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Clinical science
Cataract surgery outcomes in adult patients with Down's syndrome
  1. Emmy Y Li1,2,
  2. Tommy C Chan1,2,
  3. Nai Man Lam1,2,
  4. Vishal Jhanji1,2,3
  1. 1Hong Kong Eye Hospital, Kowloon, Hong Kong
  2. 2Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong
  3. 3Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
  1. Correspondence to Dr Vishal Jhanji, Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, 3/F, 147K, Argyle Street, Hong Kong, Hong Kong; vishaljhanji{at}cuhk.edu.hk

Abstract

Purpose To describe the outcomes of cataract surgery in adult patients with Down's syndrome at a tertiary eye hospital in Hong Kong.

Methods Retrospective case-file analysis was performed to identify patients with Downs's syndrome who underwent cataract surgery between January 2002 and December 2012. Morphology of cataract, associated ocular features and surgical and visual outcomes were analysed.

Results Cataract surgery was performed in 33 eyes of 20 patients (12 males, 8 females, mean age 42.9±10.6 years) over a 10-year period. Nine patients (9/20, 45.0%) had bilateral cataracts at the time of diagnosis. White cataracts were noted in 12 eyes of 10 patients (12/33, 36.3%) at the time of presentation. Associated ocular problems included myopic maculopathy (18 eyes, 54.5%), keratoconus (12 eyes, 36.3%), nystagmus (2 eyes, 6.0%), corneal scar (2 eyes, 6.0%) and glaucoma (2 eyes, 6.0%). Five eyes (15.1%) underwent extracapsular cataract extraction whereas a phacoemulsification was performed in 28 (84.9%) eyes. Intraocular lens implantation was performed in 32/33 eyes. The most common postoperative complication was posterior capsular opacification (8 eyes, 24.2%). The mean best-corrected visual acuity improved from 0.07±0.11 preoperatively to 0.17±0.19 at 3 months postoperatively (p=0.000).

Conclusions A high incidence of bilateral cataracts as well as white cataracts was observed in patients with Down's syndrome in our study. Although the surgical outcomes of cataract surgery were good, the visual outcomes were suboptimal in our cases due to associated ocular comorbidities.

  • Lens and zonules
  • Vision

http://dx.doi.org/10.1136/bjophthalmol-2013-304825

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    Introduction

    Down's syndrome is the most common chromosomal derangement in live births.1 Individuals with Down's syndrome have a higher incidence of functional and structural abnormalities of the eyes. Some ocular abnormalities such as epicanthic folds and oblique slanting of the palpebral fissures are commonly found on paediatric examination and have no functional significance. Other anomalies such as refractive errors, cataracts, nystagmus, strabismus, nasolacrimal duct obstruction, blepharoconjunctivitis, retinal abnormalities, glaucoma, iris Brushfield spots and keratoconus may have important functional and therapeutic implications.2–8 Of these, refractive errors and cataract should be corrected at the earliest in order to avoid preventable ocular morbidity related to these disorders. A recent study from Hong Kong revealed the incidence of refractive errors and cataracts in adult patients with Down's syndrome to be 86.3% and 72.2%, respectively.8 The authors suggested that uncorrected refractive errors and cataracts are the main visually debilitating ophthalmological abnormalities in this group of patients.8 However, not all patients with Down's syndrome may receive a regular and timely ophthalmological assessment. Consequently, some of the ocular diseases may not be diagnosed until late, thereby causing unnecessary ocular morbidity. Previous studies have reported the occurrence of cataracts early in life in patients with Down's syndrome.9 Nevertheless, the outcomes of cataract surgery have been reported to be good in children with Down's syndrome.10 In the present study, we evaluated the surgical and visual outcomes of cataract surgery in adults with Down's syndrome.

    Methods

    A retrospective case-file analysis was conducted for all cases with Down's syndrome who underwent cataract surgery at the Hong Kong Eye Hospital, Hong Kong, between January 2002 and December 2012. As per the standard operating procedures of the hospital, all cases with Down's syndrome received surgery under general anaesthesia. Consecutive patients with Down's syndrome that underwent cataract surgery over a 10-year period were selected from the hospital database. The Institutional Review Board of the Hong Kong Eye Hospital, Hong Kong, approved the conduct of the study. The study adhered to the tenets of the Declaration of Helsinki.

    The patients were referred from various sources, including assessment centres, general practitioners and regional eye clinics. Ocular examination included assessment of visual acuity and ocular motility, slit-lamp biomicroscopy, cycloplegic retinoscopy and indirect ophthalmoscopy. Snellen E test, isolated E and Sheridan–Gardiner test were the preferred methods for checking visual acuity. For those patients unable to understand, preferential looking test with the Cardiff acuity cards was used. Orthoptists or optometrists were responsible for carrying out the visual acuity assessments. The patients underwent slit-lamp biomicroscopy for examination of the cornea, iris and the lens. Corneal topography was used for those patients suspected of having keratoconus. Cataracts were defined as any opacity of the lenses involving one or both eyes.

