Documenta Ophthalmologica 80: 127-132, 1992. 9 1992 Kluwer Academic Publishers. Printed in the Netherlands.
Central retinal vein occlusion in young people G I U S E P P E GIUFFRt~, G A E T A N O R A N D A Z Z O - P A P A & CARLO PALUMBO Istituto di Clinica Oculistica, Universitg~ di Palermo, Via L. GiuffrO 13, 1-90127 Palermo, Italy
Accepted 5 December 1991 Key words: Central retinal vein occlusion, young people Abstract. In a study performed on 20 subjects with central retinal vein occlusion (CRVO) aged 40 years or less we found the ischemic form in 20%. Disc edema was a common finding at the onset, while macular edema was less frequently seen. Systemicor ocular disorders that could be related with the development of the CRVO were often found; a patient was affected with myasthenia gravis and another with Sturge-Weber syndrome: these two diseases were not previously reported in association with CRVO. In only two of the 11 patients followed-up the visual acuity improved. The visual prognosis in CRVO of young people is often poor; the more frequent cause of the reduced visual acuity is chronic cystoid macular edema.
Introduction Central retinal vein occlusion ( C R V O ) is an u n c o m m o n disease in young subjects, while it is frequently seen in adult and old persons [1-3]. C R V O of the youth has been the object of many studies; however some questions still remain open. For example, according to certain authors the etiology of the C R V O of the young people is different from that of the elderly subjects [4, 5], but others say that most etiological factors are c o m m o n to the C R V O of the two age groups [6]. Regarding the type of the C R V O , some ophthalmologists found that the ischemic form is infrequent in young adults [7], while others reported that ischemic C R V O in young subjects is as c o m m o n or even more c o m m o n than in old subjects [5, 6]. We studied the etiology, clinical features and prognosis of C R V O in a group of young individuals affected with this disease. With the aim to contribute to clarify some obscure points about the disorder we followed-up many of them for a long period of time.
Subjects and methods Two hundred and thirty-five cases of C R V O were identified by the fundus fluorescein angiographies performed in our institution from 1978 to 1990.
128 Twenty (8.5%) of them concerned subjects of 40 years or less and are the object of this study. The diagnosis of CRVO was made on the basis of sudden blur of vision in a subject presenting a unilateral dilation of the retinal venous tree accompanied with multiple retinal hemorrhages. Retinal ischemia was defined as presence of areas lacking blood perfusion; it was evaluated in the fluorescein angiography photographs of the posterior pole and midperiphery. When the retinal ischemia was absent o r involved less than 30% of the retinal surface the form was classified as non ischemic CRVO; when the retinal ischemia involved more than 30% of the retina the disease was classified as ischemic CRVO. The presence of macular and disc edema (seen as fluorescein leakage in the macula or optic disc) as well as the presence of neovascularization of the fundus of the eye was looked for. Macular edema was graded into three classes: class 0 was absence of edema; class 1 was presence of slight edema; class 2 was presence of marked edema with cystoid appearance or macular degeneration secondary to the chronic edema. Disc edema was graded into 3 classes as well: class 0 was absence of edema; class 1 was presence of slight fluorescein leakage from papillary vessels; class 2 was presence of marked papillary leakage hidding the edges of the disc. For the purposes of the study we recorded the intraocular pressure and carefully looked for iris or anterior chamber neovascularization. Any systemic or ocular condition supposed to be correlated with the etiopathogenesis of the CRVO was recorded as well. Eleven subjects underwent further ocular examinations after a minimum follow-up period of 6 months. Corrected visual acuity and intraocular pressure were determined and anterior segment and fundus were examined. Fundus photographs and fluorescein angiography were taken in all patients and compared with the previous in order to identify changes in the extent of the retinal ischemia, edema of the macula and disc, and development of neovascularization.
