Treatment of amblyopia after loss of vision in the healthy eye

V. TOMMILA and A. TARKKANEN

Helsinki University . . Eye Hospitul, Helsinki, Finland

ABSTRACT. In the years 1958 to 1978.23 patients with amblyopia were treated because of loss or impending loss of vision in the healthy eye. The age range was 8 to 72 years. the mean age being 30.5 years. Fourteen patients lost vision in their healthy eye while nine patients had impending loss of vision but the good eye was finally saved. The therapy consisted of pleoptic treatment according to Bangerter. The number of treatment sessions per patient varied from 15 to 121, the mean being 54. The average duration of each treatment session was 1.5 hours. Before treatment the mean visual acuity was of the same magnitude in all age groups. The best results were obtained in the 8-20 age group, but visual acuity improved to a similar degree even in the 21-40 and 41-60 age groups. The mean observation periods varied from 4.4 in the youngest age group to 9.5 years in the 41-60 year group. N o significant decline of vision occurred during the observation period in the group in which the healthy eye was lost. On the contrary. in the group in which the healthy eye was finally saved significant long-term improvement was found only in the group aged 20 years or less. The patients who were older than 2 I years showed slight initial improvement, but the visual acuities returned to pretreatment level. After treatment, all patients in the 8-20 age group were able to continue their studies or return to work. 75% of the patients in the 21-40 age group were able to return to their previous work.

l NTRODUCTION

In most children, early treatment of their amblyopic eye can restore good visual acuity and additionally in some children good binocular vision can be achieved. On the other hand, though amblyopic persons have poor visual acuity in one eye, many of them are able to cope visually well in most occupations. Nor has anything deviating from normal been observed in the develop- ment of children whose amblyopia was

detected only at school age. However, amblyopic persons are often psychological- ly burdened by fear of losing visual capabi- lity through the loss of the healthy eye.

Only when vision is lost or loss of vision is impending in the healthy eye, does amblyopia become a real problem. Thus, amblyopia can mainly be regarded as a potential visual danger. In our previous paper the incidence of loss of vision of the healthy eye was found to be 1.75 & 0.30%0 (Tommila & Tarkkanen, 198 1).

Ophthalmic Paediatrics and Genetics

' ' Aeolus Press Arnsierdam I982 1982. Vol. 1. NO. 3 . p ~ . 177-182

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V. Tommila und A . Turkkanen

TABLE 1 . Age ofonset of strabismus or anisometropia.

Number of parients

f.rom birth. from childhood. always 2 I 1

Unknown I

Total 23

From the age of three years

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TABLE 2. Nature o f amblyopia

Number of patienrs

Strabismic amblyopia II Anisometropic amblyopia 8

Cen tral fixation 5 Paracentral fixation 3

Srrabisnius + anisometropic amblyopia 4

Total 23

TABLE 3. Previous treatment of amblyopia

Number of patients

Glasses only 7

Pleoptic treatment I Strabismus surgery I

Glasses + occluhion 2

N o treatment 12

Total 23 -

In this paper, the treatment results in 23 patients with amblyopia are reported. Four- teen of them lost vision in their healthy eye while nine patients had impending loss of vision. Their working capacity after treat- ment was also assessed.

MATERIAL A N D METHODS

The material consisted of 23 patients who, after loss of vision in their healthy eye, were

treated for amblyopia at the Helsinki Uni- versity Eye Hospital. The ages and occu- pations of these patients were stated earlier (Tommila & Tarkkanen, 1981). The age of' onset of strabismus, the type of amblyopia and the previous treatment of amblyopia are listed in Tables 1 to 3. About half of the patients had strabismic amblyopia and about half had received no treatment for amblyopia prior to the loss o f vision of the healthy eye.

TREATMENT OF AMBLYOPIA

All but one of the patients received pleoptic treatment according to the methods of Bangerter (1955). The treatment was started within a few days after injury to the healthy eye or after the diagnosis of disease in the better eye. In cases requiring enucleation. the treatment was introduced as early as before excision of the eye.

Special attention was paid to the testing of visual acuity. If the acuity was below 0.5, a special test chart was used. In this chart (Tommila, 1972) the distances between symbols and spaces between rows vary in relation to letter size and each row contains an equal number of E-letters. Furthermore, the position of the E-letters can be varied to make learning and memorizing of the chart impossible. If the visual acuity improved to 0.5 or better, a standard Snellen chart was used.

