Portada mar. 2004

INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME
Original Paper
A study of visual quality in adults
with Down´s syndrome
Marina Castañé1, Mercè Boada2,3, Isabel Hernández3
1 Departament d’Òptica i Optometria. Universitat Politècnica de Catalunya
2 Servei de Neurologia. Hospital General Universitari Vall d’Hebron
3 Fundació ACE. Institut Català de Neurociències Aplicades
Correspondence:
Marina Castañé
Escola Universitària d’Òptica i Optometria
C/ Violinista Vellsolà, 27
08222 Terrassa, Spain
e-mail: castane@oo.upc.es
Abstract
Introduction
A group of persons with Down syndrome aged Individuals with cognitive impairment are over 40 was studied to assess the presence of at a greater risk for severe eyesight problems Alzheimer’s disease and its clinical traits as well as than non-disabled persons. Severe refractive error, poor visual acuity, strabismus, and cataracts, acetylcholinesterase inhibitor, for Alzheimer’s among others, have all been described as issues disease. Assessment was neurological, physical and sensory, and also included the following According to some studies, individuals with additional examinations and cognitive scales: accommodative disorders and visual acuity (VA) psychopathological analysis, psychopathological disorders (8-11), nystagmus (12), cataracts and assessment scale, and an interview with each person’s guardian or teacher. The present paper is Similarly, individuals with cognitive disabilities a part of the main study, and specifically looks at have been found to have poor visual acuity, even refractory status and visual quality. There were 49 with the best correction possible (4).
cases, aged 40 to 62. Testing included visual acuity Some studies specifically highlight DS, citing (VA) measurement, binocular vision and ocular VA range values within the «low vision» motility assessment, retinoscopy, subjective range (14-16). Many individuals with disabilities examination, and ocular health assessment. The who ought to be wearing spectacles to counter suitability of prescription lenses already worn by patients and the visual performance they supplied spectacles are worn, but are not optimally fitted was also assessed, both for near and for distant The purpose of this study was to assess the visual quality of a group of adults with DS aged 40 Keywords:
and over, both in terms of refractive error and as Optometric prescription. Down syndrome.
INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME
Subjects and method
cycloplegic drugs. Patients who used spectacleswere examined while wearing them. The findings discussed below are part of a Binocular integrity and ocular health were general study of a group of individuals with DS who were neurologically assessed for potential Alzheimer’s disease (AD). Sensory testing of allparticipants included optometry to assess theirvisual status. The 49 subjects included in the study (27 male and 22 female) were patients with DS aged 40 to Out of 49 subjects with Down syndrome, one 62, with a mean age of 47.59. Alzheimer’s disease was excluded from the study due to acute viral was diagnosed in 12 patients, who were treated conjunctivitis at the time of assessment.
with donepezil; two patients diagnosed with AD were unable to pursue their treatment for a variety functional level thresholds: VA ≥ 0.5 was optimal, of reasons, and four patients were borderline AV< 0.5 ≥ 0.3 borderline low vision; VA < 0.3≥ 0.1 low vision, and VA < 0.1 legal blindness. Results The study looks at the whole group of patients.
were rated using habitual correction lenses on the Results comparing the two subgroups best eye.
—individuals with Down Syndrome and patients At the beginning of the study, 53% of the study with DS and AD— were discussed in a different population wore glasses habitually. In everyday article (17). No statistically significant differences viewing conditions, 54.2% of patients had low were found between the two groups in terms of the vision, or VA between 0.3 and 0.1; 25% were between 0.3 and 0.5 VA, borderline low vision; Distant-vision VA was assessed at 3 meters 2.2% had VA ≥ 0.5, which made them functionally using the broken wheel test (BWT), which is based normal, and one patient was a member of the on the Landolt C test. Two cars are shown at a Spanish National Organization for the Blind time; one of them has whole wheels, and the other (ONCE). In 18.7% of cases, assessment was has incomplete wheels which are actually Landolt C rings opening in different directions. Car size varies according to a scale that assesses acuity up retinoscopy and prescription update, 33.33% had to 20/20. The BWT is designed for a 3-meter VA between 0.3 and 0.1, 31.25% between 0.3 and distance. It is easy to understand and encourages 0.5, 10.4% attained VA higher than 0.5, and VA could not be assessed for 18.75% (Fig. 1).
