Glaucoma

Glaucoma is a condition of the eye in which the pressure inside it increases beyond a level, such that it starts damaging the optic nerve. This is not a very uncommon condition and affects approximately 1% of the adult population above the age of 40yrs, making it one of the most common causes of irreversible visual loss in the population. As much as 12% of the blind population of USA and UK is due to glaucoma.

Explanation

Our eyes are filled with a fluid called aqueous humour. It is continuously secreted inside the eye, as well as drained from it. This fluid maintains a pressure inside the eye called the intra-ocular pressure or IOP. A critical balance is maintained between inflow and outflow of aqueous so that the IOP remains within normal limits. Due to any reason when the IOP becomes elevated, it may start damaging the optic nerve. If uncontrolled, this condition may slowly progress to blindness.

Risk Factors for Glaucoma

• Advancing age – It is commoner in the elderly population, usually 40yrs or above.
• Race – It is commoner and more severe in blacks.
• Family history of glaucoma – especially in a first degree relative.
• Elevated intra-ocular pressure.
• Myopia – The optic nerve in myopes is more susceptible to damage, sometimes even at normal intra-ocular pressures.
• Diabetes
• Hypertension

Symptoms

Glaucoma can be regarded as a silent killer. The visual loss associated with this disease is slow, progressive and not associated with any objective symptoms. Due to optic nerve damage, loss of a person’s visual field starts slowly from the periphery and progresses towards the centre. As a result, a person may be unaware of the condition. This is exactly the scenario in our country where many patients present late, when as much as 40% of visual field loss has already occurred.

Treatment

The treatment of glaucoma is essentially aimed at controlling the elevated intra-ocular pressure. A host of medications are available for this purpose, in the form of eye-drops. Depending upon a patient’s condition, a single drug or their combinations may be required.

Things to remember while instilling anti-glaucoma medication:

• Wash your hands before the procedure.
• Shut your eyes after instillation for about 5 minutes and at the same time for about 2 minutes press the inner angle of the eye with the index finger. This diminishes the drainage of the drug and allows maximal drug delivery to the eye.
• Wash your hands after the procedure.
• Instill your medications at a specific time everyday.

Sometimes, patients may require surgery if the IOP cannot be controlled medically, or for other reasons. This procedure is called Trabeculectomy. The main aim of this procedure is to drain the aqueous humour from the eye, into a space called the sub-conjunctival space. The additional outflow tract created automatically lowers the pressure inside the eye.

Facts about glaucoma treatment:

• As a disease, glaucoma can be compared to diabetes – it can only be kept under control and cannot be cured. So, it is imperative that a patient takes his medication regularly so that the I.O.P. remains within normal limits.
• The visual field loss due to glaucoma is permanent and irreversible. Treatment is mainly directed to prevent further damage and preserve the patient’s existing vision.
• Some patients may develop an allergy to the anti-glaucoma drugs being used. They may develop redness, watering or irritation. This does not affect vision and merely requires the use of an alternative drug.

Investigations that may be required in Glaucoma:

• Perimetry – It is a computerized assessment of a person’s visual field.
• Retinal Nerve Fibre Layer (RNFL) test – It involves a detailed analysis of a person’s retinal nerve fibre layer at a microscopic level to ascertain the condition of the optic nerve and the extent to which it is damaged by the glaucomatous process.
• Optic Disc Analysis – a detailed analysis of the optic disc is done by the OCT machine which is also used to do the RNFL test.

Follow up

All patients of glaucoma require a regular ophthalmic check-up, at least once in 3 months. If the disease is advanced, the follow-up may be more frequent. It is also recommended that the glaucoma investigations be repeated at least every 6 months.

Amblyopia

What is Amblyopia?

When a patient has sub-normal vision in an eye that is anatomically normal, he is said to have Amblyopia. This means that even on complete examination, no such factor can be found that can account for the decreased vision.

Causes

Any factor in early childhood that hampers or interferes with the vision of the child for long can lead to Amblyopia. So, causes can be numerous and varied.

