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Published on: May 25, 2020
Ocular findings among patients with late-diagnosed or poorly controlled homocystinuria compared with a screened,
A Mulvihill1, S Yap, M O'Keefe
1Department of Paediatric Ophthalmology, The Children's Hospital, Dublin, Ireland.
Insights
Untreated homocystinuria (HCU) causes severe ocular issues like lens subluxation. Early diagnosis and treatment are crucial to prevent vision loss in HCU patients.
Area of Science:
- Ophthalmology
- Medical Genetics
- Metabolic Disorders
Background:
- Untreated homocystinuria (HCU) leads to preventable systemic and ocular complications.
- Early intervention is key to mitigating HCU's adverse effects.
Purpose of the Study:
- To investigate the ocular manifestations in homocystinuria (HCU) patients with delayed diagnosis or poor treatment adherence.
- To compare these features against a control group of early-diagnosed, well-managed HCU patients.
Main Methods:
- Retrospective analysis of ocular features in 14 late-diagnosed HCU patients.
- Comparison with a control group of 15 early-diagnosed, well-controlled HCU patients.
- Review of ophthalmology records for patients with delayed HCU diagnosis.
Main Results:
- All 14 late-diagnosed HCU patients exhibited lens subluxation or dislocation.
- Significantly reduced visual acuity (28.6% with 20/40 or better) and high prevalence of myopic astigmatism in late-diagnosed HCU.
- Progressive myopia and lens subluxation observed in patients with declining HCU control in adolescence/early adulthood.
- No lens subluxation in 15 well-controlled, early-diagnosed HCU patients; all controls had 20/20 vision.
- Highly significant differences in visual acuity (P=.0002) and refractive errors (P=.0001) between late-diagnosed and control groups.
Conclusions:
- Lens subluxation is a hallmark of untreated homocystinuria (HCU).
- A significant diagnostic delay (median 5.5 years) was observed in some HCU cases.
- Screening for HCU is recommended for young individuals presenting with progressive myopia or unexplained lens subluxation.
Introduction:
Untreated homocystinuria (HCU) leads to systemic and ocular complications preventable by early treatment.
Methods:
This study describes the ocular features in HCU patients who had late diagnosis or were noncompliant with treatment compared with a control group of early-diagnosed and well-controlled subjects.
Results:
Fourteen late-diagnosed HCU patients with a median age at diagnosis of 4 years (range, 1.25-28 years) were studied. Five patients were born outside of Ireland or before screening began. All 14 patients had lens subluxation or dislocation at diagnosis. Only 28.6% of eyes had 20/40 vision or better. Three patients were tested for HCU following the diagnosis in a sibling. Four patients attended ophthalmology departments for a median of 12.8 years (range, 4-23 years) prior to diagnosis of HCU; all had steadily progressive myopic astigmatism and lens subluxation. Six patients who became poorly controlled in their teens or early twenties showed significant progression of their myopia, and 3 had phacodonesis or lens subluxation develop. All eyes in this group had 20/40 vision or better. Fifteen patients who were detected in the newborn period and remained well controlled had no evidence of lens subluxation. All of the control group patients had 20/20 vision bilaterally. The difference in visual acuity between late-diagnosed patients and the control group was highly significant (P =.0002). The differences in refractive errors between the groups were also highly significant (P =.0001).
Conclusions:
Lens subluxation is a principal feature of untreated HCU, yet we found a median lag period of 5.5 years in 4 cases before diagnosis. Young persons with marked and progressive myopia or idiopathic lens subluxation should be screened for HCU.
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