    All records were reviewed by one of the investigators of this study for the following information: demographic profile, ocular and systemic morbidities, type of cataract, age at the time cataract surgery, intraoperative findings, postoperative complications and visual outcomes.

    Data entry and statistical analyses were done using commercially available software SPSS V.16 (SPSS Inc., Chicago, Illinois, USA). Visual acuity was converted to decimal values for statistical analysis. Descriptive statistics were reported. The differences in means were assessed using non-parametric test in view of a small sample size.

    Results

    A total of 33 eyes of 20 patients (12 males, 8 females) with Down's syndrome underwent cataract surgery under general anaesthesia over a 10-year period. The mean age at the time of diagnosis of cataract was 40.3±10.9 years (range 18–56 years) and the mean age at the time of cataract surgery was 42.9±10.6 years (18–58 years). Systemic problems were noted in 17 (85.0%) patients in the form of hypothyroidism or hyperthyroidism (n=6), recurrent pneumonia (n=4), congestive heart failure (n=4), deafness (n=3), tuberculosis (n=2), diabetes mellitus (n=2), recurrent urinary tract infections (n=2), bronchial asthma (n=1) and obstructive sleep apnoea (n=1). Associated ocular problems included myopic maculopathy (18 eyes, 54.5%), strabismus (17 eyes, 51.5%), keratoconus (12 eyes, 36.3%), nystagmus (2 eyes, 6.0%), corneal scar (2 eyes, 6.0%) and glaucoma (2 eyes, 6.0%). Nine patients (9/20, 45.0%) had bilateral cataracts at the time of presentation. White cataracts were noted in 12 eyes of 10 patients (12/33, 36.3%) at the time presentation. Posterior polar cataract was present in four eyes (4/33, 12.1%) of three patients.

    Manual extracapsular cataract surgery was performed in five eyes (15.1%) with white cataracts. Phacoemulsification was performed in 28 (84.9%) eyes. Cataract surgery was performed in the same setting in all nine patients with bilateral cataracts. Four patients (20%) received cataract surgery in the fellow eye 3 months after the first surgery. The results are summarised in table 1.

    View this table:
    Table 1

    Outcomes of cataract surgery in adult patients with Down's syndrome

    Notable intraoperative findings were low intraocular pressure (one eye, 3.0%), partially absorbed cataract (n=1, 3.0%) and thick anterior capsule (n=1, 3.0%). Intraocular lens (IOL) implantation was performed in 32/33 cases. One case with white cataract was noted to have chronic retinal detachment during intraoperative indirect ophthalmoscopy. IOL implantation was not implanted in view of guarded visual prognosis in this case. One case had posterior capsular rupture with subsequent IOL implantation in the ciliary sulcus. The most common postoperative complication was posterior capsular opacification (eight eyes, 24.2%). Of these eight cases, primary posterior capsular plaque was noted in one eye. Posterior capsular opacification was noted in 6 months in one eye, 12 months in two eyes, 18 months in two eyes, 36 months in one eye and 48 months in one eye. Fibrinous reaction was noted during the first postoperative week in one eye that underwent extracapsular cataract extraction. Intensive corticosteroid eye drops were used to manage this case. Retinal detachment was noted in this eye 15 months postoperatively. Overall, the mean best-corrected visual acuity measured with Snellen chart and single ‘E’ matching improved from 0.07±0.11 preoperatively to 0.17±0.19 at 3 months postoperatively (Wilcoxon signed rank test, p=0.000). When converted to logMAR visual acuity for analysis, there was mean change of 0.52±0.65 log units from 1.36±0.77 preoperatively to 0.84±0.55 postoperatively for all eyes (Wilcoxon signed rank test, p=0.001). The mean change in logMAR visual acuity was 0.30±0.42 from 1.13±0.70 preoperatively to 0.83±0.57 postoperatively for eyes with non-white cataracts (n=15, p=0.005, Wilcoxon signed rank test). For eyes with white cataracts, a mean change of 1.34±0.76 log units from 2.20±0.20 preoperatively to 0.86±0.56 postoperatively was observed (n=4, p=0.066, Wilcoxon signed rank test).

