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The Ocular Features of Down's Syndrome
The Ocular Features of Down's Syndrome Michael B. Shapiro, M.D., and Thomas D. France, M.D.
A combined prospective and retrospective study of patients with Down's syndrome showed that these patients have narrowed and slanted palpebral fissures but that the fissures are of normal height. Patients with Down's syndrome also had increased prevalences (compared with control subjects) of blepharitis (23 of 53 patients or 46%), strabismus (23 of 53 patients or 43%), nystagmus (five of 53 patients or 9%), light-colored and spotted irides (46 of 53 patients or 87% and 43 of 53 patients or 81%, respectively), keratoconus (eight of 53 patients or 15%), cataracts (seven of 53 patients or 13%), severe myopia (13 of 48 patients or 27%), and astigmatism of more than 3 diopters (12 of 48 patients or 25%).
DOWN'S SYNDROME is a clinical entity with a wide constellation of characteristic findings. These patients were first categorized by Langdon Down' in 1866 on the basis of an incorrect theory of racial regression. In 1959, Lejeune, Gauthien, and Turpis! demonstrated that an abnormal chromosome composition caused the syndrome. Trisomy 21 is by far the most common cytogenetic type found in Down's syndrome, followed by a translocation form and mosaicism, respectively." It is estimated that as many as 11,000 infants with Down's syndrome are born per year in the United States." Because of this relatively large population, ophthalmologists should be familiar with the multitude of ocular manifestations that these patients have. Our purpose was to review, expand, and update previous descriptions of the ocular features of patients with Down's syndrome. A combined prospective and retrospective study was carried out to meet these goals.
Accepted for publication April 1, 1985. From the Department of Ophthalmology, University of Wisconsin, Madison, Wisconsin. Reprint requests to Thomas D. France, M.D., Pediatric Eye Clinic, University of Wisconsin, CSC, F4/330, 600 Highland Ave., Madison, WI 53792.
©AMERICAN JOURNAL
OF
Subjects
and Methods
Three populations were studied. The first was prospectively examined by one of us (M.B.S.). Fiftythree nonselected patients with Down's syndrome (19 institutionalized and 34 not institutionalized) were examined at their residences. The mean age was 17.4 years with a range of 7 to 36 years. There were 28 males and 25 females. Because the setting of these examinations was such that complete ocular examinations including refraction were not possible, we studied a second group of patients. We retrospectively reviewed the charts of 54 consecutive patients with Down's syndrome seen at a pediatric eye clinic. The mean age was 9.1 years with a range of 9 months to 28 years. There were 30 males and 24 females. A third, control, group of 30 subjects had accompanied other patients to the general eye clinic and were not being treated for any ophthalmic problem. The mean age was 19.2 years with a range of 11 to 35 years. There were 15 males and 15 females. Several special ocular features were studied in the first and the third (control) groups. These were palpebral fissure slant, width, and height, blepharitis, strabismus, nystagmus, iris characteristics, keratoconus, cataracts, and refractive state. We used the second group of patients only to evaluate refractive errors.
Fig. 1 (Shapiro and France). Modified protractor devised to measure the angle of the palpebral fissure. The baseline connects the inner canthi, and the arm is then rotated to intersect the outer canthus.
OPHTHALMOLOGY 99:659-663, JUNE, 1985
659
660
June, 1985
AMERICAN JOURNAL OF OPHTHALMOLOGY
Results
Fig. 2 (Shapiro and France). Protractor used to measure slant of palpebral fissure in patient with Down's syndrome.
The angle of the palpebral fissure slant was measured with a modified protractor devised solely for this purpose (Figs. 1 and 2). Blepharitis was diagnosed when there was characteristic scaling and erythema of the eyelid margins. We identified ocular motility disorders by standard cover testing. Keratoconus was considered to be present if obvious conical corneas were clinically apparent (Fig. 3) or visible with a keratoscope as described by Rowsey, Reynolds, and Brown." Cataracts were diagnosed if the lens opacity was, evaluated with a direct ophthalmoscope, judged to interfere with vision. Statistical evaluations were done when possible with the X2 distribution.
