引用本公眾號(hào)內(nèi)容請(qǐng)?jiān)谖恼虑懊孀⒚鱽?lái)自尖峰眼科！

視疲勞這一現(xiàn)象日益受到重視，其病因之一就是集合功能不足。

第四節(jié)、集合功能不足

【癥狀】

閱讀或近距離工作時(shí)眼部不適或視物模糊。最常見(jiàn)于年輕人，也可見(jiàn)于老年患者。

【主要體征】

視近時(shí)眼球外轉(zhuǎn)，外隱斜或外斜視，表現(xiàn)為近融合性集合(輻輳)幅度過(guò)??；調(diào)節(jié)性集合/調(diào)節(jié)(AC/A)比值低；集合的近點(diǎn)較遠(yuǎn)。參見(jiàn)檢查部分。

【其他體征】

視近較視遠(yuǎn)時(shí)外隱斜更為明顯。

【鑒別診斷】

1.屈光不正未矯正 遠(yuǎn)視或近視過(guò)矯。

2.調(diào)節(jié)功能不足(AI) 通常見(jiàn)于老視前期，未矯正的低度遠(yuǎn)視或近視過(guò)矯。閱讀時(shí)戴4△基底向內(nèi)的棱鏡，調(diào)節(jié)功能不足患者視物模糊，但集合功能不足患者視物變清晰。偶有青少年患者出現(xiàn)一過(guò)性集合輕癱，需要戴用閱讀眼鏡或雙焦點(diǎn)眼鏡。這種特發(fā)性病變可在數(shù)年后痊愈。調(diào)節(jié)功能不足患者的閱讀眼鏡加用基底向內(nèi)的棱鏡可改善癥狀。

3.集合功能麻痹 外斜視急性起病，僅在視近時(shí)出現(xiàn)復(fù)視；內(nèi)收和調(diào)節(jié)正常。通常是由于四疊體或第Ⅲ顱神經(jīng)核病變引起，并且可能與Parinaud綜合征相關(guān)。

【病因?qū)W】

1.疲勞或疾病。

2.藥物(副交感神經(jīng)阻滯劑)。

3.葡萄膜炎。

4.Adie強(qiáng)直瞳孔。

5.產(chǎn)生基底向外的棱鏡效應(yīng)的眼鏡。

6.疹后腦炎。

7.外傷。

8.通常為特發(fā)性。

【檢查】

1.顯然驗(yàn)光 不使用睫狀肌麻痹。

2.測(cè)定集合近點(diǎn) 讓患者注視一可調(diào)節(jié)目標(biāo)(如鉛筆擦)，將該視標(biāo)移向患者，讓其報(bào)告何時(shí)出現(xiàn)復(fù)視。正常的集合近點(diǎn)為小于6~8cm。

3.遮蓋試驗(yàn) 檢查患者視遠(yuǎn)和視近有無(wú)外斜或內(nèi)斜，參見(jiàn)附錄3，遮蓋/去遮蓋和交替遮蓋試驗(yàn)；或馬氏桿試驗(yàn)。

4.檢查患者視近時(shí)的融合功能 讓患者注視置于其閱讀即離的一可調(diào)節(jié)目標(biāo)，將棱鏡串基底向外置于眼前，緩慢增加度數(shù)，直到患者報(bào)告眼前出現(xiàn)復(fù)視，是為融合破壞點(diǎn)；然后漸減度數(shù)，直到恢復(fù)為單像，是為融合恢復(fù)點(diǎn)。融合破壞點(diǎn)低，如10△~15△；或恢復(fù)點(diǎn)低或二者均有，表明集合功能不足。

5.患者閱讀時(shí) 在其眼前放置4△基底向內(nèi)的棱鏡，觀察字跡變清晰還是更模糊，以排除調(diào)節(jié)功能不足。

6.睫狀肌麻痹后驗(yàn)光 在以上檢查完成后進(jìn)行。

注：如果患者需用近用眼鏡，上述檢查應(yīng)要求患者戴鏡進(jìn)行。

【治療】

1.矯正屈光不正 遠(yuǎn)視應(yīng)輕度低矯，而近視應(yīng)全部矯正。

2.近點(diǎn)訓(xùn)練 囑患者注視面前一臂遠(yuǎn)的鉛筆擦，緩慢向面部移近，患者需集中精力維持鉛筆擦的單像；出現(xiàn)復(fù)視，則重新操作。囑患者每次訓(xùn)練時(shí)在維持單視的狀態(tài)下盡量拿近鉛筆。重復(fù)訓(xùn)練15次，每天5次。

