Thursday, February 16, 2012

Medical Prescription Terms

Commonly used medical prescription terms and their meaning that you should know.

Frequency or time of drug usage:
  • QID / QDS: 4 times a day (about 6 hourly)
  • TID / TDS: 3 times a day (about 8 hourly)
  • BID / BD: twice a day (about 12 hourly)
  • OD: once a day
  • HS: once at night / bedtime
  • SOS: whenever required
  • q2h: every 2 hours
  • q4h: every 4 hours, etc.
  • CM: coming morning
  • Stat: once immediately
Type of medicine preparation:
  • Tab: Tablet
  • Cap: Capsule
  • Inj: Injection
  • Oint or oc: Ointment
  • G or ED: Eye Drops
  • ND: Nasal Drops
  • Lot: Lotion
  • Cream: Skin cream
  • Suppository: per rectal application
  • Pessary: per vaginal application
Routes of administration:
  • PO: per orally or by mouth
  • Topically: local application on affected area
  • IM: intra-muscularly
  • IV: intra-venously
  • SC: sub-cutaneously or just under the skin
  • PR: per rectal or into the anus
  • PV: per vaginum or into the vagina
  • Inhalation: to be inhaled as puffs
  • Nebulize: to be atomized or nebulized using a special equipment & then inhaled with breathing
  • Sub conj: just under the conjunctiva (surface layer) of the eye
  • Intra Vit: intra-vitreally or into the vitreous cavity of the eye
  • Intra-cameral: into the anterior chamber of the eye
  • Sub-tenon: under the Tenon layer / space of the eye surface
  • Retro-bulbar: behind the eye ball
  • Intra-articular: into the joint space
  • Spinal / Sub-dural: into the spaces of vertebral spine
Other common terms:
  • NPO: nil per orally
  • F: fasting
  • PP: post-prandial or after meal (in relation to blood sugar measurement it means 2 hours after meal)
  • Infusion: slow intra-venous administration
If there is any other confusing term that you may want to understand, please mention in the comments.

Dr. Sanjay Dhawan
Senior Eye Surgeon
New Delhi & Gurgaon

Thursday, June 3, 2010

Eye Care in Summer & Monsoon Months


Eye Care in Summer & Monsoon Months

The scorching Indian summer brings with it a lot of eye problems and monsoon, while it ushers in relief from heat, it adds to the woes of the eyes.

What are the common eye problems seen during summer?

·         Eye Allergies especially spring catarrh
·         Conjunctivitis
·         Styes
·         Dry Eye
·         Trachoma & Swimming Pool Conjunctivitis
·         Other infections

What is conjunctivitis?

The surface of the white of the eye and the back surface of eyelids is covered by a thin protective membrane called conjunctiva. Inflammation i.e. redness & swelling, of this membrane is called conjunctivitis.

What causes it?

The common causes of conjunctivitis are:
·         Infection - Virus, Bacteria, Chlamydia, etc.
·         Allergy - to dust, pollen, animal dandruff, medicines, cosmetics, contact-lenses, etc.
·         Chemicals - acid, alkali, cosmetics, contact lens cleaning solutions, bleach in swimming pool, etc.
·         Injury - mechanical, heat, radiation, etc.
Viral infections are prone to occur as epidemics during rainy season when the body immunity may be low and the conditions are favorable for spread of infection. Infection tends to spread by direct contact, fingers, flies and fomites (e.g. towel, toiletries, etc).

What is the treatment?

Ideally one should consult an eye surgeon immediately and have proper treatment initiated. But if medical help is not immediately available then it may help to wash the eye gently with clean water, do some cold compresses using ice packs, and instill some mild antibiotic drops (e.g., Chloramphenicol, etc.). Self-medication should be avoided as far as possible and in no case should you use steroid eye drops without proper medical advice.

What are the precautions one may observe to prevent conjunctivitis or its spread?

Some precautions may help in making the patient more comfortable during conjunctivitis and prevent its spread to others.
·         Discontinue contact lenses immediately
·         Do not share handkerchief, towels and other toiletries
·         Avoid close contact with people suffering from conjunctivitis (casual interaction does not lead to spread of infection)
·         Wash your hands immediately after taking care of a family member suffering from conjunctivitis
·         Avoid swimming if you have conjunctivitis
·         Avoid swimming during epidemics of conjunctivitis
·         Avoid exposure to dust pollution, chemicals, fumes and bright sunlight
·         Use sunglasses if have conjunctivitis to avoid discomfort from bright light and to avoid alarming people around you
·         Avoid crowded places during epidemics

What eye allergies are common during summer months?

