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Macular degeneration in rhesus monkey (Macaca mulatta)
Ex~J.
E!ye
Res. (1978) 27, 499-50’2
LE:TTER
TO THE: EDIIWRS
Macular Degeneration in Rhesus Monkey (Macaca Mzdatta) A field study of several free-ranging social groups of rhesus monkeys (3Zacncrt )~u,Zrtt,r) was conducted in January 1978 at the Cayo Santiago and La Parguera branches of the (‘aribbean Primate Center of the University of Puerto Rico. The aim of this study was to collect information on aging of the e,ye and the joints of a subhuman primate species and to search for a model of human eye disease and arthribis. 111 the course of this investigation. an interesting retinal degeneration was tliscoverecl. Ophthalmoscopic and biomicroscopic examination showed two types of ancuualies. One is a macular pigmentary disorder showing various degrees of irregular&r in the distribution and intensity of pigmentation. including stippling and mot~tling which resembles human macular degeneration (Fig. la). The second i;; characterized by multiple discreet small, whit.ish spots mainly clnst~erecl in the paramacular area. but occurring occasionally lvithin t’he macnla and less frequently at the peril)h(hry of the retina (FLg. 1A). The distribution and size of these spots resemt&~ drusrn. IJut, they are whiter and reflect less light than those ohserred in huma.ns. These two types of degeneration were found alone or siJi~Lilt,aneousl!;ieoiis~~~ and in most case? l)ot h eyes w-tire a,ffected.
Inhnts (l-3) JnvLklr (4-5) Youn!: arlnlts ((i-15) Oltl :l~llllls
(lli--21) Total
17 15 53
21
.7-’
4 10.5
34
h 33
;1n extensive clinical investigation including floating-tip I’i~eutiiotoiiornetry, biowith slit lamp and contact lenti. biometry and direct’ and indirect ophthaltnoPcopy were carried out’ OJI 105 monkeys belonging t,o five free-ranging social groups ilIlt some animals kept in corrals. The ages of the animals varied between one and 21 years. The eye examinat)ions showetl the absence of elevxted intraocular
111icrosc0py
0014-4835/iY/lUU4HI)
) 04 $01.00/O
cj 158
Academic
Press Inc. (London)
Limited
we (Bito. Merritt and DeRousseau, personal communication) and the absence &sea ses of the anterior segment: lens and vitreous (Eisner, Denlinger and Rala perso Nnal comllluaication). of two clinical entities of retinal degeneration clearly sho Th e age tiistrilbon that some very young animals also were affected (Table I). With progressive age, 1 p”SS
FIG. maculs grvh) and hl
1. (A) Fwdus photograph of one of the affected rhesus monkeys showing macular and pa I%w drusen (arrow) and pigmentsry changes (mottlinp) within the macula. (B) FIuorescine an@:ior (venous phase) of one of the affected rhesus monkeys showing window defect within the mat & Terfluorescence in macular and paramacular izrei~s.
LETTER
TO
THE
EDITOI:S
501
incidence greatly increased. A total of 32:; of the monkeys examined showed pigmentary anomalies, and 3Oyh showed drusen type degeneration. Of the 105 animals examined, 53 (50%) were affected. Electroretinography was performed on 66 animals of which 21 showed ophthalmoscopic signs of retinal degeneration. The ERG showed relatively normal rod and cone response. The difference in the B-waves of the normal and affected animals was not significant. The cone flicker response of the a,ffect)ed animals was significant,l,v lower (P C: 0.01) than that of the unaffected ones (‘Fable II). Pluorescine angiography was carried out 011 four affectecl animals. This showed in the earl!? and late transit hyperfluorwcent~ areas wrrcsponding to t’he ophthalmoSCO]hd]y visible lesions (see Fig. 1A). There was no apparent, leakage of the d,w. although there were suggestions of slight lingering of htnin in fovea with markerll~mottled appearance and in some of the small drusen Q+pc spots (Fig. 1K). StafYortl (19S4) described in an old female rhesus monkey (age estimated at 19 years) nlacular degenerations (pigment and drusen-like) sinlilar to ones we observed. Arnonp the 465 rhesus monkey eyes examined he found 31 eyes (S*S”,,) which showed a more sul)tltA tlcpree of this condition.
