聚合近點(Near point of Convergence, NPC)的預期值比較

聚合近點(Near point of Convergence, NPC)或是內聚近點，是眼視光初步檢查中的一個重要步驟，為評估雙眼內聚能力(類似鬥雞眼動作)的重要指標之一，如果測試結果異常，則很可能在看書或近距離活動時容易眼疲勞或出現雙重影像。

操作方式一般是將視標由遠而近逐漸靠近眼睛，1.當觀看者表示出現雙重影像或2.觀察者發現雙眼之一往旁邊移開失去對焦，以上1或2兩者之一出現時，測量此時視標到觀看者鼻子(鏡框平面)之距離，稱為破裂點，如在一定範圍(預期值)之內，則此項測試為正常。

但預期值因研究者測試對象而有所不同，在不同視光教科書上有不同數值，這邊列出幾本視光常用書籍及較近的研究做個比較。

結論是許多舊版的書，破裂點數值在7cm左右，而新版的書，數值則都減少到2.5cm左右，而較近的研究則在5cm。

1.Clinical Procedures for Ocular Examination, Fourth Edition

視標為筆燈
破裂點Break 2.4-2.9 cm/回復點Recovery 4.2-5.0 cm

(同一本書，前一版的數值，破裂點Break:  5 cm 
/回復點Recovery:  7 cm )

2.PRIMARY  CARE OPTOMETRY, 5™ EDITION

視標為筆燈，破裂點預期值為8cm

原文如下
The expected value of the near point  of  convergence is approximately 8 cm or less, as measured from the spectacle plane. If the near point of convergence is found to be in the neighborhood of 12 to 15 cm on repeated testing, the examiner  should  suspect  the  convergence  insufficiency  syndrome.

3.CLINICAL MANAGEMENT OF Binocular Vision
Heterophoric, Accommodative, and Eye Movement Disorders

第四版
調節性視標Accommodative target Break: 2.5 cm ±2.5
Recovery:4.5 cm ±3.0
筆燈Penlight and red/green glasses Break: 2.5 cm ±4.0
Recovery:4.5 cm ±5.0

第三版
筆燈Penlight/red-green glasses  break:  7 cm  ±4.0 
recovery:  10 cm  ±5.0 

4.BORISH'S CLINICAL REFRACfION, SECOND EDITION

平均值3cm

原文如下
The mean NPC is 3 cm (±4 cm) from the spectacle plane (midforehead), and the recovery finding is 2 or 3 cm larger. NPC findings greater than 7 cm and recovery findings greater than 10 cm are generally regarded as inadequate and could be signs of a convergence insufficiency.


然後到Pubmed上用關鍵字搜尋，查到2017的統計
對象是20多歲的年輕人，平均值是 NPC: 5.27±3.60 cm

Strabismus. 2017 Mar;25(1):5-11. doi: 10.1080/09273972.2016.1276937. Epub 2017 Jan 17.
Binocular and Accommodative Characteristics in a Normal Population.


Yekta A1, Khabazkhoob M2,3, Hashemi H4, Ostadimoghaddam H5, Ghasemi-Moghaddam S1, Heravian J5, Doostdar A6, Nabovati P3.

Author information


Abstract

PURPOSE:


To study binocular and accommodative characteristics and their associations with age and gender in an Iranian young adult population.
METHODS:


In this cross-sectional study, multistage cluster sampling was done from the students of Mashhad University of Medical Sciences. All participants had visual acuity, refraction, and cover tests followed by measurements of the near point of convergence (NPC), amplitude of accommodation (AA), monocular and binocular accommodative facility (MAF and BAF) using ±2.00 diopter (D) flipper lenses, and negative and positive relative accommodation (NRA and PRA). Near and distance fusional vergence reserves were measured using prism bar, and near associated phoria was assessed using the Mallett unit.
RESULTS:


The mean age of the participants was 22.5±4.4 years (range: 18-35 years). The binocular and accommodative characteristics and their means in the studied sample included: mean distance dissociated phoria: 1.15 exophoria±2.04 prism diopters (PD), near dissociated phoria: 5.02 exophoria±4.74 PD, near associated phoria: 0.55 base-in±1.02, gradient accommodative convergence/accommodation (AC/A) ratio: 4.66±1.59, NPC: 5.27±3.60 cm, MAF: 11.33±5.58 cpm, BAF: 8.84±4.47 cpm, NRA: 2.08±0.33 D, PRA:-2.92±0.76 D, and AA: 11.14±2.6 D. In the multiple regression model including age and gender, near exophoria was significantly higher in men and levels of near base-out-break and near base-out-recovery were higher in females. Distance exophoria, distance base-in-break, distance base-in-recovery, and NPC increased with age and near base-out-break, PRA, BAF, MAF, and AA significantly decreased with age.
CONCLUSION:


Studied indices in this study significantly differ from available guidelines and these differences must be considered when making diagnostic or therapeutic decisions. Certain indices can be affected by age and gender.


2018對學童的統計，平均值在

near point of convergence break, 5-10cm

J Optom. 2018 Jun 7. pii: S1888-4296(18)30032-3. doi: 10.1016/j.optom.2018.03.005. [Epub ahead of print]
Normative values for clinical measures used to classify accommodative and vergence anomalies in a sample of high school children in South Africa.


Wajuihian SO1.

Author information
1

Discipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa. Electronic address: swajuihian@mweb.co.za.

Abstract

AIM:


To determine normative values for stereoacuity, accommodative and vergence measures for high school populations.
METHODS:


Using a multi-stage random cluster sampling, 1211 children (481 males and 730 females) between 13 and 18 years of age, with a median age of 16 years, were selected. Visual acuity, stereoacuity and suppression, refractive errors, near point of convergence, heterophoria and fusional vergences, as well as, amplitude of accommodation, accommodative response, facility and relative accommodation were evaluated.
RESULTS:


Most data did not have a normal distribution. The range of normality for the vergence measures were: near point of convergence break, 5-10cm, recovery, 6-13cm, near lateral phoria, 2.5-6 prism dioptre (pd) (nasal), near vertical, orthophoria to 0.50pd, negative fusional vergence break, 12-23pd, recovery, 8-17pd, positive fusional vergence break, 16-35 and recovery 11-24pd. For accommodative measures, the range of normality for accommodative measures was: amplitude of accommodation, 12-18pd, accommodative response, plano to +0.75D, binocular accommodative facility, 5-12 cycles per minute (cpm), negative relative accommodation, 1.75-2.50DS, positive relative accommodation, -2.0 to -3.0DS and 17-69s arc for stereoacuity.
CONCLUSION:


This study provides norms for clinical measures which could be used to classify accommodative and vergence parameters for children aged 13-18 years in this population or beyond. Findings should be applied in the context of the measurement techniques and the associated limitations outlined in this report.