---
id: wiki-2026-0508-안구-운동-증상-oculomotor-symptoms
title: 안구 운동 증상(Oculomotor Symptoms)
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Oculomotor Symptoms, VR Eye Strain, Vergence-Accommodation Conflict]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [vr, cybersickness, ux, accessibility, ergonomics]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: csharp
  framework: Unity-XR
---

# 안구 운동 증상 (Oculomotor Symptoms)

## 매 한 줄
> **"매 vergence와 accommodation의 decoupling이 통증을 만든다"**. VR HMD에서 눈은 가까운 가상 객체에 vergence를 맞추지만 실제 디스플레이 평면(focal distance ~1.3m)에 accommodation을 고정하기 때문에, 30분 이상 사용 시 eye strain · headache · blurred vision 의 증상이 누적된다. 2026 기준 Quest 3S, Vision Pro 2 까지도 fixed-focal-plane이라 varifocal display가 상용화되기 전까지 이 문제는 본질적으로 미해결.

## 매 핵심

### 매 SSQ Oculomotor Subscale
- **Simulator Sickness Questionnaire (Kennedy 1993)** 의 3 subscales 중 하나.
- Oculomotor = Eye strain + Difficulty focusing + Blurred vision + Headache + Fatigue.
- Score = sum × 7.58 (weighting factor).
- 임상 경계: > 15 = mild, > 20 = moderate, > 30 = severe — session 중단 권고.

### 매 원인 mechanism
- **Vergence-Accommodation Conflict (VAC)**: 양안 회전(vergence)은 가상 거리 따라 움직이나, 수정체 초점(accommodation)은 디스플레이 fixed.
- **IPD mismatch**: 사용자 IPD ≠ HMD lens 간격 → asymmetric load.
- **Pixel persistence**: low-persistence display 미적용 시 saccadic motion blur.
- **Refresh rate < 90Hz**: 잔상으로 인한 oculomotor strain.

### 매 응용
1. VR app design — 가까운 UI(<0.5m) 회피, 1-3m focal sweet spot 활용.
2. Session timer — 25-30분 후 forced break prompt.
3. Comfort rating system (Oculus/Meta Comfort Rating) 적용.

## 💻 패턴

### Comfort-aware UI placement (Unity)
```csharp
public class ComfortUIPlacer : MonoBehaviour {
    [SerializeField] float minDistance = 0.7f;   // vergence comfort
    [SerializeField] float maxDistance = 3.0f;
    [SerializeField] float idealDistance = 1.3f; // matches HMD focal plane

    void LateUpdate() {
        var head = Camera.main.transform;
        float d = Vector3.Distance(head.position, transform.position);
        if (d < minDistance || d > maxDistance) {
            transform.position = head.position + head.forward * idealDistance;
        }
    }
}
```

### SSQ-Oculomotor 자동 측정
```csharp
public class SSQTracker {
    static readonly string[] Items = {
        "General discomfort","Fatigue","Headache","Eye strain",
        "Difficulty focusing","Blurred vision"
    };

    public float OculomotorScore(Dictionary<string,int> ratings) {
        int sum = ratings["Eye strain"] + ratings["Difficulty focusing"]
                + ratings["Blurred vision"] + ratings["Headache"]
                + ratings["Fatigue"];
        return sum * 7.58f;
    }
}
```

### Forced break with fade
```csharp
IEnumerator ComfortBreakLoop() {
    while (true) {
        yield return new WaitForSeconds(25 * 60);
        yield return Fade(toBlack: true, 1.5f);
        ShowMessage("눈 휴식: 20-20-20 rule (20초 동안 20피트 떨어진 곳).");
        yield return new WaitForSeconds(60);
        yield return Fade(toBlack: false, 1.5f);
    }
}
```

### IPD calibration check
```csharp
float SystemIPD => XRSettings.eyeTextureWidth > 0
    ? OVRPlugin.GetUserIPD() : 0.063f;

void WarnIfMismatch() {
    if (Mathf.Abs(SystemIPD - userMeasuredIPD) > 0.003f)
        Debug.LogWarning("IPD mismatch — recalibrate to reduce eye strain.");
}
```

### Foveated rendering hint (Quest 3 / Vision Pro 2)
```csharp
void Start() {
    OVRManager.eyeTrackedFoveatedRenderingEnabled = true;
    OVRManager.foveatedRenderingLevel = OVRManager.FoveatedRenderingLevel.High;
    // Reduces peripheral GPU load → higher refresh, less oculomotor strain.
}
```

### Text legibility for HMD
```csharp
// Rule of thumb: 1 arcminute per stroke at 1.3m → ~20pt min for Quest 3.
text.fontSize = Mathf.RoundToInt(20 * (distance / 1.3f));
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| 단기 (< 15분) demo | comfort 영향 minimal — UX freedom 우선. |
| 30분+ 게임 | forced break + fixed-focal UI 강제. |
| 학습용 / training | SSQ pre/post 측정 의무. |
| 어린이 (< 13) | session 15분 제한, IPD mismatch 위험 큼. |

**기본값**: 1.3m focal sweet spot · 90Hz+ refresh · 25분 break loop.

## 🔗 Graph
- 부모: [[VR-Cybersickness]] · [[Human-Factors]]
- 변형: [[Vergence-Accommodation-Conflict]] · [[Visually-Induced-Motion-Sickness]]
- 응용: [[VR-UX-Design]] · [[XR-Accessibility]]
- Adjacent: [[SSQ-Questionnaire]] · [[Foveated-Rendering]] · [[IPD-Calibration]]

## 🤖 LLM 활용
**언제**: VR/XR 앱의 comfort rating 평가, SSQ score 산출, UI placement 자동 audit.
**언제 X**: 의료적 진단 (어지럼증의 vestibular 원인 vs oculomotor 원인 구분은 임상의 영역).

## ❌ 안티패턴
- **HUD locked to face (< 0.3m)**: 매 호출마다 vergence 극단 → 두통.
- **Tiny text + far placement**: accommodation 강요 → eye strain.
- **No break system**: 1시간+ session 후 SSQ-O 30 초과 빈발.
- **Default IPD 무조건 사용**: 사용자별 IPD 편차 56-72mm 무시.

## 🧪 검증 / 중복
- Verified (Kennedy et al. 1993, SSQ; Hoffman et al. 2008, VAC).
- 신뢰도 A — 30년+ accumulated VR ergonomics literature.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — VR oculomotor symptoms full content |
