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Year : 1969  |  Volume : 17  |  Issue : 6  |  Page : 250-255

Red filter in the management of eccentric fixation

Department of Ophthalmology, Maulana Azad Medical College and Associated Irwin and G. B. Pant Hospitals, New Delhi, India

Date of Web Publication11-Jan-2008

Correspondence Address:
S.R.K Malik
Department of Ophthalmology, Maulana Azad Medical College and Associated Irwin and G. B. Pant Hospitals, New Delhi
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Source of Support: None, Conflict of Interest: None

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How to cite this article:
Malik S, Choudhry S, Sen D K. Red filter in the management of eccentric fixation. Indian J Ophthalmol 1969;17:250-5

How to cite this URL:
Malik S, Choudhry S, Sen D K. Red filter in the management of eccentric fixation. Indian J Ophthalmol [serial online] 1969 [cited 2021 Sep 25];17:250-5. Available from: https://www.ijo.in/text.asp?1969/17/6/250/38549

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Table 1

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Table 1

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Amongst the various methods known today for the treatment of amblyopia and eccentric fixation, red filter method is of comparatively recent origin. It has been introduced in order to ob­viate some of the inherent short-com­ings in other pleoptic methods such as requirement of regular attendance to the Hospital, spade-work required by the attending doctor, non-availability of elaborate and expensive equipment and the inability to get full cooperation and attention from younger patients. Since the time it was first introduced by Brin­ker and Katz (1963) it is undergoing extensive trials at the various pleoptic centres.

Wratten Gelatin red filter "92" only transmits light belonging to the higher wavelengths of the visible spectrum i.e. red end of spectrum [Figure - 1]. This light preferentially stimulates the cones, the rods being insensitive to this part of the speterum. The principle of red filter treatment depends on the fact that the point of eccentric fixation is cone poor. When this filter is used the red end of the spectrum preferen­tially stimulates the cone rich foveal area. Hence red filter acts by encourag­ing the patient to use fovea in prefer­ence to the eccentric point. The distri­bution of cones in and around macular area is given in [Table - 1].

  Methods and Material Top

Thirty-two cases of eccentric fixation were treated by red filter technique. The cases of eccentric fixation were classified according to Malik, Gupta and Choudhry (1968) (See [Figure - 1]. p. 246).

Red filter which transmits light in the range of 620-700 millimicrons was fixed between two glass pieces fitted on a frame which could be attached to an ordinary spectacle with corrective tenses. The patient was encouraged to do near work with red filter in front of the amblyopic eye while the sound eye remained occluded. Treatment was gradually increased from 1/2 hour to 4 hours per day depending on the toler­ance of the patient. At other times when red filter was not being used, the patient was required to use an occluder in front of the amblyopic eye. The red filter was used for a period of two months to eighteen months.

  Observations Top

Observations regarding the response of 32 cases of eccentric fixation treated with red filter technique are given be­low

(a) Improvement in Visual Acuity [Table - 1]

From [Figure 3] it is evident that out of thirtytwo cases thirteen cases (40.6%) showed improvement in visual acuity. Cases having gross degrees of initial amblyopia i.e. vision 6/60 or less show­ed comparatively poorer results as compared to patients having lesser de­grees of initial amblyopia.

(b) Improvement in Fixational Pattern

Nine cases (28.1 %) showed improve­ment in fixational pattern. All of them attained foveal fixation. In seven cases it was accompanied with corres­ponding improvement in visual acuity. In the other two cases there was im­provement in fixation without any im­provement in visual acuity. From [Figure - 2] it is evident that cases having gross degrees of eccentric fixation showed very little improvement with red filter treatment.

(c) Overall Improvement

Out of thirtytwo cases treated by red filter, fifteen cases (46.9%) showed im­provement in vision, fixation or both. Out of these fifteen cases seven cases (21.9%,) showed improvement both in vision and fixation; in other six cases (18.7%) there was improvement in visual acuity only while in two cases (6.3%) there was an improvement in fixational pattern without any concomi­tant improvement in visual acuity.

(d) Duration of Treatment Given:

The duration of treatment varied from one to eighteen months as shown in [Table - 2]. In the last case which re­ceived treatment for eighteen months, first improvement was noticed nine months after commencement of treat­ment. His visual acuity improved from 6/18 to 6/6.

(e) Maintenance of Improvement after Stopping Treatment

Out of fifteen cases which showed improvement, in five cases the treat­ment was discontinued by the patients. Rest of the cases have been followed up for a varying period of two to twelve months after the stoppage of treatment without any relapse.

  Discussion Top

Thirty-two cases of eccentric fixa­tion received treatment with red filter. Fifteen cases (46.9%) showed improve­ment in vision, fixation or both. Cases with lesser degrees of amblyopia and eccentric fixation showed better res­ponse to red filter treatment as com­pared to cases having gross degrees of initial amblyopia and eccentric fixa­tion. No improvement was obtained in cases having paracaecal and centro­caecal fixation. In [Table - 3] we have compared our results with those report­ed by other workers.

