<!-- Do not edit this file. It is automatically generated by API Documenter. --> [Home](./index.md) > [puppeteer](./puppeteer.md) > [Page](./puppeteer.page.md) > [emulateVisionDeficiency](./puppeteer.page.emulatevisiondeficiency.md) ## Page.emulateVisionDeficiency() method Simulates the given vision deficiency on the page. <b>Signature:</b> ```typescript emulateVisionDeficiency(type?: Protocol.Emulation.SetEmulatedVisionDeficiencyRequest['type']): Promise<void>; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | type | Protocol.Emulation.SetEmulatedVisionDeficiencyRequest\['type'\] | the type of deficiency to simulate, or <code>'none'</code> to reset. | <b>Returns:</b> Promise<void> ## Example ```js const puppeteer = require('puppeteer'); (async () => { const browser = await puppeteer.launch(); const page = await browser.newPage(); await page.goto('https://v8.dev/blog/10-years'); await page.emulateVisionDeficiency('achromatopsia'); await page.screenshot({ path: 'achromatopsia.png' }); await page.emulateVisionDeficiency('deuteranopia'); await page.screenshot({ path: 'deuteranopia.png' }); await page.emulateVisionDeficiency('blurredVision'); await page.screenshot({ path: 'blurred-vision.png' }); await browser.close(); })(); ```