One can get allergy to heat, dust & sun during the summer months. There could also be allergies to certain pollen or organic dust at the onset & end of summer season. Spring Catarrh or vernal conjunctivitis is a type of allergy seen in young boys most commonly during summer months.

What is the treatment of allergy?

The best form of treatment for allergy, if at all possible, is to identify & avoid causative agent or allergen. But in most cases it is either not possible to find out exact agent causing allergy or to completely avoid it. In these situations one needs to use anti-allergy medication in the form of anti-histaminics, mast-cell stabilizing drugs &, if allergy is severe, steroids.

What is Dry Eye & how to treat it?

Dry eye is a condition where the tear film of the eye is inadequate in quantity or quality resulting in an unstable tear film which breaks frequently giving rise to dry spots on cornea of the eye. These leads to symptoms of irritation, redness, soreness, dry feeling, gritty sensation and paradoxically reflex watering. These symptoms are worsening on exposure to dry cold air, hot wind and reduced blinking seen while working on computers, watching TV or prolonged reading.
Treatment is usually in the form of frequent instillation of lubricant or artificial tear eye drops. One should also avoid conditions that aggravate dry eye. Examination by an eye surgeon can help to rule out underlying treatable causes of dry eye.

What’s a stye? What causes it & what’s the treatment?

Syte is an infection of glands of eyelids which leads to painful and sometimes pus-filled swelling at eyelid margins.  It causes red painful swelling on the eyelids with formation of pus points. The swelling may burst releasing pus and blood stained discharge which brings relief.
Sytes are commonly caused by frequent rubbing of eyes with unwashed hands and by eye strain caused by reading or working on computers.
The treatment is in the form of oral antibiotics & pain-killers and instillation of antibiotic eye drops which should be used for 2-4 weeks to prevent recurrence.

What is corneal ulcer?

Corneal ulcer is severe infection of the cornea (clear black part of the eye) which may result from trauma or be a complication of conjunctivitis or use of contaminated contact lenses. The infection can be bacterial, fungal or viral. It leads to severe pain, redness, watering, blurring of vision, photophobia and a yellowish white spot on the cornea. Immediate help of an expert eye surgeon should be sought. If medical help is not close at hand, it is advisable to start frequent instillation of broad spectrum antibiotic eye drops e.g., Chloramphenicol, etc.
Dr. Sanjay Dhawan
Addl. Director & Head of Department
Fortis Hospital, Gurgaon

Tuesday, September 8, 2009

Kajal - The harmful effects of kajal on the eyes

Kajal & Surma are traditional Indian ingredients to makeup those beautiful eyes. Originally "kajal" did not start as a makeup but as a home remedy medication. Zinc, copper sulfate and many medicinal herbs were important ingredients which had definite action on eye infections. In olden days Trachoma, conjunctivitis, corneal ulcer and other blinding infections were very common in Noth India and this part of Asia. Medical aid & medicines were not easily available or were out of reach of most. In that scenario kajal had relevance & played the role of protecting the eyes as our great grandnmothers propogated.

The constituents of kajal were selected emperically or on hearsay. The methods of preparing kajal were were crude & there was no way to define the concentration of each consituent & its actual effect on the eye. This remains the case till date.

Today witgh the availability of good drugs in precise concentration and well researched effects on the eyes & the disease that they are meant for, "kajal" looses it's relevance & role. However, kajal continues to be used widely by females as a beauty enhancer.