The results of the present series and of the series previously published Malik et al (1968) are comparable with those of von-Noorden (1965). Brinker and Katz (1963), however, obtained com­paratively much better results. Thor­leifsson (1966) reported extremely dis­couraging results with red filter. Out of ten cases treated by him, nine showed initial improvement which in eight cases was not maintained in the follow up period. Better results could have been obtained by him if he had given treatment for a longer period of time. In our series too, the percent­age of success could have been better if five cases which left treatment in between had persisted with the treat­ment.

Brinker and Katz (1963) treated two cases of paramacular fixation and six cases of peripheral fixation with red filter. Out of the eight cases treated by him, five cases (62.5%) attained central fixation. Visual improvement of varying degrees was observed in all cases but the maximum visual acuity attained was 6/12.

Binder et al (1963) too showed very good results in eight cases of Parama­cular fixation treated with red filter which was used for a period of 2½ months in each case. In his series, 87.5%; of cases attained central fixa­tion and the maximum improvement in visual acuity was 6/12.

von-Noorden (1965) treated twenty cases of peripheral fixation by red fil­ter. Eleven cases (55%) showed sig­nificant improvement in visual acuity and fixation.

Aichmair (1965) studied the res­ponse of 40 patients of amblyopia with eccentric fixation to red filter treat­ment. Vision and fixation were nor­malized in twenty-one cases (52.5%), while some improvement was observed in another twelve cases. The therapy was ineffective in seven cases.

Cowle (1967) used red filter in ten cases of amblyopia with eccentric fixa­tion. There were six cases of parama­cular fixation, two of parafoveal and two cases of fixation loss. In seven cases (70.0%) the fixation was norma­lized and maximum improvement in visual acuity was 6/12. Red filter was used on an average for a period of seven months. Once central fixation was attained, the occluder was changed to the normal eye for a period of five months. In between, to maintain cen­tral fixation, the filter was used for short intervals each day.

Malik et al (1968) treated nineteen cases of eccentric fixation. Eight cases (47.3%) showed improvement in vi­sion, fixation or both. Cases having parafoveal fixation showed the best response to treatment. The same au­thor (1968) treated twentyfive cases with red filter. Eleven cases (44.0%) showed improvement.

To some extent the variation in suc­cess rate quoted by different workers could be due to selection of different type of fixational patterns in cases se­lected for treatment, the difference in duration of treatment and assessment of cases.

Some authors consider the case to be improved only when there is improve­ment both in fixation and visual acuity while others judge their cases from the improvement in fixational pattern (Cowle 1967).

In our series we observed no im­provement in cases having gross de­grees of eccentric fixation (i.e. para­c.Tcal and centrocaecal). This observa­tion is contrary to the findings of most of the other workers---- Brinker and Katz (1963), von-Noorden (1965), Cowle (1967), who attained spectacular results even in cases of gross degrees of eccentric fixation. This disparity in results could be due to the fact that other workers have treated cases of younger age groups (all below eleven years) in whom eccentric point is still in a stage of flux and more amenable to treatment.

In those cases which showed im­provement, during the follow up period of 2-18 months after stoppage of treat­ment, no deterioration was observed either in fixation or visual acuity. Brinker and Katz (1963) found two cases out of eight treated by them showing reversion of eccentric fixation state on stoppage of treatment. Thorleifsson (1966) observed a relapse of the condition in eight cases out of nine cases showing initial improvement in his series of ten cases.

  Summary Top

Out of thirtytwo cases of eccentric fixation treated by red filter, fifteen cases (46.9%) showed improvement in vision, fixation or both. The results have been compared with those of other workers and the possible expla­nation for the disparity in results has been discussed. Better response is ob­tained in cases having lesser degree of initial amblyopia and eccentric fixation as compared to those cases which are grossly affected. The improvement ob­tained was maintained on stoppage of treatment.[8]

  References Top

Brinker, W. R.; Katz, S. L. (1963): Amer. J. Ophthal, 55, 1033.  Back to cited text no. 1
Binder, H. P.; Engel, D.; Ede. M. L.; Loon, L. (,1963): Amer. Orthopt. J. 13. 64.  Back to cited text no. 2
Aichmair. H. (1965): Klin Monatsbl. f. Augenheilk, 146, 247.  Back to cited text no. 3
Von-Noorden, G. K. (1965): Arch. Ophthal. 73, 776.  Back to cited text no. 4
Thorleifsson, H. (1966): Act. Opthal­mologica, 44, 57.  Back to cited text no. 5
Cowle, J. B. (1967), Brit. J. Ophthal, 51, 165.  Back to cited text no. 6
Malik S.R.K;: Gupta, A. K; Choudhry, S: Sen, D.K; Brit. J. Ophthal (1968)-in press.  Back to cited text no. 7
Malik, S.R.K; Gupta A.K; Choudhry, S; Amer. J Ophthal (1968)-in press.  Back to cited text no. 8


  [Figure - 1], [Figure - 2]

  [Table - 1], [Table - 2], [Table - 3]


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