All control patients had palpebral fissure slants of 5 degrees or less whereas 47 of 53 patients (89%) with Down's syndrome had palpebral slants of 6 degrees or more (Table 1). In the control group, 25 patients (83%) had palpebral fissure widths greater than 30 mm whereas only one patient (2%) with Down's syndrome did (Table 1). This difference between the two groups was statistically significant (P<.OOl). Palpebral fissure heights were remarkably similar in the two groups (Table 1). Blepharitis was present in 25 of the 53 patients (47%) with Down's syndrome and one of the 30 (3%) in the control group. This difference was statistically significant (P<.OOl). Strabismus was present in 23 (43%) ofthe patients with Down's syndrome. All but one had an esodeviation with or without a vertical component. Nystagmus was present in five of the 53 patients (9%) with Down's syndrome. No ocular motility disorders were noted in the control group. Table 2 shows iris characteristics. Forty-six (87%) patients with Down's syndrome had blue or gray irides and 43 (81%) had Brushfield spots or speckles (Fig. 4). Fourteen (47%) of the control group had blue or gray irides and four (13%) had Brushfield spots or speckles. There were no cases of heterochromia or unilateral iris markings in either group. Keratoconus was diagnosed in eight of 53 patients (15%) with Down's syndrome, with four patients having obvious conical corneas. In another four patients, the diagnosis was based on keratoscopic evaluation of the corneal topography. Lens changes sufficient to cause a decrease in visual acuity were found in seven (13%) of the patients. In the retrospective study of 54 patients with Down's syndrome seen in our pediatric eye clinic, six patients did not have refractions charted. Thirteen (27%) of the remaining 48 patients had myopia of more than 5 diopters (spherical equivalent) compared to only two of 30 (7%) in the control group (Table 3). Twelve patients (25%) with Down's syndrome had astigmatism of more than 3 diopters compared to one (3%) in the control group. This difference was statistically significant (P<.05).
Discussion
Fig. 3 (Shapiro and France). Keratoconus with acute hydrops of cornea. Note neovascularization (arrows).
Although the complex of ocular features seen in Down's syndrome has been described.v'" these reports are all more than two decades old and should be updated.
Vol. 99, No.6
661
Ocular Features of Down's Syndrome
TABLE 1 PALPEBRAL FISSURE MEASUREMENTS
PALPEBRAL FISSURE MEASUREMENTS'
PATIENTS WITH DOWN'S SYNDROME (NO, = 53)
CONTROL SUBJECTS (NO, ~ 30) NO.
NO.
%
Palpebral
FIssure
Slant
Mean (degrees)
1.0
10.6
Range (degrees)
-2 to-5
3 to 10
o to 5 degrees
%
30
100
6
11
6 to 10 degrees
0
0
23
43
>10 degrees
0
0
24
45
>14 degrees
0
0
5
9
Palpebral
Fissure
Width
Mean (mm)
30.9
24.0
Range (mm)
28 to 34
15 to 30
<20 mm
0
0
4
8
20 to 25 mm
0
0
32
60
5
17 83
16
30
1
2
26 to 30 mm >30mm
25
Palpebral
Fissure
Helgh1
Mean (mm)
11.5
11.4
Range (mm)
9 to 13
7 to 12
<10 mm
4
13
8
15
>10mm
26
87
45
85
'Both fissures averaged together,
The shape of the palpebral fissure is often a noticeable feature in patients with Down's syndrome but measurements of this aperture have not been well quantitated. Eissler and Longenecker" found "slanting" palpebral fissures in 43% of their patients with Down's syndrome but they did not specify their method of measuring fissures or their criteria for calling a fissure slanted. Lowe" described the palpebral apertures as oblique, short, and, less commonly, narrow but gave no quantitative values. We found the mean slant of the palpebral fissure to be 10.6 degrees vs 1 degree in the control group. The mean width was almost 7 mm shorter in the patients with Down's syndrome. The mean height, however, was almost the same in the two groups. The prevalence of blepharitis in patients with Down's syndrome has been variously reported. Cullen and Butler" and Skeller and Oster? found 2% and 67% of their patients respectively to have blepharitis. We found a prevalence of 47% (25 of 53 patients). This wide range probably represents differing criteria for diagnosing this condition. In our control group only one patient had blepharitis. We do not know whether the high incidence of eyelid infections
in patients with Down's syndrome results from poor hygiene, from decreased resistance to infection, or from some other cause. Strabismus has been previously reported to occur in 21% to 44% of this population.v!' We found ocular misalignment in 23 (43%) of our patients with Down's syndrome. Our finding only one patient with an exodeviation was in accord with other invesTABLE 2
IRIS CHARACTERISTICS
CONTROL SUBJECTS (NO. = 30) IRISCHARACTERISTICS
PATIENTS WITH DOWN'S SYNDROME (NO. = 53)
NO.
