{"id":2315,"date":"2016-07-09T23:41:18","date_gmt":"2016-07-09T23:41:18","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2315"},"modified":"2024-09-02T13:36:29","modified_gmt":"2024-09-02T13:36:29","slug":"olho-humano-globo-ocular-defeitos-da-visao","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/optica\/optica-fisiologica\/olho-humano-globo-ocular-defeitos-da-visao\/","title":{"rendered":"Olho humano \u2013 Globo ocular \u2013 Defeitos da vis\u00e3o"},"content":{"rendered":"

Olho humano \u2013 Globo ocular \u2013 Defeitos da vis\u00e3o<\/b><\/span><\/span><\/span><\/p>\n

Globo Ocular<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>globo ocular <\/b><\/span><\/span><\/span>\u00e9 o <\/b><\/span><\/span><\/span>elemento fundamental<\/b><\/span><\/span><\/span> para nossa <\/b><\/span><\/span><\/span>vis\u00e3o. Consta basicam<\/b><\/span><\/span><\/span>ente dos seguintes <\/b><\/span><\/span><\/span>elementos:<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>Escler\u00f3tica<\/b><\/span><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span> <\/b>fibra fina e branca <\/b><\/span><\/span><\/span>que tem em\u00a0 toda sua <\/b><\/span><\/span><\/span>superf\u00edcie interna a cor\u00f3ide <\/b><\/span><\/span><\/span>que \u00e9 uma <\/b><\/span><\/span><\/span>membrana fina e escura.<\/b><\/span><\/span><\/span> Ambas <\/b><\/span><\/span><\/span>revestem todo o olho, <\/b><\/span><\/span><\/span>exceto por uma <\/b><\/span><\/span><\/span>abertura circular na frente, para a entrada da luz.<\/b><\/span><\/span><\/span><\/p>\n

\"\"\"\"<\/p>\n

\"\"\u00a0<\/span>C\u00f3rnea<\/b><\/span><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span> Parte <\/b><\/span><\/span><\/span>circular da frente do olho<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>transparente e esf\u00e9rica<\/b><\/span><\/span><\/span>, onde vemos o <\/b><\/span><\/span><\/span>branco do olho e a \u00edris.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\" Cristalino<\/b><\/span><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span> <\/b>Lente convergente,<\/b><\/span><\/span><\/span> gelatinosa e el\u00e1stica, de <\/b><\/span><\/span><\/span>dist\u00e2ncia focal vari\u00e1vel <\/b><\/span><\/span><\/span>que, atrav\u00e9s da <\/b><\/span><\/span><\/span>varia\u00e7\u00e3o dos m\u00fasculos ciliares focaliza na retina a luz que sai do objeto e que entra no olho.<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>\u00cdris<\/b><\/span><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span> <\/b>Parte circular e opaca <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>d\u00e1 cor ao olho. <\/b><\/span><\/span><\/span>Tem uma <\/b><\/span><\/span><\/span>abertura central, a pupila.<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>Pupila<\/b><\/span><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span> <\/b>Abertura circular da \u00edris <\/b><\/span><\/span><\/span>por onde a <\/b><\/span><\/span><\/span>luz entra no olho. <\/b><\/span><\/span><\/span>Seu <\/b><\/span><\/span><\/span>di\u00e2metro \u00e9 vari\u00e1vel <\/b><\/span><\/span><\/span>pois controla a entrada da luz, <\/b><\/span><\/span><\/span>sendo menor no claro e maior no escuro.<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>Retina<\/b><\/span><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span> Composta de <\/b><\/span><\/span><\/span>c\u00e9lulas sens\u00edveis \u00e0 luz <\/b><\/span><\/span><\/span>(cones e bastonetes), onde se <\/b><\/span><\/span><\/span>formam as imagens<\/b><\/span><\/span><\/span> que s\u00e3o <\/b><\/span><\/span><\/span>transformadas em sinais nervosos <\/b><\/span><\/span><\/span>e que s\u00e3o <\/b><\/span><\/span><\/span>transmitidas ao c\u00e9rebro <\/b><\/span><\/span><\/span>pelo nervo \u00f3ptico.<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0O <\/b><\/span><\/span><\/span>globo ocular pode ser comparado a uma m\u00e1quina fotogr\u00e1fica <\/b><\/span><\/span><\/span>onde o <\/b><\/span><\/span><\/span>cristalino seria a lente<\/b><\/span><\/span><\/span> (ou <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

