|Year : 1969 | Volume
| Issue : 6 | Page : 250-255
Red filter in the management of eccentric fixation
S.R.K Malik, S Choudhry, DK Sen
Department of Ophthalmology, Maulana Azad Medical College and Associated Irwin and G. B. Pant Hospitals, New Delhi, India
|Date of Web Publication||11-Jan-2008|
Department of Ophthalmology, Maulana Azad Medical College and Associated Irwin and G. B. Pant Hospitals, New Delhi
Source of Support: None, Conflict of Interest: None
|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
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|| |
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|| |
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|| |
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|| |
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.
| References|| |
Brinker, W. R.; Katz, S. L. (1963): Amer. J. Ophthal, 55, 1033.
Binder, H. P.; Engel, D.; Ede. M. L.; Loon, L. (,1963): Amer. Orthopt. J. 13. 64.
Aichmair. H. (1965): Klin Monatsbl. f. Augenheilk, 146, 247.
Von-Noorden, G. K. (1965): Arch. Ophthal. 73, 776.
Thorleifsson, H. (1966): Act. Opthalmologica, 44, 57.
Cowle, J. B. (1967), Brit. J. Ophthal, 51, 165.
Malik S.R.K;: Gupta, A. K; Choudhry, S: Sen, D.K; Brit. J. Ophthal (1968)-in press.
Malik, S.R.K; Gupta A.K; Choudhry, S; Amer. J Ophthal (1968)-in press.
[Figure - 1], [Figure - 2]
[Table - 1], [Table - 2], [Table - 3]