Results
The average age of the 20 young patients with CRVO was 29-+ 6 years (range: 17-40). Eleven of them were males and 9 females. In all cases the first examination was performed within 40 days from the onset of CRVO. Visual acuity was variously affected; in 6 cases it was below 20/100 (Table 1). The fluorescein angiography showed that 4 cases were of the ischemic type and 16 of the non ischemic type. In 11 cases macular edema was present, but only in one it was marked. In 8 cases the fluorescein angiog-
129 Table 1.
Clinical
Patient
Age
No.
data of the 20 young subjects affected with central retinal vein occlusion Sex
Visual
Type of CRVO
Grade Grade of macular of disc edema edema
Associated disorders
acuity (yrs)
I 2 3 4
32 27 26 38
M F M M
2/200 4/200 20/40 20/20
Non ischemic Ischemic Non ischemic Non ischemic
1 1 1 0
1 2 1 0
Platelet hyperaggregation Myasthenia gravis Open angle glaucoma Open angle glaucoma; platelet hyperaggregation
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19" 20
17 37 30 22 37 37 35 40 28 25 26 20 28 25 27 37
M F F F F M M M F M F M F F M M
20/20 HM 20/100 20/50 20/50 CF 20/200 20/30 20/25 4/200 20/40 20/20 20/60 20/40 20/60 20/30
Non ischemic Ischemic Non ischemic Non ischemic Non ischemic Ischemic Non ischemic Non ischemic Non ischemic Ischemic Non ischemic Non ischemic Non ischemic Non ischemic Non ischemic Non ischemic
0 1 1 0 1 1 1 0 1 1 0 0 2 0 0 0
2 0 1 1 2 1 1 0 1 2 2 0 1 2 0 2
Arterial
hypertension Platelet hyperaggregation Raynaud's disease Anemia (hypermenorrhea) Hyperglycemia; hyperviscosity Hypertriglyceridemia Sturge-Weber syndrome Arterial hypertension Head trauma -
Hemorrhage (post-partum) -
Arterial hypertension
central retinal vein occlusion; M = male; F = f e m a l e ; H M = hand movement; C F = counting fingers at 1 m ; * = c o n c o m i t a n t cilioretinal a r t e r y occlusion. CRVO =
raphy revealed the presence of slight disc edema; in further 7 cases the disc edema was more pronounced. A concomitant occlusion of a cilioretinal artery was observed in one case. The intraocular pressure of the affected eye was within 20 mm Hg in 17 patients; in one subject it was 23 mm Hg in absence of visual field defects; the remaining two patients had open angle glaucoma and intraocular pressure values of 23 and 27 mm Hg respectively. In 15 patients we found a disorder that could have a cause-effect relationship with the development of the CRVO (Table 1). In addition to the two patients with glaucoma, three patients had arterial hypertension and two had suffered from profuse blood loss in recent times (hypermenorrhea and post-partum hemorrhage). A patient developed CRVO after a head trauma. In three cases platelet hyperaggregation was found, but the aggregometry was performed only in 13 patients. Some patients showed diseases not usually associated with CRVO; among them a case of myasthenia gravis and one of Sturge-Weber syndrome were recognized. The follow-up period ranged from 6 to 158 months (Table 2). The visual acuity was unmodified or showed very slight changes in 9 patients; it improved markedly in the remaining 2 patients. In no case a significant worsening of the visual acuity with respect to the early examination was recorded.
130 Table 2. Clinical data of the subjects affected with central retinal vein occlusion at follow-up examination. The patients are the top 11 of Table 1
Patient No. 1
2* 3 4 5 6** 7 8 9 10" 11
Follow-up period (months)
Visual acuity at follow-up
Grade of macular edema
Grade of disc edema
147 7 6 109 25 30 6 111 158 96 85
CF 4/200 20/50 20/20 20/20 LP 20/200 20/20 20/30 HM 20/200
2
1
2 2 0 0 2 1 0 0 2 2
1 1 0 2 1 i 0 0 0 0
* =panretinal argon laser photocoagulation; ** =tractional retinal detachment, optic disc neovascularization and neovascular glaucoma in the same eye and macular branch retinal vein occlusion in the fellow eye; CF = counting fingers at 1 m; LP = light perception; HM = hand movement.