Kajal can have adverse effects on the eyes. Some of them are listed below:
  • Conjunctivitis - chemical, toxic & infective
  • Allergy
  • Toxicity / Chemical Reaction
  • Meibomitis
  • Stye & Hordeolum - infections of the glands of the eye lids
  • Corneal ulcer - which can potentially lead to blindness
  • Uveitis - certain chemicals in kajal can incite inflammation inside the eye
  • Glaucoma - some constituents  can increase eye pressure leading to glaucoma
  • Dry Eye - regular use of kajal can be assiciated with scarring of tear / lacrimal glands causing dry eye syndrome
  • Conjunctival discoloration
It advisable to altogether avoid use of kajal / surma or any makeup that goes inside the eye. The makeup that remains out side e.g. eye-liner, eye-shadow, mascara, etc. are alright to be used but should be meticulously removed at the end of the day. During the period of any eye infection, injury, surgery, etc. no eye makeup should be used.

Eyes are precious and very beautiful even without any makeup, we should take good care of them.

Dr. Sanjay Dhawan
Senior Eye Surgeon
New Delhi / Gurgaon, India

More about eye diseases & their treatment at

Monday, August 31, 2009

Combined Glaucoma & Cataract Treatment: Dilemma in management

What if a person has both Cataract & Glaucoma?
Co-existence of glaucoma & cataract pose difficulty in management of either. There is always a dilemma whether to operate them together or one at a time.

As a general principle, in cases of patient with both Cataract & Glaucoma it is desirable to control glaucoma first and then proceed for cataract surgery. If the pressure / glaucoma control is easily achieved by 1-2 drugs then one can go for cataract surgery without worrying about glaucoma. In cases of advanced glaucoma or when the pressure requires more than 2-3 drugs for control then one may have to consider glaucoma surgery. Although it is possible to do both glaucoma & cataract surgery together at the same time, however, the results may be slightly compromised. It is ideal to do glaucoma surgery first and cataract surgery later, if the clinical condition of the eye & the patient permits.

Only in advanced glaucoma & advanced cataract with impending complications, is it justified to proceed with Combined Cataract & Glaucoma Surgery also called Phaco-Trab or Phacotrabeculectomy.

Dr. Sanjay Dhawan
Senior Eye Surgeon
New Delhi & Gurgaon

More about Cataract and Glaucoma

Monday, August 24, 2009

Which Intraocular Lens (IOL)? A confusing array of choices.

Which Intraocular Lens (IOL) is most suitable for my eyes?

People suffering from cataract and planning for cataract surgery are faced with this difficult question & a frustrating list of choices. I will attempt to make it simple, let me start by explaining a few characteristics of the Intraocular Lenses (IOL):

What is Intraocular Lens (IOL)?
In cataract surgery the natural lens of the eye is removed. This leads a significant decrease in the optical convergence power of the eye or hypermetropia. Intraocular lenses are small lenses made of polymers and implanted into the eye in place of natural lens to help focus the light on to retina.

Foldable vs. Non-foldable Lenses
In conventional cataract surgery & in SICS a large cut / incision is made in the eye to remove the cataract. This is followed by insertion of a rigid 6.0/6.5 mm lens through the incision into the eye. These lenses are rarely used these days.
In phacoemulsification the entire operation done through a small hole of 3.0 mm or less. It is not possible to implant a rigid lens. This difficulty is overcome by use of very flexible lenses which can be folded and loaded in special injectors aninserted through the small hole into the eye. These are currently the preferred lens to be used.

Lens Material (Silicone, Hydrophillic & Hydrophobic Acrylic)
Foldable Intraocular Lenses are commonly made of silicone or acrylic polymer (hydrophobic or hydrophillic).
Silicone was used in older lenses & gave good optical results in the immediate post-operative period. But these lenses were somewhat bulky and lead to severe thickening of anterior & posterior capsules (membrane covering of natural lens which is left behind to provide support for artificial intraocular lens). This lead to deterioration of vision and required treatment by YAG Laser Capsulotomy.
Hydrophillic Acrylic lenses are highly flexible and slim, therefore, can be introduced through extremely small incisions. They have good immediate visual results but suffer from tendency to cause thickening of posterior lens capsule.
Hydrophobic Acrylic lenses are slightly less flexible and somewhat thicker than their hydrophillic counterparts. But they are extremely inert and do not lead to lens capsule thickening. Due to these properties they are ideal for use in children, young adults and the eyes predisposed to inflammation. Being hydrophobic in nature it is possible to incorporate a color tint to avoid blue chromatopsia after surgery.