%
NO.
%
Blue or gray
14
47
46
87
Brown
10
33
5
9
Other
6
20
2
4
4
13
43
81
Brushfield spots or speckles
662
June, 1985
AMERICAN JOURNAL OF OPHTHALMOLOGY
Fig. 4 (Shapiro and France). Typical Brushfield spots or speckles in a patient with Down's syndrome.
tigators who found few exodeviations in this population. Hiles, Hoyme, and McFarlane" claimed that satisfactory results can be achieved in these patients with standard medical and surgical techniques. Nystagmus was present in 9% of our patients (five cases) compared with previous reports of 5% to 17%.6.9 The nystagmus was purely horizontal and there were no other ocular abnormalities in these cases. The iris characteristics of patients with Down's syndrome are well known.6.10.12.13 Our findings of a blue or gray iris in 46 of 53 patients (87%) and Brushfield spots or speckles in 46 of 53 (81%) were
consistent with the other reports. We found these changes in 13% of the control group (four of 30 subjects), confirming that Brushfield spots cannot be considered diagnostic or specific for Down's syndrome. The cause of these iris changes is not known. Eight of the 53 patients with Down's syndrome (15%) manifested corneal changes consistent with keratoconus. Four of these patients had severely conical corneas with a positive Munson's sign and stromal scarring. In the other affected patients the diagnosis was made with a keratoscope and based on corneal topographic irregularities consistent with keratoconus. No cases were found in the control group. Other investigators'v-" have found the incidence of severe keratoconus to be 5% to 8%. This is consistent with our finding of a 7.5% incidence of severe corneal changes (four patients) but we discovered an additional 7.5% with moderate keratonus. The cause of this increased incidence of keratoconus in Down's syndrome is unknown. Several investigators have suggested eye rubbing as a probable cause. These patients are chronic eye rubbers, perhaps because of the irritation caused by blepharitis. Another clinical entity with an increased incidence of keratoconus is Leber's congenital amaurosis. 1; Patients with this condition also rub their eyes frequently (oculodigital reflex). However, one cannot dismiss the possibility that there is an inherent defect in the structure or composition of the corneas in patients with Down's syndrome. Probably various factors playa part in the development of keratoconus in Down's syndrome. The usual treatment of penetrating keratoplasty for this condition may be successful despite the lack of cooperation from these mentally retarded patients. 16 We found significant cataracts in seven of the 53 patients (13%) we studied and none in the control
TABLE 3 REFRACTIVE CONDITION
REFRACTIVE CONDITION (DIOPTERS)'
Emmetropia (-1.00 to + 1.00) Hypermetropia +1.00 to +5.00 >+5.00 Myopia -1.00 to -5.00 >-5.00 Astigmatism (>3.00) "Both eyes averaged together.
PATIENTS WITH DOWN'S
CONTROL SUBJECTS (NO. ~ 30)
SYNDROME (NO.
~
46)
NO.
%
NO.