3.戴基底向外的棱鏡做近點(diǎn)訓(xùn)練 適用于集合近點(diǎn)尚可或無(wú)需配戴棱鏡即可進(jìn)行鉛筆尖訓(xùn)練者?；颊咭谎鄞?△基底向外的棱鏡，鉛筆的操作如前所述。

4.近距離工作的間歇期 應(yīng)有充足的照明和休息放松時(shí)間。

5.對(duì)老年人或雖經(jīng)近點(diǎn)訓(xùn)練但癥狀無(wú)改善者 閱讀眼鏡加用基底向內(nèi)的棱鏡可有所幫助。

【隨訪】

非急癥，1個(gè)月后復(fù)查。

13.4 Convergence Insufficiency

Symptoms

Eye discomfort or blurred vision from reading or near work. Most common in young adults, but may be seen in older people.

Signs

Critical. An exodeviation (either a phoria or tropia) at near in the presence of poor near-fusional convergence amplitudes, a low accommodative convergence/accommodation (AC/A) ratio, and a remote near point of convergence (see Work-up).

Other. An exophoria greater at near than at distance.

Differential Diagnosis

Uncorrected Refractive Error: Hyperopia or over-minused myopia.

Accommodative insufficiency (AI): Often in prepresbyopia age range from uncorrected low hyperopia or over-minused myopia. While reading, a 4-diopter base-in prism placed in front of the eye blurs the print in AI, but improves clarity in CI. Rarely, adolescents may acquire transient paresis of accommodation, requiring reading glasses or bifocals. This idiopathic condition resolves in several years. Patients with AI may benefit from reading glasses with base-in prism.

Convergence paralysis: Acute onset of exotropia and diplopia on near fixation only; normal adduction and accommodation. Usually results from a lesion in the corpora quadrigemina or the third cranial nerve nucleus, and may be associated with Parinaud syndrome.

Etiology

Fatigue or illness.

Drugs (parasympatholytics).

Uveitis.

Adie tonic pupil.

Glasses inducing a base-out prism effect.

Postexanthematous encephalitis.

Traumatic injury.

Often idiopathic.

Work-Up

Manifest (without cycloplegia) refraction.

Determine the near point of convergence: Ask patient to focus on an accommodative target (e.g., a pencil eraser) and to state when double vision develops as you bring the target toward them; a normal near point of convergence is <6 to 8 cm.

Check for exodeviations or esodeviations at distance and near by using the cover tests (see Appendix 3, Cover/Uncover and Alternate Cover Tests) or the Maddox rod test.

Measure the patient's fusional ability at near. Have patient focus on an accommodative target at their reading distance. With a prism bar, slowly increase the amount of base-out prism in front of one eye until patient notes double vision (the break point), and then slowly reduce the amount of base-out prism until a single image is again noted (the recovery point). A low break point (e.g., 10 to 15 prism diopters) or a low recovery point, or both, are consistent with CI.

Place a 4-diopter base-in prism in front of one eye while patient is reading. Determine whether the print becomes clearer or more blurred to rule out AI.

Perform cycloplegic refraction after the previous tests.

Note

These tests are performed with the patient's spectacle correction in place (if glasses are worn for near work).

Treatment

Correct any refractive error. Slightly undercorrect hyperopia, and fully correct myopia.

Near-point exercises (e.g., pencil push-ups): The patient focuses on a pencil eraser while slowly moving it from arm's length toward the face. Concentrate on maintaining one image of the eraser, repeating the maneuver when diplopia manifests. Try to bring the pencil in closer each time while maintaining single vision. Repeat the exercise 15 times, five times per day.

Near-point exercises with base-out prisms (for patients whose near point of convergence is satisfactory or for those who have mastered pencil push-ups without a prism): The patient performs pencil push-ups as described previously, while holding a 6-diopter base-out prism in front of one eye.

Encourage good lighting and relaxation time between periods of close work.

For older patients, or those whose condition shows no improvement despite near-point exercises, reading glasses with base-in prism can be useful.

Follow-Up

Nonurgent. Patients are reexamined in 1 month.