RETINITIS PIGMENTOSA

 

 

Retinitis Pigmentosa (RP) refers to a group of inherited diseases that damage the light sensitive rods and cones in the retina. The rods are affected more than the cones. The rods provide peripheral vision and night vision. The cones provide colour vision and clear central vision. RP patients initially have night blindness (nyctalopia) and peripheral vision loss that may subsequently lean onto central vision loss.

 

 

Inheritance

 

·        Autosomal recessive – most common type of RP. The chance of having this condition is higher if the patients are related (eg:cousins).

·        Autosomal dominant - in this form of RP, only one parent has the gene and is usually affected by the disease as well. Each child has a 50 percent chance of inheriting this gene and developing RP.

·       
X linked – if the father is affected, all sons will be unaffected and all daughters will be carriers. If the mother is the carrier, 1 in 2 sons will be affected and in 2 daughters will be carriers.

 

 

Prevalence and Demography

 

·        Prevalence – RP is considered a rare disorder. It is generally estimated that the disorder affects roughly 1 in 4000 people.

·        Age – It appears in the childhood and progress slowly, often resulting in blindness in advanced middle age.

·        Sex – Males are more commonly affected than females in a ratio of 3:2.

·        Laterality –  Disease is almost invariably bilateral and both eyes are equally affected.

 

Pathogenesis

            

RP is an inherited disorder that results from harmful changes in any one of more than 50 genes. These genes carry the instructions for making proteins that are needed in cells in the retina, called photoreceptors. Some of the changes, or mutations with in genes are so severe that the gene can’t make the required protein, limiting the cells functions. Other mutations produce a protein that is toxic to the cell. Still other mutations lead to an abnormal protein in that doesn’t function properly. In all these cases, the result is damage to the photoreceptors.

 

Clinical Features

 

Typically RP, in which rods are degenerated early and cones are involved late, is characterized by following features:

 

1.       Visual changes –

·        Night blindness- It is the characteristic and earliest features and may present several years before the visible changes in the retina appear. It occurs due to degeneration of the rods.

·        Dark adaptation- Light threshold of the peripheral retina is increased, though the process of dark adaptation itself is not affected untill very late.

·        Tubular vision, ie) loss of peripheral vision with preservation of central vision occurs in advanced cases.

·        Central vision is also lost ultimately after many years.

 

2.       Fundus changes –

·        Retinal pigmentary changes- These are typically perivascular (around veins) and jet black spots resembling bone corpuscles in shape. Initially, these changes are found in the equatorial region only and later spread both anteriorly and posteriorly.   

Retinal arterioles are narrowed and may become thread- like in late stages.

·        Thinning and atrophy of retinal pigment epithelium is seen in peripheral retina.

·        Optic disc becomes pale and waxy in later stages and ultimately consecutive optic atrophy occurs.

 

3.      Visual field changes –

·        Annular or ring shaped scotoma is a typical feature which corresponds to the degenerated equatorial zone of retina.

 

Associations of Retinitis pigmentosa

 

  1. Ocular associations

·        Myopia

·        Primary open angle glaucoma

·        Microphthalmos

·        Conical cornea

·        Posterior subcapsular cataract

2. Systemic associations

·        Laurence Moon Biedl syndrome- It is characterized by retinitis pigmentosa, obesity, hypogenitalism, polydactyly and mental deficiency.

·        Cockayne's syndrome- It is characterized by retinitis pigmentosa, peripheral neuropathy and cerebellar ataxia.

·        Usher's syndrome- It includes retinitis pigmentosa and labyrinthine deafness.

·        Hallgren's syndrome- It comprises retinitis pigmentosa, vestibulocerebellar ataxia, congenital deafness and mental deficiency.

 

Diagnosis

 

·        Acuity test – measures the accuracy of central vision.

·        Colour vision testing – helps determine the status of cone cells.

·        Visual field test – to determine the extent of vision loss.

·        Dark adaptation – measures how well eyes adjust to change in lighting.