sistema de lentes) <\/b><\/span><\/span><\/span>convergente,<\/b><\/span><\/span><\/span> a<\/b><\/span><\/span><\/span> <\/b>\u00edris<\/b><\/span><\/span><\/span> seria o diafragma da m\u00e1quina fotogr\u00e1fica que abre ou fecha permitindo maior ou menor entrada de luz e a <\/b><\/span><\/span><\/span>retina<\/b><\/span><\/span><\/span> seria o filme ou sensor onde a imagem real, invertida e menor \u00e9 formada<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n

Defeitos da vis\u00e3o<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

Sempre que a <\/b><\/span><\/span><\/span>vis\u00e3o \u00e9 n\u00edtida <\/b><\/span><\/span><\/span>o olho \u00e9 considerado <\/b><\/span><\/span><\/span>emetrope ou normal<\/b><\/span><\/span><\/span>. Mas, <\/b><\/span><\/span><\/span>existem anomalias da vis\u00e3o<\/b><\/span><\/span><\/span> (ametropias) das quais as <\/b><\/span><\/span><\/span>principais s\u00e3o:\u00a0\u00a0<\/b><\/span><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0 <\/span>Miopia<\/b><\/span><\/span><\/span><\/p>\n

Na <\/b><\/span><\/span><\/span>miopia,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>imagem \u00e9 formada antes da retina <\/b><\/span><\/span><\/span>devido ao fato de o <\/b><\/span><\/span><\/span>olho<\/b><\/span><\/span><\/span> ser <\/b><\/span><\/span><\/span>anormalmente longo ou <\/b><\/span><\/span><\/span>por <\/b><\/span><\/span><\/span>excesso de curvatura no cristalino,<\/b><\/span><\/span><\/span> <\/b>na c\u00f3rnea, ou nos dois.<\/b><\/span><\/span><\/span><\/p>\n

Os <\/b><\/span><\/span><\/span>m\u00edopes enxergam mal de longe.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Corrige-se esse defeito <\/b><\/span><\/span><\/span>com o uso de <\/b><\/span><\/span><\/span>lentes (\u00f3culos ou lentes de contato) <\/b><\/span><\/span><\/span>divergentes<\/b><\/span><\/span><\/span> <\/b>que <\/b><\/span><\/span><\/span>deslocam a imagem para tr\u00e1s, sobre a retina <\/b><\/span><\/span><\/span>(vide figura). Atualmente, <\/b><\/span><\/span><\/span>existem tratamentos cir\u00fargicos.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0A\u00a0 <\/b><\/span><\/span><\/span>posi\u00e7\u00e3o mais afastada do olho<\/b><\/span><\/span><\/span> com que uma pessoa <\/b><\/span><\/span><\/span>pode enxergar nitidamente a imagem de um objeto<\/b><\/span><\/span><\/span> (ponto remoto), <\/b><\/span><\/span><\/span>para uma pessoa de vis\u00e3o normal <\/b><\/span><\/span><\/span>encontra-se no <\/b><\/span><\/span><\/span>infinito <\/b><\/span><\/span><\/span>e nesse caso a <\/b><\/span><\/span><\/span>imagem do objeto forma-se sobre a retina. <\/b><\/span><\/span><\/span><\/p>\n

J\u00e1, para <\/b><\/span><\/span><\/span>um m\u00edope,<\/b><\/span><\/span><\/span> <\/b>esta imagem forma-se antes da retina.<\/b><\/span><\/span><\/span> A <\/b><\/span><\/span><\/span>corre\u00e7\u00e3o \u00e9 feita com a lente levando<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>imagem do objeto para o ponto onde ele consegue enxerga-la nitidamente (na retina), ou seja, a pessoa v\u00ea a imagem fornecida pela lente num ponto onde ela \u00e9 projetada sobre a retina..<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>lente de corre\u00e7\u00e3o divergente deve \u201ctrazer\u201d a imagem P de um objeto no infinito (P = <\/b><\/span><\/span><\/span>\u221e<\/b><\/span><\/span><\/span>) para o ponto onde o olho consiga enxerga-la nitidamente (ponto remoto)<\/b><\/span><\/span><\/span><\/p>\n