• Childhood cataracts left un-operated for long
• Droopy upper eyelids (Ptosis)
• Dense opacities in the cornea
• Moderate to high refractive errors left uncorrected
• Squint
• Large differences in the refraction (power) of the two eyes

Due to any of the factors mentioned above, the vision of the child gets disturbed. As a compensatory mechanism to obtain clearer vision, the brain, instead of fusing images received from both eyes, suppresses the one received from the affected eye. This, ultimately, leads to Amblyopia in the weaker eye. When there is deprivation of the visual stimulus on both sides, Amblyopia can be bilateral.

Treatment

If Amblyopia is detected early, appropriate therapy can help reverse the condition. However, if ignored, Amblyopia becomes permanent so that vision does not improve by any means.

First, the factors predisposing to Amblyopia need to be addressed. Cataracts may require extraction, ptosis is surgically corrected and glasses are used to correct refractive errors.

The child may then be advised daily exercises on a special instrument, the synoptophore (pleoptics), that help to break Amblyopia.

At home, parents can contribute to the treatment by making the child use the affected eye. This can be done by covering or ‘patching’ the normal eye. Patching can be done for a few hours everyday or as advised by the ophthalmologist. Also, the child may be advised to do eye exercises for stimulation of vision, like reading, threading a needle or other fine work. It is important for the child and his parents to realize that Amblyopia treatment requires months to years of consistent efforts before adequate results can be obtained.

Conjunctivitis

What is Conjunctivitis?

The front of the eye which one can see is covered on the outside with a transparent, membranous structure called the conjunctiva. Its inflammation is called conjunctivitis, commonly referred to as eye-flu.

Causes

Conjunctivitis occurs as a result of infection of the conjunctiva. Bacterial and viral infections are the commonest. Exposure to dust and dirt, injuries or contact with infected persons may be responsible.

Symptoms

A person with conjunctivitis may experience one or more of the following:-

• Redness.
• Watering.
• Irritation.
• Pus discharge.

Treatment

Antibiotics are the mainstay of treatment. Eye-drops are used. An antibiotic eye-ointment may be used at bedtime. In case of other infections, the appropriate drug is prescribed.

Advice to patients

• Avoid touching your eyes repeatedly.
• In case you do touch your eyes, wash your hands with soap and water.
• Do not touch objects with your infected hands as this can spread the infection to others.
• Wash your eyes with cold water in case there is a lot of irritation.

What is Allergic Conjunctivitis?

This is another, fairly common form of conjunctivitis, often termed spring catarrh. It usually affects children and young adults who may have a family or personal history of other allergic disorders. As the name indicates, the condition is commoner in the spring and summer seasons. It manifests with itching in the eyes, watering, irritation or stringy discharge. The disease is normally of no danger to eyesight and can easily be controlled with anti-allergic eye-drops. Allergens aggravating the condition can be many and varied like dust or pollens. It helps if the patient can identify and avoid these.

Dry Eye Syndrome

What is Dry Eye?

The tear film covers the outer surface of the eye that is exposed. It is protective to the eyes and also helps provide lubrication. When this tear film is deficient or disturbed, dry eye is the result. This is a leading cause of ocular discomfort affecting millions of people all around the world. The implications range from mild ocular distress to even sight threatening complications.

Causes

Usually, severe cases of dry eye are seen in middle-aged or elderly individuals who suffer from some autoimmune disorder. Increasingly, however, dry eye is becoming common in the younger population as well, particularly those who work on computers for prolonged periods. This is due to a decreased blink rate. Dryness is also caused or aggravated by air pollution, dust, room heaters, air conditioners or dry weather. Sometimes, there may be an anomaly in the constituents of the tear film itself that leads to its instability, causing dryness.

Symptoms

The symptoms of dry eye are very non-specific and varied. Patients may complain of mild ocular discomfort, irritation, foreign body sensation, etc. Disturbances in the tear film even affect the clarity of vision. In severe dry eye, the patient may be so distressed as to be unable to open the eyes.

Treatment

Most cases of dry eye can be managed with eye drops of artificial tears or tear supplements. A gel form of the same drug may be used at bedtime. More severe cases may require serum drops or even occlusion of the lacrimal puncta to reduce the outflow of tears. Further modalities of treatment may be added or substituted according to the condition of the eye.

Refractive Errors

What are refractive errors?