·        ERG test (electrophysiological test)- records the electrical currents produced by the retina due to light stimulus.

Electroretinogram (ERG) is the most critical diagnostic test for RP because it provides an objective measure of rod and cone function across the retina.

 

Treatment

 

There is no effective treatment for retinitis pigmentosa. There are some general measures for supportive management.

 

·        Vitamin A Palmitate- High doses of this compound may slow RP.

·        Systemic acetazolamide for associated cystoid macular edema.

·        Sunglasses- These make eyes less sensitive to light and protect eyes from harmful UV rays that may spread vision loss.

·        Low vision aids in the form of 'magnifying glasses' and ' night vision device' may be of some help.

·        Replacement of damaged cells or tissues with healthy ones under investigation.

·        Gene therapy to put healthy genes into the retina under trial.

·        Bionic Eye System, a visual prothesis designed to restore functional vision to the blind suffering from RP.

·        Rehabilitation of the patient should be earned out as per his socioeconomic background.

·        Prophylaxis- Genetic counselling for no consanguineous marriages may help to reduce the incidence of disease.

 

 

 

Dr. Devin Prahbakar MS, FRCS

www.DivyaPrabha.in

 

 

 

COVID-19 and the EYE

The new coronavirus behind the pandemic causes a respiratory illness called COVID-19. Its most common symptoms are a fever, coughing, and breathing problems. Rarely, it also can cause an eye infection called conjunctivitis. Based on data so far, doctors believe that 1%-3% of people with COVID-19 will get conjunctivitis, also called pinkeye. It happens when the virus infects a tissue called conjunctiva, which covers the white part of your eye or the inside of your eyelids.

Symptoms are:

• ·         Red
• ·         Swollen
• ·         Itchy

If you have conjunctivitis, it doesn’t necessarily mean you have COVID-19. The more likely causes are the many different viruses, bacteria, chemicals, and allergens that can irritate your eyes. Many forms of conjunctivitis go away with over-the-counter treatments in about 1-2 weeks. But if you also have a fever, cough, or shortness of breath, ask your doctor what, if anything, you should do. Call before you head to a hospital or a medical center to see if it’s safe for you to visit and for any instructions for your arrival.

The new coronavirus, named SARS-CoV-2, gets passed on primarily through droplets from a cough or a sneeze. These particles most often enter through your nose or mouth as well as your eyes. It’s also possible to catch the virus if you touch a contaminated countertop, doorknob, or other surfaces. But this doesn’t seem to be the main way the virus spreads.

If you have conjunctivitis from COVID-19, you may infect others with SARS-CoV-2 if you touch your eyes and then touch people or surfaces without washing or disinfecting your hands. Avoid touching your face, especially the mucous membranes in your mouth, nose, and eyes.

How to Protect Your Eyes

Guarding your eyes — as well as your hands, nose, and mouth — can slow the spread of coronavirus. Here are some ways to you can keep your eyes safe and healthy during this coronavirus outbreak. Like everyone, be sure to wash your hands often and stay home whenever you can. If you go out, keep 6 feet away from others.

It also may be a good idea to:

Wear glasses. If you wear contact lenses, switch to glasses for a bit. That may help keep your hands away from your eyes. Also, the lenses may help protect your eyes from any respiratory droplets. If you don’t wear glasses, try sunglasses. And if you’re caring for someone ill, don safety glasses or goggles.

Stock up eye medication. Check with your insurer to see if you can refill glaucoma drops and other essential prescriptions in advance. You might be able to get a 3-month supply. Ask your doctor or pharmacist for any help.

Don’t rub your eyes. It can be a hard habit to break. Moistening drops may help ease itchiness. Wash your hands for 20 seconds before and after you do it. If you must touch your eyes, use a tissue instead of your fingers.

Expect changes to eye exams and procedures

You should wear a mask to your appointment. If you do not have a mask, one may be provided for you.

·         The clinic may ask you to wait outside, or in your car, instead of in the normal waiting room. This is to protect you, the other patients, and the office staff from possible virus exposure in crowded waiting areas.

