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Pupillary Light Reflex in Amblyopia

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Pupillary Light Reflex in Amblyopia No. 4 Reports 467 Pupillary Light Reflex in Amblyopia Monobu Ko.se, Renpei Nago.ro., Arsushi Yoshido, and Issei Honodo The pupillary light reflex of 15 strabismic and anisometropic 0.8 or better. Their ages ranged from 8 to 12 years, amblyopes, and eight subjects who had recovered from func- and the visual acuity of the amblyopic eyes before the tional amblyopia was studied by using an infrared electro- treatments ranged from 0.03 to 0.6. The duration of pupillogram. Ten of the fifteen amblyopes had significantly treatments was from 9 months to 3 years. Six of the longer latencies of contraction when the amblyopic eyes were subjects had anisometropic amblyopia and two had stimulated than when the normal eyes were stimulated. How- strabismic amblyopia. ever, there was no relationship between the delay in pupillary All of the subjects were dark-adapted for 10 min, light reflexes and reduced visual acuity of amblyopic eyes. The amplitudes and maximum velocities of the contraction and the pupillary light reflex was recorded by an in- were not altered significantly in amblyopic and normal eyes. frared electropupillogram (Iris corder, Hamamatsu TV All of the subjects who had recovered showed no significant Co.) that measures the pupillary area continuously. difference of the latencies of the pupillary responses to stim- The sampling rate is 16.7 msec and variation of am- ulation between normal and amblyopic eyes. These findings plitude is below ±1%.3 The stimulus was diffuse light indicate that a retinal mechanism in amblyopic eyes may be of 500 msec duration. The intensity of the light stimulus responsible for the abnormally long pupillary light reflex was fixed at one lux. Subjects were instructed to fixate latency. Invest Ophthalmol Vis Sci 25:467-471, 1984 a red spot that was placed 1 m in front of them. The direct pupillary reflex of both eyes and the consensual Electrophysiological and psychophysical studies have reflex of amblyopic eye were recorded for each subject, shown that functional amblyopia is associated with while in four cases the consensual reflex of normal eye abnormal visual processing at various levels of visual was also measured. Light stimulation was performed system. It has also been shown that amblyopic pupils carefully so that light entered the eye along the visual show static and dynamic anomalies to light. Harms1 axis, especially when the consensual reflex for strabis- made pupilloscopic studies with perimetric stimulation mic amblyopia was recorded. Individual pupillary re- of light and found that the pupillomotor sensitivity sponses were measured three times at an interval of 5 was greater with peripheral than central stimulation min because the sampling time of 16.7 msec is relatively in the amblyopic eyes. Dolenek2 also reported that the large for the latency of pupillary reflexes. Signals of pupillary light reflex had longer latencies of contraction pupillary area and light stimulus were stored on mag- and dilation on stimulation of amblyopic eyes than of netic tape. A signal processor (San Ei Sokki Co.) was normal eyes. It, however, remains unclear wherein the used to digitalize the data with a time bin of 1 msec. pupillomotor system the pupillary abnormalities lie, The latency of the light reflex was determined as the and whether they are correlated with depth of ambly- time between the onset of stimulus and the point that opia. Therefore, it was felt that a quantitative analysis declined below the baseline and followed by continuous of pupillary responses to light may be important to decrease in pupillary area. The amplitude was defined understand the mechanism for amblyopia. as the largest values of the contractions and the max- In the present study, an infrared electropupillograph imum velocity was calculated as the largest values of was used to measure pupillary area precisely. The pur- the derivative from contractions. The mean values of pose was to examine the pupillary light reflex of stra- these parameters of contractions were measured from bismic and anisometropic amblyopia and to clarify the three trials. the relationship between parameters of pupillary re- Results. Patients with amblyopia: In 10 of the 15 sponses and depth of amblyopia. patients with unilateral functional amblyopia, the la- Materials and Methods. The pupillary light