In a normal or emmetropic eye, the light rays falling upon it are brought to a sharp and clear focus onto the retina. When this mechanism is disturbed and the light rays are focused not onto the retina but in front or behind it, a refractive error is said to be present. This causes blurred vision. There are mainly two forms of refractive errors – myopia and hypermetropia. Astigmatism is a special type of refractive error that often co-exists with the above two forms, but sometimes may also occur alone. Presbyopia, sometimes termed old sightedness, sets in around the age of 40.

Myopia

In myopia or near sightedness, light rays falling upon the eye are focused in front of the retina. Such patients have difficulty in seeing distant objects but have clear vision for near. They may squeeze their eyes in an attempt to achieve better distance vision. Many myopes may complain of headaches, more so in the evenings.

Causes of Myopia

Any factor that leads to a convergence of light rays in front of the retina, causes myopia. By far the commonest cause of myopia is an increase in the length of the eyeball. Sometimes, however, it may be due to an increase in the curvature of the cornea or an increase in the power of the lens.

Hypermetropia

Hypermetropia is also termed far-sightedness. In this condition, light rays falling upon the eye, are brought to a focus behind the retina. Patients have difficulty in seeing near as well as distant objects. Patients with this refractive error often complain of headaches after long hours of near work. Squint may often co-exist in hypermetropic children.

Causes of Hypermetropia

Hypermetropic eyes are often smaller in size. This leads to the focusing of light rays behind the retina. Sometimes, decrease in power of the lens or a decrease in the curvature of the cornea may also cause hypermetropia.

Astigmatism

This is a special form of refractive error that occurs due to an asymmetry of the optical system about the optical axis. This means that the converging power of the eye is not the same in all meridia. Commonly, it occurs due to imperfections in the shape of the cornea that leads to different refractions in different meridia. Astigmatism is corrected with the help of cylindrical lenses, the optical powers of which vary at different angles. Depending upon whether the light rays are focused in front of, or behind the retina, astigmatism can be myopic, hypermetropic or mixed.

Presbyopia

Presbyopia usually sets in around the age of forty. With age, the ability of the eye to focus on near objects gradually diminishes so that by this time, most people require near vision glasses. Following this, the glass power usually goes on increasing with age. The first symptom that most people notice is difficulty in reading fine print, particularly in dim light, eye-strain when reading for long periods, blur at near or momentarily blurred vision when transitioning between viewing distances.

Causes of Presbyopia

Similar to grey hair and wrinkles, presbyopia is caused by the natural course of aging. It may be due to a loss of power of the ciliary muscle that helps focus the lens, or due to a decrease in elasticity of the lens itself.

Treatment for refractive errors

Spectacles are the commonest method of correction of refractive errors. ‘+’ numbers are used to correct hypermetropia and presbyopia, ‘-‘  numbers for myopia and cylindrical lenses for astigmatism. Generally, uptill the age of 18-19yrs, the eyeball grows, and the number keeps changing. It is, therefore, advised that all patients below this age should have a periodic eye check-up to determine a change in refraction. It is particularly important for small children to wear glasses, or carelessness could lead to underdeveloped vision, often termed Amblyopia (lazy eye), in which case vision cannot be increased to 6/6 or 20/20 by any means.

Contact lenses are another popular mode of correction of refractive errors, particularly if spectacles are not desired. Patients above the age of 14-15yrs may opt for contacts. They also have the option of Refractive Surgery, popularly termed LASIK.

Read More about Refractive Surgery

Age-Related Macular Degeneration

Age-Related Macular Degeneration is also referred to as AMD. It is the most common cause of irreversible visual loss in the developed world in people above the age of 50yrs. As much as 30% of the general population above 75yrs is affected in USA to some extent, by AMD. The incidence of the condition was earlier believed to be much less amongst Indians, but now it is known that it is not so.

AMD is a medical condition of older adults that threatens the central vision. It is due to involvement of the macula that undergoes a form of degeneration. AMD may occur in one of the two forms- dry or wet. The dry form is more common, constituting about 85% of all cases, in which the macula becomes thin and atrophic. This may result in a variable degree of visual loss. The wet form, though less common, can cause loss of central vision much faster than the dry form. It is characterized by the development of new blood vessels in the choroid that grow and invade the retina. Bleeding and leakage from these friable new vessels results in the formation of a membrane. This, if not treated, causes scarring of the macula with permanent loss of central vision.