The treatment was given by a specially trained pleoptist with several years' full- time experience. The same pleoptist carried out the whole course in any given patient. Before and after treatment the patients were examined by one of us (V.T.) who also studied the patients during treatment at least once a week. The number of pleoptic

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Trealment of amblyopia after. loss o j vision in the healthy eye

treatment sessions per patient varied from 15 to 121, the average being 54. One to two treatment sessions for each patient were given daily and the average duration ofeach session was 1.5 hours. The session was started with pleoptophore treatment combined with finger to spot light exercises. ‘1’0 improve fixation, a localizer was also used. As acuity improved ‘Haidinger brush’ exercises combined with centrophore and synoptophore were added to achieve central fixation. When this was achieved, optotype exercises, e.g., reading, followed. Separation difficulties were treated with a separator or ’Trennungstrainer’. Surgery for strabismus was performed on one patient to improve ti x a t i on.

Treatment was continued until the visual acuity of the amblyopic eye reached 1.0 or n o improvement was observable.

KESU LTS

Results of pleoptic treatment In Table 4 the results of the pleoptic

treatment are broken into two groups in the following manner: (A) Patients with loss of vision in their healthy eye, ( B ) Patients whose healthy eye was finally saved.

The over-all improvement seems to be better in the A group. Three out of four patients aged 8-20 years had lasting visual acuity of 0.6 or more after follow-up period. In the group of 2 1-40 years one out of five patients improved from 0.1 to 1.0 and one patient out of four in the group 41-60 years lrom 0.4 to 1.0.

In the B group where the healthy eye was finally saved one patient in the group 8-20 years improved to 1 .O while in the older age groups visual acuity had returned to pre- treatment level after an observation period

TABLE 4. Results of pleoptic treatment in two groups: ( A ) Patients with permanent loss of vision of their healthy cyc. (B) Patients whose healthy eye was finally 5:IVed

A B a h c a h c

0.1 1.0 1.0 0.15 0.4 0.4 0.25 0.5 0.6 0.2 0.3 0.25 0.6 0.8 0.05 0.05 0.2 0.10 0.4 0.2 0.30 1.0 1.0

0.18 0.63 0.65 0.18 0.44 0.53 Mean

Age group 21-40~,vurs (Npu/ienr.s)

0.1 1.0 1.0 0.3 0.5 0.3 0.05 0.5 0.05 0.1 0.4 0.15 0.01 0.05 0.25 0.6 0.25 0.15 0.40 0.1 0.30 0.30

0.06 0.38 0.45 0.22 0.5 0.23 Mean

Age group 41 -60 years (6 patienis)

0.1 0.3 0.15 0. I 0.25 0.1 0.1 0.4 0.1 0.25 0.05 0.2 0.5 0.30 0.4 1.0 1.0

0.2 0.55 0.46 0.1 0.25 0.08 Mean

Age group over 61 yeur.7 ( I purienr)

0.15 0.4 0.2

a = visual acuity before treatment b = viwal acuity after pleoptic treatment c = visual acuity after Observation period

from 4.4 to 9.5 years although at the end of the treatment slight improvement had taken

In Table 5 fixations at the beginning of treatment, on completing the pleoptic treatment as well as at the end of the obser- vation period are presented. I t can be seen that the improvement is of the same mag-

place.

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V. Tonimilu and A . Turkkunen

TABLE 5 . Fixation of the amblyopic eyes before treatment. on completing the pleoptic treatment. and at the end of observation period

Fi.un~ion

Age group 8-20 years 2 I -40 years 41 -6Oyears Over 60years

Number o f patients 8 8 6 1

a b c a b c a b c a b c

Peripheral 3 5 I I I I Paramacular 3 2 I 1 2 I Para foveal I I I Labile central 1 2 3 5 1 2 4 1 Central 1 4 3 1 3 1 I 1 2 Not known I 5 2

a = fixation before treatment h = fixation after pleoptic treatment c = fixation after observation period

nitude in each group, and there was no significant decline during the observation periods ranging from a mean of 4.4 years to 9.5 years in the 41-60 year age groups.

The working capacity of the patients after treatment has been summarized in Table 6. All patients in the young group were able to continue their studies or return to their previous work while only 50% of the patients aged 21-40 years did so. A further 25% found suitable work while 25% had to retire. The percentage of retirement was

higher in the 4 1-60 year group, although the visual results were of the same magnitude as those in the younger age groups.

COMMENT

I t was difficult to clarify the age of onset of strabismus, but according to the infor- mation obtained strabismus, as expected, had developed at a very early age. After the healthy eye had become affected i t was also difficult to establish whether strabismus or

TABLE 6. Working ability o f 23 patients after pleoptic treatment

Agi' group 8-20 years 2 1-40 .years 41-60,vears over 60.vears

Number of patients 8 School or previous work 8 Suitable work -

Incapable to work (pension) -

8

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Treatment of amblyopia after loss oj'vision in the healthy eye

anisometropia-am blyopia was involved, but the distribution of the patients follows approximately the common distribution of strabismus and anisometropia-amblyopia (Frandsen, 1960). As indicated by the visual acuity and fixation before treatment the present cases of amblyopia were deep and difficult to treat.

