Simple Retinoscopic Screening

Eye (1988) 2, 309-313 Simple Retinoscopic Screening JMOLVER Cardiff Summary A simplified retinoscopic technique to screen for refractive errors in children is presented. The technique described was assessed in 98 children and the results correlated with full retinoscopic refractions. All tests were done with cycloplegia. Orthoptists' results using the simple retinos copy compared well with the full retinoscopic findings of the ophthalmologists, with an overall sensitivity of 90% and specificity of 74%. These results compare favourably with more techni cal refractive screening methods. This technique may be suitable as an adjunct to vision screening in pre-school children. Why screen? stUdy population, perhaps by photorefrac Ingram in 19771 reviewed cases of strabismus tion. Ideally, if planning a refractive screen and amblyopia seen in one year and found ing programme it should be demonstrable that 75% of amblyopes identified after the that the treatment offered is beneficial - ie age of 5 years had no detectable deviation that spectacle correction at an early age does clinically and suggested that a screening test reduce the prevalence of amblyopia and was required to identify this group of strabismus in the community. This would 'straight eyed amblyopes' at an earlier age require a well planned prospective ran and thus prevent the amblyopia. He domised trial. This is being done by Atkinson refracted a sample of children with esotropia and preliminary reports (unpublished) and/or amblyopia2 and found a significant suggest that spectacle corrected hyperopic association with hypermetropia of +2. 0 DS infants do have a significantly lower inci or more and/or anisometropia of a similar dence of strabismus and amblyopia than amount. He therefore recommended consid untreated hypermetropic infants. ering refraction as a screening procedure. In Taylor6 has argued that only bilateral vis 19793 he reported the effective use of full cyc ual handicap is socially significant and loplegic refraction in one year old children debilitating, whereas unilateral amblyopia is and a correlation of hypermetropia of +2.5 rarely debilitating unless there is injury to the DS or more at this age with the development other eye which is uncommon as shown by of later amblyopia and/or strabismus. Tommila and Tarkkanen.7 Taylor therefore However, Ingram4 found that spectacle recommends caution when considering a correction of very high hypermetropia from screening program lest it be cost ineffective the age of one year did not reduce the sever and divert resources from important research ity of amblyopia or incidence of strabismus, in to the cause of amblyopia. and suggested5 that proposed screening at age three years for mild refractive errors has How to screen? yet to be evaluated on a larger scale than his Having decided to screen for refractive errors From, University Hospital of Wales, Cardiff Correspondence to: Jane M Olver FRCS, Moorfields Eye Hospital, City Road, London EC1V 2PD Presented at the Annual Congress of the Ophthalmological Society of the United Kingdom, April 1987 310 J. OLVER Table I Previously described methods of screenings for refractive errors RETINOSCOPIC Use of Cycloplegia FULL RETINOSCOPY Ingram. (3) + RAPID RETINOSCOPY Friedman et al. (8) NEAR RETINOSCOPY Mohindra. (9) PHOTOGRAPHIC Photographic screening. Kaakinen (10) -/+ Otago photo screener. Molteno et al. (11) Photorefraction. Atkinson et al. (12) -/+ the methods available include retinos Table II copic3•8•9 and photorefractive. IO,II,12 (See Table I). Basic equipment guttae cyclopentolate 1 % Ingram3 used full cycloplegic retinoscopy streak retinoscope as a screening technique and found it imprac plus 3 ds lens tical as it was lengthy, and hence costly in terms of personnel. Friedman et al8 used rapid retinoscopy on tributing to our knowledge of the type and 38,000 small children without cycloplegia and changes of refraction with age in children. 13,14 without trial lenses. This had a high false However, photorefraction has not found positive rate of almost 52%. widespread application as a screening Mohindra9 described a near retinoscopy method in this country, The methods are technique without cycloplegia performed technical, require interpretation and may be with monocular fixation at 50cms on the dim costly, e. g. video photorefraction. retinoscopy light and employing trial lenses. Mohindra's near refraction correlates well Who should do the screening? with full retinoscopy and is a possible alterna Orthoptists are already involved in VISIOn tive method for screening although it has not screening programmes for the detection of been used as such. amblyopia and squint. This role might The photorefractive methods use relatively