Spheric vs. Aspheric IOL
Spheric are the conventional lenses where both surfaces of the lens are uniformly curved or are part of a sphere. These lenses have inherent problem of spherical aberrations caused by excessive bending of light at the edges.
Aspheric or advanced optics lenses have their curvatures flattening out towards the periphery or edge, thereby, minimizing spehrical aberrations.
Aspheric lenses give much sharper vision and better contrast but due to decreases depth of focus, the need for reading glasses becomes more urgent. On the other hand spheric lenses, though lack the sharpness & contrast to some extent but have better depth of focus leading to slightly better near vision. However, almost all lens manufacturers are replacing their spherical lenses with aspheric.

Monofocal vs. Multifocal IOL
Monofocal lenses have a single focal length and unlike the natural lens do not possess the ability to change the focus. Therefore the patient needs to wear reading glasses in order to focus at near fine print. But these lenses provide much better contrast and image clarity.
Multifocal lenses have 2 foci - a distance and a near focus. This is achieved by having multiple optical zones fashioned in the lens in the form of alternating rings for distance and near. This leads to splitting of light into distance and near foci. As a result both the distant and near objects can be focussed in the eye at the same time. However, the contrast and sharpness of the vision is reduced significantly. There lenses are also prone to more glare and haloes of light during driving at night time.
So for patients who need sharp vision and better contrast and do not hesitate in wearing reading glasses, monofocal lenses are most suitable. Whereas, those who do not want dependence on reading glasses but are willing to compormise on contrast and sharpness of vision, can opt for multifocal lenses.
Please note that both eyes should have the same type of lens - monofocal OR multifocal.

Toric vs. Non-toric
Toric lenses, besides having spherical power, also have cylindrical power which corrects astigmatism present in the eye. Non-toric lenses do not have any cylindrical power. Eyes with no or negligible astigmatism require non-toric lens and the eyes with significant astigmatism would benefit from toric lenses. Toric lenses are especially useful in patients with high degree of against the rule corneal astigmatism which is not amenable to correction but incision placement.

My preferred lens
Currently I prefer to use Foldable Hydrophobic Acrylic Aspheric Monofocal Lens with a natural color tint and toric where required. Multifocal is preferred where cosmetic requirements is more important and there are no critical visual needs.

Dr. Sanjay Dhawan
Senior Eye Surgeon
New Delhi & Gurgaon, India
Click here to learn more about Cataract Surgery

Saturday, August 22, 2009

LASIK: Standard Lasik vs. Custom Lasik

What is standard Lasik & what is custom Lasik? Which is better for me & why? I am often asked this question by my patients.

Standard Lasik
This is the conventional type of Lasik Laser where only the refractive error (myopia, astigmatism or hypermetropia) is taken into account in the Laser protocol and corrected.
This type of Lasik treatment does not correct aberrations (finer optical defects in the eye) and may actually increase them.

Custom Lasik
In this Lasik treatment in addition to refractive error, finer optical aberrations are also taken into account. The Laser ablation protocol attempts to correct the aberrations as well.
The information about the aberrations in the eye is provided by an instrument called aberrometer which forms an additional link in the treatment chain.

Which is better & why?
High levels of aberrations in the eye adversely affect contrast and night / low light vision. So if aberration level is high (RMSh > 0.25) then certainly Custom Lasik is better as it provide better quality of vision, better contrast and better night vision by correction of aberrations along with the refractive errors.
If the aberration level is low (RMSh < 0.25) then Custom Lasik is not really required and standard Lasik works as well.
It may be noted that the vision in bright day light is the same after both forms of Lasik (standard or custom) and it's only in mesopic or low light conditions that there is a difference in the quality of vision. And the difference is very subtle & mild - not a dramatic difference

Dr. Sanjay Dhawan
Senior Eye Surgeon
New Delhi & Gurgaon
Click here to learn more about Lasik at

Thursday, March 12, 2009

Convergence Exercises for Healthy Eyes

We all spend a lot of time scanning the computer screens or browsing text on paper as an unavoidable part of our life. Prolonged visual strain leads to weakness of eye muscles or convergence weakness and discomfort in eyes. The only remedy is to strengthen your eyes muscles by regular eye exercises.