Near vision was assessed at a 25-cm distance.
Although most standard near-vision tests involve refractive correction had been optimized in the text or letters, the test chosen in this case was one low-vision borderline range. The rate of low vision that involved numbers, as illiteracy was fairly due to poor VA was also lowered with prescription updates. To summarize, correct lens prescription VA was measured monocularly and binocularly, improved distant vision for 39.6% of patients, as well as under normal conditions for the subject failed to improve it for 14.6%, required a change (i.e., wearing spectacles if prescribed). After of prescription for 16.7%. No lenses were required refractive status was assessed, VA was measured For near vision, the cut-off point was set at Refractive status was assessed using Mohindra VA≥ 0.4: this is the threshold for low vision, and it retinoscopy, which requires total darkness in order is also the level for typical typeface size on most to control for accommodation (18,19) to ensure printed matter (books, magazines, newspaper accurate correction of refractive error and avoid articles, etc.). Only 4.2% of the population —that is, 2 patients— had been using spectacles for near undercorrection of hyperopia, as well as the use of vision before the study. VA values obtained in INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME
and one patient received spectacles for the firsttime. VA improved in 26.7% of cases and did notchange in 13.3%. VA figures obtained with newrefractive correction were: VA ≥ 0.5 in 13.3%; VA< 0.5 ≥ 0.3 in 13.3%; finally, assessment wasimpossible in a single case (Fig. 3).
Once the prescription was updated, visual Figure 1. - A comparison of distant-vision VA under everyday refraction (Rx hab.) and induced refraction (Rx ind.), in the best eye.
functionally acceptable in 13.3% of cases, asopposed to none in prior everyday conditions.
normal viewing conditions were as follows: Degree of refractive error was analyzed for the VA≥ 0.4 in 6.25% of patients; VA< 0.4 in 46% of patients. Assessment at this distance level was hyperopia were established: low (0 to 2.75 impossible for 48% of patients due to lack of diopters), medium (3 to 6 diopters), and high (>6 cooperation or failure to recognize numbers diopters). The purely astigmatic component(Fig. 2).
Following refractive assessment, VA testing was repeated using the correct prescription for independently and also sorted into three near vision. The following values were obtained: levels: low (0 to 0.75 cylinder diopters), medium VA ≥ 0.4 in 18.75%; VA < 0.4 in 6.25%; (1 to 2 cylinder diopters) and high ( > 2 cylinder prescription in 2.1% of cases (Fig. 2).
Additional correction for near vision was follows: low myopia (0-2.75D) in 14.6% of eyes, prescribed for 29.2% of patients: 25% received medium myopia (3-6D) in 25% of eyes, high myopia (>6D) in 21.9% of eyes (Fig. 4). At the The age range suggests that presbyopia may be time of assessment, 42.7% were using prescription present in every one of the study subjects. The DS lenses for myopia; 12.5% were advised to change population has low accommodative capacity (2-4), their prescription, 28.1% required no change, and a fact which also explains near-vision difficulties, spectacles were prescribed for the first time for 14.6%; VA improved in 24.6% of cases with the Where binocular vision is concerned, the rate of strabismus and motility disorders was 66.7%.
Ocular health assessment turned up the following hyperopia (0-2.75D), 6.25% medium (3-6D), and results: among other findings, 59.4% had lens none had high hyperopia (>6D) (Fig. 4); 7.3% had opacities, 25% had nystagmus, 15.6% had had been wearing spectacles, changes in prescription were advised for 5.2%, no changes were required abnormalities, and 6.2% had keratoconus. in 2.1%, and spectacles were prescribed for the The group of individuals who had undergone first time in 8.3%. Prescription changes were cataract surgery was specifically studied and theirVA was analyzed using the same ranges as above:no patient had VA ≥ 0.5; 20% had VA < 0.5 ≥ 0.3;26.7% had VA < 0.3 ≥ 0.1 and VA could not beassessed in 6.7% of cases (Fig. 3).