At the beginning of the pleoptic treat- ment the mean visual acuity was approximately of the same magnitude in all age groups. Before treatment, the age group 2 1-40 had clearly more peripheral fixations than the other age groups. In the youngest age group, the treatment results and their permanence were best, as expected.

For the present patients the previous amblyopia treatment had been in- significant: only two had received occlusion treatment and one pleoptic treatment. Thus the significance of the previous treatment for the later pleoptic treatment remained unknown in this study.

The results confirm the preliminary impression by one of us (Tommila. 1964) that pleoptic treatment may be beneficial at all ages, if the amblyopic patient is at risk of losing vision in his healthy eye. The results were clearly better in those patients in all age groups who permanently lost vision in their healthy eye. Thus the patients are well motivated for efforts to improve the vision in the amblyopic eye. In the youngest age group the results of treatment and their permanence were good in the group in which the vision of the healthy eye was later restored. However, in the groups aged 21 years or more where the healthy eye was finally saved the visual acuities slightly improved after treatment, but returned to pretreatment level after observation. The treatment was of no permanent value to

these patients. Their impending loss of vision was, however, the reason for thera- peutic trial of the amblyopic eye.

When combined with visual improve- ment, fixations also improved and were still well retained in the 41-60 age group. For a successful result i t is important that treat- ment be started immediately after the impending loss of vision in the healthy eye has been diagnosed, because then i t is often possible to use the fixation of the healthy eye for treatment. The fact that the patient may either become a visual cripple or his working capacity may be restored by treat- ment, makes long-term treatment (two months) justified. In our series the influence of age factor on the fixation results is not demonstrable as has been reported before (Flynn & Cassady, 1978). As a difference to their series we would like to emphasize the intensity of our treatment: the number of treatment sessions per patient varied from 15 to 121, the mean being 54. When each treatment session lasted approximately 1.5 hours, the patients received from 22 to 180 hours of pleoptic treatment.

The benefit of the pleoptic treatment was best reflected in the number of patients who returned to work. I t has been observed earlier that only rarely does the patient gain a sufficient standard of vision to enable him to undertake precision work or prolonged reading (Lyle, 1971). In our series even those patients in the 8-2 1 age group who lost vision in their healthy eye were able to con- tinue normally at school o r in their jobs. In the 21-40 age group all patients except two, who before treatment had very poor visual acuity and peripheral fixation, regained their working capacity. In the 41-60 age group, three of the four patients who lost their healthy eye, had to retire. However,

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V. Tommilu and A . Tarkkanen

three of the total of six patients in this group were able to return to their previous occu- pation. This reflects the significance of age for return to work.

On the other hand, the numbers of patients in all age groups are very small for drawing conclusions. I t should be noted that considerable improvement of visual acuity i n the amblyopic eye was achieved with pleoptic treatment in a patient as old as 72 years, but this acuity was reduced during the observation period. The patient who lost vision in his healthy eye as a result of central artery occlusion, experienced a substantial vibual improvement due to treatment.

The results seem to support the views of V o n Noorden & Crawford (1979) that i t is n o longer justified to speak of the ‘sensitive’

period of the development of‘ the mammalian visual system in general. Rath- er, i t becomes necessary to define sensitivity in terms of behaviour. cortical physiology. or geniculate anatomy.

When good visual acuity in both eyes is achieved by amblyopia treatment in childhood, the patient is freed also from fear of losing his healthy eye and to a great ex- tent a f his feeling of incapacity. Further- more, a normal binocular vision can be achieved with early treatment in childhood in many patients. Therefore. trealment of amblyopia in the first years o f life when good results are quickly achieved with simple methods, should be considered i m port a n t a nd be n e fic i a 1.

REFERENCES BANGERTER. A.: Anth!vopiehehandlung, 2nd edn. S. Karger AG, Basel 1955 FLY”. J . T. & CASSADY, J . C.: Current trends in amblyopia therapy. Oph/ha/molog~~ (Rochc,s/rr) X.(:428-450.

FKANDSEN. A. D. : Occurrence of squint. Acra ophrhul. (Khh.) Suppl. 62, 1960 LYLE. T. K.: Pleoptics in treatment o f esotropia with noncentral fixation. In / . ophrhul. Clin. //:250-252. 1971 VON NOORDEN. G . K . & CRAWFORD. M. L. J.: The sensitive period. Trans. oph/hul. Sot,. U K 99442-446.

TOMMILA. V . : Treatment of amblyopia in loss of vision in the other eye. A m ophrhal. (Khh.) 4?:489-494, 1964 ’TOMMILA. V . : A new chart for testing line acuity in amblyopia. Acru ophrhal. (Khh.) 50:565-569. 1972 TOMMILA, V . & TARKKANEN. A, : Incidence of loss of vision in the healthy eye. Bri/. J . Ophrhol. 65:575-577.

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