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Peli Prisms for Hemianopia


Want to discuss Peli Prisms?

Make an appointment with Natalie by calling our practice or emailing by clicking the button below. Peli Prism appointments cannot be arranged via Health Engine.

One of our orthoptic team, Natalie, is experienced in using ‘Peli Prisms’ to assist patients who have a persistant homonymous hemianopia after stroke or brain injury. These prisms have been used for around 20 years, and can expand the visual field by up to 30 degrees beyond the midline in successfully adapted cases.

These prisms have been called a range of names including: peli lenses, field expansion prism and spot prisms, but they all represent the same thing.

The diagram below comes from the original research paper by Eli Peli and clearly shows how, over time and will training, the patient will perceive some expansion of visual field. This improvement in awareness is seen in approximately 75% of patients who trial these prisms.

What is Hemianopia?

Homonymous hemianopia, also known as homonymous hemianopsia, is a type of visual field defect seen after strokes, brain injuries and tumours and causes a loss of the visual field to one side. The picture below demonstrates the vision following a left homonymous hemianopia.

Will Peli Prisms work for me?

It is impossible to say whether Peli Prisms will work for an individual without a thorough assessment, which includes Goldmann visual fields (as recommended by Peli himself) and an in clinic trial before training/trial prisms are fitted.

Peli Prism Program

Research suggests that fitting Peli Prisms is just the first step in gaining success with this type of treatment, a staged program with prescribed exercises is best to get the most out of them.

The Peli program at Adelaide Orthoptics is clearly laid out to patients from the start, and is based firmly within the research outlined in the original and subsequent articles, along with minor adaptations made following experience of using these in the clinic environment. 

Treatment Timeline - 3 -6 months

Step 1
Discussion regarding Peli Prisms, plus Goldmann visual fields for each eye individually, and binocularly. If the patient and orthoptist are in agreement, then a Fresnel Prism is fitted to the top section of the glasses only.
Step 2
If all has gone well, the bottom Fresnel Prism segment is fitted. In clinic assessment of fixation and visual field to confrontation is made, and then basic training is undertaken with the orthoptist. An at home training program is then prescribed.
Step 3
Binocular Goldmann visual fields are repeated and then discussed with the patient, along with discussion regarding use of prisms and whether the patient perceives any benefit. The Fresnel is then replaced with a true Peli Prism.
Step 4
Patient continues at home exercises to promote appropriate use of Peli Prism trial prisms. Repeat binocular Goldmann visual fields are undertaken to see whether the transition to true Peli Prisms has further increased the patient's visual field.
Step 5
If all the previous steps have been successful then the patient will be referred to an optometrist who can dispense Peli Prism glasses with a permanent (not stuck on) segment in both the upper and lower fields.
Initial Appointment
1 month later
2-4 weeks later
1-2 months later
Recommendation made

Want to discuss Peli Prisms?

Make an appointment with Natalie by calling our practice or emailing by clicking the button below. Peli Prism appointments cannot be arranged via Health Engine.

More to explore

…but what is vision therapy?

This blog outlines what vision therapy, also known as eye therapy or orthoptic exercises, can do to help patients of ages 5+.

Stroke and the Eyes

Vision problems post stroke occur in approximately 65% of stroke survivors. These problems can range from visual field loss to problems with eye movements and double vision and can severely impact daily life.

Happy World Orthoptic Day!

A day to celebrate the orthoptic profession, to raise awareness of what we are, who we help and our role in the eye team

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