·         The clinic is likely restricting the number of people that enter. If you do not need someone to be there with you for the actual appointment, please do not bring anyone into the building with you.

·         Your temperature may be checked on entry to the building.

·         Your eye doctor may use a special plastic breath shield on the slit lamp machine they use to look into your eyes. They will also wear a mask, and may also wear gloves, goggles or a plastic shield over their eyes.

·         Your doctor may ask you to wait to speak until after your eye exam is complete. Then they can talk with you and answer questions when they can be a safe distance from you.

You will be asked to follow certain precautions

·         If you have a cough or a fever, or have been in close contact with someone who has these symptoms, you must call your doctor’s office ahead of time and let them know. If your visit is not an emergency, you may need to stay home.

·         If you arrive sick, your doctor may ask you to return home. If you have a problem that cannot wait to be seen, you will be asked to wait in a special room away from other patients. The clinic staff and your physician may wear additional protective equipment, such as gowns and gloves.

·         If you need to cough or sneeze during your exam, move back from the slit lamp microscope machine. Bury your face in the crook of your arm or cover your face with a tissue. Wash your hands with soap and water right away.

Li Wenliang, MD, Ophthalmologist, Wuhan

The 33-year-old doctor was the first to raise the alarm about the coronavirus in late December 2019. Using the Chinese social media platform Weibo, Li attempted to warn his colleagues about a cluster of SARS-like pneumonia cases. As his posts went viral, he realized that he “would probably be punished." Within days, he was summoned by Chinese officials and forced to sign a letter accusing him of "making false comments" that had "severely disturbed the social order". A copy of that letter was later posted on Weibo.

Following the incident, Dr. Li returned to work and, unfortunately, contracted the virus from an asymptomatic glaucoma patient in early January. In several interviews with Chinese media, he said that the patient eventually developed a fever and CT scans showed an unknown virus in her lung. Soon after, he started coughing, became febrile and was hospitalized. Tests confirmed he was infected with the coronavirus on Jan. 31. Wuhan Central Hospital confirmed his death on February 7 after a series of conflicting reports about his condition.

The news of his demise has sparked a public outpouring of anger and grief. Many have hailed him a martyr and a national hero for his attempts to warn the public.

Your Child's eye during COVID Lockdown and online classes

We used to ask our children not to look at the TV or computer for long time, but now during the COVID lockout they need to sit for hours in front of the TV and computer to attend school lessons. Parents are genuinely concerned about how this prolonged viewing of the computer will affect the eyes and vision of their child.

Computer Vision Syndrome (CVS) is the term used to describe the condition commonly seen in persons working on computers for long hours. The symptoms of Computer Vision Syndrome involve not only the eyes but also the musculoskeletal system.

Eye problems consist of:

• Eye strain, Watering

• Irritation and Foreign body sensation

• Headaches or pain in and around eyes

• Blurred vision

Musculoskeletal problems consist of:

• Pain in the neck

• Pain in lower back

• Pain in the wrist

• Inability to concentrate after a while

• Disturbed sleep

Other Problems:

Uncorrected refractive errors are the single most important factors that trigger off this disorder. Hence even a small refractive error need correction. It is ideal to check your child's vision at five years of age. Thereafter it is prudent to check the eyes if the child complaints of headache, eyestrain or blurred vision.

The CVS can be reduced by adjusting the computer monitor as follows

• Sit farther away from your computer screen. A good rule is to be at least 25 inches, or roughly an arm’s length, away. 

• Adjust the height of the chair to keep the upper edge of the monitor screen below the level of your eyes so that you do not have to extend your neck or keep your eyes wide open to see the screen.

• Background should be light & letters dark. Black letters on a white background are easiest to read and least strenuous on the eyes.

• Keep the font size at least two points larger than the size you can read easily. Prefer scrolling on the screen rather than zooming down to have every thing in one view.

• Dim your screen if it’s much brighter than the rest of the light in the area. You could also adjust the room lighting so the contrast is lessened.

