Journal of Neuro-Ophthalmology, March 1990, Volume 10, Issue 1

Relative afferent pupillary defect in the "better" eye.

A relative afferent pupillary defect usually occurs in an eye with unilateral or asymmetric optic nerve or extensive retinal disease. In general, the eye with poorer visual acuity has the afferent pupillary defect. Twenty-five patients are reported, however, in whom an afferent pupillary defect occurred in the eye with better visual acuity. These eyes had optic nerve or retinal dysfunction. The eyes with worse visual acuity but no afferent pupillary defect had an abnormality of the ocular media (corneal opacity, hyphema, anterior segment membrane, cataract, or vitreous opacity), amblyopia, refractive error, age-related macular degeneration, or cystoid macular edema. An afferent pupillary defect does not necessarily occur in the eye with poorer visual acuity.

Journal of CliniCilI Neuro- ophthalmology 10( 1): 45- 51, 1990. © 1990 Raven Press, Ltd., New York Relative Afferent Pupillary Defect in the " Better" Eye John D. Bullock, M. D., M. S., F. A. C. S. A relative afferent pupillary defect usually occurs in an eye with unilateral or asymmetric optic nerve or exten­sive retinal disease. In general, the eye with poorer vi­sual acuity has the afferent pupillary defect. Twenty- five patients are reported, however, in whom an afferent pupillary defect occurred in the eye with better visual acuity. These eyes had optic nerve or retinal dysfunc­tion. The eyes with worse visual acuity but no afferent pupillary defect had an abnormality of the ocular media ( corneal opacity, hyphema, anterior segment mem­brane, cataract, or vitreous opacity), amblyopia, refrac­tive error, age- related macular degeneration, or cystoid macular edema. An afferent pupillary defect does not necessarily occur in the eye with poorer visual acuity. Key Words: Afferent pupillary defect- Pupil- Marcus Gunn pupil. From the Department of Ophthalmology, Wright State Uni­versity School of Medicine, Dayton, Ohio. Address correspondence and reprint requests to Dr.. J. D. Bullock at Suite 230, Intermed Building, 1520 South Mam St., Dayton, OH 45409, U. s. A. Presented, in part, at the American Academy of Ophthalmol­ogy Annual Meeting, October 10, 1988, Las Vegas, Nevada. 45 In patients with unilateral or asymmetric optic nerve or extensive retinal lesions, differences in the pupillary light responses between the two eyes occur. This difference in pupillary light reactivity is known as an afferent pupillary defect ( APD). The concept of an APD was first described by Hirsch­berg ( 1) in 1884, but other authors have contrib­uted additional information in clarifying this entity ( 2). Kestenbaum ( 3) credited Gunn ( 4,5) with the discovery, and it is now also known as the " Marcus Gunn pupil." Further modifications in the diagnostic technique were made by Levatin ( 6,7), Thompson ( 8), and Gruber and Lessel ( 9). Thompson et a1. ( 10) have described a method to quantitate the APD using neutral density photo­graphic filters of progressive logarithmic values. These are placed over the normal eye until the APD is eliminated in the involved eye. This tech­nique has been used to quantitate relative afferent pupillary defects ( 11,12). In the present study, however, no attempt was made to quantitate the APD. As the test is now performed, subtle differences in pupillary reactivity can be exaggerated by quickly alternating a light from one eye to the other. As the light shifts from the normal to the affected eye, the direct stimulus is no longer capa­ble of maintaining the previously evoked degree of pupillary constriction; thus, both pupils redilate. The magnitude of this redilation is proportional to the severity of the conduction or visual field defect in the affected eye. In general, this phenomenon is