective Pentacam measures suggest potential progression in MPS I and MPS VI.
- No significant difference in corneal clouding progression was observed between patients receiving ERT, HSCT, or no treatment.