• Keep your screens clean. Dirty screens with fingerprints and other debris can strain your eyes even more.

• Viewing distance should be comfortable. Place monitor in such a way that there is no reflection of light on the screen. The source of light should be on your sides to avoid reflection on the screen. If a bright source of light e.g. a window is directly in front of your eyes, the glare will be highly disturbing. Some people feel comfortable working in a dimly lit room. Maintaining absolutely essential brightness is necessary to avoid straining eyes.

• If you have to work for long hours, use support for the lower back. Position your key board, mouse and monitor in such a way that the body remains in a straight posture to see as well as handle these.

• The eyes are constantly moving and accommodating while working on computers. To rest your eyes follow a 20:20:20 rule. It means that every 20 minutes take a break for 20 seconds and get up to look at a distance more than 20 feet. This will rejuvenate your eyes and make working more comfortable

• Computer glasses make working on computers comfortable and are not needed otherwise, for distance or near vision correction. Computer glasses should ideally be UV protective and have a good quality anti-reflective coating to avoid the glare.

BLUE LIGHT

Blue colour has elicited a of of interest nowadays. Blue light is the visible light spectrum with the shortest wavelength and highest energy, and similar to ultraviolet rays. The short-wavelength, high-energy light rays on the blue end of the visible light spectrum scatter more easily than other visible light rays when they strike air and water molecules in the atmosphere. The higher degree of scattering of these rays makes the cloudless sky look blue. Our eye only lets less than one percent of UV radiation from the sun to reach the retina. On the other hand, virtually all visible blue light passes through the cornea and lens and reaches the retina. Many eye care providers are concerned that the added blue light exposure from computer screens, smartphones and other digital devices might increase a person's risk of macular degeneration later in life. More research is needed, though, to determine how much natural and man-made blue light is "too much blue light" for the retina.

Because short-wavelength, high energy blue light scatters more easily than other visible light, it is not as easily focused. When you're looking at computer screens and other digital devices that emit significant amounts of blue light, this unfocused visual "noise" reduces contrast and can contribute to digital eye strain. Research has shown that lenses that block blue light with wavelengths less than 450 nm (blue-violet light) increase contrast significantly. Therefore, computer glasses with yellow-tinted lenses may increase comfort when you're viewing digital devices for extended periods of time.

White LEDs may actually emit more blue light than traditional light sources, even though the blue light might not be perceived by the user. This blue light is unlikely to pose a physical hazard to the retina. But it may stimulate the circadian clock (your internal biological clock) more than traditional light sources, keeping you awake, disrupting sleep, or having other effects on your circadian rhythm.

A lot of mobiles have got blue light filters and some spectacles lens come with blue light filter. Hence many parents enquire about effects of blue light. Blue light is of concern because it has more energy per photon of light than other colors in the visible spectrum, i.e. green or red light. Blue light, at high enough doses, is therefore more likely to cause damage when absorbed by various cells in our body. Current research shows that for normal use a person need not be too much concerned about blue light and it's effect on the eye.

DRY EYE

Tears are constantly secreted in our eyes to keep the front surface of the eye wet. This wetness of front surface is absolutely essential for clear and comfortable vision. If there is tear deficiency, it will cause dry eyes and lead to computer vision syndrome. At times of extreme concentration like studying on a computer, the blinking rate usually decreases. Humans normally blink around 15 times each minute. When staring at screens, this number decreases to a half or third that often. That can lead to dry, irritated, and tired eyes. Tears dry up faster leading to a to false dry eye state. Such cases can be helped by artificial tears, available as Eye Drops. One should also try and blink as normally as possible. A simple method is called the 20 20 20 rule.

Every 20 minutes take a break for 20 seconds by looking at an object more than 20 feet away. This gives rest to the eye muscles and helps replenish the tear film. 

OUTDOOR ACTIVITY

Some research has shown that lack of outdoor activity and sunlight exposure may cause myopia or short sight. So it is prudent that children spend atleast one hour outside and get some exposure to sunlight. 