easily observed and, when the test is performed properly, it reveals very subtle differences in the photomotor input from each of the two eyes ( 13). An APD also can be detected in patients with a fixed or unseen pupil ( as from a hyphema, corneal scar, or anterior segment membrane). If a patient has a fixed or unseen pupil and normal retinal and optic nerve function in that eye and the other eye has an optic nerve or extensive retinal lesion, then 46 J. D. BULLOCK FIG. 1. ( A) External photograph ( case 1) shows bilateral pupillary constriction when the handlight is directed into the left eye. ( B) External photograph ( case 1) shows bilateral pupillary dilation when the handlight is directed into the right eye. ( A and B document a right afferent pupillary defect.) when light is directed into the fixed or unseen pu­pil, the other pupil constricts, and when the light is directed into the other eye, that pupil dilates. If a patient has a fixed or unseen pupil and an optic nerve or extensive retinal lesion in the same eye, and a normal other eye, then when light is directed into the normal other eye its pupil constricts; when light is directed quickly into the eye with the fixed or unseen pupil, the pupil of the normal other eye dilates. An APD usually occurs in an eye with unilateral or asymmetric optic nerve or extensive retinal dis­ease, which is usually the eye with poorer visual acuity. Thompson et al. ( 14) demonstrated, how­ever, that an afferent pupillary defect is not pro­portional to visual acuity loss, but is proportional to visual field loss. Their finding was recently ver­ified by Johnson et al. ( 15). The present communi-cation substantiates not only a lack of correlation between visual acuity and pupillary function, but reports that, in fact, an APD can occur in the eye with better visual acuity. This phenomenon of pu­pillary response- acuity dissociation is recognized by neuro- ophthalmologists, but is less well known to general ophthalmologists, neurologists, or neu­rosurgeons. Its occurrence is reported in 25 pa­tients. CASE REPORTS Case 1 A 48- year- old woman was first seen complaining of " trouble with my good eye." The patient had a long history of poor left eye vision and, as a child, she had undergone strabismus surgery on the left FIG. 2. ( A) Fundus photograph, right eye ( case 1), shows slight optic atrophy, chronic papilledema, and choroidal folds in the macular area. ( B) Fundus photograph, left eye ( case 1), shows normal appearance of optic disc. • '/! RELATIVE AFFERENT PUPILLARY DEFECT 47 FIG. 3. ( A) Computerized tomographic scan, axial view ( case 1), shows a high- density fusiform mass in the right posteromedial orbit, attached to the optic nerve. ( 8) Coronal view ( case 1). eye. Her corrected visual acuity measured 20/ 30 - 2 in the right eye and 20/ 200 in the left eye. The external examination showed 1 mm of right proptosis. In addition, there was resistance to ret-ropulsion of the right globe. An APD was noted on the right ( Fig. lA and B). The right globe elevated poorly, and diplopia was noted on upgaze. The right fundus examination revealed slight optic atrophy, chronic papilledema, and choroidal folds in the macular area ( Fig. 2A). The fundus examination on the left was normal ( Fig. 2B). Gold­mann visual field testing of the right eye showed marked peripheral and central constriction, espe­cially inferiorly, and a full field on the left. An orbital roentgenogram revealed a calcified mass in the right orbit. A computerized tomographic ( Cf) scan of the orbits showed a high- density fusiform mass in the right posteromedial orbit attached to the optic nerve ( Fig. 3A and B). Optic foramina views showed no enlargement. Clinical diagnoses of a right perioptic meningioma and left amblyopia were made. During the next 5 months the visual