Our studies show a very high incidence (50”b) of ret’inal degenerat’ion which is age relatetl (see Table I) hut not sex related (25 females ancl 88 males affected). The high incidence of macular degeneration may be related to inbreeding Imt was present in five social groups with considerably different parentages. Since both types of the descrilwtl retinal pathology were. present in infant,s (ll”;,) anal juveniles (33”;,) hereditar,v factors are suspected. The ret,inal degeneration in rhesus monkey Edith its pigment~ar,v changes: drusen t,ylw apl’earance ancl the minor effect on ERG resembles human senile macular (legeneration (Gass, 1977). It is inlportant to establish this relat’ionship since a subhurnan primate model for the stuciy of this leading cause of I)lindness in man would I)e extwmel,y useful. A genetic survey of the examined macaque population am1 histological and electromicroscol~iasbudieson the ret*inasof several affected anin& are in progress.
The il,Ut~tlOrs \vi5li to express their gr;ttitu(le for the ext,raorcliuary help 2tnd cooper:~tion of the st,itff of the Caribbean Prirniltc C’ent,er : Bill Kerber, Richard Raxlins, John Herbert, ilnd their associiltes.
ALL EL-MOFTY, PETER GOURAS, GICORC: EISNER* AND ENDRE A. BALAZS
ResearchDivisio~e, Department of Ophthalmoloyy, 6ollege of Physicia~zsand hhrgeOnS, Columbia. lhiversity, New York, N.Y. 10032, U.S.A.
REFERENCES Gass, J. D. 31. (1977). Stereoscopic Atlas oj’Yaculnr Diseases. 2nd Ed. C. V. Xosby Co., St Louis, MO. Stafford, T. J. (1974). Maculopathy in an elderly subhuman primate. Xod. I’robl. Ophthalnd. 12,214-19.
E!ye
Res. (1978) 27, 499-50’2
LE:TTER
TO THE: EDIIWRS
Macular Degeneration in Rhesus Monkey (Macaca Mzdatta) A field study of several free-ranging social groups of rhesus monkeys (3Zacncrt )~u,Zrtt,r) was conducted in January 1978 at the Cayo Santiago and La Parguera branches of the (‘aribbean Primate Center of the University of Puerto Rico. The aim of this study was to collect information on aging of the e,ye and the joints of a subhuman primate species and to search for a model of human eye disease and arthribis. 111 the course of this investigation. an interesting retinal degeneration was tliscoverecl. Ophthalmoscopic and biomicroscopic examination showed two types of ancuualies. One is a macular pigmentary disorder showing various degrees of irregular&r in the distribution and intensity of pigmentation. including stippling and mot~tling which resembles human macular degeneration (Fig. la). The second i;; characterized by multiple discreet small, whit.ish spots mainly clnst~erecl in the paramacular area. but occurring occasionally lvithin t’he macnla and less frequently at the peril)h(hry of the retina (FLg. 1A). The distribution and size of these spots resemt&~ drusrn. IJut, they are whiter and reflect less light than those ohserred in huma.ns. These two types of degeneration were found alone or siJi~Lilt,aneousl!;ieoiis~~~ and in most case? l)ot h eyes w-tire a,ffected.
