INDUCCIÓN 10 SEMESTRE - EXAMEN OFTALMOLÓGICO

Introduction to Ophthalmological Examination

Objectives of the Ophthalmological Exam

• The primary goal is to evaluate visual function and ocular health.

• Specific objectives include obtaining a comprehensive ocular and systemic history, identifying risk factors for eye diseases, and documenting signs or symptoms of systemic diseases.

• It also aims to determine the optical state and health of the eye, diagnose ocular diseases, and discuss findings with patients.

Essential Ophthalmic Equipment

• Key tools include:

• Snellen Visual Acuity Chart: Used for assessing distance vision.

• Near Vision Chart: For evaluating near visual acuity.

• Pinhole Occluder: Helps in determining refractive errors by blocking peripheral light rays.

• Slit Lamp: Primarily used for examining the anterior segment of the eye; can be combined with auxiliary lenses for posterior segment evaluation.

Detailed Instruments Used in Eye Exams

Additional Diagnostic Tools

• Goldmann Applanation Tonometer: Measures intraocular pressure when attached to a slit lamp.

• Retinoscope: Provides objective measurements of a patient's refractive status through retinoscopy.

• Direct/Indirect Ophthalmoscopes: Used for examining the posterior segment and assessing red reflexes; indirect ophthalmoscopes require special lenses.

Specialized Measurement Devices

• Keratometer: Measures corneal curvature, essential for contact lens fitting and diagnosing conditions like keratoconus.

• Exophthalmometer: Evaluates the position of eyeballs by measuring distances from orbital rim to cornea vertex.

Assessing Visual Acuity

Measuring Visual Acuity

• Visual acuity is defined as the ability to discern fine details; it is measured under standardized lighting conditions at specific distances (6m or 20 feet).

• The Snellen chart displays letters of varying sizes; normal vision is recorded as 20/20 (or equivalent). A patient with 20/40 vision sees at 20 feet what a person with normal vision sees at 40 feet.

Procedure for Testing Distance Vision

• Steps include covering one eye without applying pressure on the eyelid, having patients read from top to bottom, then repeating with the other eye while recording results both with and without corrective lenses if applicable.

Understanding Refractive Errors

Identifying Refractive Issues

• If visual acuity is low, use a pinhole occluder to differentiate between refractive errors (like myopia or hyperopia) versus organic causes (like cataracts). If vision improves using this tool, it indicates an uncorrected refractive error; no improvement suggests an underlying pathology such as retinal disease or optic nerve issues.

Alternative Tests When Standard Charts Fail

• If patients cannot read even large optotypes (e.g., 20/400), alternative assessments involve counting fingers or detecting hand movements before progressing to light perception tests until establishing whether they perceive light or not (NPL).

Ocular Motility Assessment

Evaluating Eye Movement

• The second step involves assessing ocular motility through extraocular muscles divided into recti (medial/lateral/superior/inferior) responsible for various movements like adduction/abduction/elevation/intorsion/extorsion based on cranial nerve innervation patterns.

This structured approach provides clarity on key aspects discussed in María Antonia Cárdena's presentation regarding ophthalmological examinations while ensuring easy navigation through timestamps linked directly to relevant content sections.

Ocular Motility and Clinical Tests

Eye Muscle Functions

• The inferior rectus muscle is responsible for depression, extorsion, and adduction of the eye, innervated by the third cranial nerve.

• The superior oblique muscle performs intorsion, depression, and abduction, moving the eye inward and downward; it is innervated by the fourth cranial nerve (trochlear nerve).

• The inferior oblique muscle facilitates extorsion, elevation, and abduction, moving the eye inward and upward; it is also innervated by the third cranial nerve.

Ocular Movements

• Ocular motility refers to the coordinated movement of eyes in all directions for binocular alignment and stable vision involving 12 ocular muscles (6 per eye).

• Monocular movements (ductions) include adduction (inward), abduction (outward), elevation (upward), depression (downward), intorsion (rotation towards nose), and extorsion (rotation towards temple).

• Binocular movements are classified into versions (same direction movements) or vergences (opposite direction movements); versions involve coordinated action of muscles from both eyes.

Vergence Movements

• Versions allow simultaneous movement in one direction; for example, right gaze involves lateral rectus of right eye and medial rectus of left eye.

• Vergences include convergence (both eyes move inward to focus on near objects) and divergence (both eyes move outward to focus on distant objects).

Clinical Tests for Eye Alignment

• The Brookner test uses a direct ophthalmoscope at about 1 meter distance to assess red reflex symmetry; an asymmetric reflex may indicate strabismus or visual axis opacity.

• The Hirschberg test compares corneal reflections with a flashlight; centered reflections suggest normal alignment while decentered ones indicate strabismus.

Pupillary Response Examination

• Pupillary examination assesses light response integrity through size, shape, symmetry at rest; anisocoria (>1mm difference in pupil size) can be pathological.

• The light reflex evaluates pupillary constriction in response to light: direct reflex occurs in illuminated pupil while consensual reflex occurs in opposite pupil when one is illuminated.

Pathway of Light Reflex

• Light stimulus travels via optic nerve to optic chiasm where nasal fibers partially decussate before reaching pretectal nucleus projecting bilaterally to Edinger-Westphal nuclei.

• Efferent fibers travel with oculomotor nerve to ciliary ganglia where postganglionic fibers reach sphincter pupillae causing bilateral miosis upon illumination.

Additional Testing Techniques

• Alternating light test assesses afferent pupillary pathway detecting relative afferent pupillary defect or Marcus Gunn pupil by illuminating each eye alternately without fusion.

