5.0 pediatric refraction


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  • The assessment of refractive status in very young children is often not conducted in the same manner as for adult patients. In particular, the child’s age, their cooperation and dynamic refractive status will be key factors which influence the accuracy of refraction. For this reason, it is often necessary to choose procedures which inhibit or minimise accommodative activity. This can be achieved by fogging with positive lenses or rousing the tonic (resting) accommodation
    (dry refraction), or with pharmacological agents (wet refraction).
  • Near retinoscopy is valuable in certain situations in which a cycloplegic refraction may not be appropriate. Such cases may include cases in whom
  • 5.0 pediatric refraction

    1. 1. PAEDIATRIC REFRACTION Gaurish Shrestha, M.Optom, FIACLE Program Co-ordinator Bachelor of Optometry program Institute of Medicine
    2. 2. Introduction  To determine the refractive status of infants and preverbal children, an objective refraction is usually used  A great expertise is necessary in determining refractive state in terms of judgement of  Alteration in fixation  Brightness, thickness and movement of light  process of emmetropization  Relationship b/w vision, refraction, state of BSV, and age of a child
    3. 3. Emmetropization  A process operating to produce a greater frequency of emmetropia that would be expected on the basis of chance is known as emmetropization.
    4. 4. Estimation  ½ of variance in refractive error – due to axial length  ¼ of variance – due to corneal curvature  ½o of variance – due to anterior chamber  1/5 of variance – due to measurement errors & variation in lens & refractive index.
    5. 5. What is required in Paediatric refraction?  This technique must be appropriate for non- verbals un-cooperatives, non-communicatives in a child’s part  This technique must provide important information in refractive state of eye repeatably and reliably in instrumental part  This technique must be understandable, easily assessable and accessible  Practitioner must be competent enough to deliver a perfect judgement
    6. 6. What is the greatest challenge to pediatric refraction? A great ability of a child to maintain a wide range of accommodation Un-cooperation Greater range of refraction Difficulty in quantifying visual status Risk of visual deprivation Difficulty in making a child understand wear glasses
    7. 7. What are the instruments we have?  Keratmeter- preferably hand held  Retinoscope– A great weapon  Autorefractor (Need to be portable)
    8. 8. Gauri S. Shrestha,M.Optom, FIACLE Keratometers: uses  CL fitting and verification  Monitoring corneal shape  Calculate the power of intraocular Lens  Helpful to determine ocular refraction
    9. 9. Keratometer-What is its use?  Estimate corneal refractive astigmatism  Regular/ irregular  Distortion in corneal light reflex  Find out abnormal corneal conditions that cause significant refractive error  Predict success of amblyopia therapy
    10. 10. Near retinoscopy (Mohindra retinoscopy)  Near retinoscopy is used with infants and preverbal children from birth to about 3 years of age.  Accurate evaluation of refractive error requires accommodation be stable  This is usually achieved by one of the three methods:  By having the patient fixate at the distance  By using cycloplegic agent  By using a target that doesn’t present an effective accommodative stimulus
    11. 11. Principle of near retinoscopy  The retinoscope is viewed in a dark surround, the filament is not an effective accommodative stimulus  accommodation remains stable during this technique
    12. 12. Actually what happens?  Most patients exhibits anomalous myopia during near retinoscopy  This excessive refractive power reflects a shift of accommodation towards the patients intermediate resting focus under reduced stimulation  To compensate for this effect, a tonus factor is applied to the gross refraction obtained with near retinoscopy  Tonus factor is +0.75
    13. 13. Compensations  In addition, the working distance allowance must be taken into consideration.  If the working distance is 50cm, the WD adjustment is -2.00. the total adjustment factor used is a combination of the working distance allowance and the tonus factor (-2.00D + 0.75D = -1.25)