%
7
23
13
27
10
33 3
14 3
29
1
10
33
5
10
2 1
7
13
3
12
27 25
6
Vol. 99, No.6
Ocular Features of Down's Syndrome
group. We made no attempt to classify the type of cataracts because of the difficulty of examining these patients. Others have reported disabling lenticular opacities in 12% to 46% of patients with Down's syndrome.P:" Lowe" was able to examine these patients with a slit lamp and described the classic lens changes as being flake opacities and arcuate opacities. The refractive state of the eyes of patients with Down's syndrome has not been well described for the past 33 years. 7 We found a 27% incidence (13 of 48 patients) of myopia of more than 5 diopters. This is much more than the 5% that previous studies found.I:" We can offer no explanation of the strong association between Down's syndrome and severe myopia. Additionally, 25% of our patients (12 of 48) had astigmatism of more than 3 diopters. The reason for this may be similar to the causes of keratoconus, that is, eye rubbing or underlying structural abnormalities in the cornea.
References 1. Down, J. L. H.: Observations of ethnic classifications of idiots. London Hosp. Rep. 3:259, 1866. 2. Lejeune, J., Gauthien, M., and Turpis, R.: Les chromosomes humanins en culture de tissues. C. R. Seances Acad. Sci. 248:602, 1959.
663
3. Wright, S. W., Day, R.W., Muller, H., and Weinhouse, R.: The frequency of trisomy and translocations in Down's syndrome. J. Pediatr. 70:420, 1967. 4. Benda, C. E.: The Child With Mongolism New York, Grune and Stratton, 1960, pp. 4 and 5. 5. Rowsey, J. J., Reynolds, A. E., and Brown, R.: Corneal topography. Arch. Ophthalmol. 99:1093, 1981. 6. Lowe, R. F.: The eyes in mongolism. Br. J. Ophthalmol. 33:131, 1949. 7. Skeller, E., and Oster, J,: Eye symptoms in mongolism. Acta Ophthalmol. 29:149, 1951. 8. Eissler, R., and Longenecker, L. P.: The common eye findings in mongolism. Am. J. Ophthalmol. 54:398, 1962. 9. Cullen, J. F., and Butler, H. G.: Mongolism and keratoconus. Br. J. Ophthalmol. 47:321, 1963. 10. Ormond, A. W.: Notes on the ophthalmic condition of forty-two mongolian imbeciles. Trans. Am. Ophthalmol. Soc. 32:69, 1912. 11. Hiles, D. A., Hoyme, S. H., and McFarlane, F.: Down's syndrome and strabismus. Am. Orthop. J. 24:63, 1974. 12. Brushfield, T.: Mongolism. Br. J. Child. Dis. 21:241, 1924. 13. Donaldson, D.: The significance of spotting of the iris in mongoloids. Arch. Ophthalmol. 65:26, 1960. 14. Walsh, S. Z.: Keratoconus and blindness in 469 institutionalized subjects with Down syndrome and other causes of mental retardation. J. Ment. Defic. Res. 25:243, 1981. 15. Karel, 1.: Keratoconus in congenital diffuse tapetoretinal degeneration. Ophthalmologica 155:8, 1968. 16. Slusher, M. M., Laibson, P. R., and Mulberger, R. D.: Acute keratoconus in Down's syndrome. Am. J. Ophthalmol. 66:1137, 1968.
A combined prospective and retrospective study of patients with Down's syndrome showed that these patients have narrowed and slanted palpebral fissures but that the fissures are of normal height. Patients with Down's syndrome also had increased prevalences (compared with control subjects) of blepharitis (23 of 53 patients or 46%), strabismus (23 of 53 patients or 43%), nystagmus (five of 53 patients or 9%), light-colored and spotted irides (46 of 53 patients or 87% and 43 of 53 patients or 81%, respectively), keratoconus (eight of 53 patients or 15%), cataracts (seven of 53 patients or 13%), severe myopia (13 of 48 patients or 27%), and astigmatism of more than 3 diopters (12 of 48 patients or 25%).
