Achint Kaur, B.Optom
Optometry Intern, Dr Shroff’s Charity Eye Hospital, New Delhi, India
We all want to live independently but living with low vision is not easy, these patients have a hard time coping with how they will reserve their independence as their sight begins to drop.
According to World Health Organisation (WHO) a person with low vision is one who has visual impairment even after treatment and/or any standard refractive correction and has a visual acuity of less than 6/18 to light perception in the better eye, or a visual field less than 10 degree from point of fixation or is potentially able to use vision for planning and or execution of a task.
Retinitis Pigmentosa (RP) belongs to the group of pigmentary retinopathies, a generic name that covers all retinal dystrophies presented with a loss of photoreceptors and retinal pigment deposits. RP is a retinal degenerative disease characterised by pigment deposits predominantly in the peripheral retina and by relative sparing of the central retina. In most cases of RP there is a primary degeneration of rod photoreceptors, with secondary degeneration of cones.(1) RP is commonly genetic in nature. Approximately 60-80% of those with RP inherit it by autosomal recessive transmission.(2)
Stages of RP in non-syndromic conditions, these are as follows:-
FIRST STAGE: This is a very crucial stage often ignored by many patients, and the main symptom is night blindness. In dim light, peripheral visual field is affected, this defect is not much appreciated by patients and patients have normal daily life activities. Every other finding will be normal like visual acuity, fundus examination, optic disc, etc.
SECOND STAGE: In this stage night blindness is more evident and patients will have difficulty in driving, walking, and performing activities at night. Also, the peripheral visual field in daylight is getting more affected, while driving patients might not be able to see pedestrians or side coming cars and there will be difficulty in walking as they step into objects.
THIRD OR LAST STAGE: In this last stage, difficulty is enhanced in a patient’s mobility because of peripheral vision loss, patients cannot read and require glasses, photophobia occurs to a large extent . Retinal vessels get thin and the optic disc gets more pallor.
CHALLENGES FOR LOW VISION IN RP PATIENTS
- Reduced vision in dim light makes mobility difficult in places like movie theatres, sunsets.
- Gradual loss of peripheral vision making it difficult to move freely as they will bump into objects due to tunnel vision.
- Loss of central vision makes it difficult to proceed with their hobbies like reading, stitching
- Patients find it difficult to function at night, and will take time to adjust their eyes between bright and darker places.
- Colour vision is also affected, will have difficulty in distinguishing between similar colours and hence, cannot opt for their dream jobs.
AS OPTOMETRISTS WE CAN HELP THESE PATIENTS BY PROVIDING (3)
- Spectacles, and simple magnification including CCTV
- Glare control and proper illumination for reading and mobility
- Use of field enhancers for side view and mobility
- Vision enhancement lenses known as BIOPTIC TELESCOPES are used to improve distance vision
- Counselling is very important for moral support, etc.
Take home message: Awareness and acceptance of the condition is key to this condition. Positive attitude towards them will change their perception about life and will motivate them.
- Hamel C. Retinitis pigmentosa. Orphanet journal of rare diseases. 2006 Dec;1(1):1-2.
- Rundquist J. Low Vision Rehabilitation of Retinitis Pigmentosa. Journal of Visual Impairment & Blindness. 2004;98(11):718-724.
- 3.Weiss NJ. Low vision management of retinitis pigmentosa. J Am Optom Assoc. 1991 Jan;62(1):42-52.