Risk Factors for development of AMD

• Age – AMD is mainly a disease of the elderly, usually beyond 50yrs.
• Family History – people with a blood relative who has AMD may have as much as a four fold greater risk of developing the disease.
• Race – it is commoner in Caucasians.
• Smoking
• Hypertension
• Cardiovascular Disease – Obesity, high blood cholesterol.
• Drusens – presence of drusens, particularly soft drusens at the macula, increases the risk of developing AMD.
• High Fat Intake
• Oxidative Stress

Symptoms

• Impairment of central vision – In dry AMD, there is a very gradual impairment of vision while patients with the wet form notice a rapid onset of visual loss.
• Central Scotomas – shadows or missing areas of central vision.






• Distorted Vision – a grid of straight lines appears wavy or parts of the grid may be missing.
• Diminished Contrast Sensitivity
• Trouble discerning colours
• Slower recovery of visual function after exposure to bright light

The Amsler Grid Test is one of the simplest and most effective methods for patients to monitor the health of the macula. The Amsler Grid is essentially a pattern of intersecting lines (identical to graph paper) with a black dot in the middle. The central black dot is used for fixation (a place for the eye to stare at). With normal vision, all lines surrounding the black dot will look straight and evenly spaced with no missing or odd looking areas when fixating on the grid's central black dot. When there is disease affecting the macula, as in macular degeneration, the lines can look bent, distorted or missing.

Treatment

Treatment of dry AMD is not possible as yet. Medications are aimed mainly to retard the progression of an already developed AMD and/or to prevent its occurrence in the fellow eye. These include vitamin C, vitamin E, zinc, beta-carotene, lutein and zeaxanthin. Patients of wet AMD may require to be investigated initially with FFA (Fundus Fluorescein Angiography) or ICG (Indocyanine Green Angiography) after which an appropriate modality of treatment may be chosen – intravitreal anti-VEGF injections, intravitreal steroids or PDT (Photodynamic Therapy).

Corneal Ulcer

When an inflammatory process involves the cornea, the condition is termed keratitis. An ulcer developing in the cornea is usually accompanied by keratitis, but more importantly involves a loss of the covering epithelium, many a time with the tissue underneath it as well. It is a relatively common condition as the cornea is exposed to the environment. Corneal ulcers tend to be more common in the tropical countries, especially where agriculture is in abundance, as in India. They may be a cause of great visual morbidity and economic loss to the individual.

Causes

Infective corneal ulcers are, by far, the commonest causes of ulcers in the tropics. Among these, bacterial infections are quite frequently encountered. Predisposing factors like trauma may lead to bacterial corneal ulcers, which tend to severer than other infections. Fungal infections may occur, especially, after injuries with vegetative matter like leaves or twigs. Viral corneal ulcers with the Herpes Simplex virus are very common.

Symptoms

Patients of corneal ulcers are very distressed and disturbed with their condition. There is a lot of pain due to exposure of naked nerve endings. Redness and watering are marked. The patient is intolerant to bright light. There may be other symptoms as well, especially if the infection is severe, like headache, malaise and fever. Symptoms are more marked in case of bacterial ulcers and quieter with fungal ulcers.

Consequences

Corneal ulcers are potentially serious and even sight threatening conditions. Consultation with an ophthalmologist should never be delayed if the above symptoms are present. Some, very superficial ulcers may heal fast without any sequelae. But many are associated with complications. Infection may spread leading to corneal thinning and perforation. It may spread to the interior of the eye leading to endophthalmitis. Scarring may occur in the cornea, as occurs in other parts of the body. This scar tissue tends to be opaque compared to the normal cornea, thereby, obstructing light and causing blurred or diminished vision.

Treatment

After a proper examination under a slit-lamp and other tests that may sometimes be necessary, the type of infection is recognized and a line of therapy selected. Bacterial ulcers are treated with topical fortified antibiotic preparations. These are not available commercially and have to be prepared from injectable forms of the same antibiotics. Fungal ulcers require anti-fungal eye drops. Herpetic ulcers are treated with topical anti-virals like acyclovir. Supportive therapy for the dilatation of the pupil and relaxation of the ciliary muscle is usually added. Oral medication in the form of pain-killers or anti-fungals may be required.