    14. 14. Indication for near retinoscopy Frequent follow up visits are necessary A child is anxious about the instillation of the drops A child is at risk for an adverse effect to cycloplegic drops (low weight, neurologically impaired) A child has previously had an adverse reaction to cycloplegic drugs
    15. 15. Procedure  All the room light are extinguished and the child is encouraged to fixate the retinoscope light by calling their name and talking reassuringly  Babies will instinctively fixate the light  Retinoscopy is performed monocularly at the working distance of 50cm
    16. 16. The potential sources of error  Too much room illumination. If the room is not dark the retinoscope becomes an effective accommodative target and accommodation becomes active  Performing the procedure at an incorrect working distance  A very active child who will not maintain fixation on the retinoscope
    17. 17. Caution  high refractive errors, poor fixation, poor cooperation, variable pupil,
    18. 18.  Cycloplegia  It is the paralysis of the ciliary muscle of the eye, resulting in the loss of visual accommodation Cycloplegic refraction
    19. 19. Gauri S Shrestha, M.Optom, FIACLE Principle of cycloplegic refraction  Determination of total refractive error during temporary paralysis of cilliary muscles as an instillation of cycloplegic drugs which otherwise doesn’t manifest on subjective non-cycloplegic refraction Total Hyperopia Latent hyperopia Manifest hyperopia facultative hyperopia Absolute hyperopia
    20. 20. Gauri S Shrestha, M.Optom, FIACLE Indication for cycloplegic refraction  Accommodative esotropia  All children younger than 3 yrs  Suspected latent hyperopia  Suspected pseudomyopia  Uncooperative/noncommunicative patients  Variable and inconsistent end point of refraction
    21. 21. Gauri S Shrestha, M.Optom, FIACLE Indication for cycloplegic refraction  Visual acuity not corrected to a predicted level  Strabismic children  Amblyopic children  Suspected malingering and hysterical patients
    22. 22. Gauri S Shrestha, M.Optom, FIACLE Selection and use of specific cycloplegic agents  Variable degree of pupil dilatation and cycloplegia  Instill cycloplegic alone or with mydriatrics Agent [C%] Dosage Max cyclople Duration of effect Residual accom Atropine sulfate 1, 2 1D TID 3 days 3-6 hrs 10-18 days Ngble Sco-mine HBR 0.25% 1D TID 60 mins 5-7 days ngble Cyclo- late HCL 0.5, 1, 2 1D TID 30-45 mins 24 hrs minimal Tro-mide HCL 0.5, 1 1D TID 20-30 mins 4-8 hrs moderate
    23. 23. Important notes  Children with disorders/ Down’s syndrome, cerebral palsy, trisomy 13 and 18, and other central nervous system disorders may have an increased reaction to cycloplegics  Low weight infants may need a modification of dosage
    24. 24. Static retinoscopy  Distance fixation retinoscopy can be used for children from about 2 years upwards, depending on the child and what target is used to gain the child’s attention
    25. 25. Streak motion  Hyperopic patients Light focuses behind the retina Streak movement in same direction as the retinoscope . i.e., displays with motion Add plus lenses to bring the focusing point up to the retina
    26. 26.  Myopic patients Light focuses at the point before the retina Streak movement in opposite direction as the retinoscope i.e., against movement Add minus lenses to move the focal point back onto the retina.
    27. 27.  Emmetropic patients No motion of the reflex observed in the pupil Also known as neutral motion or complete flashing
    28. 28. Gauri S Shrestha, M.Optom, FIACLE What does our practice say?  Advise atropine cycloplegic refraction invariably in the children younger than 2 years  Advise atropine cycloplegic refraction in esotropic children (accommodative type) up to 4 years  After 4 years, advise cyclopentolate cycloplegic refraction up 25-30 years  Above 30 years, check amplitude and lag of accommodation, then advise cycloplegic refraction
    29. 29. Gauri S Shrestha, M.Optom, FIACLE Spectacle prescribing  Prescribing spectacle from cycloplegic finding is an art rather precise science  How to prescribe spectacle? Concept of emmetropization is necessary Esotropic children younger than 4 years, full refractive correction is prescribed With older children, amount of plus can be reduced till fusion is maintained