T h e t h r e e cases o f i s c h e m i c C R V O r e m a i n e d i s c h e m i c also at f o l l o w - u p , as well as t h e 8 cases o f n o n i s c h e m i c C R V O at first e x a m i n a t i o n w e r e n o n i s c h e m i c at f o l l o w - u p . I n 6 cases t h e m a c u l a r e d e m a b e c a m e w o r s e ; in o n e c a s e t h e e d e m a p r e v i o u s l y p r e s e n t d i s a p p e a r e d . A s r e g a r d s t h e disc e d e m a , in o n e case it a p p e a r e d at f o l l o w - u p , while in 5 cases an e a r l y e d e m a d i s a p p e a r e d o r was r e d u c e d . O n e o f t h e p a t i e n t s with i s c h e m i c C R V O f o l l o w e d - u p d e v e l o p e d t r a c t i o n al r e t i n a l d e t a c h m e n t , disc n e o v a s c u l a r i z a t i o n a n d n e o v a s c u l a r g l a u c o m a ; this p a t i e n t d e v e l o p e d a m a c u l a r b r a n c h r e t i n a l v e i n o c c l u s i o n in the fellow e y e . T h e o t h e r two p a t i e n t s with i s c h e m i c C R V O f o l l o w e d - u p u n d e r w e n t panretinal argon laser photocoagulation and did not develop ocular neovascularization.
Discussion
C R V O in y o u n g p e r s o n s is a r e l a t i v e l y r a r e d i s o r d e r . I n o u r s t u d y we f o u n d t h a t o n l y 8 . 5 % o f t h e s u b j e c t s with C R V O w e r e 4 0 - y e a r s - o l d o r y o u n g e r . In o t h e r s t u d i e s t h e p e r c e n t a g e of y o u n g s u b j e c t s a f f e c t e d with C R V O is n o t m u c h d i f f e r e n t to t h a t f o u n d b y us, r a n g i n g f r o m 8 to 15% [1, 2, 7]. T h e i s c h e m i c t y p e o f C R V O was s e e n in 2 0 % o f o u r cases. This figure is s i m i l a r to t h a t f o u n d in a n o t h e r s t u d y p e r f o r m e d in y o u n g s u b j e c t s with C R V O [5] a n d to t h e r a t e of t h e i s c h e m i c f o r m f o u n d in s u b j e c t s of any age a f f e c t e d w i t h C R V O t h a t is a b o u t 2 2 % [3]. H o w e v e r , o t h e r studies s h o w t h a t t h e r a t e o f t h e i s c h e m i c f o r m o f C R V O in y o u n g p e r s o n s r a n g e s f r o m
131 6% to 64% [6, 7]. These discrepanices can be due to the fact that many studies were performed on selected populations. Our own investigation, however, mainly includes serious cases of CRVO which produced blurred vision and needed hospitalization or at least a fluorescein angiographic examination. Since many mild cases of CRVO escaped our observation it is probable that the true rate of the ischemic form is lower than the above reported. We found a very low final visual acuity in cases of ischemic CRVO and a visual acuity ranging from good to low in eyes with non ischemic CRVO. In our study the number of young subjects affected with CRVO having a low visual acuity at follow-up is higher in respect to that found in other studies [5, 7]. The main cause of reduced visual acuity was cystoid macular edema (or macular degeneration) that frequently seemed to be greater at follow-up than at first examination. One patient with CRVO showed a concomitant occlusion of a cilioretinal artery. This association is not rare in young subjects; in these instances the CRVO is generally of the non ischemic type and the visual prognosis good [81. In young people it is relatively common to find a disease suspected to be connected with the development of the CRVO. In them, as well as in middle-aged and old subjects, the risk factors more frequently associated with CRVO are glaucoma [9, 10], arterial hypertension and diabetes [11, 12], with the important addition of the autoimmune diseases [4, 6, 7]. In our patients glaucoma and arterial hypertension were often found, but we observed that not infrequently the development of the CRVO followed an acute event like a considerable hemorrhage or a head trauma. Head trauma can cause hemorrhage within the optic nerve sheath and compression of the retinal vein in its intraneural tract [13, 14]. If acute disorders like these can produce CRVO, it can be explained in part why the risk of developing a late CRVO in the fellow eye is rare in young persons [7]. In addition, risk factors for CRVO in young as in elderly people could be disorders that modify the composition of blood and plasma: hyperviscosity, hypertriglyceridemia and platelet hyperaggregation were found by us as well as by others [5] in young persons affected with CRVO. In two of our patients we observed associations between CRVO and systemic diseases not previously described. In one case the CRVO was found in a young woman affected with myasthenia gravis. Myasthenia gravis is frequently associated with collagen vascular disorders as well as with thymoma (15) as in the case of our patient. Since collagen disorders like systemic lupus erythematosus and polymyositis have been demonstrated to be cause of CRVO [4, 16] it is not surprising that myasthenia can be associated with CRVO. In another case the CRVO was associated with a Sturge-Weber syndrome. The patient had the typical lesions of the central nervous system, the facial hemangioma and the retinal vascular abnormalities in form of peripheral
132
arteriovenous communications. The suggested pathogenetic mechanism of the CRVO in cases of arteriovenous communications of the retina hypothesizes an increased retinal venous pressure, greater turbulence of blood flow and 'arterialization' of the vein; an endothelial damage and the development of CRVO can follow [17]. This mechanism could work also in cases of CRVO in subjects with Sturge-Weber syndrome. Even if other authors did not find it [4, 7], our study showed frequent associations between CRVO of the youth and systemic diseases. While it can be debated whether many of these diseases have a role in the development of CRVO we retain that a great importance must be given to careful physical and serological examinations.