Occasionally required modalities that may be added include bandage contact lenses, conjunctival flaps, scraping of the ulcer, etc. A corneal transplant may be essential if the ulcer has healed leaving a large scar that obstructs vision.

It is important for patients to realize that steroids and anesthetic drops should be avoided in case of corneal ulcers. They delay healing and may actually make the condition worse. They should only be used after consultation with an ophthalmologist.

Uveitis

What is Uveitis?

The eye is shaped like a three layered ball. The outermost layer is the sclera, the inner layer is the retina and the middle layer is termed the uvea ( highlighted in red ). Inflammation of this middle layer of the eyeball is called Uveitis.

Causes

In most cases of Uveitis, the underlying cause leading to the condition remains unknown even after detailed laboratory tests. Thus, most cases of Uveitis are termed idiopathic (no underlying cause). The rest of the cases of Uveitis may be associated with various systemic diseases like rheumatoid arthritis, sarcoidosis, inflammatory bowel disease, etc. Some may be due to auto-immunity to ocular antigens while others may occur as a result of infection (viral, bacterial, fungal, parasitic) or trauma.

Types of Uveitis

• Anterior Uveitis – The uvea in the front portion of the eye is affected.
• Intermediate Uveitis – The middle portion of the uvea is affected, particularly the muscle that focuses the lens.
• Posterior Uveitis – Affects the uvea at the back of the eye. The retina may also be affected with posterior Uveitis.
• Panuveitis – Affects the entire uvea, anterior, intermediate, as well as posterior.

Consequences of Uveitis

The uvea is that part of the eye that contains a lot of blood vessels, and thereby, provides nourishment to the tissues of the eye. Uveitis, when untreated, can affect the nourishment and nutrition of the eye, and may even prove to be sight threatening.

Symptoms

Patients may experience one or more of the following.

• Redness of the eyes.
• Watering.
• Ocular pain.
• Glare and intolerance to bright lights.
• Decreased vision.
• Blurry vision.
• Black spots in front of the eyes.

Investigations that may be required

Patients may require a host of blood tests, X-rays, other tests in order to find out the cause of the condition. Some may even require Fundus Photography, Fundus Fluorescein Angiography (FFA) or Optical Coherence Tomography (OCT) for visualization of the posterior part of the eye.

Treatment

Medical treatment suffices for most patients of Uveitis. The aim is to control inflammation. Steroids are given as eye drops or tablets. They may even be injected into or around the eye in some cases. Eye drops to dilate the pupil and relax the ciliary muscle are prescribed. Consequently, patients might experience increased glare and difficulty in near work, but this is merely drug induced. Additional drug therapy may be added, directed to an underlying cause, if found.

When inflammation is severe or unresponsive, immunosuppressive drugs can be resorted to. The latter do have side-effects but are mostly reversible on stoppage of treatment.

Important advice for Uveitis patients

• Use medications as prescribed by the doctor.
• Medications, should preferably, be scheduled and used at a particular time.
• When on steroids, oral or eye-drops, never stop the drug suddenly without consulting the doctor, or the consequences could be very serious.
• In case of any deterioration in symptoms or vision, the doctor should be informed.

Cataract

What is a Cataract?

The normal eye contains a structure called the crystalline lens. This, under normal circumstances, is transparent in nature. A clouding up or opacification of the lens is called a cataract. It may cause disturbance or diminution of vision.

Causes

Cataracts, usually, are age-related in nature. They tend to affect older people more often, usually over the age of 50yrs. Sometimes they may occur in younger individuals as well and may be related to predisposing factors like diabetes, certain eye diseases like uveitis, excessive use of some medications like steroids, over-exposure to ultra-violet light, trauma, etc. Cataracts are uncommon in infants and children but may be caused by metabolic disorders, genetic diseases or injury.

Symptoms

The clear crystalline lens helps to focus light rays onto the retina of the eye. When a cataract develops, irregular refraction of light by the same lens results in visual disturbances. Some of the symtoms which a patient with cataract can experience include the following :-

• Diminution of vision
• Glare, specially with headlights of oncoming traffic
• Halos around lighted objects
• Multiple images, like multiple moons
• Difficulty in bright light with better vision in dim light
• Difficulty in dim light with better vision in bright light
• Blurring of vision
• Frequent change of glass power

  Treatment

The universal treatment of cataract involves the removal of the cloudy lens which is then replaced by an artificial lens. Phaco-emulsification is most commonly used for cataract extraction. Cataracts are not amenable to medical treatment. They cannot be treated with any topical, oral or other medication.