What to do if you have a heart burn due to GERD

GERD is a recurrent and chronic disease for which long-term medical therapy is usually effective. It is important to recognize that chronic reflux does not resolve itself. There is not yet a cure for GERD. Long-term and appropriate treatment is necessary.

Treatment options include lifestyle modifications, medications, surgery, or a combination of methods. Over-the-counter preparations provide only temporary symptom relief. They do not prevent recurrence of symptoms or allow an injured esophagus to heal. They should not be taken regularly as a substitute for prescription medicines – they may be hiding a more serious condition. If needed regularly, for more than two weeks, consult a physician for a diagnosis and appropriate treatment.

While diet does not cause GERD, reflux and its most frequent complaint of heartburn can be aggravated by foods.

 Common foods that can worsen reflux symptoms include

1. citrus fruits
2. chocolate
3. drinks with caffeine or alcohol
4. fatty and fried foods
5. garlic and onions
6. mint flavorings
7. spicy foods
8. tomato-based foods, like spaghetti sauce, salsa, chili, and pizza

Lifestyle Changes

1. If you smoke, stop.
2. Eat breakfast as early as possible after waking up. 
3. Avoid foods and beverages that worsen symptoms.
4. Lose weight if needed.
5. Eat small, frequent meals.
6. Wear loose-fitting clothes.
7. Avoid lying down for 3 hours after a meal.
8. Raise the head of your bed 6 to 8 inches by securing wood blocks under the bedposts. Just using extra pillows will not help.
9. Avoid late night snacks
10. Sleep on the left side of your body

Tip: Don't lie down within 3 hours of eating. That's when acid production is at its peak, so plan early dinners and avoid bedtime snacks.


How to eat

How is perhaps more important than what you eat. A large meal will empty slowly from the stomach and exert pressure on the LES. A snack at bedtime is well positioned to reflux when you lie down. It is best to eat early in the evening so that the meal is digested at bedtime. You might try having the main meal at noon and a lighter one at dinnertime. All meals should be eaten in relaxed stress-free surroundings. Trips to the kitchen to fetch food or the performance of other tasks such as minding children should be suspended during, and for a time after, eating. Smaller meals and an upright, relaxed posture should help minimize reflux.

What you eat

Certain foods compromise the sphincter's ability to prevent reflux, and are best avoided before lying down or exertion. These differ from person to person. Many person find that fats, onions, and chocolate as particularly troublesome. Alcohol often provokes heartburn, by compromising the LES, irritating the esophagus, and by stimulating stomach acid production. Common beverages such as coffee (both caffeinated and decaffeinated), tea, cola, tomato juice, and citrus juice may aggravate symptoms by irritating the esophagus or stimulating stomach acid production.[3] Certain other foods may bother some people; upon their discovery a period of avoidance or reduction may be of benefit.

Tip: Experiment to find what does and does not work best for you. Start by reducing fatty foods, onions, and chocolate.

Some oral medications such as potassium supplements or the antibiotic tetracycline will burn if allowed to rest in the esophagus. To be safe, one should always swallow medication in the upright position and wash it down with lots of water.

Foods to Avoid

1. Alcohol 
2. Coffee (both caffeinated and decaffeinated),
3. Tea
4. Cola
5. Tomato juice
6. Citrus juice 
7. Fatty foods
8. Onions
9. Chocolate.

Other factors
Being overweight can promote reflux. Excess abdominal fat puts pressure on the stomach and the loss of even a moderate amount of weight makes many people feel better.

Proton pump inhibitors (PPIs)
Proton pump inhibitors (PPIs) limit acid secretion in the stomach. They allow rapid resolution of symptoms and healing of the esophagus in 80-90% of patients. The drug is also useful in managing stricture, one of the more serious complications of GERD.

Even after symptoms are brought under control, the underlying disease remains present. It is possible that a person may need to take a medication for the rest of their life to manage GERD. Long-term use of medication – whether prescription or nonprescription – should be under the direction and supervision of a physician. Side effects are rare; nonetheless, any drug can potentially have adverse effects.