acuity in the right eye deteriorated to 20/ 200. A biopsy and de­compression of the right optic nerve was then per­formed. Histopathological examination showed a psammomatous meningioma of the right optic nerve ( Fig. 4). Postoperatively, the visual acuity in the right eye stabilized at 20/ 400 and the papilledema resolved. The right optic nerve remained atrophic ( Fig. 5). Four years postoperatively, the visual acuity mea­sured counting fingers in the right eye and 20/ 100 in the left eye. The right APD persisted. Ten years postoperatively, the best corrected visual acuity measured no light perception in the right eye and 20/ 80 + 1 in the left eye. Case 6 A 46- year- old woman with left optic neuritis was upholstering a chair when a spring shattered her FIG. 4. Photomicrograph of biopsy specimen from optic nerve ( case 1) shows meningeal cells arranged in whorls, together with a psammoma body ( hematoxylin and eosin x244). I Clin Neuro- ophthalmol. Vol. 10. No. 1. 1990 48 ]. D. BULLOCK flu. : » . t- unaus pnotograpn, ngnt eye ( case 1) atter biopsy and decompression of the right optic nerve. Optic atrophy and resolution of the papilledema are noted. glasses, severely lacerating the previously normal right eye. An examination in the emergency room revealed an uncorrected visual acuity of light per­ception in the right eye and " counting fingers" in the left eye. An extensive corneal- scleral laceration with uveal prolapse was noted ( Fig. 6). The lacer­ation was repaired surgically. Two months later ( Fig. 7) an intraocular glass foreign body was re­moved from the right eye and an anterior segment membranectomy and cataract extraction proce­dures were performed. One year later the visual acuity measured " hand movements" in the right eye and 20/ 200 in the left eye. When a light was directed into the right eye, the left pupil con- FIG. 6. External photograph ( case 0) shows extensfve inferior corneal- scleral laceration with uveal pro­lapse. J Lilli Ncuru- vpIJtlllillfllll, Vol Iii, ,~ II I I'I'- il! FIG. 7. External photograph ( case 6) 8 weeks after re­pair of laceration shows sutured inferior corneal­scleral laceration, mature cataract, and anterior seg­ment membrane. stricted and when the light was directed quickly into the left eye, the left pupil dilated ( Fig. 8A and B). These findings suggested that the right optic nerve and retina were functional. Slit- lamp exam­ination of the right eye showed bullous keratopa­thy, corneal fibrosis, and slight rubeosis of the iris ( Fig. 9). Contact B- scan ultrasonography of the right eye showed a normal posterior segment with a clear vitreous cavity ( Fig. 10). Fundus examina­tion demonstrated left optic atrophy ( Fig. 11). Sev­eral months later the patient developed sudden decreased vision in the left eye. Examination at that time revealed a visual acuity of " hand movements" in the right eye and no light percep­tion in the left eye. The patient was treated with oral prednisone, 60 mg per day. A CT scan of the brain and orbits was normal. One week later the visual acuity measured " hand movements" in each eye. The prednisone dosage was eventually tapered during a 3- month period. One year later, the visual acuity measured " hand movements" in each eye. The patient then underwent a right pen­etrating keratoplasty, a right anterior segment membranectomy, and a right anterior vitrectomy. The patient did well postoperatively ( Fig. 12) and 6 weeks later, the corrected aphakic visual acuity measured 20/ 80 - 2 in the right eye and " hand movements" in the left eye. The right retina was completely attached, and the posterior pole ap­peared normal ( Fig. 13). A repeat corneal trans­plant was performed 18 months later due to opaci­fication of the cornea. The patient subsequently developed a retinal detachment. She was lost to