appropriately be extended to include screen expensive equipment and correlate well with ing for refractive errors which can be signific full retinoscopic refractions. ant in the development of amblyopia and The photorefractive 'camera flash' strabismus, technique used by KaakinenlO can screen for The aim of this study was to see if orthop both strabismus and refractive errors by tists could use a simple retinoscopic screening photography of corneal and fundus reflexes technique, to detect refractive errors in chil without cycloplegia. The accuracy is dren; it does not question the rationale for increased with cycloplegia. screening, only offers a possible method. The Otago photoscreener11 also uses a camera to detect both strabismus and refrac Methods tive errors without the use of cycloplegia. Ninety-eight consecutive children , aged 6 Isotropic photo refraction by Atkinson et months to 11 years, median 2 years, newly al12 USes three photographs, one of the pupils referred to the Orthoptic Department in Car and two with set values of defo cus to produce diff were screened for refractive errors by an 'blur circles', the size of which are used to orthoptist using simplified retinoscopy under calculate focusing and hence refractive status cycloplegia, (See Table II for basic equip of the eye, Cycloplegia is not usually used. ment used). Those children found to have Photorefraction has proved an invaluable refractive errors were placed ,Into four research tool in vision research greatly con- categories according to defined criteria SIMPLE RETINOSCOPIC SCREENING 311 Table III Criteria used for diagnostic classification ophthalmologist was due to overdiagnosis 141 93 (15%) which was particularly true for 1 MYOPIA Light reflexAGAINST hypermetropia and astigmatism. movement without any The number of unco-operative children lens. THRESHOLD -1.5 DS was 5/98 (5.1 %) who were all infants. The 2 HYPERMETROPIA: Light reflex WITH results of repeat screening of these children movement with +3.0DS are not included in the Tables. lens. THRESHOLD + 1.5 DS Discussion 3 ASTIGMATISM Light reflex The results using simple retinoscopy compare DIFFERENT between favourably with other methods of screening vertical and horizontal described. It is not possible to compare all axis. the methods directly because the data pre THRESHOLD +0.5 DS sented are not always in a similar form and 4 ANISOMETROPIA: Light reflex DIFFERENT between the refractive thresholds selected differ eyes. slightly. (Table VI). THRESHOLD +0.5 DS In this study using simple retinoscopy + 1.5D was allowed for working distance with no subtraction made for cycloplegia. Hence, when using either no lens in front of the child (Table III). The simple retinoscopic test uses a threshold of -I.5DS is detected and with a a streak retinoscope first without and then +3.0 DS lens a refractive threshold of with a plus 3.0 DS lens both in the horizontal + 1.5DS. The orthoptists detected low and vertical meridian of each eye. The amounts of astigmatism and anisometropia orthoptist was asked simply to note the direc easily. tion of movement of the retinoscopic shadow Eleven orthoptists participated in the study in each of the four test situations on each eye, after receiving a brief instruction period; thus detecting approximately myopia or their individual relative inexperience contri hypermetropia exceeding 1.5 D and anything buted initially to the number of false nega more than a small astigmatic error or tives which decreased with their increasing anisometropia. expertise as the study progressed. Each child was then refracted by an Inadequate cycloplegia probably contributed ophthalmologist. All tests were performed in to a small number of false negatives. The a dim room at a working distance of 2/3 m over-referral rate of 15% (false positives) under cyclopentolate 1 % cycloplegia. included children with off axis retinoscopy. Neither the orthoptist nor the ophthal These are practical points which once recog mologist had prior information on the child nised can be avoided. The rate of overdiag or of each other's findings. The refractive nosis is acceptable for a screening method classifications by the orthoptists using simple especially as it should reduce with practice. retinoscopy were compared with the full Rapid retinoscopy by Friedmann8 without retinoscopic refractions by the opthal cycloplegia has a false positive rate of almost mologists and the sensitivity and specificity of 52%. Photorefraction using Kaakinen's the orthoptist ' s screening were computed. method without cycloplegia IS had a low false The McNemar test was used to assess the sig positive rate and the small number of false nificance of differences. negatives were of low refractive errors. The test without cycloplegia

Load more