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Myopic shift and its mechanism in nephropathia epidemica or Puumala virus infection
M Kontkanen1, T Puustjärvi, J Lähdevirta
1Department of Ophthalmology, Savonlinna Central Hospital, Finland.
Abstract:
Nephropathia epidemica (NE) is a zoonose caused by Puumala virus. NE belongs to the group of haemorrhagic fevers with renal syndrome. Transient myopia has been described in the acute phase of the disease. This prospective study presents the changes of refraction and the results of ophthalmic A scan measurements of patients who were managed at Savonlinna Central Hospital for NE during an epidemic in the winter of 1992-3. This involved 37 patients and 74 eyes. The incidence of transient myopia was 8.1% and that of myopic shift 40.5%. A scan ultrasound measurements were performed in patients in the acute phase and after total recovery of their general illness. Statistical analysis revealed that there were significant differences in anterior chamber depth and lens thickness between the acute and control phases of the disease and between the patients who had myopic shift compared with those who did not have a significant myopic change in refraction. Based on these results it seems that the reason for transient myopic shift of NE is mainly a combination of two factors: forward movement of the anterior diaphragm and thickening of the crystalline lens. The term myopic shift should be used rather than transient myopia because it better describes the overall refractive change in NE.
Insights
Nephropathia epidemica (NE), a Puumala virus zoonose, can cause significant myopic shifts. This study found changes in anterior chamber depth and lens thickness contribute to this refractive error.
Area of Science:
- Ophthalmology
- Infectious Diseases
- Virology
Background:
- Nephropathia epidemica (NE) is a zoonotic disease caused by Puumala virus, belonging to the Hantavirus genus.
- It is characterized as a hemorrhagic fever with renal syndrome.
- Transient myopia has been anecdotally reported during the acute phase of NE.
Observation:
- A prospective study investigated refractive changes and ocular biometry in 37 patients with NE during a 1992-1993 epidemic.
- Ophthalmic A scan ultrasound measurements were conducted during the acute phase and after recovery.
- Refractive changes, including myopic shift, were assessed in 74 eyes.
Findings:
- The incidence of myopic shift was 40.5%, significantly higher than transient myopia (8.1%).
- Statistical analysis revealed significant differences in anterior chamber depth and lens thickness between acute and recovery phases.
- These biometric changes correlated with the degree of myopic shift observed.
Implications:
- The primary cause of refractive changes in NE appears to be a combination of anterior chamber shallowing and increased lens thickness.
- The term 'myopic shift' is more accurate than 'transient myopia' for describing the refractive alterations in NE.
- Understanding these ocular changes is crucial for managing patients with NE and potential visual disturbances.