Preste aten\u00e7\u00e3o nesse exemplo:<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>maior dist\u00e2ncia com que uma pessoa consegue enxergar nitidamente um objeto <\/b><\/span><\/span><\/span>(ponto remoto) <\/b><\/span><\/span><\/span>\u00e9 50cm.<\/b><\/span><\/span><\/span> Determine a <\/b><\/span><\/span><\/span>converg\u00eancia ou verg\u00eancia <\/b><\/span><\/span><\/span>da lente que corrige essa <\/b><\/span><\/span><\/span>miopia.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O <\/b><\/span><\/span><\/span>feixe de luz proveniente do infinito ( P\u00a0=\u00a0<\/b><\/span><\/span><\/span>\u221e<\/b><\/span><\/span><\/span>\u00a0) <\/b><\/span><\/span><\/span>deve ter sua <\/b><\/span><\/span><\/span>imagem, fornecida pela lente, formada no ponto P\u2019 = – 50cm <\/b><\/span><\/span><\/span>onde o <\/b><\/span><\/span><\/span>olho conjuga a imagem n\u00edtida (fornecido pelo exerc\u00edcio).<\/b><\/span><\/span><\/span><\/p>\n

Usando a equa\u00e7\u00e3o dos pontos conjugados para essa lente \"\" <\/b><\/span><\/span><\/span>1\/f = 1\/P + 1\/P\u2019\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0 1\/f = 1\/<\/b><\/span><\/span><\/span>\u221e<\/b><\/span><\/span><\/span>\u00a0+ 1\/50\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

\"\" \u00a0 1\/f = 0 + 1\/50\u00a0 \"\"\u00a0 <\/b><\/span><\/span><\/span>f = 50cm\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 como <\/b><\/span><\/span><\/span>a lente \u00e9 divergente\u00a0f \u00e9 negativa \"\" f = -50cm.<\/b><\/span><\/span><\/span><\/p>\n

Para que a <\/b><\/span><\/span><\/span>verg\u00eancia ou converg\u00eancia <\/b><\/span><\/span><\/span>esteja em <\/b><\/span><\/span><\/span>dioptrias (di) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>dist\u00e2ncia focal <\/b><\/span><\/span><\/span>tem que estar em <\/b><\/span><\/span><\/span>metros (m) \"\"<\/b><\/span><\/span><\/span> <\/b>C = – 0,5m<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

Equa\u00e7\u00e3o da verg\u00eancia \"\"<\/b><\/span><\/span><\/span> <\/b>C = 1\/f\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 C = 1\/-0,5\u00a0 \"\"\u00a0\u00a0<\/b><\/span><\/span><\/span>C = – 2,0 di.<\/b><\/span><\/span><\/span><\/p>\n

\"\" Hipermetropia\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Na <\/b><\/span><\/span><\/span>hipermetropia<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>forma\u00e7\u00e3o da imagem ocorre, teoricamente, atr\u00e1s da retina<\/b><\/span><\/span><\/span>, porque o <\/b><\/span><\/span><\/span>olho \u00e9 curto demais e porque o cristalino n\u00e3o consegue se acomodar para focalizar a imagem sobre a retina. <\/b><\/span><\/span><\/span><\/p>\n

Os <\/b><\/span><\/span><\/span>hiperm\u00e9tropes n\u00e3o conseguem enxergar objetos pr\u00f3ximos com nitidez.<\/b><\/span><\/span><\/span> <\/b> <\/b><\/p>\n

O <\/b><\/span><\/span><\/span>defeito \u00e9 corrigido <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>lentes convergentes.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Ponto pr\u00f3ximo <\/b><\/span><\/span><\/span>\u00e9 o <\/b><\/span><\/span><\/span>ponto mais perto do olho <\/b><\/span><\/span><\/span>com que uma pessoa <\/b><\/span><\/span><\/span>consegue ver com nitidez. <\/b><\/span><\/span><\/span><\/p>\n

