science

Photovoltaic retinal prosthesis

Photovoltaic retinal prosthesis is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Photovoltaic retinal prosthesis rather than just read about it. In short: Photovoltaic retinal prosthesis is a technology for restoration of sight to patients blinded by degenerative retinal diseases, such as retinitis pigmentosa and age-related macular degeneration (AMD), when patients lose the 'image capturing' photoreceptors, but neurons in the 'image-processing' inner retinal layers are relatively well-preserved. This subretinal prosthesis is designed to restore sight by electrically…

Key takeaways

Photovoltaic retinal prosthesis belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Photovoltaic retinal prosthesis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Photovoltaic retinal prosthesis from memory before moving on to harder problems.

Reference excerpt

Photovoltaic retinal prosthesis is a technology for restoration of sight to patients blinded by degenerative retinal diseases, such as retinitis pigmentosa and age-related macular degeneration (AMD), when patients lose the 'image capturing' photoreceptors, but neurons in the 'image-processing' inner retinal layers are relatively well-preserved. This subretinal prosthesis is designed to restore sight by electrically stimulating the surviving inner retinal neurons, primarily the bipolar cells. Photovoltaic retinal implants are wireless and powered by near-infrared illumination (880 nm) projected from the augmented-reality (AR) glasses. Lack of trans-scleral cable greatly simplifies the implantation procedure compared to other retinal implants. Images captured by a camera on the AR glasses are processed and projected onto the retinal implant. Each pixel converts this light into electric current flowing through the retina and stimulating the nearby retinal neurons. Optical activation of the photovoltaic pixels allows scaling the implants to thousands of electrodes and retains natural coupling of the eye movements to visual perception. Preclinical studies demonstrated that prosthetic vision with such subretinal implants preserves many features of natural vision, including flicker fusion at high frequencies (>20 Hz), adaptation to static images, antagonistic center-surround organization and non-linear summation of subunits in receptive fields, providing high spatial resolution. Clinical trials with the first-generation of such implants (PRIMA, Science Corporation, former Pixium Vision) having 100μm pixels demonstrated that AMD patients perceive letters and other patterns with spatial resolution closely matching the pixel size (20/420). Moreover, central prosthetic vision is perceived simultaneously with the remaining natural peripheral vision. Using electronic zoom, patients can read much smaller fonts – down to equivalent acuity of 20/63, with the average improvement of visual acuity by 5 lines on ETDRS chart, compared to baseline.

The next-generation implants with 20μm pixels provided grating acuity matching the natural limit of resolution in rats (28μm). Currently, such high-resolution implants are being optimized for human retina by Palanker group at Stanford University. If successful in clinical trials, this pixel size may provide visual acuity up to 20/80 without zoom, and up to 20/20 with zoom.

References

External links Photovoltaic retinal prosthesis restores high-resolution responses to single-pixel stimulation in blind retinas

Illustrations

Worked examples

Example 1 — a first encounter with Photovoltaic retinal prosthesis

Start with the simplest possible case. Write down what Photovoltaic retinal prosthesis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Photovoltaic retinal prosthesis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Photovoltaic retinal prosthesis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Photovoltaic retinal prosthesis

In research: Photovoltaic retinal prosthesis appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Photovoltaic retinal prosthesis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Photovoltaic retinal prosthesis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Applications of photovoltaics, Blindness equipment, Medical treatment stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Photovoltaic retinal prosthesis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Photovoltaic retinal prosthesis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Photovoltaic retinal prosthesis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Photovoltaic retinal prosthesis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Photovoltaic retinal prosthesis in simple terms?

Why does Photovoltaic retinal prosthesis matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Photovoltaic retinal prosthesis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Photovoltaic retinal prosthesis.