Instructions for Convergence Exercises
Our eyes are parallel to each other while looking straight ahead at a far off object. When we look at a near object the two eyes move towards each other – converge. Normally the eyes can converge to look at an object as close as 5 to 8 cm from the eyes. In convergence insufficiency this point recedes more than 12 cm away. Weakness of convergence can occur in individuals involved with a lot of near or computer work or those who suffer from any systemic illness. The exercise described below can help improve the convergence over a period of 4 to 8 weeks.
Exercise Steps
1. Sit or stand straight and look at a far off small object.
2. Hold out a pen at an arm’s length and look at its tip.
3. Slowly bring the tip close to your eyes, keeping the tip at level with your eyes.
4. Hold the tip for about 10 seconds at the point where you feel some strain or heaviness in the eyes. The tip should continue to appear clear and single – should not appear double.
5. Then again take it back to an arm’s length and hold it there for 10 seconds.
6. Again slowly bring the tip close to your eyes to the point where you feel some strain.
7. Repeat this 10 times and then again look at the far off small object. Then again repeat the whole cycle
Exercise Schedule
• To begin with, do this exercise for 5 minutes in the morning and 5 minutes in the evening at a time when you are relatively fresh.
• Gradually increase the duration of the exercise to 15 minutes over a period of next 2 weeks.
• Carry it on religiously regularly for 2 months, after which once a day exercise for 5 minutes is sufficient to maintain good convergence of the eyes.
• It is normal to feel slightly more strain, pain in eyes and even headache for a few days when you begin convergence exercises. Rest assured that gradually you will recover and your symptoms due to convergence insufficiency will soon be better.

Feel free to comment or ask questions.

Dr. Sanjay Dhawan
Senioe Eye Surgeon
Delhi & Gurgaon

Read about Computer Vision Syndrome at Click Here !

Thursday, September 18, 2008

Retinopathy of Prematurity

What is it?
Retinopathy of Prematurity (ROP) is a retinal disorder seen in prematurely born babies which if left untreated can lead to a lifetime of bilateral total blindness.
Retina is that part of the eye on which the image forms before it is sent to the brain to interpret. So it is like the film of a camera. This film, i.e. retina is a living film and has a blood supply. ROP is a disorder of maldevelopment of this blood supply of the retina. The blood supply of the retina starts developing while the baby is in the mother's womb from the nerve of the eye which is close to the centre of the retina. The blood vessels then proceed towards the circumference of the retina, which they almost reach by the time the baby is full term. In pre-mature babies the blood vessels have not reached very far towards the circumference. In case the growth of these vessels gets arrested, ROP is said to occur. Subsequently in children with ROP, abnormal blood vessels start developing in the retina. These abnormal vessels can cause bleeding in the eye or even pull the retina and detach it from its place. Imagine how severe the vision loss would be if the film (retina) is not in place or has blood in front of it.

What causes it and who is at risk?
The exact cause of this maldevelopment of blood vessels in pre-mature infants is not known. But infants who are at risk are -
1) Infants with a birth weight of less than or equal to 1500gm
2) Gestational age of 34weeks or less
3) Infants more than 1500g with an unstable clinical course felt to be at high risk by their attending pediatrician or neonatologist.
4) Babies at higher risk for ROP apart from the above include –
5) Exposure to oxygen for more than 30 days
6) Respiratory distress syndrome
7) Sepsis
8) Multiple blood transfusions
9) Multiple births
10) Apnoeic episodes

How is it diagnosed?
As the disease is of pre-mature infants, it is mandatory that all newborn nurseries should have a protocol to have the eyes of babies at risk examined by a retina specialist.

A retina specialist can detect ROP by examining the retina after dilation of the child's pupil.

This examination can be carried out in the nursery itself. The examination is not very traumatic for the child as anaesthesia drops are put in the eyes before examining to prevent pain. The first eye examination should generally be done within 4 wks of the birth of the child. Subsequent follow up examinations till the retina of the baby is fully mature are done as desired by the eye specialist.

What is the treatment?
Fortunately early stages of ROP are reversible on their own in many babies. But if the disease reaches a particular threshold then it is better to treat with LASER to prevent sight damaging complications. LASER can be done in the nursery itself in a few sessions. The response to LASER in most cases is good. In case LASER fails, there are a few surgical options available. However, the results of these surgeries are not very encouraging as of date.

What are the outcomes?
The outcome of timely laser is generally good with few side-effects.