Pupillary Response and Visual Field Examination

Pupillary Response Assessment

• The pupillary response is evaluated by repeatedly changing the light source between both eyes, observing direct pupillary reactions. If both pupils constrict without dilation when switching the light, it indicates intact afferent pathways.

• In cases of afferent pupillary defect, stimulating the affected eye with light results in insufficient signals to activate the pupillary reflex, leading to reduced miosis or slight midriasis in both pupils.

Campimetry: Understanding Visual Fields

• Campimetry measures the total visual field area a person can see while focusing on a central point, including peripheral vision. Each eye has its own visual field with binocular overlap.

• There are different types of campimetry: confrontation (manual and quick) compares patient and examiner fields, useful for detecting significant defects like hemianopsias or scotomas.

• Computerized campimetry is more precise and quantitative; it generates detailed maps of visual fields through patient fixation on points responding to light stimuli, identifying scotomas and patterns typical of conditions like glaucoma.

External Eye Examination

• The external examination systematically evaluates ocular structures and surrounding areas to detect early signs of ophthalmic diseases or anatomical anomalies; it's foundational in any ophthalmological assessment.

• Initial observations include facial symmetry, ocular alignment, eyelid position/mobility, and visible signs such as proptosis or ptosis; these can indicate underlying orbital pathology or other issues.

Palpation and Additional Tests

• Soft palpation around the orbit may reveal pulsations from the globe; tests like Schirmer's assess tear production in conditions such as Sjögren's syndrome. Auscultation may identify vascular sounds associated with carotid-cavernous fistulas indicated by pulsatile proptosis.

Biomicroscopy Techniques

• Biomicroscopy utilizes a slit lamp for magnified examination of ocular tissues using various lighting techniques; it allows cross-sectional views of transparent/translucent tissues essential for diagnosis.

• The evaluation order begins with lacrimal glands/skin around the orbit followed by eyelids/lashes, conjunctiva/sclera/cornea/iris/lens/vitreous body ensuring thorough inspection for abnormalities at each level.

Identifying Eyelid Anomalies

• Common eyelid issues include lagophthalmos (inability to fully close eyelids), ectropion (outward turning), entropion (inward turning), and infections like dacryocystitis affecting tear drainage systems. Assessing these conditions is crucial for proper management strategies.

Ocular Examination Techniques

Understanding Pingueculae and Pterygia

• Pingueculae and pterygia are conditions affecting the conjunctiva, with emphasis on evaluating scleral hyperemia which may present as a bluish coloration.

• Epiescleritis is described as an immunologically mediated inflammation that is benign, short-lived, and painless, contrasting with scleritis which involves deep hyperemias and prolonged pain.

Assessing Tear Film Stability

• The tear film meniscus and breakup time (BUT) are critical for diagnosing dry eye syndrome; BUT measures the stability of the tear film.

• A drop of fluorescein is placed in the conjunctival sac to observe under cobalt blue light for areas indicating tear film rupture.

Corneal Health Evaluation

• Corneal ulcers and vascularization can be detected through positive fluorescein staining indicating corneal epithelial loss.

• Anterior chamber anatomy is discussed, highlighting its role in assessing conditions like traumatic hyphema (blood accumulation) or hypopyon (pus presence).

Gonioscopy: Evaluating Anterior Chamber Angles

• Gonioscopy assesses angular openness to evaluate closure risk; grades range from 0 (closed angle) to 4 (open angle).

• This technique aids in glaucoma diagnosis by visualizing structures at the iris-corneal junction where aqueous humor drains.

Intraocular Pressure Measurement

• Tonometría measures intraocular pressure crucial for glaucoma management; normal values range from 10 to 21 mmHg.

• Goldmann applanation tonometry is considered the gold standard for measuring intraocular pressure using fluorescein dye.

Posterior Segment Examination Techniques

• The posterior segment includes evaluation of the optic nerve, retina, pigment epithelium, choroid, and sclera under pharmacological dilation.

• Indirect ophthalmoscopy utilizes binocular viewing systems with adjustable lighting to assess posterior structures effectively.

Optic Nerve Assessment

• Observations include evaluating disc color (normal should be pink), defining borders clearly, and assessing excavation depth indicative of potential optic neuropathy or glaucoma damage.

Examination of the Eye: Key Pathologies and Findings

Optic Nerve and Retinal Assessment

• The presence of papilledema indicates potential optic nerve issues, with blurred disc margins suggesting conditions like glaucoma, ischemic optic neuropathy, optic neuritis, or papilledema.

• In retinal examinations, signs such as bright foveal reflex in the macula and well-defined vessels are crucial; absence of hemorrhages or exudates is also important for a healthy retina.

• Common retinal pathologies include retinal detachment and central retinal vein occlusion. Diabetic retinopathy presents with hard exudates and multiple punctate hemorrhages.

• Hypertensive retinopathy may show arteriovenous crossings, hard exudates, and cotton wool spots. The macula is vital for fine vision; its anatomical relationship to the optic nerve should be preserved.

Macular Health Indicators

• Normal macular appearance includes a healthy fovea; conditions like cystoid macular edema or diabetic macular edema can significantly alter its structure.

Vitreous Body Considerations

• The vitreous body is a gelatinous substance that maintains eye shape; it normally adheres to the retina but can detach with age due to liquefaction.

• Posterior vitreous detachment is common in aging individuals. Severe cases may lead to traction on the retina causing tears or detachments. Hemorrhage within the vitreous cavity is another critical finding during physical examination.