Read More about cataract surgery

Diabetic Eye Disease

Diabetes is a common lifestyle disorder that poses a major health problem to the world. There may be many predisposing factors like an unhealthy diet, sedentary lifestyle, genetic factors, and others. Two types of diabetes are commonly recognized- namely, type 1 that affects the younger population, and type 2 that affects older people. As per WHO estimates, there are about 25 million diabetics in India. Our country is expected to become the diabetes capital of the world by 2025.

The majority of diabetics suffer from a complication called Diabetic Retinopathy. The latter is one of the leading causes of blindness in India. It is a vascular disease of the retina, i.e. which affects the blood vessels. The risk of visual loss is 25 times higher in diabetics than in non-diabetics.

How Diabetes affects the eye

Diabetic Retinopathy affects the blood vessels of the eye. They become weak, particularly, the smaller vessels. Such changes are accompanied by others within the retina, and may contribute to visual deterioration. Retinopathy, broadly, occurs in two stages:

• Non-proliferative retinopathy – changes are less severe than in the proliferative stage. However, decrease in vision may occur as in Macular Oedema.
• Proliferative retinopathy – characterized by the development of new blood vessels. They grow, bleed and lead to complications like Retinal Detachment and Neovascular Glaucoma.

Symptoms

Diabetic Retinopathy is a slowly progressive disease of the eye so that patients may not have any symptoms initially. Diminution of vision due to diabetes is only late in the course of the disease so that the condition is often recognized in its advanced stages when intensive control can only minimize its progression but not reverse it. Since only an ophthalmologist can recognize the early signs of Diabetic Retinopathy, it is advised that all diabetics should have their eyes examined at least once a year.

Investigations that may be required

The patient may require certain ophthalmic tests in case retinopathy is detected.

• Fundus Fluorescein Angiography (FFA) – in this test, a photograph of the retina of the eye is taken after injecting a dye into the blood stream. This helps study the vasculature of the retina in greater detail, detect areas of leakage and neovascularization.
• Optical Coherence Tomography (OCT) – may be required in some diabetics in case macular oedema is suspected. It helps to measure the degree of fluid accumulated and decide an appropriate mode of treatment for it.

Treatment

The treatment for Diabetic Retinopathy depends upon the stage of the disease. In the early stages, control of blood sugar levels helps control the disease and even reverses the changes that have occurred. But later on, Argon Laser Photocoagulation of the retina may be required to control disease progression. Macular Oedema can be sight threatening if treatment is delayed. It requires injection of a steroid inside the eye, or an ‘anti-VEGF’ agent if severe. Proliferation requires laser treatment, even injection of anti-VEGF agents, if extensive. A number of complications may also occur inside the eye in very advanced stages. Of these, Retinal Detachment is quite common. It requires surgical intervention.

Keratoconus

What is Keratoconus?

This is a condition that affects the cornea of the eye. The normal cornea is nearly hemispherical in shape. However, in this condition it starts becoming conical (kerato=cornea, conus=conical). The cornea near the centre starts becoming thinner, and thereby, weaker so that it bulges under the influence of the intra-ocular pressure (IOP, the pressure inside the eye).

Consequences

The normal, nearly hemispherical cornea helps to focus light rays onto the retina. However, this function is significantly affected in case of Keratoconus. Because of the conical shape, a high degree of astigmatism is induced, causing distorted vision.

Investigations that may be required

Imaging of the cornea with an instrument called the Pentacam is usually advised. It helps to study the corneal condition in great detail – the corneal thickness, bulge, level of Keratoconus and other parameters.

Treatment

In the initial stages of Keratoconus, spectacles may suffice in improving vision. However, rigid contact lenses are advised. They help by providing support to the cornea, and by partly correcting its curvature, reduce astigmatism and improve vision.

A new modality of treatment called C3R or Corneal Collagen Cross-linking is also helpful. It increases the rigidity of the cornea and helps in stopping the progression of Keratoconus, sometimes even inducing regression. Corneal transplantation may be required in severe cases or those with complications.