References 1. Vannas S, Raitta C. Anticoagulant treatment of retinal venous occlusions. Am J Ophthalmol 1966; 62: 874-84. 2. Kohner EM, Cappin JM. Do medical conditions have an influence on central retinal vein occlusions? Proc R Soc Med 1974; 67: 1052-4. 3. Hayreh SS. Classification of central retinal vein occlusion. Ophthalmology 1983; 90: 458-74. 4. Priluck IA, Robertson DM, Hollenhorst RW. Long-term follow-up of occlusion of the central retinal vein in young adults. Am J Ophthalmol 1980; 90: 190-202. 5. Magargal LE, Gonder JR, Maher V. Central retinal vein obstruction in the young adult. Trans Pa Acad Ophthalmol Otolaryngol 1985; 38: 148-53. 6. Frucht J, Yanko L, Merin S. Central retinal vein occlusions in young adults. Acta Ophthalmol 1984; 62: 780-6. 7. Wakers RF, Spalton DJ. Central retinal vein occlusion in people aged 40 years or less: a review of 17 patients. Br J Ophthalmol 1990; 74: 30-5. 8. Glacet-Bernard A, Gaudric A, Touboul C, Coscas G. Occlusion de la veine centrale de la r6tine avec occlusion d'une art~re cilio-r6tinienne: ~ propos de 7 cas. J Fr Ophtalmol 1987; 10: 269-77. 9. Vannas S, Tarkkanen A. Retinal vein occlusion and glaucoma: tonographic study of the incidence of glaucoma and of its prognostic significance. Br J Ophthalmol 1960; 44: 583-9. 10. Dryden RM. Central retinal vein occlusions and chronic simple glaucoma. Arch Ophthalmol 1965; 73: 659-63. 11. Rubinstein K, Jones EB. Retinal vein occlusion: long-term prospects. 10 years' follow-up of 143 patients. Br J Ophthalmol 1976; 60: 148-50. 12. Dodson PM, Kritzinger EE. Underlying medical conditions in young patients and ethnic differences in retinal vein occlusion. Trans Ophthalmol Soc UK 1985; 104: 114-9. 13. Hupp SL, Buckley EG, Byrne SF, Tenzel RR, Glaser JS, Schatz NS. Posttraumatic venous obstructive retinopathy associated with enlarged optic nerve sheath. Arch Ophthalmol 1984; 102: 254-6. 14. Noble MJ, Alvarez EV. Combined occlusion of the central retinal artery and central retinal vein following blunt ocular trauma: a case report. Br J Ophthalmol 1987; 71: 834-6. 15. Seybold ME. Myasthenia gravis: a clinical and basic science review. JAMA 1983; 250: 2516-21. 16. Silverman M, Lubeck MJ, Briney WG. Central retinal vein occlusion complicating systemic lupus erythematosus. Arthritis Rheum 1978; 21: 839-43. 17. Mansour AM, Wells CG, Jampol LM, Kalina RE. Ocular complications of arteriovenous communications of the retina. Arch Ophthalmol 1989; 107: 232-6.
Central retinal vein occlusion in young people G I U S E P P E GIUFFRt~, G A E T A N O R A N D A Z Z O - P A P A & CARLO PALUMBO Istituto di Clinica Oculistica, Universitg~ di Palermo, Via L. GiuffrO 13, 1-90127 Palermo, Italy
Accepted 5 December 1991 Key words: Central retinal vein occlusion, young people Abstract. In a study performed on 20 subjects with central retinal vein occlusion (CRVO) aged 40 years or less we found the ischemic form in 20%. Disc edema was a common finding at the onset, while macular edema was less frequently seen. Systemicor ocular disorders that could be related with the development of the CRVO were often found; a patient was affected with myasthenia gravis and another with Sturge-Weber syndrome: these two diseases were not previously reported in association with CRVO. In only two of the 11 patients followed-up the visual acuity improved. The visual prognosis in CRVO of young people is often poor; the more frequent cause of the reduced visual acuity is chronic cystoid macular edema.
