Biomedical subjects
Publications and source records attributed to R M Ingram.
Follow-up of a series of 221 children identified by the present methods of screening, and presenting consecutively with squint and/or amblyopia, shows that there has been no demonstrable improvement in the overall incidence and severity of amblyopia 3 or more years later. A new approach to the problem is required, and this might be based on the identification and treatment of amblyopia during the 'sensitive period'.
215 preschool siblings of children presenting with squint/amblyopia were screened by refraction after cycloplegia. The presence of +2.00 or more D of spherical hypermetropia in both eyes, or +1.00 or more D sphere or cylinder of anisometropia was significantly associated (P=0.0779%) with that child being identified 2+ years later as having either squint or amblyopia or both. Astigmatism of +1.50 or more D in either eye was significantly associated with anisometropia (P=0.000 0013%). If bilateral hypermetropia of +2.00 or more DS and/or +1.50 or more D of astigmatism in either eye had been taken as criteria for abnormality (ignoring anisometropia), there was a more significant association (P=0.0025%) between refraction and squint/amblyopia in these siblings. Such a child had 4 times more chance of having a visual defect than one who had no error of refraction when screened. These findings suggest that an environmental factor such as blurred vision may be relatively more important as a cause of squint/amblyopia than a genetically determined neurological abnormality.
Cycloplegic refraction of 1-year-old children is technically possible and is acceptable to mothers as a method for screening children for visual defects. The range of refractions found in a sample of 186 1-year-old children is reported. Prediction of which children are significantly at risk for squint and/or amblyopia is possible on the basis of refractions at age 1 year according to the criteria selected for an 'abnormal' refraction. Bilateral hypermetropia and/or astigmatism or anisometropia at age 1 year was significantly (P less than 1 in 10 000) associated with a child eventually being found to have squint or amblyopia. Both the age of screening and criteria of abnormality will probably need modification. +2.50 or more D hypermetropia in any one meridian of either eye at age 1 year was even more significantly (P = 0.000 000 05%) associated with squint and/or amblyopia. The possibility that meridional hypermetropia could be the basic defect in squint and amblyopia is discussed.
A study has been made of the changes in refraction as a sample of 148 children grew between the ages of 1 and 3 1/2 years. There was no decrease in hypermetropia, but there was a significant decrease in the incidence of astigmatism. Study of the changes in the refraction in the horizontal and vertical meridia of individual eyes gave clear evidence of a trend towards emmetropia if the initial refraction in either meridian was myopic or less than +2.50 D. Above that level the refraction became more or less hypermetropic.
The refractions of 1648 children aged 11 to 13 months are reported. Atropine 1% was used for cycloplegia. 11.83% of the children had bilateral hypermetropia of +2.00 or more D. 13.23% of them had +1.50 or more D astigmatism in one or both eyes, and 6.5% had anisometropia. Anisometropia was significantly (P=0.000 001%) associated with bilateral hypermetropia, but even more significantly (P=0.000 000 4%) associated with astigmatism of +1.50 or more D in one or both eyes.
Cyclopentolate 1% is significantly less effective than atropine 1% at producing cycloplegia in 1-year-old children. If cycloplegic refraction is to be used for investigation or screening children for visual defects during the sensitive period, the more prolonged and profound cycloplegia following atropine could potentially have a disastrous effect on the development of vision. Cyclopentolate 1% would have to be used, and allowance made for its inadequacy as a cycloplegic.
Recovery from general anaesthetic and ocular discomfort may be the only logical reasons for hospitalization after retinal surgery, and 3 days should be sufficient for this--24 hours in most cases. Some patients, discreetly chosen, could be managed on a day case basis, having surgery under local anaesthetic.
All the cases of squint and amblyopia referred to both hospital and school clinics in one district during one calendar year have been reviewed in order to clarify when, where, and how these cases first present to the ophthalmologist. The types of case at present seen in "hospital" and "school" clinics are quite different, and effective screening methods are unlikely to be developed if these two services continue to be regarded as separate entities. Exotropia is much less frequent than esotropia (only 15% of all cases of squint). The concept of a single peak number of first attendances of children with esotropia at age 3 to 4 years is not substantiated. There is a second peak at age 5 years, when children first go to school. In fact 49% first attended after their fifth birthday. The majority (69%) of cases of amblyopia presented after the age of 5 years. Three-quarters of these (46% of the total) have no clinically detectable squint. Neither they, nor those children who have a strabismic amblyopia, but not a cosmetically noticable squint, will at present be detected until they have a sight test at school. This is a measure of the need to re-examine our long-established methods of screening children for amblyopia. One screening test designed to identify both the "squinter" and the "straight-eyed amblyope" is required.
+2-00 to +2-75 dioptres of spherical hypermetropia in the more emmetropic of a pair of eyes is significantly associated with esotropia (P less than 0-001) and the presence of amblyopia (P less than 0-01). Anisometropia is not significantly associated with esotropia (P = 0-31) unless there is spherical hypermetropia of +2-00 dioptres or more in the more emmetropic eye (P less than 0-001). Hypermetropic anisometropia of +1-00 DS or +1-00 D.Cyl. is associated with the presence of amblyopia (P less than 0-001). In the absence of esotropia there is also a significant association between the amount of anisometropia and the initial depth of amblyopia (P less than 0-01). The additional presence of esotropia increases the depth of amblyopia further (P less than 0-05) but not the incidence of amblyopia (P greater than 0-30). The level of significance of the association of refractive errors with squint/amblyopia was itself significantly higher (P less than 0-01) than that between a family history of squint or "lazy eye" on the one hand and squint and/or amblyopia on the other hand. 72 +/- 3% of all cases of esotropia and/or amblyopia in this sample of children had a refractive error of +2-00 DS or more spherical hypermetropia in the more emmetropic eye, or +1-00 D. or more spherical or cylindrical anisometropia. Since there is a close association between the refraction and how, when, and whether a child presents with squint and/or amblyopia, it would seem reasonable to reconsider refraction as a basis for screening young children for visual defects.
A consecutive series of 140 children was observed after strabismus surgery. All the postoperative problems are attributable to general anaesthesia, vomiting and drowsiness being the principal ones. Respiratory difficulties were unusual. There is no reason to keep a healthy child in hospital for longer than one night, and day case strabismus surgery appears to be safe if (1) an experienced doctor gives the anaesthetic, (2) there is adequate supervision for 3 to 4 hours after surgery, (3) the appropriate district nurse is forewarned that a child is returning home after general anaesthesia, and (4) facilities are available to retain a child in hospital if a problem arises before discharge. Signs of emotional trauma may be less in children treated as day cases than in those hospitalized for one or more nights.
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