Para uma <\/b><\/span><\/span><\/span>pessoa de vis\u00e3o normal este ponto est\u00e1 localizado a 25cm do olho <\/b><\/span><\/span><\/span>(do cristalino) que \u00e9 <\/b><\/span><\/span><\/span>denominada dist\u00e2ncia m\u00ednima de vis\u00e3o distinta <\/b><\/span><\/span><\/span>(posi\u00e7\u00e3o normal onde se coloca o livro de leitura).\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

J\u00e1, para o <\/b><\/span><\/span><\/span>hiperm\u00e9trope este ponto pr\u00f3ximo localiza-se a uma dist\u00e2ncia superior a 25cm.\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Assim, <\/b><\/span><\/span><\/span>um objeto situado a p = 25cm <\/b><\/span><\/span><\/span>(dist\u00e2ncia m\u00ednima de vis\u00e3o distinta) <\/b><\/span><\/span><\/span>deve conjugar, atrav\u00e9s da lente convergente, uma imagem no ponto P\u2019 = – d, <\/b><\/span><\/span><\/span>que \u00e9 onde a <\/b><\/span><\/span><\/span>pessoa enxerga bem. <\/b><\/span><\/span><\/span>(o sinal negativo indica que a <\/b><\/span><\/span><\/span>imagem \u00e9 virtual<\/b><\/span><\/span><\/span>).<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>imagem fornecida pela lente funciona como objeto para o olho.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Usa-se a <\/b><\/span><\/span><\/span>equa\u00e7\u00e3o dos pontos conjugados<\/b><\/span><\/span><\/span> \u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>1f = 1\/0,25 + 1\/-P\u2019<\/b><\/span><\/span><\/span><\/p>\n

Preste aten\u00e7\u00e3o nesse exemplo:<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>menor dist\u00e2ncia com <\/b><\/span><\/span><\/span>que uma <\/b><\/span><\/span><\/span>pessoa consegue enxergar um objeto \u00e9 0,8m.<\/b><\/span><\/span><\/span><\/p>\n

Determine a <\/b><\/span><\/span><\/span>verg\u00eancia ou converg\u00eancia<\/b><\/span><\/span><\/span> da lente convergente utilizada para corrigir essa hipermetropia.<\/b><\/span><\/span><\/span><\/p>\n

A lente deve <\/b><\/span><\/span><\/span>ser tal que, de um objeto colocado a P = 25 cm de seu olho deve conjugar uma imagem em P\u2019= – 0,8m, <\/b><\/span><\/span><\/span>onde <\/b><\/span><\/span><\/span>ele enxerga bem <\/b><\/span><\/span><\/span>(sinal negativo porque a <\/b><\/span><\/span><\/span>imagem \u00e9 virtual<\/b><\/span><\/span><\/span>)<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span>Utilizando a equa\u00e7\u00e3o dos pontos conjugados 1\/f = 1\/P + 1\/P\u2019<\/b><\/span><\/span><\/span>\u00a0 \"\"\u00a0 1\/f = 1\/0,25 + 1\/-0,8\u00a0 \"\"\u00a0 1\/f = 1\/0,25 – 1\/0,8\u00a0\u00a0 \"\"\u00a0 <\/b><\/span><\/span><\/span>f = 4\/11 m.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

C\u00e1lculo da <\/b><\/span><\/span><\/span>verg\u00eancia ou converg\u00eancia <\/b><\/span><\/span><\/span>dessa lente \"\" <\/b><\/span><\/span><\/span>C = 1\/f\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0\u00a0<\/b><\/span><\/span><\/span>C= 11\/4 di ou C= 2,75di.<\/b><\/span><\/span><\/span><\/p>\n

\"\" \u00a0<\/span>Presbiopia<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span> <\/b><\/p>\n

\u00a0<\/span>Presbiopia<\/b><\/span><\/span><\/span>\u00a0ou vista cansada <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>comum<\/b><\/span><\/span><\/span> nas pessoas <\/b><\/span><\/span><\/span>ap\u00f3s os 45 anos. <\/b><\/span><\/span><\/span><\/p>\n

