CHAPTER 15

CLOSING REMARKS

As outlined in the introduction, the object of the present study was to elucidate the influence of the ”trauma of prematurity” upon the subsequent development and function of the eye. On the basis of the results, an overall assessment will be given below, divided into four items (A to D).

(A) Differences in Ocular Status Between the Premature and Mature Group Around the Age of 10 Years

The premature group (n = 302) of the present material (upper birth weight limit 2000 g) proved to differ from the mature control group (n = 237) in a number of respects:

(1) A slight shift in refractive values towards myopia in the prematures was explicable by a special fraction of early myopia (pre-school myopia), believed to represent ”myopia o f prematurity”.

(2 ) As to repaction components the premature group showed a size deficit manifesting itself primarily in lower values for axial length and corneal curvature radius. The small fraction of pre-school myopes was particularly loaded in several respects, and the prematurity appears to have influenced particularly the develop- ment of the anterior eye segment.

(3) The ocular size deficit in prematures was not isolated, but concurrent with other signs of inhibited somatic development (lower values for body height, circum- ference of skull, etc).

(4) Visual acuities in the premature group showed a significant shift towards the lower acuity levels.

(5) As compared with the mature group, the premature group had a marked preponderance of children with squint and other binocular defects.

(6) A relatively larger number of children in the premature group had signs of retinal lesions (assessed ophthalmoscopically) and visible changes of the lens.

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Visual Disablement in the Premature Group

The literature on the sequelae to prematurity is characterized to some extent by the most severe and most disabling syndromes, within the ophthalmological as well as the paediatric-neurological field. In contradistinction, the present premature group may be considered representative - by virtue of a high tracing and follow-up rate. On this basis it is possible to state the incidence of the various ocular problems (including also the minor ones) in prematures and assess their significance.

(1) Blindness was observed in 1% of the children in the premature group. This frequency must be considered relatively high, compared with that in the general population. On the other hand, it is low when compared with the frequency of blindness in series of prematures from the early years of oxygen therapy.

(2) This, fairly favourable impression still applies when assessing the ophthal- mologikal handicap in the remaining 99% of the premature group. The deviations were only exceptionally disabling per se. Thus, all 99% were considered capable of standing up to the demands of regular school from the visual point of view (with corrected visual acuity 2 6/18). In the long run, however, the increased incidence of binocularity disturbances among the prematures may influence the subsequent choice of occupation, and similarly squint amblyopia is tantamount to a poorer visual reserve. On the other hand, a squint is rarely a real handicap in the course of education.

(C) The ”Trauma of Prematurity”

The surplus of ophthalmologically deviant conditions in the premature group is interpreted as a consequence of the Prematurity per se. It was not possible to arrive at supplementary explanations, neither on the basis of heredity nor in the assessment of a large number of adverse perinatal factors. In other words, the eyes have ex- hibited less possibility of optimal development and function when the violent change of environment at birth has taken place an appreciable time before term. - The lowest birth weight classes appear to be particularly at risk.

(D) Practical Consequences of the Study

The most important practical consequences of the present study are : (1) The main prophylactic measure is still to prevent the occurrence of retro-

lental fibropkzsia. In general, then, there is a question of measures which (a) reduce the frequency of premature birth and (b) secure an optimal obstetrical-paediatric service in connection with birth and neonatal period. - This should include regular ophthalmological follow-up of oxygen-treated prematures within at least the first months of life.

(2) For prematures of a low birth weight (e.g. below the present selected limit of 2000 g) annual ophthalmological follow-up is recommended. This is based partly

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upon knowledge concerning the greatly increased risk of ophthalmological defects (severe as well as mild), partly upon the wish for early therapeutic measures (pro- phylaxis against amblyopia in cases of squint and anisometropia; correction of myopia of prematurity and other major refractive anomalies; social/educational measures in cases of isolated visual defect and of visual impairment combined with other handicaps). - Considering the limited number of children in the lowest birth weight classes, such routine ophthalmological examinations during pre-school age ought to be practicable, at least in countries with a good medical service.

The four items A to D may be summed up briefly as follows:

Premature children who have been of low birth weight exhibit more often than mature children a deviant ocular status, judging by a number of functional and morphological criteria.

Apart porn the few cases of blindness, the ophthalmological defects must be considered predominantly mild, where the functional aspects are concerned. On the basis of an isolated assessment of the ocular findings, it is estimated that 98-99% of the children in the present premature group have a possibility of fending for them- selves without special ophthalmological measures (apart from ordinary glass correc- tion and the like).

The prematurity per se is held responsible for the increased number of oph- thalmological defects in the group of prematurely born children. - The lowest birth weight classes seem to be particularly at risk.

Prematures of a low birth weight must be considered to be ophthalmologically on the whole a group at risk. Therefore, routine prophylactic measures should be carried through, not only during the neonatal period but throughout childhood. The important measures are amblyopia prophylaxis and glass correction, besides the more general opticaleducational aspects.

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