follow- up; when she returned 7 years later her vi­sual acuity measured no light perception in each eye. The right eye was phthisical. A cranial CT scan was otherwise normal. RELATIVE AFFERENT PUPILLARY DEFECT 49 FiG. 6. ( Aj external pi1Olograpn lcase b) snows lett pupillary constriction when the handlight is directed into the right eye. ( B) External photograph ( case 6) shows left pupillary dilation when the handlight is directed into the left eye. ( A and B document a left afferent pupillary defect.) FIG. 9. External photograph, right eye ( case 6) shows corneal opacification from bullous keratopathy and corneal fibrosis. I , V' I.. ~, FIG. 10. Contact B- scan ultrasonogram ( case 6) shows a normal posterior segment with an acousti­cally clear vitreous cavity. FIG. 11. Fundus photograph, left eye ( case 6) shows optic atrophy. FIG. 12. External photograph ( case 6) 6 weeks after right penetrating keratoplasty, anterior segment mem­branectomy, and anterior vitrectomy, shows a clear central cornea. I Cli" NeuTo- ophlhalmol. Vol. 10. No. 1, 1990 50 J. D. BULLOCK FIG. 13. Fundus photograph ( case 6) taken 6 weeks after surgery, showing normal disc and macula. DISCUSSION Reduced vision can occur by a variety of mech­anisms; some affect pupillary function and others do not. If a patient with bilateral loss of vision has a different condition in each eye, then different pupillary responses may occur when each eye is stimulated with light. It is therefore possible to have an APD occur in an eye with a lesser degree of visual acuity loss, and, thus, pupillary reaction­acuity dissociation will be present. Table 1 summarizes the diagnoses and visual acuities of 25 such patients. The listed visual acu­ities are those that were present at the time that pupillary response- acuity dissociation was first noted; in many cases, the acuities in each eye later changed, as illustrated by the case reports. The eyes with the APD all had optic nerve or retinal dysfunction: optic nerve meningioma, retinal de- TABLE 1. Summary of clinical data Patient no. lsexl Eye with afferent pupillary defect Eye with normal pupillary function age ( yr) VIA Diagnosis VIA Diagnosis 1/ F/ 48a 20/ 30- 2 Optic nerve meningioma 20/ 200 Amblyopia 21M/ 66 20/ 25 Status post retinal detachment 20/ 30 Refractive error 3/ M/ 23 20/ 60 Traumatic optic atrophy 20/ 400 Amblyopia 4/ M/ 64 20/ 30 Glaucoma 20/ 70 Cataract 5/ M/ 61 20/ 50 Status post retinal detachment 20/ 400 Cataract 6/ F/ 46a 20/ 200 Optic neu ritis HM Corneal scar/ anterior segment membrane 7/ F/ 29 20/ 20 Status post panretinal CF Vitreous hemorrhage photocoagulation 8/ F/ 18 20/ 70 Status post retinal detachment CF Congenital cataract/ anterior segment membrane 9/ M/ 79 20/ 50 Status post retinal detachment 20/ 200 Cataract 10/ F/ 65 20/ 25 Status post retinal detachment 20/ 50 Cataract 11/ M/ 64 20/ 40 Ischemic optic neuropathy 20/ 400 Age- related macular degeneration 12/ F/ 66 20/ 25 Retinal detachment 20/ 200 Cataract 13/ F/ 61 20/ 100 Ischemic optic neuropathy CF Cataract 14/ F/ 55 20/ 25 Orbital metastatic breast cancer 20/ 100 Amblyopia 15/ M/ 60 20/ 30 Glaucoma 20/ 80 Amblyopia 16/ M/ 31 20/ 20 - 2 Traumatic peripapillary choroidal 20/ 30 Amblyopia rupture 17IM/ 66 20/ 25 Orbital extension of squamous cell 20/ 80 Age- related macular degeneration carcinoma of maxillary sinus 18/ M/ 64 20/ 40 Status post retinal detachment/ status CF Cataract post acute pseudaphakic pupillary block glaucoma 19/ F/ 77 20/ 30 Glaucoma 20/ 50 Cataract 20/ M/ 53 20/ 40 Orbital metastatic oat cell carcinoma 20/ 50 Amblyopia 21/ M/ 24 20/ 40 Traumatic optic atrophy HM Hyphema 22/ F/ 81 20/ 40 Retinal detachment 20/ 200 Cataract 23/ M/ 53 20/ 50 Retinal detachment 20/ 400 Cystoid macular edema 24/ F/ 50 20/ 25 - 2 Status post panretinal 20/ 40 Vitreous hemorrhage