Introduction Central retinal vein occlusion ( C R V O ) is an u n c o m m o n disease in young subjects, while it is frequently seen in adult and old persons [1-3]. C R V O of the youth has been the object of many studies; however some questions still remain open. For example, according to certain authors the etiology of the C R V O of the young people is different from that of the elderly subjects [4, 5], but others say that most etiological factors are c o m m o n to the C R V O of the two age groups [6]. Regarding the type of the C R V O , some ophthalmologists found that the ischemic form is infrequent in young adults [7], while others reported that ischemic C R V O in young subjects is as c o m m o n or even more c o m m o n than in old subjects [5, 6]. We studied the etiology, clinical features and prognosis of C R V O in a group of young individuals affected with this disease. With the aim to contribute to clarify some obscure points about the disorder we followed-up many of them for a long period of time.
Subjects and methods Two hundred and thirty-five cases of C R V O were identified by the fundus fluorescein angiographies performed in our institution from 1978 to 1990.
128 Twenty (8.5%) of them concerned subjects of 40 years or less and are the object of this study. The diagnosis of CRVO was made on the basis of sudden blur of vision in a subject presenting a unilateral dilation of the retinal venous tree accompanied with multiple retinal hemorrhages. Retinal ischemia was defined as presence of areas lacking blood perfusion; it was evaluated in the fluorescein angiography photographs of the posterior pole and midperiphery. When the retinal ischemia was absent o r involved less than 30% of the retinal surface the form was classified as non ischemic CRVO; when the retinal ischemia involved more than 30% of the retina the disease was classified as ischemic CRVO. The presence of macular and disc edema (seen as fluorescein leakage in the macula or optic disc) as well as the presence of neovascularization of the fundus of the eye was looked for. Macular edema was graded into three classes: class 0 was absence of edema; class 1 was presence of slight edema; class 2 was presence of marked edema with cystoid appearance or macular degeneration secondary to the chronic edema. Disc edema was graded into 3 classes as well: class 0 was absence of edema; class 1 was presence of slight fluorescein leakage from papillary vessels; class 2 was presence of marked papillary leakage hidding the edges of the disc. For the purposes of the study we recorded the intraocular pressure and carefully looked for iris or anterior chamber neovascularization. Any systemic or ocular condition supposed to be correlated with the etiopathogenesis of the CRVO was recorded as well. Eleven subjects underwent further ocular examinations after a minimum follow-up period of 6 months. Corrected visual acuity and intraocular pressure were determined and anterior segment and fundus were examined. Fundus photographs and fluorescein angiography were taken in all patients and compared with the previous in order to identify changes in the extent of the retinal ischemia, edema of the macula and disc, and development of neovascularization.
Results
The average age of the 20 young patients with CRVO was 29-+ 6 years (range: 17-40). Eleven of them were males and 9 females. In all cases the first examination was performed within 40 days from the onset of CRVO. Visual acuity was variously affected; in 6 cases it was below 20/100 (Table 1). The fluorescein angiography showed that 4 cases were of the ischemic type and 16 of the non ischemic type. In 11 cases macular edema was present, but only in one it was marked. In 8 cases the fluorescein angiog-
129 Table 1.
Clinical
Patient
Age
No.
