🌟 Cues

• Visual Reflexes
  • Corneal reflex
  • Pupillary light reflex
  • Accommodation reflex
• Diagnosis and correction of errors of refraction
• Near point of vision
• Colour vision testing
• Visual field testing
• Ophthalmoscopy

🗒️ Notes

Visual Reflexes

1. Corneal Reflex
Definition: Reflex closure of both eyes when the cornea is touched by a foreign body.
Procedure: Touch the cornea with soft cotton, observe reflexive closure of eyelids.
Pathway: Afferent: Trigeminal nerve (CN 5); Efferent: Facial nerve (CN 7).
Significance: Protects the eye and tests reflex arc integrity.

2. Pupillary Light Reflex
Definition: Light exposure causes constriction in both pupils.
Procedure: Shine light in one eye and observe pupil changes.
Significance: Controls light entering the eye and tests pathway integrity.

3. Accommodation Reflex
Definition: Adjusting the optical system of the eye for near vision.
Procedure: Shift gaze from far to near object and observe pupil size and eye alignment.
Significance: Decreases light entering, increases lens convexity, and ensures visual focus on the fovea.

Diagnosis of Refractive Errors

1. Examination of Visual Acuity
Definition: Eye’s ability to detect fine details.
Charts: Landolt C, Snellen chart, Tumbling E chart.
Method: Test each eye individually at 6 meters, both with and without glasses.

2. Pinhole Test
Purpose: Exclude organic eye lesions by determining if acuity improves with pinholes.

3. Auto-Refractometer
Purpose: Measures type and degree of refractive error, confirmed with trial lenses.

Near Point of Vision

Definition: Nearest distance where an object can be seen clearly with maximum accommodation.
Changes with Age: Near point increases with age due to reduced lens elasticity.

Colour Vision Testing

Mechanism: Young-Helmholtz theory – cones sensitive to red, green, and blue.
Test: Ishihara charts used to identify color blindness.

Measurement of Visual Field

Definition: Area visible to the eye while gazing at a fixed point.
Significance: Tests for visual pathway lesions.

Ophthalmoscopy

Purpose: Examines the internal structure of the eye, especially the retina and optic disc.
Conditions Detected: Cataracts, retinal tears, optic disc swelling (papilledema), retinal vessel abnormalities.

📝 Summary

This session covered key aspects of visual reflexes, the diagnosis of refractive errors, and essential eye tests. The corneal, pupillary, and accommodation reflexes help protect the eye and maintain visual clarity. Refractive errors are identified using visual acuity charts, pinhole tests, and auto-refractometers. The near point of vision tests eye accommodation ability, while color vision and visual field assessments detect vision deficiencies. Finally, ophthalmoscopy is used to diagnose internal eye conditions.