DOWN'S SYNDROME is a clinical entity with a wide constellation of characteristic findings. These patients were first categorized by Langdon Down' in 1866 on the basis of an incorrect theory of racial regression. In 1959, Lejeune, Gauthien, and Turpis! demonstrated that an abnormal chromosome composition caused the syndrome. Trisomy 21 is by far the most common cytogenetic type found in Down's syndrome, followed by a translocation form and mosaicism, respectively." It is estimated that as many as 11,000 infants with Down's syndrome are born per year in the United States." Because of this relatively large population, ophthalmologists should be familiar with the multitude of ocular manifestations that these patients have. Our purpose was to review, expand, and update previous descriptions of the ocular features of patients with Down's syndrome. A combined prospective and retrospective study was carried out to meet these goals.
Accepted for publication April 1, 1985. From the Department of Ophthalmology, University of Wisconsin, Madison, Wisconsin. Reprint requests to Thomas D. France, M.D., Pediatric Eye Clinic, University of Wisconsin, CSC, F4/330, 600 Highland Ave., Madison, WI 53792.
©AMERICAN JOURNAL
OF
Subjects
and Methods
Three populations were studied. The first was prospectively examined by one of us (M.B.S.). Fiftythree nonselected patients with Down's syndrome (19 institutionalized and 34 not institutionalized) were examined at their residences. The mean age was 17.4 years with a range of 7 to 36 years. There were 28 males and 25 females. Because the setting of these examinations was such that complete ocular examinations including refraction were not possible, we studied a second group of patients. We retrospectively reviewed the charts of 54 consecutive patients with Down's syndrome seen at a pediatric eye clinic. The mean age was 9.1 years with a range of 9 months to 28 years. There were 30 males and 24 females. A third, control, group of 30 subjects had accompanied other patients to the general eye clinic and were not being treated for any ophthalmic problem. The mean age was 19.2 years with a range of 11 to 35 years. There were 15 males and 15 females. Several special ocular features were studied in the first and the third (control) groups. These were palpebral fissure slant, width, and height, blepharitis, strabismus, nystagmus, iris characteristics, keratoconus, cataracts, and refractive state. We used the second group of patients only to evaluate refractive errors.
Fig. 1 (Shapiro and France). Modified protractor devised to measure the angle of the palpebral fissure. The baseline connects the inner canthi, and the arm is then rotated to intersect the outer canthus.
OPHTHALMOLOGY 99:659-663, JUNE, 1985
659
660
June, 1985
AMERICAN JOURNAL OF OPHTHALMOLOGY
Results
Fig. 2 (Shapiro and France). Protractor used to measure slant of palpebral fissure in patient with Down's syndrome.
The angle of the palpebral fissure slant was measured with a modified protractor devised solely for this purpose (Figs. 1 and 2). Blepharitis was diagnosed when there was characteristic scaling and erythema of the eyelid margins. We identified ocular motility disorders by standard cover testing. Keratoconus was considered to be present if obvious conical corneas were clinically apparent (Fig. 3) or visible with a keratoscope as described by Rowsey, Reynolds, and Brown." Cataracts were diagnosed if the lens opacity was, evaluated with a direct ophthalmoscope, judged to interfere with vision. Statistical evaluations were done when possible with the X2 distribution.
All control patients had palpebral fissure slants of 5 degrees or less whereas 47 of 53 patients (89%) with Down's syndrome had palpebral slants of 6 degrees or more (Table 1). In the control group, 25 patients (83%) had palpebral fissure widths greater than 30 mm whereas only one patient (2%) with Down's syndrome did (Table 1). This difference between the two groups was statistically significant (P<.OOl). Palpebral fissure heights were remarkably similar in the two groups (Table 1). Blepharitis was present in 25 of the 53 patients (47%) with Down's syndrome and one of the 30 (3%) in the control group. This difference was statistically significant (P<.OOl). Strabismus was present in 23 (43%) ofthe patients with Down's syndrome. All but one had an esodeviation with or without a vertical component. Nystagmus was present in five of the 53 patients (9%) with Down's syndrome. No ocular motility disorders were noted in the control group. Table 2 shows iris characteristics. Forty-six (87%) patients with Down's syndrome had blue or gray irides and 43 (81%) had Brushfield spots or speckles (Fig. 4). Fourteen (47%) of the control group had blue or gray irides and four (13%) had Brushfield spots or speckles. There were no cases of heterochromia or unilateral iris markings in either group. Keratoconus was diagnosed in eight of 53 patients (15%) with Down's syndrome, with four patients having obvious conical corneas. In another four patients, the diagnosis was based on keratoscopic evaluation of the corneal topography. Lens changes sufficient to cause a decrease in visual acuity were found in seven (13%) of the patients. In the retrospective study of 54 patients with Down's syndrome seen in our pediatric eye clinic, six patients did not have refractions charted. Thirteen (27%) of the remaining 48 patients had myopia of more than 5 diopters (spherical equivalent) compared to only two of 30 (7%) in the control group (Table 3). Twelve patients (25%) with Down's syndrome had astigmatism of more than 3 diopters compared to one (3%) in the control group. This difference was statistically significant (P<.05).
