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Retinoscopy Part 2 Objective Refraction MKSharma Ophthalmic Education Ophthalmology
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Retinoscopy || Objective Refraction || M.K.Sharma [Ophthalmic Education] Part-2 • 💠 Use of cycloplegics in retinoscopy:- • Cycloplegics are the drugs which cause paralysis of accommodation and dilate the pupil (cycloplegia). When retinoscopy is performed after instilling cycloplegic drugs it is termed as wet retinoscopy in converse to dry retinoscopy (without cycloplegics). The commonly employed cyclopegics areas as follows:- • 1. Atropine:- • Atropine is indicated in children below the age of 5 years. It is used as 1% ointment thrice daily for 3 consecutive days before performing retinoscopy. Its effect lasts for 10 to 20 days. • 2. Homatropine:- • Homatropine is used as 2% drops. One drop is often instilled every 10 minutes for 6 times and the retinoscopy is performed after 1 to 2 hours. Its effect Jasts for 48 to 72 hours. It is used for most of the hypermetropic individuals between 5and 25 years ofage. • 3. Cyclopentolate:- • Cyclopentolate is a short acting cycloplegic. Its effect lasts for 6 to 18 hours. It is used as 1% eyedrops in patients between 8 and 20 years of age. One drop of cyclopentolate is instilled after every 10 -15 minutes for 3 times (Havener's recommended dose) and the With retinoscopy is performed about 60 to 90 min. later (afterestimating the residual accommodation which should not exceed one dioptre) • 4. Only mydriatic (10% phenylephrine) may be needed in elderly patients when the pupil is narrow or media is slightly hazy. • Note. The mydriatics should be used with care in adults with shallow anterior chamber, owing to the danger of an attack of narrow-angle glaucoma. In older people, mydriasis should be counteracted by the use of miotic drug (2% pilocarpine). • ◾Observations and inferences:- • Depending upon the movement of the red reflex when a plane mirror retinoscope is used at a distance of 1 meter the results are interpreted as: • 1. No movement of red reflex indicates myopia of 1D. • 2. With movement of red reflex along the movement of the retinoscope, indicates either emmetropia or hypermetropia or myopia of less than 1D. • 3. Against movement of red reflexto the movement of the retinoscope implies myopia of more than 1D. • ◾Neutralization:- • when the red reflex moves with or against the movement of retinoscope we do not exactly know the amount of refractive error. However, when the red glow in the pupil does not move then we know for certain that patient has myopia of 1D. Therefore, to estimate the degree of refractive error, the movement of red reflex is neutralized by addition of increasingly convex (+) spherical lenses (when the red reflex was moving with the movement of plane mirror) or concave (-) spherical lenses (when the red reflex was moving against the movement of plane mirror). When a simple spherical error alone is present, the movements of red reflex will be neutralized in both vertical as well as the horizontal meridia. However, in the presence of an astigmatic refractive error, one meridian is neutralized by adding appropriate cylindrical lens with its axis at right angle to the meridian to be neutralized. It is important to note that sometimes, especially, when pupil is dilated, two light reflexes — one central and other peripheral — may be seen. Under such circumstances one should neutralize the central glow because the central parts of cornea and lens are more important in forming the image on the retina. • ◾Rough estimate of refractive error after retinoscopy Objectively, a rough estimate of refraction is made by taking into account the retinoscopic findings, deductions for distance (eg, 1D for 1 m and 1.5D when retinoscopy is performed at 2/3rd m distance) and deduction for the cycloplegic when used (eg, 1D for atropine, 0.5D for homatropine and 0.75D for cyclopentolate). • • Retinoscopy Part- 1 • 👇👇 • • Retinoscopy Part- 1 || Objective Refr... • • Follow us on:- 👇👇 • / ophthalmiceducation • / ophthalmiceducation • Telegram} t.me/OphthalmicEducation • / dr_sharmamanish • • #thecornea #eyestructure #ophthalmicpart #retinoscopy #ophthalmology #ophthalmiceduction #eye
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