True regarding accommodative esotropia is
D i.e. Miotics are used in high AC/ A ratio Accomodative Esotropia Near vision involves both accommodation and convergence. Accomodation is the process by which the eye focuses on a near target, by altering the curvature of the crystalline lens. Simultaneously, the eyes converge, in order to fixate bifoveally on the target. Typical history is of intermittent esotropia that appears between 6 months and 7 years of age (average 30 months) toward the end of the day or when the child is very tired, ill or day dreaming (especially at near fixation distances, such as across the dinner table). At onset, the child may experience asthenopia (as fusional divergence amplitudes are stressed) and may rub the eyes or squint), an older children may complain of headaches or diplopia. As the esotropia becomes more frequent, abnormal retinal correspondence & suppression, when available, relieve asthenopic suymptoms at the possible expense of fusional divergence amplitude. Classification & Manifestations Refractive accommodative esotropia Accomodative convergence/ Accomodation (AC/A) ratio is normal and esotropia is a physiolocal response to excessive hypermetropia, usually between +4.0 and +7.0D. Patients with high hyperopia must generate large accommodative input to see clearly at near fixation and thus stress fusional divergence amplitudes. They may choose blurred vision and maintain comfoable single binocular vision, or they may choose clear vision and risk asthenopia or esotropia. The patient with high hypermetropia (hyperopia) who do not develop esotropia, yet who maintain excellent visual acuity, often have low AC/A ratio. The magnitude of the detion varies little (usually < 10 A) between distance and near vision. The ocular detion is usually greater for near than for distance fixation. (wrong in Parson) Fully accommodative type is completely eliminated by optical correction of hypermetropia; where as paially accommodative is reduced, but not eliminated. Non-refractive accommodative esotropia It is associated with high AC/A ratio in which a unit increase of accommodation is accompanied by a dispropoionately large increase of convergence in the absence of significant hypermetropia. The two types are : - Convergence excess, is characterized by high AC/A ratio d/t increased AC (Convergence is exaggerated but accommodation is normal), normal near point of accommodation and straight eyes for distance, but esotropia for near. - Hypoaccomodation esotropia, is characterized by high AC/A ratio d/t decreased A (accommodation is weak, necessitating increased effo, which is accompanied by a strong convergence response), remote near point of accommodation, and small refractive error. Mixed Accomodative esotropia Hypermtropia and high AC/A coexist, resulting in esptropia for distance, which increases markedly (> 104) on near fixation. Treatment plan Refractive correction Record the distant vision & angle of detion of each eye. Then estimate error of refraction by retinoscopy after prescribing atropine ointment 1% tds for 3 days. The angle of detion is likely to be less under atropine in case of hypermetropes with convergent squint or more in myopes with divergent squint. In hypermetropes no deduction for effect of atropine should be made. - In a children under the age of 6 years, the full cycloplegic refraction revealed on retinoscopy should be prescribed (with a deduction only for working distance). And the child is reavaluated after a month's full time wear of the prescription. If the distance & near esodetions are reduced to with in the monofixational range ( 8 Aof estropia) and the child has a comfoably controlled phoria & no aesthenopia signs & symptoms, the treatment is considered successful & the patient is re-evaluated 3-6 months later. Now if the distance tropic is greater than the above limit, the cycloplegic refraction is repeated; if it is still so with the new refraction the patients becomes a candidate for surgery. If the distance detion is controlled but an esotropia greater than the above limit is present at near fixation or if symptomatic phoria at near fixation persists, the patient is given bifocal glasses. - After the age of 8 years, retinoscopy should be performed without cycloplegia & the maximum amount of plus that can be tolerated prescribed. - Bifocals act by relaxing the accommodation & thereby decreasing the accommodative convergence. It may be prescribed if there is accommodative esotropia for near. (high AC/A ratio). The minimum lens power that conves esotropia to an esophoria is prescribed to prevent excessive relaxation of accommodation. They should initially be prescribed in executive type, in which the intersection crosses the lower border of pupil. - Children with non refractive accommodative esotropia are prescribed bifocals with near addition of +3.0 D to eliminate accommodative convergence by removing the need to accommodate for viewing near objects. - The patients is asked to wear the bifocals for 1 month and then return for reevaluation; rarely except for V-pattern esotropia, does the near detion not respond to bifocal prescription if the distance detion is controlled using full cycloplegic refraction. Patients with V-pattern accommodative esotropia may require miotics alone or in addition to single vision glasses, as bifocal require downgaze fixation & detion is largest in downgaze in such patients. - The strength of lower segment should be gradually reduced at about 6 years of age, roughly 0.5-0.75 D every 6 months, beginning with bifocals. It is often possible to rid children of their bifocals by 8-9 years of age and of their mild to moderate hyperopic correction by the early teens. Patients who have high hyperopia, astigmatism or anisometropia may require optical correction for acuity purposes after their accommodative esotropia has resolved. Contraindications for treatment with bifocals are the presence of amblyopia and the reduction but not complete elimination of esotropia at near fixation. - Miotic therapy can be used sho term in younger children (< 1 year) with accommodative esotropia d/t high AC/A ratio who will not wear spectacles. Ecothiopate iodine 0.125% once daily or 4% pilocarpine q.i.d. are used. The formation of iris cyst induced by ecothiopate can be prevented by simultaneous administration of 2.5% phenylephrine dropsQ twice daily. It works by inducing peripheral accommodationQ (i.e. direct stimulation of ciliary muscle rather than that mediated by 3"1 cranial nerve.) Less accommodative effo is therefore required by patient for near vision & thereby less accommodative convergence is induced. It however results in blurred distant vision. As a rule glasses and miotics are equally effective treatments and it is rare for a patient to respond to one but not the,otherQ, conversely use of both together rarely 104) on near fixation. " v:shapes="_x0000_s1026">salvages a patient who does not respond to one or otherQ. An intellectual preference exists for refractive treatment for the highly hyperoic refractive accommodative esotropia and miotic treatment for the patient who has a high AC/A ratioQ. Treatment of amblyopia & ohoptic training - Ohoptic training by synaptophore cultivate binocular vision & stereoscopic fusion. It is of great value but rarely cures a squint of over 10 degrees detion or one of the long standing. It is rarely wohwhile to persist with it as a sole method of treatment if the detion is not corrected within 3 months. Surgery is classically done for nonaccomodative component of distance esodetionQ, with an arbitrary addition (1mm additional recession per medial rectus) for a high AC/A ratio. - Surgery is indicated when angle of squint is 10deg or more with correcting lenses and in children when ohoptic training has failed to correct the detion with in a reasonable time. As a general rule if it has to be done it should be undeaken early & ceainly as soon as child is old enough to co-operate in post operative ohoptic treatment, usually between 4 & 5 years of age but preferably as early as 18 months if required (gives better results). Postponment until the child is 10 years old or more usually results in permanent amblyopia & failure to establish binocular vision. The operation is then purely cosmetic.
Glasses are used when miotics ineffective
Miotics are used when glasses are ineffective
Use of both together salvage patient who does not respond to one
Miotics are used in high AC/ A ratio