Discussion
Fig. 3 (Shapiro and France). Keratoconus with acute hydrops of cornea. Note neovascularization (arrows).
Although the complex of ocular features seen in Down's syndrome has been described.v'" these reports are all more than two decades old and should be updated.
Vol. 99, No.6
661
Ocular Features of Down's Syndrome
TABLE 1 PALPEBRAL FISSURE MEASUREMENTS
PALPEBRAL FISSURE MEASUREMENTS'
PATIENTS WITH DOWN'S SYNDROME (NO, = 53)
CONTROL SUBJECTS (NO, ~ 30) NO.
NO.
%
Palpebral
FIssure
Slant
Mean (degrees)
1.0
10.6
Range (degrees)
-2 to-5
3 to 10
o to 5 degrees
%
30
100
6
11
6 to 10 degrees
0
0
23
43
>10 degrees
0
0
24
45
>14 degrees
0
0
5
9
Palpebral
Fissure
Width
Mean (mm)
30.9
24.0
Range (mm)
28 to 34
15 to 30
<20 mm
0
0
4
8
20 to 25 mm
0
0
32
60
5
17 83
16
30
1
2
26 to 30 mm >30mm
25
Palpebral
Fissure
Helgh1
Mean (mm)
11.5
11.4
Range (mm)
9 to 13
7 to 12
<10 mm
4
13
8
15
>10mm
26
87
45
85
'Both fissures averaged together,
The shape of the palpebral fissure is often a noticeable feature in patients with Down's syndrome but measurements of this aperture have not been well quantitated. Eissler and Longenecker" found "slanting" palpebral fissures in 43% of their patients with Down's syndrome but they did not specify their method of measuring fissures or their criteria for calling a fissure slanted. Lowe" described the palpebral apertures as oblique, short, and, less commonly, narrow but gave no quantitative values. We found the mean slant of the palpebral fissure to be 10.6 degrees vs 1 degree in the control group. The mean width was almost 7 mm shorter in the patients with Down's syndrome. The mean height, however, was almost the same in the two groups. The prevalence of blepharitis in patients with Down's syndrome has been variously reported. Cullen and Butler" and Skeller and Oster? found 2% and 67% of their patients respectively to have blepharitis. We found a prevalence of 47% (25 of 53 patients). This wide range probably represents differing criteria for diagnosing this condition. In our control group only one patient had blepharitis. We do not know whether the high incidence of eyelid infections
in patients with Down's syndrome results from poor hygiene, from decreased resistance to infection, or from some other cause. Strabismus has been previously reported to occur in 21% to 44% of this population.v!' We found ocular misalignment in 23 (43%) of our patients with Down's syndrome. Our finding only one patient with an exodeviation was in accord with other invesTABLE 2
IRIS CHARACTERISTICS
CONTROL SUBJECTS (NO. = 30) IRISCHARACTERISTICS
PATIENTS WITH DOWN'S SYNDROME (NO. = 53)
NO.
%
NO.
