Fresnel Prism
Conditions
Keywords
homonymous hemianopia, fresnel prism, visual field impairment
Brief summary
Background: Homonymous hemianopia is a visual field defect that causes functional disabilities, such as decreased self-confidence, limited mobility, and increased risk of falls. Studies related to the effectiveness and comfort of Fresnel prisms, especially in the Indonesian population are limited. Objective: To evaluate the effectiveness and comfort level of Fresnel prisms in expanding visual field in an Indonesian patient population with homonymous hemianopia.
Detailed description
: Fresnel prisms with a power of 40∆ were fitted to the patient's spectacles for two weeks. Visual field parameters were analysed using the Humphrey Field Analyzer with the SITA 24-2 algorithm, while the Pelli-Robson and ETDRS charts were used to assess contrast sensitivity and visual acuity, respectively. After visual assessment, comfort was quantitatively assessed using a comfort scale.
Interventions
DEVICEFresnel prism
The Fresnel prism chosen was of 40∆ power (the largest size available) with the aim of the largest visual field expansion, which was 20 degrees that the patient felt during environmental orientation and mobilisation. Fresnel prism fitting was performed using the patient's spectacles (if wearing spectacles) or plano glasses provided by the researcher. The patient was given object movement stimulation to identify the visual field boundary and the Fresnel prism was placed 2 mm away from the healthy visual field area. The Fresnel prism was placed on the inner side of the lens. Vertical correction was performed in homonymous hemianopia depending on the visual field defect. The patient was then asked to practice scanning before being asked to wear the Fresnel prism for 5.5 hours daily for two weeks. Patients were given a wear sheet to evaluate the duration of wear in a day.
Sponsors
Indonesia University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* subjects with a diagnosis of partial or complete homonymous hemianopia based on the results of the Humphrey perimetry examination; * age 18 years or older; * corrected visual acuity of 6/18 or better; and * willing to give consent for this study and consistently follow the rehabilitation process.
Exclusion criteria
* ocular motility disorders; the primary position of the eyeball was not orthophoric; and * walking disorders that resulted in poor fixation of glasses.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Visual Fied | 2 weeks | Mean Deviation (dB) Pattern Standard deviation (dB) Visual field index (%) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| TPDK | 2 weeks | Sharp vision with correction (log mar) |
| Contrast sensitivity | 2 weeks | Contrast sensitivity (log units) |
Countries
Indonesia
Outcome results
None listed