What are the complications?
In case no treatment is done and the ROP keeps progressing, it will ultimately pull and detach the retina. There can also be bleeding within the eye. This finally leads to near total blindness.

Tuesday, September 16, 2008

Diabetic Retinopathy

What is it?
Diabetes is a disease, which affects the small blood vessels of all the organs of the body. As the disease progresses it inevitably involves the microvascular architecture i.e. the blood supply of the retina (sensory part of the eye) also. This manifestation of diabetes is called as diabetic retinopathy.

To simplify – It is a disease of the blood vessels of the retina due to diabetes.

What causes it & Who are at risk?
The main cause is long standing diabetes.
Among younger-onset patients with diabetes, upto 8% of individuals will have this disease after 3 years of diagnosis and 25% at 5 years, 60% at 10 years, and 80% of diabetics will have this eye problem by 15 years.

In older type 2 diabetics up to 21% of patients have diabetic retinopathy at the time of first diagnosis of diabetes, and most develop some degree of retinopathy over time.
Uncontrolled diabetes , High blood pressure, High cholesterol, Kidney disease and Low Haemoglobin worsen diabetic retinopathy.

What are the symptoms & signs?
It may be asymptomatic for a long time.
Once the macula , i.e. the central part of the retina develops swelling , there would be a deterioration in eyesight.
If there is bleeding within and in front of the retina, floaters would be seen or the vision may be drastically reduced. Floaters is seeing black spots or lines moving in front of the eye.
Once the central retina is detached the vision loss becomes severe and chances of recovery even after surgery become less.

How is it diagnosed?
It can be diagnosed by a simple dilated eye examination to see the retina in detail. If significant changes are found then investigations like Fluorescein Angiography and Optical Coherence Tomography may be done.
Fluorescein Angiography involves taking photographs of the retina after injecting a dye in a vein in the patient’s arm. The dye reaching the eye helps to clarify the type and extent of disease, including detail of abnormal vessels and leakage.

Optical Coherence Tomography : In this test photographs of the retina are taken to show its microscopic detail. So it can help detect any early thickening of the retina in areas of leakage. The type and amount of thickening can be delineated and an assessment of any pull on the retina can also be made. It is an excellent tool to follow up after treatment to assess the effect of the treatment done and need for re-treatment.

What is the treatment?
The gold standard of therapy is LASER photocoagulation.
LASER can help to prevent a bleed in the eye and also decrease swelling of the retina. However, it cannot usually restore vision lost due to the retinal damage. It has to be appropriately timed.
Other options now available are injecting drugs like steroids and AVASTIN into the eye. These drugs also aim to reduce the swelling in the retina and help in drying up of the abnormal blood vessels. These are quite effective and can even improve vision in some cases. A major drawback is the effect of these drugs is time limited and many patients require re-injections.
Combination therapy of LASER and injections is also being done.

What are the surgical options?
Advanced cases with non-resolving bleed in the eye or retinal detachment require advanced microsurgery.
This involves highly complex Vitreo-Retinal surgical procedures.
Today with highly advanced technology, some amount of visual recovery can be achieved in a large number of advanced cases also.

What are the outcomes?
Cases which present early and are adequately lasered generally maintain good vision. A good control of diabetes is most important to slow the progression of disease. A combination of injectable drugs and laser has improved the outcome in moderately advanced cases also. The outcome may not be very good in advanced cases even after surgery, however still some useful vision can be retained.

What are the complications?
Complications of diabetic retinopathy are non resolving swelling of the retina, bleeding into the eye and detachment of the retina.
Complications of LASER are minimal. In some cases the swelling of the retina might increase initially, but this also normalizes in most patients.

Complications of AVASTIN per se are also minimal , but the main risk is of infection during the injection procedure. To prevent infection we routinely perform the injection in our operation theatre , taking all aseptic precautions.

Complications of steroid injection can again be infection, rise in eye pressure (glaucoma) and cataract.

Complications of surgery can be repeat bleeding into the eye or damage to the retina.