    Discussion

    The occurrence of early cataract among children aged up to 17 years with Down's syndrome has been reported to be up to 50%.11–14 There is an increased incidence of both acquired (11–60%) and congenital cataracts (2–6%) in patients with Down's syndrome as compared with the general population. In previous studies of congenital or infantile cataracts, 3–5% of cases were associated with Down's syndrome.15–18 The incidence of Down's syndrome in Hong Kong is 1.28 per 1000 live births,19 which is slightly higher than the 1.00 per 1000 live births reported in the USA.20 The incidence of age-related cataract in patients with Down's syndrome has been shown to be as high as 35–50%.8 ,21 ,22 The occurrence of early cataract has been attributed to multiple factors such as susceptibility to oxidative stress23 and accumulation of amyloid precursor protein and amyloid-β peptides24 ,25 in the lens. Previous studies have reported the management and outcomes of childhood cataract in Down's syndrome.9 ,10 In the present study, we evaluated the outcomes of cataract surgery in adult patients with Down's syndrome. A successful cataract surgery with IOL implantation was performed in all but one cases in our study. Posterior capsular rupture was noted in one case. An overall significant improvement in the visual acuity was noted postoperatively.

    To the best of our knowledge, ours is the largest case series in the literature describing cataract extraction in adult Down’s syndrome patients. In our series of adult Down's syndrome patients, we found a high prevalence of bilateral cataracts. Some of these cases had white cataracts at the time of presentation. The detection of white cataracts in patients with Down's syndrome in our study may reflect a lack of regular ophthalmic screening in these cases. It is known that the ophthalmological disorders in Down's syndrome increase in frequency with age. About 38% of children less than 12 months of age and 80% of those aged 5–12 years have ophthalmic disorders that need monitoring or intervention.26 The American Academy of Pediatrics recommends that an eye exam should be carried out in these children by 6 months of age with follow-up exams once per year or more frequently if indicated by the ophthalmologist.26 Therefore, ophthalmological assessments should continue annually to screen for other disorders such as cataract and keratoconus that could develop in the second decade or later in life.14 Certain other factors may also lead to a delay in diagnosis of visual problems in patients with Down's syndrome. One of the most relevant systemic problems in patients with Down's syndrome is subnormal mental intelligence. It is therefore difficult to assess the visual function and visual acuity in these patients. Furthermore, other systemic problems related to cardiac or endocrine system may delay surgery in these patients.

    In our study, there was no significant difference between the age of presentation and the age at the time of cataract surgery (results not shown). Most of the cases were operated very early after the first presentation. This was pertinent since many patients had white cataracts and poor vision during their first visit to our hospital. Furthermore, bilateral cataract surgery was performed in the same sitting in cases with bilateral white cataracts. This was mainly done in order to avoid the risk of second exposure to general anaesthesia and expedite the visual rehabilitation in our patients. Although simultaneous bilateral cataract surgery is still debatable27 in normal adult patients, it is common practice in some settings. In our study, the number of cases that underwent simultaneous bilateral cataract surgery in our study is low; nevertheless, we believe that in the presence of adequate facilities, this could be safely performed in cases with Down's syndrome with poor visual acuity in both eyes.

    We found a high prevalence of associated ocular comorbidities in our study. Some of these comorbidities such as myopic maculopathy and keratoconus were responsible for poor visual outcomes. Nevertheless, an overall improvement of visual acuity was observed in our study. We were unable to assess the exact role of an amblyopic component in our patients, but there is a possibility that some of the patients did not attain good vision postoperatively due to amblyopia.28 It has also been suggested that individuals with Down's syndrome may have a wide variation in visual acuity due to differential characteristics between the eye and the brain29 and other associated neuropathologies.30 Also, as mentioned previously, it may be difficult to accurately assess the visual function and visual acuity in these patients due to subnormal mental intelligence.

    The main limitations of the current study are its retrospective design and small case numbers. Overall, our study reported optimal surgical and visual outcomes of cataracts surgery in adult patients with Down's syndrome. A high incidence of bilateral cataracts and white cataracts is a significant finding in our study. It is unfortunate that this already underprivileged group of patients suffer from unnecessary visual impairment due to an easily correctable ocular disease. With increasing safety and efficacy of cataract surgery in the present world, screening and early treatment for visually significant cataracts may be beneficial in this population. Simultaneous bilateral cataract surgery may be considered in this group of patients in order to enhance the quality of life. Proper precautions and protocols relevant to simultaneous bilateral cataract surgery should be strictly followed to ensure optimal outcomes.

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    Footnotes

    • Contributors Concept and design: EYL and VJ. Analysis and interpretation: EYL and VJ. Writing the article: EYL, TCC, NML and VJ. Critical revision of the article: EYL, TCC and VJ. Final approval of the article: EYL, TCC, NML and VJ. Data collection: EYL and TCC. Provision of materials, patients or resources: EYL and NML. Statistical expertise: EYL.

    • Competing interests None.

    • Ethics approval Kowloon Central Cluster Ethics Committee, Hospital Authority, Hong Kong.

    • Provenance and peer review Not commissioned; externally peer reviewed.