data of the 20 young subjects affected with central retinal vein occlusion Sex
Visual
Type of CRVO
Grade Grade of macular of disc edema edema
Associated disorders
acuity (yrs)
I 2 3 4
32 27 26 38
M F M M
2/200 4/200 20/40 20/20
Non ischemic Ischemic Non ischemic Non ischemic
1 1 1 0
1 2 1 0
Platelet hyperaggregation Myasthenia gravis Open angle glaucoma Open angle glaucoma; platelet hyperaggregation
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19" 20
17 37 30 22 37 37 35 40 28 25 26 20 28 25 27 37
M F F F F M M M F M F M F F M M
20/20 HM 20/100 20/50 20/50 CF 20/200 20/30 20/25 4/200 20/40 20/20 20/60 20/40 20/60 20/30
Non ischemic Ischemic Non ischemic Non ischemic Non ischemic Ischemic Non ischemic Non ischemic Non ischemic Ischemic Non ischemic Non ischemic Non ischemic Non ischemic Non ischemic Non ischemic
0 1 1 0 1 1 1 0 1 1 0 0 2 0 0 0
2 0 1 1 2 1 1 0 1 2 2 0 1 2 0 2
Arterial
hypertension Platelet hyperaggregation Raynaud's disease Anemia (hypermenorrhea) Hyperglycemia; hyperviscosity Hypertriglyceridemia Sturge-Weber syndrome Arterial hypertension Head trauma -
Hemorrhage (post-partum) -
Arterial hypertension
central retinal vein occlusion; M = male; F = f e m a l e ; H M = hand movement; C F = counting fingers at 1 m ; * = c o n c o m i t a n t cilioretinal a r t e r y occlusion. CRVO =
raphy revealed the presence of slight disc edema; in further 7 cases the disc edema was more pronounced. A concomitant occlusion of a cilioretinal artery was observed in one case. The intraocular pressure of the affected eye was within 20 mm Hg in 17 patients; in one subject it was 23 mm Hg in absence of visual field defects; the remaining two patients had open angle glaucoma and intraocular pressure values of 23 and 27 mm Hg respectively. In 15 patients we found a disorder that could have a cause-effect relationship with the development of the CRVO (Table 1). In addition to the two patients with glaucoma, three patients had arterial hypertension and two had suffered from profuse blood loss in recent times (hypermenorrhea and post-partum hemorrhage). A patient developed CRVO after a head trauma. In three cases platelet hyperaggregation was found, but the aggregometry was performed only in 13 patients. Some patients showed diseases not usually associated with CRVO; among them a case of myasthenia gravis and one of Sturge-Weber syndrome were recognized. The follow-up period ranged from 6 to 158 months (Table 2). The visual acuity was unmodified or showed very slight changes in 9 patients; it improved markedly in the remaining 2 patients. In no case a significant worsening of the visual acuity with respect to the early examination was recorded.
130 Table 2. Clinical data of the subjects affected with central retinal vein occlusion at follow-up examination. The patients are the top 11 of Table 1
Patient No. 1
2* 3 4 5 6** 7 8 9 10" 11
Follow-up period (months)
Visual acuity at follow-up
Grade of macular edema
Grade of disc edema
147 7 6 109 25 30 6 111 158 96 85
CF 4/200 20/50 20/20 20/20 LP 20/200 20/20 20/30 HM 20/200
2
1
2 2 0 0 2 1 0 0 2 2
1 1 0 2 1 i 0 0 0 0
* =panretinal argon laser photocoagulation; ** =tractional retinal detachment, optic disc neovascularization and neovascular glaucoma in the same eye and macular branch retinal vein occlusion in the fellow eye; CF = counting fingers at 1 m; LP = light perception; HM = hand movement.
T h e t h r e e cases o f i s c h e m i c C R V O r e m a i n e d i s c h e m i c also at f o l l o w - u p , as well as t h e 8 cases o f n o n i s c h e m i c C R V O at first e x a m i n a t i o n w e r e n o n i s c h e m i c at f o l l o w - u p . I n 6 cases t h e m a c u l a r e d e m a b e c a m e w o r s e ; in o n e c a s e t h e e d e m a p r e v i o u s l y p r e s e n t d i s a p p e a r e d . A s r e g a r d s t h e disc e d e m a , in o n e case it a p p e a r e d at f o l l o w - u p , while in 5 cases an e a r l y e d e m a d i s a p p e a r e d o r was r e d u c e d . O n e o f t h e p a t i e n t s with i s c h e m i c C R V O f o l l o w e d - u p d e v e l o p e d t r a c t i o n al r e t i n a l d e t a c h m e n t , disc n e o v a s c u l a r i z a t i o n a n d n e o v a s c u l a r g l a u c o m a ; this p a t i e n t d e v e l o p e d a m a c u l a r b r a n c h r e t i n a l v e i n o c c l u s i o n in the fellow e y e . T h e o t h e r two p a t i e n t s with i s c h e m i c C R V O f o l l o w e d - u p u n d e r w e n t panretinal argon laser photocoagulation and did not develop ocular neovascularization.