Inhnts (l-3) JnvLklr (4-5) Youn!: arlnlts ((i-15) Oltl :l~llllls
(lli--21) Total
17 15 53
21
.7-’
4 10.5
34
h 33
;1n extensive clinical investigation including floating-tip I’i~eutiiotoiiornetry, biowith slit lamp and contact lenti. biometry and direct’ and indirect ophthaltnoPcopy were carried out’ OJI 105 monkeys belonging t,o five free-ranging social groups ilIlt some animals kept in corrals. The ages of the animals varied between one and 21 years. The eye examinat)ions showetl the absence of elevxted intraocular
111icrosc0py
0014-4835/iY/lUU4HI)
) 04 $01.00/O
cj 158
Academic
Press Inc. (London)
Limited
we (Bito. Merritt and DeRousseau, personal communication) and the absence &sea ses of the anterior segment: lens and vitreous (Eisner, Denlinger and Rala perso Nnal comllluaication). of two clinical entities of retinal degeneration clearly sho Th e age tiistrilbon that some very young animals also were affected (Table I). With progressive age, 1 p”SS
FIG. maculs grvh) and hl
1. (A) Fwdus photograph of one of the affected rhesus monkeys showing macular and pa I%w drusen (arrow) and pigmentsry changes (mottlinp) within the macula. (B) FIuorescine an@:ior (venous phase) of one of the affected rhesus monkeys showing window defect within the mat & Terfluorescence in macular and paramacular izrei~s.
LETTER
TO
THE
EDITOI:S
501
incidence greatly increased. A total of 32:; of the monkeys examined showed pigmentary anomalies, and 3Oyh showed drusen type degeneration. Of the 105 animals examined, 53 (50%) were affected. Electroretinography was performed on 66 animals of which 21 showed ophthalmoscopic signs of retinal degeneration. The ERG showed relatively normal rod and cone response. The difference in the B-waves of the normal and affected animals was not significant. The cone flicker response of the a,ffect)ed animals was significant,l,v lower (P C: 0.01) than that of the unaffected ones (‘Fable II). Pluorescine angiography was carried out 011 four affectecl animals. This showed in the earl!? and late transit hyperfluorwcent~ areas wrrcsponding to t’he ophthalmoSCO]hd]y visible lesions (see Fig. 1A). There was no apparent, leakage of the d,w. although there were suggestions of slight lingering of htnin in fovea with markerll~mottled appearance and in some of the small drusen Q+pc spots (Fig. 1K). StafYortl (19S4) described in an old female rhesus monkey (age estimated at 19 years) nlacular degenerations (pigment and drusen-like) sinlilar to ones we observed. Arnonp the 465 rhesus monkey eyes examined he found 31 eyes (S*S”,,) which showed a more sul)tltA tlcpree of this condition.
Our studies show a very high incidence (50”b) of ret’inal degenerat’ion which is age relatetl (see Table I) hut not sex related (25 females ancl 88 males affected). The high incidence of macular degeneration may be related to inbreeding Imt was present in five social groups with considerably different parentages. Since both types of the descrilwtl retinal pathology were. present in infant,s (ll”;,) anal juveniles (33”;,) hereditar,v factors are suspected. The ret,inal degeneration in rhesus monkey Edith its pigment~ar,v changes: drusen t,ylw apl’earance ancl the minor effect on ERG resembles human senile macular (legeneration (Gass, 1977). It is inlportant to establish this relat’ionship since a subhurnan primate model for the stuciy of this leading cause of I)lindness in man would I)e extwmel,y useful. A genetic survey of the examined macaque population am1 histological and electromicroscol~iasbudieson the ret*inasof several affected anin& are in progress.
The il,Ut~tlOrs \vi5li to express their gr;ttitu(le for the ext,raorcliuary help 2tnd cooper:~tion of the st,itff of the Caribbean Prirniltc C’ent,er : Bill Kerber, Richard Raxlins, John Herbert, ilnd their associiltes.
ALL EL-MOFTY, PETER GOURAS, GICORC: EISNER* AND ENDRE A. BALAZS
ResearchDivisio~e, Department of Ophthalmoloyy, 6ollege of Physicia~zsand hhrgeOnS, Columbia. lhiversity, New York, N.Y. 10032, U.S.A.
REFERENCES Gass, J. D. 31. (1977). Stereoscopic Atlas oj’Yaculnr Diseases. 2nd Ed. C. V. Xosby Co., St Louis, MO. Stafford, T. J. (1974). Maculopathy in an elderly subhuman primate. Xod. I’robl. Ophthalnd. 12,214-19.