Esse <\/b><\/span><\/span><\/span>defeito \u00e9 devido \u00e0 impossibilidade de o cristalino se acomodar para vis\u00e3o de objetos pr\u00f3ximos. <\/b><\/span><\/span><\/span>Por isso, as <\/b><\/span><\/span><\/span>pessoas idosas enxergam muito mal de perto.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Essa <\/b><\/span><\/span><\/span>defici\u00eancia pode ser corrigida com lentes convergentes <\/b><\/span><\/span><\/span>e da <\/b><\/span><\/span><\/span>mesma maneira com que se corrige hipermetropia mas com verg\u00eancia ou converg\u00eancia maior pois deve convergir mais fortemente os raios de luz.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sinais de presbiopia:<\/b><\/span><\/span><\/span><\/p>\n

\"\"Dificuldade para ler
\n\"\" Dificuldade para ver a tela do computador com nitidez<\/b><\/span><\/span><\/span><\/p>\n

\"\" Astigmatimo<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

O <\/b><\/span><\/span><\/span>Astigmatimo<\/b><\/span><\/span><\/span>\u00a0consiste em defeito na curvatura da c\u00f3rnea e mais raramente, do cristalino. <\/b><\/span><\/span><\/span><\/p>\n

Em <\/b><\/span><\/span><\/span>conseq\u00fc\u00eancia, o olho n\u00e3o \u00e9 capaz de distinguir, <\/b><\/span><\/span><\/span>ao <\/b><\/span><\/span><\/span>mesmo tempo, com a mesma nitidez, <\/b><\/span><\/span><\/span>linhas <\/b><\/span><\/span><\/span>verticais e horizontais e, com o movimento produz imagem distorcida.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Essa <\/b><\/span><\/span><\/span>anomalia pode se somar \u00e0 miopia ou \u00e0 hipermetropia.<\/b><\/span><\/span><\/span><\/p>\n

Sua <\/b><\/span><\/span><\/span>corre\u00e7\u00e3o \u00e9 feita atrav\u00e9s de lentes cil\u00edndricas (convergentes ou divergentes). <\/b><\/span><\/span><\/span><\/p>\n

Para corrigir a imperfei\u00e7\u00e3o <\/b><\/span><\/span><\/span>elas s\u00e3o feitas de modo a apresentarem espessuras diferentes em toda sua superf\u00edcie, <\/b><\/span><\/span><\/span>apresentando assim <\/b><\/span><\/span><\/span>comportamento oposto ao do cristalino ou da c\u00f3rnea.<\/b><\/span><\/span><\/span><\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n

O que voc\u00ea deve saber, informa\u00e7\u00f5es e dicas<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

\"\"\u00a0<\/span>Para voc\u00ea calcular a verg\u00eancia ou converg\u00eancia<\/b><\/span><\/span><\/span> da <\/b><\/span><\/span><\/span>lente <\/b><\/span><\/span><\/span>divergente<\/b><\/span><\/span><\/span> <\/b>que<\/b><\/span><\/span><\/span> corrige miopia <\/b><\/span><\/span><\/span>basta voc\u00ea chamar de <\/b><\/span><\/span><\/span>f = – P\u2019 (em metros) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>maior dist\u00e2ncia com que a pessoa consegue enxergar nitidamente<\/b><\/span><\/span><\/span> (ponto remoto) e <\/b><\/span><\/span><\/span>substitu\u00ed-la na express\u00e3o<\/b><\/span><\/span><\/span> <\/b>C = 1\/f = – 1\/P\u2019.<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

\"\"\u00a0<\/span>Para voc\u00ea calcular a verg\u00eancia ou converg\u00eancia de uma lente <\/b><\/span><\/span><\/span>convergente<\/b><\/span><\/span><\/span> <\/b>que <\/b><\/span><\/span><\/span>corrige hipermetropia <\/b><\/span><\/span><\/span>voc\u00ea <\/b><\/span><\/span><\/span>deve usar a express\u00e3o 1\/f = 1\/P + 1\/P\u2019 <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>P sendo sempre 0,25 <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>P\u2019 que \u00e9 a menor dist\u00e2ncia com que a pessoa consegue enxergar nitidamente (fornecida)<\/b><\/span><\/span><\/span> sendo <\/b><\/span><\/span><\/span>negativa<\/b><\/span><\/span><\/span> pois a <\/b><\/span><\/span><\/span>imagem \u00e9 virtual.<\/b><\/span><\/span><\/span><\/p>\n