Discussion
C R V O in y o u n g p e r s o n s is a r e l a t i v e l y r a r e d i s o r d e r . I n o u r s t u d y we f o u n d t h a t o n l y 8 . 5 % o f t h e s u b j e c t s with C R V O w e r e 4 0 - y e a r s - o l d o r y o u n g e r . In o t h e r s t u d i e s t h e p e r c e n t a g e of y o u n g s u b j e c t s a f f e c t e d with C R V O is n o t m u c h d i f f e r e n t to t h a t f o u n d b y us, r a n g i n g f r o m 8 to 15% [1, 2, 7]. T h e i s c h e m i c t y p e o f C R V O was s e e n in 2 0 % o f o u r cases. This figure is s i m i l a r to t h a t f o u n d in a n o t h e r s t u d y p e r f o r m e d in y o u n g s u b j e c t s with C R V O [5] a n d to t h e r a t e of t h e i s c h e m i c f o r m f o u n d in s u b j e c t s of any age a f f e c t e d w i t h C R V O t h a t is a b o u t 2 2 % [3]. H o w e v e r , o t h e r studies s h o w t h a t t h e r a t e o f t h e i s c h e m i c f o r m o f C R V O in y o u n g p e r s o n s r a n g e s f r o m
131 6% to 64% [6, 7]. These discrepanices can be due to the fact that many studies were performed on selected populations. Our own investigation, however, mainly includes serious cases of CRVO which produced blurred vision and needed hospitalization or at least a fluorescein angiographic examination. Since many mild cases of CRVO escaped our observation it is probable that the true rate of the ischemic form is lower than the above reported. We found a very low final visual acuity in cases of ischemic CRVO and a visual acuity ranging from good to low in eyes with non ischemic CRVO. In our study the number of young subjects affected with CRVO having a low visual acuity at follow-up is higher in respect to that found in other studies [5, 7]. The main cause of reduced visual acuity was cystoid macular edema (or macular degeneration) that frequently seemed to be greater at follow-up than at first examination. One patient with CRVO showed a concomitant occlusion of a cilioretinal artery. This association is not rare in young subjects; in these instances the CRVO is generally of the non ischemic type and the visual prognosis good [81. In young people it is relatively common to find a disease suspected to be connected with the development of the CRVO. In them, as well as in middle-aged and old subjects, the risk factors more frequently associated with CRVO are glaucoma [9, 10], arterial hypertension and diabetes [11, 12], with the important addition of the autoimmune diseases [4, 6, 7]. In our patients glaucoma and arterial hypertension were often found, but we observed that not infrequently the development of the CRVO followed an acute event like a considerable hemorrhage or a head trauma. Head trauma can cause hemorrhage within the optic nerve sheath and compression of the retinal vein in its intraneural tract [13, 14]. If acute disorders like these can produce CRVO, it can be explained in part why the risk of developing a late CRVO in the fellow eye is rare in young persons [7]. In addition, risk factors for CRVO in young as in elderly people could be disorders that modify the composition of blood and plasma: hyperviscosity, hypertriglyceridemia and platelet hyperaggregation were found by us as well as by others [5] in young persons affected with CRVO. In two of our patients we observed associations between CRVO and systemic diseases not previously described. In one case the CRVO was found in a young woman affected with myasthenia gravis. Myasthenia gravis is frequently associated with collagen vascular disorders as well as with thymoma (15) as in the case of our patient. Since collagen disorders like systemic lupus erythematosus and polymyositis have been demonstrated to be cause of CRVO [4, 16] it is not surprising that myasthenia can be associated with CRVO. In another case the CRVO was associated with a Sturge-Weber syndrome. The patient had the typical lesions of the central nervous system, the facial hemangioma and the retinal vascular abnormalities in form of peripheral
132
arteriovenous communications. The suggested pathogenetic mechanism of the CRVO in cases of arteriovenous communications of the retina hypothesizes an increased retinal venous pressure, greater turbulence of blood flow and 'arterialization' of the vein; an endothelial damage and the development of CRVO can follow [17]. This mechanism could work also in cases of CRVO in subjects with Sturge-Weber syndrome. Even if other authors did not find it [4, 7], our study showed frequent associations between CRVO of the youth and systemic diseases. While it can be debated whether many of these diseases have a role in the development of CRVO we retain that a great importance must be given to careful physical and serological examinations.
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