Any other information?
Most importantly to slow the progression of diabetic retinopathy the following parameters must be strictly maintained –

1) Tight blood sugar control . Maintain Glycosylated haemoglobin (HBA1C) < 7%. This test reflects the sugar control over the past 3 months.
2) Control blood pressure
3) Rule out loss of protein in urine ( microalbuminuria) and treat kidney disease as far as possible.
4) Reduce LDL cholesterol
5) Maintain Haemoglobin more than 12gm%

Age Related Macular Degeneration

What is it ?
ARMD is degeneration of the most sensitive part of the retina (sensory part of the eye) called macula. It is mostly seen in people over the age of 50 years.
Initially it is a silent disease and can affect one eye to begin with. At this stage it might be detected by an ophthalmologist on routine retina evaluation. Gradually vision loss increases mainly in the center allowing vision at sides, but makes reading or close work difficult without the use of special low vision aids.
The early stages of ARMD typically start with appearance of deposits beneath the retina called Drusen. These do not affect vision very much by themselves and most people with Drusen will never have a serious loss of vision. However, certain changes may occur that lead to the late stage of ARMD which leads to marked visual loss.
What Causes it and Who is at Risk ?
The exact cause of macular degeneration is not known though following risk factors have been identified: age, heredity, sex (women more affected then men), light ocular pigmentation, hypertension, cardiovascular diseases, diabetes, photo toxicity and cigarette smoking.
Types: There are 2 types of ARMD: “Dry” and “Wet”
Dry ARMD is the most common form accounting 80-90% of all cases and is associated with ageing. It is caused by degeneration in visual cells leading to yellow-white deposits in layers of retina called drusen or formation of atrophic areas in macula. Overtime dry ARMD may develop into wet type.
Wet or Exudative ARMD is the more severe variety where abnormal blood vessels form beneath the macula which leak fluid and blood under the retina. Blood under the retina is toxic to the photoreceptors and can lead to severe loss of function of retina.
What are the Sign & Symptoms ?
If only one eye is affected to begin with, the symptoms may not be noticeable in early stages. Gradually as disease progresses or if both eyes are involved, reading or close work may become difficult. Common symptoms are distortion of objects which are looked at directly, for eg-bulges or curved appearance of a straight door, distorted print lines in book, missing of letters or words while reading, a dark or blank spot in the center of vision, or fading of colors specially blue.
How is it Diagnosed ?
As initially it is a silent disease, mostly it is picked up in a routine retina examination by an ophthalmologist .The retinal examination done by an ophthalmoscope will show the findings of this disease process. To assess the condition in detail, certain other test are done:
Amsler Grid: It is a test paper with graphic picture to be used at reading distance with near glasses on. This is used to check for extent of sight loss-dark spot, distortion or missing of straight lines and also is given to the patient to take home so that he can monitor his symptoms at home and report immediately if there is worsening.
Fluorescin Angiography / ICG: the photographs of macula are taken after injecting a dye in patient’s arm. The dye reaching the eye helps to clarify the type and extent of disease, including detail of abnormal vessels, leaks and membrane formations.
Optical Coherence Tomography : In this test photographs of the retina are taken to show its microscopic detail. So it can help detect any early thickening of the retina in wet ARMD. Also it can delineate the abnormal blood vessels ( choroidal neovascularisation ) from where the blood oozes. Changes of dry ARMD such as drusen can also be demonstrated. Also it is an excellent tool to follow up after treatment to assess the effect of the treatment done and need for re-treatment.
How can it be Prevented ?
There is no prevention of ARMD. Early detection is the key to prevent severe loss of vision. All individuals above 50,especially if there is a family history of ARMD, history of cardiovascular disease, light ocular pigmentation, should get yearly retinal check up for the same. Anyone experiencing following symptoms should consult an ophthalmologist immediately:
Straight lines appearing distorted-specially in the center of vision
Dark blurry or white patch in the center of vision
Color perception changes
Smoking is a risk factor and should be avoided at all costs if any of the risk factor is present.
According to some recent international multicentric trials, multivitamins may slow down progression of dry ARMD. However, excess of fat soluble multivitamins can have their own side-effects and thus consult your doctor before regularly taking multivitamin pills.
How can it be Treated ?
There is no permanent cure for dry ARMD. The aim of management is to keep a vigilant check on progression of disease and take measures to improve functional capability of the patient.
· Nutrition: Eat fresh fruits, dark green leafy vegetables. The role of antioxidants/zinc in retarding the progression is not very clear but supplementation with Vitamins A, C and E, zinc and selenium may have a positive effect. A multicentric international trial has demonstrated that Multivitamins slow progression of moderate dry ARMD to severe dry ARMD.
· Sunlight: Blue rays of the spectrum seem to accelerate macular degeneration. Sunglasses with good UV filters for outdoor activities are recommended.
· Smoking: quit smoking as this accelerates the process of ARMD
· Early detection: Monitoring of vision by Amsler grid-report immediately to eye surgeon if any change noticed (the development of wet type may need urgent treatment)
· Low vision aids and lighting –These are devices, which can improve quality of living by improving vision for day-to-day activities, specially reading. Special optical devices like magnifiers (hand held, desktops or in spectacles) can be used in various ways. Adequate lighting will make reading more comfortable with 50-watt indoor bulb in metal shade then fluorescent light.