At the time of examination, 26.7% of surgery patients were using spectacles, 20% were not, and20% had received an intraocular lens implant inthe course of surgery. Following refractive examination, 26.7% of Figure 2. - A comparison of near-vision VA under everyday refraction (Rx patients had changes in their refractive prescription hab.) and induced refraction (Rx ind.), in the best eye.
INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME
Figure 3. - A comparison of distant-vision VA under everyday refraction(Rx hab.) and induced refraction (Rx ind.), in the best eye of patients who Figure 5. - Distribution of spectacle wearers and of proposed prescription found to have improved VA in 12.5% of cases Our group had a 53% rate of spectacle wearers, a fairly high rate compared to other studies.
As to astigmatism, 22.9% of prescriptions had a Another finding was that individuals who benefit cylindrical component, 7.3% had low astigmatism from the use of spectacles for distant vision (0-0.75DC), 29.2% medium (1-2DC), and 7.3% achieve greater visual quality, though still below high (>2DC) (Fig. 6). A change in cylindrical what is considered normal. These findings are power was prescribed for 7.3%, change was similar to those of other studies (3,6).
Another point worth highlighting is that, component was prescribed for the first time in although many prescriptions ought to be reviewed and modified, the challenges posed by thesepatients and the high rate of severe ametropia maycall for partial prescriptions (but we are not aware Discussion
of whether this had been the case of the patientswho were already wearing spectacles before the These results support the statement that the study). VA for near vision was within the expected visual quality of individuals with DS is clearly range for this group, given both their age and the compromised, particularly where distant vision is reduced accommodative capacity apparently concerned. Results obtained in this study are linked to Down syndrome, which would further similar to the findings of earlier studies of groups explain loss of vision at all distances, especially with learning disabilities (4,5) and DS specifically (8,9,11), as well as studies involving age groups A point that must not be forgotten is the number of subjects for whom VA could not be measured at this distance range, probably because the test percentage of individuals with low VA in everyday employed was not ideally suited to their learning Figure 4. - Myopic and hyperopic eye distribution. Figure 6. - Distribution of astigmatic eyes.
INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME
changes in prescription were not very frequentbecause vision did not improve with better fit.
Where prescriptions were changed or lenses wereprescribed for the first time, VA did increase; thesechanges were therefore deemed favorable. significance of securing appropriate visual care forthese individuals. We also point out that in ourexperience they can benefit significantly through Figure 7. - Distribution of spectacle wearers with cylindrical prescriptions improved visual quality by the use of spectacles for both near and distant vision. In most cases, useof spectacles does not require a great effort by After adding a prescription for near vision, relatives or other caregivers: the obvious visual quality clearly improved. The fact that high improvement in vision, quality of life and reading performance is not required of these individuals does not mean that their near-distance visual needs should be ignored. After all, manymembers of the DS population are in shelteredworkshops, where activities often involve near Acknowledgments
vision and precision is frequently required.
Specific lenses for near vision, whether monofocal We wish to thank all the volunteers who took or bifocal, may therefore improve performance part in this study, as well as their relatives and and level of comfort. This is borne out by our own findings in this study and those of Woodhouse (6) This study was carried out with the institutional and financial support of Fundació Catalana Also worth noting is the number of subjects Síndrome de Down, Fundació ACE, Institut Català de Neurociències, Universitat Politècnica de nevertheless had very low visual acuity in Catalunya, Pfizer SA, and the Department of everyday conditions. Once refractive correction Health and Social Security of the Government of was updated, VA improved and a significant number of patients achieved levels consideredfunctionally acceptable.
Appropriate treatment for cataracts should References
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