C = 1\/f = 1\/0,25 \u2013 1\/P\u2019<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

\"\"\u00a0<\/span>A corre\u00e7\u00e3o da <\/b><\/span><\/span><\/span>presbiopia<\/b><\/span><\/span><\/span> <\/b>\u00e9 realizada com <\/b><\/span><\/span><\/span>lentes convergentes <\/b><\/span><\/span><\/span>e da <\/b><\/span><\/span><\/span>mesma maneira <\/b><\/span><\/span><\/span>com que se <\/b><\/span><\/span><\/span>corrige hipermetropia.<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

\"\"\u00a0<\/span>Quando se olha para um objeto\u00a0 muito distante (no infinito), <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>imagem forma-se na retina sem<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span><\/span>seja necess\u00e1rio nenhum esfor\u00e7o de acomoda\u00e7\u00e3o com o cristalino<\/b><\/span><\/span><\/span> (ou sistema c\u00f3rneo-cristalino) <\/b><\/span><\/span><\/span>relaxado.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

1\/f = 1\/P + 1\/P\u2019<\/b><\/span><\/span><\/span><\/span> \"\" 1\/f = 1\/<\/b><\/span><\/span><\/span><\/span>\u221e <\/b><\/span><\/span><\/span><\/span>+ 1\/P\u2019 \"\" 1\/f = 0<\/b><\/span><\/span><\/span><\/span> <\/b>+ 1\/25 \"\" <\/b><\/span><\/span><\/span><\/span>f = 25 mm. <\/b><\/span><\/span><\/span><\/span><\/p>\n

Nesse caso, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>dist\u00e2ncia focal do cristalino <\/b><\/span><\/span><\/span>est\u00e1 entre <\/b><\/span><\/span><\/span>ele e a retina <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>essa dist\u00e2ncia vale 25mm <\/b><\/span><\/span><\/span>ou <\/b><\/span><\/span><\/span>2,5 cm ou 0,25 m. <\/b><\/span><\/span><\/span><\/p>\n

Portanto,\u00a0<\/b><\/span><\/span><\/span>para um <\/b><\/span><\/span><\/span>objeto no infinito, a dist\u00e2ncia focal do cristalino vale f = 0,25 m<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Quando o <\/b><\/span><\/span><\/span>objeto se aproxima do olho, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>dist\u00e2ncia focal<\/b><\/span><\/span><\/span> e consequentemente o <\/b><\/span><\/span><\/span>raio de curvatura diminuem,<\/b><\/span><\/span><\/span> pois a <\/b><\/span><\/span><\/span>verg\u00eancia deve aumentar porque <\/b><\/span><\/span><\/span>C = 1\/f.<\/b><\/span><\/span><\/span><\/p>\n

Esse <\/b><\/span><\/span><\/span>aumento de verg\u00eancia <\/b><\/span><\/span><\/span>da <\/b><\/span><\/span><\/span>retina<\/b><\/span><\/span><\/span> deve ocorrer <\/b><\/span><\/span><\/span>para que os raios de luz sofram maior desvio <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>consigam incidir na retina<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

<\/h3>\n

Confira os exerc\u00edcios sugeridos<\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

Olho humano \u2013 Globo ocular \u2013 Defeitos da vis\u00e3o Globo Ocular O globo ocular \u00e9 o elemento fundamental para nossa vis\u00e3o. Consta basicamente dos seguintes elementos: \u00a0Escler\u00f3tica\u00a0 fibra fina e branca que tem em\u00a0 toda sua superf\u00edcie interna a cor\u00f3ide que \u00e9 uma membrana fina e escura. Ambas revestem todo o olho, exceto por uma abertura circular na frente, para<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2312,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-2315","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2315","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/comments?post=2315"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2315\/revisions"}],"predecessor-version":[{"id":2323,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2315\/revisions\/2323"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2312"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2315"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}