photocoagulation 25/ F/ 70 20/ 30 Glaucoma; age- related macular 20/ 40 Age- related macular degeneration degeneration VIA, visual acuity; CF, counting fingers; HM, hand movements. a Reported in text. RELATIVE AFFERENT PUPILLARY DEFECT 51 tachment, optic neuritis or atrophy, peripapillary choroidal rupture, glaucomatous cupping, panret­inal photocoagulation, ischemic optic neuropathy, and orbital malignancy. The fellow eyes had visual loss ( greater in each case than the eye with the pupillary abnormality) due to amblyopia, a refrac­tive error, corneal scarring, hyphema, anterior seg­ment membrane, cataract, vitreous hemorrhage, age- related macular degeneration, or cystoid mac­ular edema. In the eyes with amblyopia and refractive errors the pupillary reactions are usually normal. Several authors, however, have reported an APD in eyes with amblyopia, but noted a lack of correlation be­tween pupillary response and visual acuity ( 16,17). An abnormality of the ocular media ( corneal opac­ity, hyphema, anterior segment membrane, cata­ract, or vitreous hemorrhage) is an optical barrier to light, but does not affect processing of the visual stimulus or transmission of the electrical impulse. If the optical barrier produces light reduction, however, rather than light diffusion, then an APD can occur by the same mechanism as that which occurs with a neutral density filter ( 18). Age­related macular degeneration and cystoid macular edema affect the macula but, in general, not enough neural elements are destroyed to produce an APD. Macular lesions have been reported as a cause of an APD, but the macular lesion must be extensive ( 6,19- 21). An APD is present when a relative difference in pupillary light reactivity exists. If one eye is per­fectly normal and the other eye has an optic nerve or retinal lesion, amblyopia, an extensive macular lesion, a total hyphema, or, perhaps, a vitreous hemorrhage, then an afferent pupillary sign can occur in the affected eye with worse visual acuity. However, an APD can also occur in an eye with better visual acuity, affected by a retinal or optic nerve abnormality, if the vision in the other eye is affected to a greater degree by a refractive error, amblyopia, an abnormality of the ocular media, or limited macular disease. REFERENCES 1. Hirschberg J. Neuritis Retrobulbaris. Zentralbl Prakt Augen­heilled 1884; 8: 185. 2. Baquis E. La reazione pupillare come elemento diagnostico differenziale tra I'amaurosi isterica e quella da nevrite ret­robulbare. Ann OttaI1901; 30: 3. 3. Kestenbaum A. Clinical methods of neuro- ophthalmological ex­amination. New York: Grune & Stratton, 1946: 28&- 91. 4. Gunn RM. Functional or hysterical amblyopia. Ophthal Rro 1902; 21: 271- 80. 5. 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Disorders of pupillary function, accommoda­tion, and lacrimation. In: Walsh and Hoyt's clinical neuro­ophthalmology, ed 4. Baltimore: Williams and Wilkins, 1985: 476. 14. Thompson HS, Montague P, Cox TA, Corbett H. The rela­tionship between visual acuity, pupillary defect, and visual field loss. Am JOphthalmol 1982; 93: 681- 8. 15. Johnson LN, Hill RA, Bartholomew MJ. Correlation of af­ferent pupillary defect with visual field loss on automated perimetry. Ophthalmology 1988; 95: 1649- 55. 16. Portnoy JZ, Thompson HS, Lennarson L, Corbett H. Pupil­lary defects in amblyopia. Am JOphthalmoI1983; 96: 609- 14. 17. Greenwald MJ, Folk ER. Afferent pupillary defects in am­blyopia. JPediatr Ophthalmol Strabismus 1983; 20: 63- 7. 18. Striph GG, Halperin LS, Stevens JL, Chu FC Afferent pu­pillary defect caused by hyphema. Am J Ophthalmol 1988; 106: 352- 3. 19. Newsome DA, Milton RC, Gass JDM. Afferent pupillary defect in macular degeneration. Am J Ophthalmol 1981; 92: 396- 402. 20. Thompson HS. 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