Squint

1. SQUINT Made By GH JA HU RA BH

2. ) SQUINT (STRABISMUS DEFINITION: It is the condition in which visual axis of the eyes are not directed simultaneously to the same fixation point. OR Squint ( tropia ) is misalignment of visual axis of the two eyes. VISUAL AXIS: It is imaginary line, which joins the object of regard to the fovea.

3. CLASSIFICATION OF SQUINT Pseudo Strabismus or apparent squint Latent Squint or heterophoria Manifest Squint or heterotropia Uniocular Alternating Convergent Divergent Convergent Divergent Paralytic (Non–Concomitant) Squint Concomitant (Non–Paralytic) Squint

4. ORTHOPHORIA: It is the ideal condition in which visual axis of eyes are directed simultaneously to the same point of fixation both at near and distance when fusion is suspended. PSEUDO SQUINT OR APPARENT SQUINT: It is the condition in which visual axis are in fact parallel, but the eyes appear to have squint. OR The presence of epicanthal and high errors of refraction simulate squint but in fact there is no squint. CAUSES: Prominent epicanthus fold gives false appearance of esotropia . Wide separation of two eyes gives false appearance of exotropia . LATENT SQUINT (HETEROPHORIA) In latent squint, a tendency for deviation of the eyes is present when the fusion is broken. However, the eyes regain their normal alignment or position with fusion.

5. TYPES ESOPHORIA : There is tendency for deviation of the eyeball inwards. It is more common in: Younger age group Hypermetropes due to excessive use accommodate. EXOPHORIA : There is a tendency for deviation of the eyeball outwards. It is more common in: Older age group Myopes due to less use of accommodative convergence.   HYPERPHORIA : There is a tendency for deviation of the eyeball upwards. CYCLOPHORIA : There is a torsional deviation of the eye. ANISoPHORIA : The deviation of the eyeball varies with the direction of gaze. SYMPTOMS: Over lapping of words while reading. Headache or eyeache is the most common. Difficulty in changing focus from one distance to another is often noticed. Photophobia is very common, which is relived by closing one eye. Blurring or crowding of words while reading. Intermittent diplopia . CAUSES: Occupations requiring too much close work such as goldsmith, watchmakers. General poor health, fatigue and advancing age.

6. INVESTIGATION: Cover test, Maddox rod test (for distance), Maddox wing test (for near), Prism vergence test. COVER TEST: PRINCIPLE: Fusion of the two eyes is abolished by covering one eye . MADDOX ROD TEST: PRINCIPLE: This test is done to find out heterophoria for distance. It alters the appearance of the retinal image in one eye. There is no stimulation given to fusion. MADDOX WING TEST: The Maddox Wing Is an instrument that dissociates the two eyes, for near fixation (one – third of a meter) and measures the amount of heterophoria . PRISM VERGENCE TEST: PRINCIPLE: The actual measurement for the deviation and strength of the muscles involved are tested. The muscles are forced to act with maximum effort against prism. TREATMENT: Eso and Exophoria cause no symptoms & need no special treatment. R. error is determined and corrected. Exercises includes: PENCIL EXERCISE: A pencil is held in the hand and brought slowly towards the nose until the tip appears double. The two images are then fixed into a single image by an effort 8–10 times. This is respected 3–4 times a day for several weeks. 5. Prism can be prescribed in the spectacles. 6. Proper position, distance and illumination while doing near work. 7. And at last surgery. MANIFEST SQUINT (HETEROTROPIA) In manifest squint the deviation of eye is present as such. It is of two main types namely concomitant squint and Paralytic squint. TYPES: The types of tropia (squint) depend upon the direction of deviation. ESOTROPIA: Convergent Squint EXOTROPIA: Divergent Squint

7. HYPERTROPIA: Upward Deviation HYPOTROPIA: Downward Deviation INCYCLOTROPIA: Upper end of vertical corneal meridian deviates nasally. EXCYCLOTROPIA: Upper end of vertical corneal meridian deviates temporally. CAUSES Paralytic (Non–concomitant) squint Non–Paralytic (Concomitant) squint PARALYTIC (NON–CONCOMITANT) SQUINT: In paralytic squint there is a deviation of the eye caused by the paralysis of EOM. The deviation of the eye varies in different directions of gaze. OR It is the deviation of the eyes, which is irregular and varies in different directions of the gaze. CAUSES: It is caused by neurological lesion one of the EO nerves such as 3 rd , 4 th or 6 th nerve. The lesion may be. Congenital–present at birth Acquired Trauma Inflammations such diabetes mellitus neuropathy. Infection–virus and bacteria (syphilis) Raised intra cranial Pressure. SYMPTOMS: Diplopia or double vision. Due to diplopia nauxia SIGNS: Sudden as occur at any age. LIMITATIONS OF MOVEMENT: Test the ocular movements in all the cardinal direction. If a muscle is paralysed , there will be limitation of movement. FALSE ORIENTATION: The patient is not able to grasp or point the object correctly on the side of action of paralysed muscle . POSITION OF THE HEAD: The patient’s head and face is turned towards the direction of the action of the paralysed muscle. INVESTIGATION: Blood pressure Blood CP & ESR Blood Sugar

8. MANAGEMENT : Limitation of ocular movements. Cover test Diplopia chart Worth’s four dot test Hess screen Synoptophore TREATMENT: Diplopia main symptom treated by prism Botax (injection) into the opposite overactive muscle causes its denervation, the muscle become weak hence eye becomes straight.   SURGERY : After 6–9 months till the recovery of nerve function is stabilized. NON – PARALYTIC (CONCOMITANT) SQUINT: It is the deviation of the eyes, where deviation remain the same in all direction of the gaze. TYPES: Esotropia (convergent squint ) Exotropia (Divergent Squint) CAUSES: Ref, error Hypermetropia is associated with convergent squint Myopia is associated with convergent squint Astigmatism is associated with convergent squint. CLINICAL FEATURES: Deviation may be: Uniocular – associated with reduced vision Alternate – associated with more or less equal vision in both eye. Amblyopia (Lazy eye) INVESTIGATION: Hirschberg test Cover test Synoptophere TREATMENT: Optical correction of ref – error Amblyopia therapy Bifocal glass: Convex glasses, for near correct the deviation, when it is due to abnormal ratio of accommodative convergence to accommodation. Orthoptic exercises: To achieve the Binocular single vision.

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