accommodation and convergence.pptx
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This document discusses different types of convergence in the eyes. It defines accommodative convergence as convergence that occurs during accommodation or when the eyes receive an impulse to accommodate. The near reflex triad is defined as the reflex of the eyes to focus on a near object, consisting of accommodation, convergence, and miosis. It also discusses the AC/A ratio, which is a measurement of accommodative convergence, and how abnormalities in this ratio can cause different types of strabismus. Proximal convergence is induced by the proximity of an object rather than its optical properties, and has an inverse relationship with changes in fixation distance.
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Treatment options including refractive correction, orthoptic exercises, prisms, botulinum toxin, and surgery are mentioned for different types of esotropia.
Hypermetropia
Hypermetropia, also known as hyperopia or longsightedness, is a refractive error where the eye focuses images behind the retina rather than directly on it. It can be caused by the eyeball being too short, the cornea being too flat, or changes in the lens with age. Hypermetropia is classified as simple, pathological, or functional. It is usually corrected using convex lenses, contact lenses, or refractive surgery depending on the degree of nearsightedness and any other factors. Early diagnosis and treatment of hypermetropia in children is important to prevent vision problems.
RETINOSCOPY BY DR. PUSHKAR DHIR.pptx
Dr. Pushkar Dhir presented on retinoscopy. Retinoscopy is an objective refraction technique used to assess refractive error by observing the movement of the red reflex in the pupil when a light source is moved. It can be used for infants, children, and uncooperative patients. There are different types of retinoscopes. Retinoscopy involves illuminating the retina and observing the light reflex. Various factors are assessed like size, speed and brightness of the reflex to determine refractive error. Cycloplegic retinoscopy is used with young children and hyperopes to paralyze accommodation. Problems like small pupils or hazy media can make the reflex difficult to see. Subjective refraction then refines the
Retinoscopy
Dr. Pushkar Dhir gave a seminar on retinoscopy. He discussed how retinoscopy works by illuminating the retina and observing the light reflex. Both objective and subjective retinoscopy were covered. Various techniques like streak retinoscopy and how to determine the cylinder axis were explained. Potential problems in retinoscopy like an unclear red reflex and accommodative responses were addressed. The document provided a comprehensive overview of the retinoscopy procedure and techniques.
Retinoscopy
Dr. Pushkar Dhir gave a seminar on retinoscopy. He discussed how retinoscopy works by illuminating the retina and observing the light reflex. It can be used to objectively measure refractive error in infants and others who cannot communicate. Both dry and wet retinoscopy were explained. Challenges like an unclear red reflex due to media opacity or high refractive error were addressed. Subjective refinement using techniques like the Jackson Cross Cylinder was also covered. The seminar provided an in-depth overview of the retinoscopy procedure and techniques.
Accommodation by the eye.pptx
This document discusses accommodation by the eye and catoptric images. It explains that the eye has the ability to accommodate by changing the shape of the crystalline lens, allowing objects at varying distances to focus clearly on the retina. The ciliary muscles contract to make the lens thicker for near vision and relax to make it thinner for distant vision. It also describes the four Purkinje images formed in the eye and their uses in various optical measurements and assessments of ocular structures.
Retinoscopy and its principles
This document provides an overview of retinoscopy, including:
- A brief history and the development of different types of retinoscopes.
- The optical principles behind how retinoscopy works to assess refractive error.
- Different techniques for performing retinoscopy, including static, dynamic, and near retinoscopy.
- Factors that can impact the results or make retinoscopy more difficult in some patients.
- Uses of retinoscopy beyond assessing refractive error, such as detecting other ocular issues.
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Esotropia , classification , diagnosis and management
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accommodation and convergence.pptx
- 2. ACCOMMODATIVE CONVERGENCE: • It is the convergence that occurs when eyes accommodate or when a nerve impulse to accommodate is discharged to the eyes. • Stimulus: • Blurred retinal images
- 4. NEAR REFLEX TRIAD: • What is the near reflex triad? • The near reflex is the action of the eye for adjustment to fixate on a near object. The reflex is a triad which consists of accommodation, convergence and miosis. Spasm of the near reflex (SNR) is when this triad persists when the patient is not fixating on a near object.
- 5. AC/A RATIO: • Accommodative convergence is measured in prism diopters. • Myopes have high AC/A ratio. • Hypermetropes have low AC/A ratio. • Pupillary distance must also be considered in determining the AC/A ratio.
- 6. ABNORMALITIES OF AC/A RATIO: • High AC/A ratio cause excessive convergence and produces convergent squint (esotropia). • Low AC/A ratio cause divergent squint (exotropia).
- 7. PROXIMAL CONVERGENCE: • It is induced by the proximity of the object of regardor the awareness of proximity of near object. Example: • Haploscope optically set at infinity, proximal convergence is used.
- 9. INVERSE RELATIONSHIP: • Proximal convergence ×1/ change in fixation distance • Change in fixation distance is expressed as change in vergence of light i.e in diopters. • Each diopter of change of fixation distance ,an approximate change of 1.5∆ occurs in proximal convergence.