Dr PremNandhini Satgunam, Associate Research Optometrist, L V Prasad Eye Institute (LVPEI), Hyderabad, has done a study on near vision in individuals with Down syndrome: a vision screening study.
Speaking about the study, Dr Satgunam said, “Human eye has a lens that needs to focus for different viewing distances. Especially when looking at near, the focusing power of the lens should increase. As we age this focusing power decreases and by the age of 40 or so, almost everyone has a requirement for reading spectacles. We don’t expect children to have focusing problem for near. However for children with Down syndrome, this could be an issue and they would require reading spectacles as well.
“In the past it was thought that those who hold books at a closer distance have good focusing power and should have good near vision. Our study showed that there is no correlation between the distance at which a child holds the book and the measure of the near vision with the accuracy of their focusing power. What this means is that, just because a child can hold a book closer to his/her face, and at times is able to read few words from the book, it does not mean his/her focusing ability is good and accurate. If there are problems in this focusing ability, the child may have difficulty to do sustained near tasks like reading. A specific test called dynamic retinoscopy should be performed for these children to determine how accurate they are in focusing.
“Based on this test result, some children (particularly those with Down syndrome) may need reading spectacles,” concluded Dr Satgunam.
Dr PremNandhini Satgunam received her bachelor’s degree in optometry from Elite School of Optometry, Sankara Nethralaya BITS, Pilani, graduating as the Best Outgoing Student in her class. She received her MS and PhD in Vision Science from Ohio State University, USA. She has received the Ohio Lions Eye Research Graduate Student Fellowship, Minnie Flaura Turner Memorial Award for Impaired Vision Research, and the Arene T Wray Graduate Student Fellowship to recognise her research in the field of optometry. She worked as a postdoctoral fellow in the field of vision rehabilitation at Schepens Eye Research Institute, Harvard Medical School, Boston, USA. She has received several travel grants, presented at national and international conferences and published papers in international peer-reviewed journals. Her current research interests are in the areas of paediatric vision rehabilitation, visual development in children with vision impairment and binocular vision.
In an exclusive interview with India Medical Times, Dr PremNandhini Satgunam talked about her recent ‘vision screening study’ on near vision in individuals with Down syndrome.
Can children also suffer from near vision problems? What is the role of Down syndrome in this?
Typically, by the age of 40 years or so adults begin to get problems with their near vision, requiring reading spectacles (or reading glasses). This condition is called Presbyopia. This happens because the human eye loses its ability to increase the focusing power for near viewing. Those people who have myopia (wearing minus power) compensate for the plus power, simply by removing their spectacles to read.
Now to the question of children: if a child has a plus power, then for reading they need even more plus power. If they are not wearing the correct spectacle power, then they can also have near vision problems, not in the same way as how adults face. In children the problem can manifest as their inability to read for long-time, lack of concentration or tired eyes. This is not due to presbyopia but due to the refractive error condition called hypermetropia.
With regards to individuals having Down syndrome, studies done in UK and Canada have shown that children with Down syndrome require bifocal reading spectacles like presbyopic adults. However, the reason is not fully understood.
Can there be also other factors or conditions that may cause near vision in children?
Sometimes there can be eye muscle coordination issues that can cause problem in near vision for children. A coordination mismatch between eye muscle capacity and focusing capacity can also cause several binocular vision (ability to use both eyes) dysfunctions. A thorough binocular vision and orthoptics evaluation by a trained optometrist can pinpoint to the correct diagnosis.
How many children are suffering from near vision in India?
Only a couple of studies have come out from India. One landmark study looking at binocular vision problems in school going children came from the Optometry team in Sankara Nethralaya, Chennai. According to this study, the prevalence increased from 25% to 36% in 7 to 17 years old children, as the near work demand increases.
How Dynamic Retinoscopy helps in diagnosing near vision in children?
Dynamic retinoscopy is a test done to determine whether a person is able to accurately focus on a near object. Through this test we can find out errors in the focusing mechanism of the eye.
How many children in India have been tested for near vision through this test? What percentage of them was found to be suffering from near vision?
The device used to measure power required for spectacle correction is retinoscope. It is a simple hand held device. With the same device, we can do the procedure of dynamic retinoscopy. The procedure is not normally done in regular clinics, which is why near vision problems can get missed. Our study on individuals with Down syndrome recommends the incorporation of this test into routine eye checkup.
Is there a case study or research in this regard? If yes, what are the key findings?
In the study on individuals with Down syndrome, we found about 41% of children showing a lower focusing ability for near objects. These children may require a bifocal correction to overcome this problem. We also showed that just because a child can read something at a close distance, it will not mean that they can sustain and read for long duration without discomfort.
How expensive is this test? How many machines are currently being used in India?
This is only a modification of an available instrument. Any eye care practitioner (optometrist/ophthalmologist) can get easily trained for this test and can use it in their practice. It would only take less than a minute to do this extra test.
How Dynamic Retinoscopy can benefit doctors?
The technique will reveal whether a patient is viewing a near object with accurate focus. Such a result can indicate if there will be a need for spectacle correction or bifocal correction.
How would be the trend for near vision in children in coming years?
Long term studies are needed to comment on this question.