The mainstay of treatment of wet ARMD at present is injection of anti-VEGF drugs into the eye. These are special molecules designed to stop further development of blood vessels. So once the abnormal vessel growth under the retina gets inhibited the leakage of fluid and blood also reduces. However at present these injections need to be repeated at regular intervals as once the effect of the drug wanes off the abnormal vessels star growing again. The two main such drugs being used at present are AVASTIN & LUCENTIS. Presently we donot have a drug which can altogether end the process of this abnormal neovascularisation. A lot of research is ongoing to find a permanent cure for ARMD.
Other treatment modalities available for wet ARMD are -
Photodynamic therapy (PDT) – This involves treating the abnormal vessels with a LASER after injecting a dye which selectively enhances LASER energy absorption by the new vessels only thus preventing damage to the overlying retina. This therapy also may be required to be repeated upto 3 times or more. International studies using this dye have found it to prevent further loss of vision in many cases but it is also not hundred percent effective. Also it does not improve vision but aims to stabilise it, whereas the anti-VEGF injections can improve vision also.

Conventional Laser treatment-This procedure uses a high-energy laser beam to destroy the fragile leaking blood vessels. This will also not improve vision but may reduce further progressive vision loss. However since the high energy laser also destroys retina, it can only be done for lesions away from the central most sensitive part of the retina.

Combinations treatments combining anti-VEGF injections, intraocular steroid injections and PDT are also being tried in some cases.

Optical Coherence Tomography ( OCT )

OCT is a tool by which highly magnified photographs of the retina can be taken to study it's microscopic structure. The patient has to just sit in front of a machine for a few minutes and look at a particular light while these special images are acquired. It also helps to measure the retinal thickness in microns. So the doctor can determine if the retina is getting thicker or thinner. Also which layers of the retina are getting more affected can be evaluated and the response to treatment can be judged by serial examinations.

Monday, September 15, 2008

Fluorescein Angiography

Fluorescein Angiography (FA) is an investigation to further investigate the cause of the retinal disease. In this 3ml of a water soluble fluorescent dye is injected into a vein on the patient's arm. As the dye reaches the blood vessels of the retina ( It takes only 10sec !! ) , sequential photographs are taken using a sophisticated digital camera. The abnormal leakage of dye or absence of normal pattern of dye gives the doctor clues regarding the diagnosis and severity of the retinal disease.
This test is simple with generally no significant side-effects.



What is Retina ?

Consider the eye to be a camera. The camera has a system of lenses in front which focus light on a film or digital sensors on the back. In the same way the eye has a system of lenses in front which focus light onto a layer at the back called the Retina. This layer has living sensors to sense the light form and send a signal to the brain which interprets these signals as the image we see. The retina is connected to the brain though a living cable which is called the optic nerve.

Retina has a very complex structure having ten layers. The light detector cells (photoreceptors) of the retina are called rods and cones. Cones help more with daylight vision and colour sensing whereas rods are primarily responsible for night vision or vision in low light conditions.

The central part of the retina called the macula has the maximum light sensitivity and resolution ability.

So any disease process which distorts the retina or makes it thicker/thinner or reduces the functional ability of the cells of the retina gravely affect the vision.

To diagnose various retinal diseases certain tests are done such as Fluorescein Angiography and Optical Coherence Tomography. These tests and some common retinal diseases are described in various sections.