reflex tencies of the direct pupillary reflexes were longer when was measured from 15 unilateral functional amblyopic the amblyopic eyes were stimulated. In the remaining patients and 8 subjects who had recovered from am- five patients, the difference of latencies between am- blyopia by appropriate treatment. Eight out of the fif- blyopic and normal eyes was less than 16.7 msec. Six teen patients were strabismic and seven were aniso- of the ten patients had strabismic amblyopia, and four metropic amblyopes. The visual acuity of the normal had anisometropic amblyopia (Table 1A). The visual eyes was 0.9 or better, with or without correction, acuity of the amblyopic eyes in the patients who had whereas that of the amblyopic eyes was 0.5 or less. increased latencies ranged from 0.06 to 0.5. The pupil- Their ages ranged from 8 to 51 years with no history lographic patterns of the light reflex in two cases are of treatment for amblyopia. All of the subjects who shown in Figure 1. Two responses of each reflex were had recovered from amblyopia had visual acuity of superimposed with the onset of stimulus aligned. These Downloaded from iovs.arvojournals.org on 10/01/2021 468 INVESTIGATIVE OPHTHALMOLOGY b VISUAL SCIENCE / April 1984 Vol. 25 Table 1. Clinical data of the 10 patients having longer latencies to stimulation of amblyopic eyes (A) and of the eight subjects who had recovered from amblyopia (B) A Case Sex Age Phoria or tropia Visual acuity 1 F 10 ortho R.E. 0.1 (0.5X + 3.5Dcyl + 1.0D900) L.E. 1.5 (n.c.) 2 M 12 +20* R.E. 0.1 (0.2X -0.5D) L.E. 1.5 (n.c.) 3 F 24 ortho R.E. 0.8 (1.0X - 1.5D) L.E. 0.01 (n.c.) 4 M 25 +40* R/L 16* R.E. 0.06 (n.c.) L.E. 1.5 (n.c.) 5 M 16 -12* R.E. 0.7 (0.9X cyl - 0.5D 180°) L.E. 0.05 (0.1X - 5.0D) 6 M 9 +20* R.E. 1.2 (n.c.) L.E. 0.3 (n.c.) 7 M 51 ortho R.E. 0.02(0. IX - 5.5D) L.E. 0.8 (1.2X - 1.0D) 8 M 8 + 14* R.E. 1.0 (n.c.) L.E. 0.2 (0.4X + 1.5D) 9 M 30 ortho R.E. 0.9 (n.c.) L.E. 0.2(0.3X + 1.0D) 10 F 25 -30*L/R20* R.E. 0.01 (n.c.) L.E. 1.2 (n.c.) Visual acuity B Case Age Sex Before After Duration 1 11 M R.E. 1.0 1.0 2 yrs L.E. 0.06 1.0 2 9 M R.E. 0.6 2.0 1 yr L.E. 0.08 1.0 3 9 M R.E. 1.2 1.5 1 yr L.E. 0.5 0.9 4 8 F R.E. 1.5 1.5 9 mon L.E. 0.03 0.9 5 12 F R.E. 0.4 0.8 3 yrs L.E. 0.9 1.2 6 12 M R.E. 0.03 1.2 1 yr L.E. 0.6 1.5 7 11 M R.E. 0.04 0.8 2 yrs L.E. 1.0 1.2 8 12 F R.E. 0.1 0.9 1 yr L.E. 1.2 1.2 responses demonstrate the trajectories and latencies of 284 msec with mean of 267 ± 12.3 msec. The direct the contractions for each trial condition. The latencies reflex and consensual reflex of amblyopic eye had a of direct reflex of normal eye (1), direct reflex of am- mean latency of 295 ± 14.5 msec and 275 ± 10.9 blyopic eye (2), and consensual reflex of amblyopic msec, respectively. The direct reflex of amblyopic eye eye (3) in Figure 1A were 263 msec, 300 msec, and was significantly longer than the direct reflex of normal 267 msec, respectively. In Figure IB, consensual reflex eye and the consensual reflex of amblyopic eye (t of normal eye had approximately the same increased = 4.67, P < 0.0001 and t = 3.34, P < 0.001). There latency as the direct reflex of amblyopic eye; the direct was, however, no significant difference of pupillary reflex of normal eye (1) had latency of 271 msec, direct reflex latencies between normal and amblyopic eyes reflex of amblyopic eye (2) 292 msec, consensual reflex when the normal eyes were stimulated (t = 1.54, P of amblyopic eye when the normal eye was stimulated < 0.05). (3) 275 msec, and consensual reflex of normal eye In order to determine whether the prolongation of when the amblyopic eye was stimulated (4) 300 msec. latency was correlated with the depth of amblyopia, The mean latencies of the 10 patients calculated from relationship between the difference of latency and yisual three trials are shown in Table 2 A. The latency of the acuity of amblyopic eye was studied. The difference direct reflex of normal eye ranged from 243 msec to of latency of direct reflex between normal and amr Downloaded from iovs.arvojournals.org on 10/01/2021 No. 4 Reports 469 blyopic eyes ranged from 17 msec to 50 msec with Table 2. Mean latencies of pupillary light reflexes in average of 28.1 msec. A calculation of the correlation amblyopes (A) and in the subjects who had between difference of latency and visual acuity indi- recovered from amblyopia (B) cated that there was no significant correlation (coef- Amblyopic eye ficient of correlation: -0.216) (Fig.
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