%
Blue or gray
14
47
46
87
Brown
10
33
5
9
Other
6
20
2
4
4
13
43
81
Brushfield spots or speckles
662
June, 1985
AMERICAN JOURNAL OF OPHTHALMOLOGY
Fig. 4 (Shapiro and France). Typical Brushfield spots or speckles in a patient with Down's syndrome.
tigators who found few exodeviations in this population. Hiles, Hoyme, and McFarlane" claimed that satisfactory results can be achieved in these patients with standard medical and surgical techniques. Nystagmus was present in 9% of our patients (five cases) compared with previous reports of 5% to 17%.6.9 The nystagmus was purely horizontal and there were no other ocular abnormalities in these cases. The iris characteristics of patients with Down's syndrome are well known.6.10.12.13 Our findings of a blue or gray iris in 46 of 53 patients (87%) and Brushfield spots or speckles in 46 of 53 (81%) were
consistent with the other reports. We found these changes in 13% of the control group (four of 30 subjects), confirming that Brushfield spots cannot be considered diagnostic or specific for Down's syndrome. The cause of these iris changes is not known. Eight of the 53 patients with Down's syndrome (15%) manifested corneal changes consistent with keratoconus. Four of these patients had severely conical corneas with a positive Munson's sign and stromal scarring. In the other affected patients the diagnosis was made with a keratoscope and based on corneal topographic irregularities consistent with keratoconus. No cases were found in the control group. Other investigators'v-" have found the incidence of severe keratoconus to be 5% to 8%. This is consistent with our finding of a 7.5% incidence of severe corneal changes (four patients) but we discovered an additional 7.5% with moderate keratonus. The cause of this increased incidence of keratoconus in Down's syndrome is unknown. Several investigators have suggested eye rubbing as a probable cause. These patients are chronic eye rubbers, perhaps because of the irritation caused by blepharitis. Another clinical entity with an increased incidence of keratoconus is Leber's congenital amaurosis. 1; Patients with this condition also rub their eyes frequently (oculodigital reflex). However, one cannot dismiss the possibility that there is an inherent defect in the structure or composition of the corneas in patients with Down's syndrome. Probably various factors playa part in the development of keratoconus in Down's syndrome. The usual treatment of penetrating keratoplasty for this condition may be successful despite the lack of cooperation from these mentally retarded patients. 16 We found significant cataracts in seven of the 53 patients (13%) we studied and none in the control
TABLE 3 REFRACTIVE CONDITION
REFRACTIVE CONDITION (DIOPTERS)'
Emmetropia (-1.00 to + 1.00) Hypermetropia +1.00 to +5.00 >+5.00 Myopia -1.00 to -5.00 >-5.00 Astigmatism (>3.00) "Both eyes averaged together.
PATIENTS WITH DOWN'S
CONTROL SUBJECTS (NO. ~ 30)
SYNDROME (NO.
~
46)
NO.
%
NO.
%
7
23
13
27
10
33 3
14 3
29
1
10
33
5
10
2 1
7
13
3
12
27 25
6
Vol. 99, No.6
Ocular Features of Down's Syndrome
group. We made no attempt to classify the type of cataracts because of the difficulty of examining these patients. Others have reported disabling lenticular opacities in 12% to 46% of patients with Down's syndrome.P:" Lowe" was able to examine these patients with a slit lamp and described the classic lens changes as being flake opacities and arcuate opacities. The refractive state of the eyes of patients with Down's syndrome has not been well described for the past 33 years. 7 We found a 27% incidence (13 of 48 patients) of myopia of more than 5 diopters. This is much more than the 5% that previous studies found.I:" We can offer no explanation of the strong association between Down's syndrome and severe myopia. Additionally, 25% of our patients (12 of 48) had astigmatism of more than 3 diopters. The reason for this may be similar to the causes of keratoconus, that is, eye rubbing or underlying structural abnormalities in the cornea.
References 1. Down, J. L. H.: Observations of ethnic classifications of idiots. London Hosp. Rep. 3:259, 1866. 2. Lejeune, J., Gauthien, M., and Turpis, R.: Les chromosomes humanins en culture de tissues. C. R. Seances Acad. Sci. 248:602, 1959.
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