Assessment of the Catford drum in visual acuity testing and its use as a measurement of visual performance in low-vision patients

Evaluating the precision of an online visual acuity test tool

OBJECTIVE

The aim of this study was to assess the precision of a web-based tool in measuring visual acuity (VA) in ophthalmic patients, comparing it to the traditional in-clinic evaluation using a Snellen chart, considered the gold standard.

METHODS

We conducted a prospective and in-clinic validation comparing the Eyecare Visual Acuity Test® to the standard Snellen chart, with patients undergoing both tests sequentially. Patients wore their standard spectacles as needed for both tests. Inclusion criteria involved individuals above 18 years with VA equal to or better than +1 logMar (20/200) in each eye. VA measurements were converted from Snellen to logMAR, and statistical analyses included Bland-Altman and descriptive statistics.

RESULTS

The study, encompassing 322 patients and 644 eyes, compared Eyecare Visual Acuity Test® to conventional methods, revealing a statistically insignificant mean difference (0.01 logMAR, P = 0.1517). Bland-Altman analysis showed a narrow 95% limit of agreement (0.22 to -0.23 logMAR), indicating concordance, supported by a significant Pearson correlation (r = 0.61, P < 0.001) between the two assessments.

CONCLUSION

The Eyecare Visual Acuity Test® demonstrates accuracy and reliability, with the potential to facilitate home monitoring, triage, and remote consultation. In future research, it is important to validate the Eyecare Visual Acuity Test® accuracy across varied age cohorts, including pediatric and geriatric populations, as well as among individuals presenting with specific comorbidities like cataract, uveitis, keratoconus, age-related macular disease, and amblyopia.

Surveillance of vision and ocular disorders in children with Down syndrome

Children with Down syndrome have a high prevalence of ocular disorders. The UK Down's Syndrome Medical Interest Group (DSMIG) guidelines for ophthalmic screening were locally implemented into a protocol that included neonatal eye examination by an ophthalmologist and a comprehensive ophthalmological examination (cycloplegic refraction, ophthalmoscopy, and orthoptic assessment) by at least the age of 3 years, followed by preschool follow-up as indicated. We audited retrospectively surveillance for ocular disorders before and after the DSMIG-based guidelines were locally adopted in 1995. Results were compared for children born before and after the implementation of screening guidelines. A total of 81 children (43 females, 38 males) with Down syndrome were identified. After the DSMIG protocol, 34/36 children received a full ophthalmological examination in the neonatal period, compared with 9/27 children before 1995 (p<0.001). Neonatal screening resulted in the detection of cataracts in three infants. Mean age of first comprehensive ophthalmic screening outside the neonatal period was similar in the two groups (1y 6mo before guidelines vs 1y 9mo after), as were the proportion of children receiving preschool eye checks (27/30 before; 17/18 after). Overall, 65.7% children were screened in accordance with the guidelines, improving to 100% in recent years. At school age, 43% of the study population had significant refractive errors, with 27% having hypermetropia and astigmatism. Earlier prescription of glasses for refractive errors was seen (mean age 5y 6mo before guidelines; 3y 6mo after; p<0.001). Prevalence of other ocular disorders included strabismus (34/72, 47%), nasolacrimal duct obstruction (26/73, 35.6%), cataracts (5/64, 7.8%), and nystagmus (12/72, 16%). Establishment of the DSMIG-based local protocol has streamlined ocular surveillance. It is anticipated that this will improve developmental and functional outcomes in Down syndrome.